Link 8-The dark secret of life 

www.tightrope.it/nicolaus/index.htm 

 

Reflections on the chemico-biological role of interstellar black material and the appearance of life in the universe.

Appendix from P.Ehrenfreund and S.B.Charnley

 

Summary.

Simple organic molecules have been identified among the grains of interstellar clouds.In our view, heterocyclic polymers must also be present in space. Their synthesis is presumed to occur during certain evolutionary stages of stars. Similarly the presence of acetylene black in space is predicted.A triple role has been assigned to these black materials:

- supporting structures of interstellar grains through mechanical, electrical and optical properties (charge transfer, diffraction and absorption of radiation, transformation of light into current);

- accumulators of chemical energy;

- space storehouses of C, H, N (from which simple oxygenated and/or nitrogenated molecular fragments, "biogenetic bricks", are built).

In fact, the black materials can be considered as solid compact parcels of C, H, N and allow simultaneous transport of these key elements avoiding losses (oxygen, the fourth key element, is shipped as frozen water H2O).

These polycyclic blacks are split into smaller fragments by "photolysis" (similar reactions occur on Earth by laser beam and other radiation). These fragments are later recombined with oxygen radicals, obtained from frozen H2O. Oxygenated and/or nitrogenated biomonomers are formed accordingly (equal or similar to those already known on our planet).The properties of prebiotic, biotic and spatial black matter are compared and discussed. Special reference is given to conductivity, the graphitic-fullerene structure and to surface and interstitial properties. Consequently, the hypothesis that prebiotic melanins were instrumental as enzymatic prototypes during the process of self-assembling primigenous organic molecules is developed and supported.It is supposed that the organic black matter in the interstellar clouds protects organic material from cosmic rays and regulates the ion/radical/molecule balance.The nature of black particles is many fold: from one point of view they are instrumental in assembling atoms and molecules, from another in generating new molecular species by self destruction.A unique architectonic principle appears to act on organising living and interstellar matter: cosmic tensegrity.

 

 

1 - Preface

In interstellar space there is solid black matter.Numerous nitrogenated, sulphurated and oxygenated organic molecules known on Earth are found to be associated with black matter: these are of different types and complexities and always almost in radical and/or ionic form, stabilised by the particular interstellar environment. It is possible to think that this mixture of organic molecules has its origins in black particles.From the composition of the degradation material one can deduce that the black material is composed of carbon, polycyclic carbon (graphite, fullerenes) and of polyheterocyclic carbon (N,S,O).Almost all the terrestrial black materials widespread in nature (carbon, graphite, melanins) and the synthesised blacks (polycondensed heterocycles) are sensitive to different physical agents (FAB,, LASER, pyrolysis, etc,): under such action they explode and fragment into smaller pieces. It is possible that this terrestrial chemical behaviour finds a parallel in the interstellar black material. The organic molecules, therefore, have origins in the explosive photolysis of the interstellar black particles. (1)

 

2 -Natura enim simplex est

During the last 50 years, the vision of the universe has undergone more than drastic changes.Initially we inherited the reassuring image of a placid, bucolic world from Ptolemey and the ancient Egyptians, with a tranquil Earth at the centre kissed by the sun and venerated by other planets.Copernicus brutally woke us up from this idyllic vision which had lasted millennia and suddenly the Earth has been forced to run a breathless circle around the sun as well as up and down the universe.Today we have made a further leap towards a neurotic cosmos, towards a universe which tends towards an infinite dispersion, sudden fruit of an enormous catastrophe with the monstrous name of Big Bang. (2)Beyond the provincial Milky Way, which was once mistaken for the immutable expression of an eternal order, there are apocalyptic dramas: stellar explosions, collisions of stars and comets, gigantic encounters between galaxies. The sun and the stars, the perfect spheres which faithfully accompanied merchants and navigators over millennia, are today hydrogen bombs, patiently waiting their inevitable end. Sooner or later they will finish as they started, in catastrophe. Fear of the apocalypse has given way to mathematics and the cold, rational certainty of the inevitable end. Divine providence has packed its bags, hope is dead and buried. The galaxies are born and die like prehistoric animals, like cosmic dinosaurs. The universe, once only order and peace, boils, is agitated, flaps in spasms of geneses and convulsions of agony. The depth of the blue coloured sky, where we had transferred Olympus, is today the theatre of nova, supernova and of their explosions. Mad elementary particles, quarks, atoms, ions and molecules with no fixed abode alternate with storms of deathly rays. Condensation of energy into matter, and vice versa the annihilation of the same material, are the order of the day. Flashes of mortal light dance across the dense clouds of dark matter, of gasses and of cosmic dust which obscure our view. These clouds will sooner or later collapse giving life to stars and planets. (Fig. 1).

 

Fig. 1 - Constellation of the Centaur: Bok’s Globules

 

This frightening picture is not the product of a sick mind. It was conceived one piece at a time, after the recent progress of astro-physics and physics together with the new space vectors. Spectroscopy, already amply used in the study of the structure of materials, and radioastronomy (3), used to scrutinise spaces, has demonstrated that empty interstellar space does not exist. Space contains a confusion of complex organic and inorganic molecules. Surprising results have been reached thanks to recent measurements made outside the Earth’s atmosphere, a fortunate filter of space radiation.So that today we know that at thousands of light years from us, there are many of the composites necessary for the synthesis of macromolecules like proteins and peptides. Products which will play a highly relevant role in the appearance of life.Today we also know that these "biological bricks" existed in space before our solar system and our planet.Therefore, life came to Earth from far away shores, or developed on earth and other hospitable planets, parting from the same building bricks.The discussion on how and where life arose is still open.On this question, which has an antique flavour, we later propose a new reply, even if we remain the ashes and dust of stars. (4)

 

3 - From space garbage to tensegrity

 

Space is not empty, as the ancients believed when admiring the depth of the sky on starry nights. Space is occupied by material, although it is rarefied and with a non-uniform distribution between stars, planets and galaxies.The interstellar material (5) of our galaxy and perhaps of the entire universe is composed of hydrogen (70%) and helium (28%) in the gaseous state. Only a very small part (2%) is formed of tiny solid particles, called cosmic dust or interstellar grains. Among these elements like O, C, N, Ni, S, Al and Fe and also various organic and inorganic molecules have been identified.An important role in the evolution of the interstellar material is played by these grains, responsible for the absorption and diffraction of radiation, grain/grain collisions, absorption of various substances on their surfaces and electrical conductance. These latter properties allow electrical charge transfer inside the molecular clouds, regulating the ion/molecule interaction, in turn a source of further reactions. Thanks to their optical properties, the grains also play a role as filters in protecting the organic molecules from the demolishing action of electromagnetic radiation and of various corpuscles.The grains are amorphous and heterogeneous. According to spectroscopic analyses, they are formed by silicon oxides, water ice H2O, ammonia ice NH3, mixed ices of H2O + NH3, various forms of carbon (fuligines, graphites, fullerenes) polyarenes (polycyclic aromatic hydrocarbons), silica carbon and metallic oxides.Of all these products, the most interesting for us are certainly the carboneous products, from which life sooner or later took form. The grains are subject to growth and reduction. One could say that they "live" their inorganic, but organised, life. Their dimensions increase in the dense clouds, by chemical reaction with gaseous types absorbed on the surface (H2O; NH3, CH3OH, CO, etc). A reduction of dimension comes about, instead, from the increase in temperature of the coating, radiation with cosmic rays, grain-grain collisions or nearing a newly formed star. The surface of the grains represents a valid site of synthesis through photofragmentation and association between atoms and radicals.The chemical reactions in the gaseous phase are often disadvantaged because of the high rarefaction of the components and of the low temperature which makes the binary and ternary interactions between neutral molecules improbable. The reactions on the surface of the grains therefore become a necessary alternative for the chemistry of space.The carboneous material of the clouds derives from nuclear fusion inside the giant stars. We can imagine how these "furnaces" have produced the carbon, oxygen and nitrogen from which we are made, from hydrogen and helium, by erupting burning fumes into the frozen space.(6)These then converge into interstellar clouds, where there are demolished and chemically recombined until they form a biogene molecule.Our cradle of life seems to lie precisely in these immense clouds which seem real space laboratories. Living organisms are composed of four key elements C, H, O, and N while various other elements (S, P, Fe) are present in small quantities or traces. The appearance of the first forms of life, even if still simple and primitive, presume that these four elements have already encountered long before, in the right place and at the right time.Today one thinks that this four-way meeting, a possible but improbable event, happened in the interstellar grains, where carbon and hydrogen were supplied by the photolysis of PAH (Polycyclic Aromatic Hydrocarbon), the oxygen from that of water ice and the nitrogen from the nitrogen ice also present.Therefore, PAH, H2O and NH3 would be the three ingredients from which the first organic molecules at the base of every further reaction derive.However, the heterocyclic blacks, to which we shall shortly return, have not been identified in space, to date, and neither have they been mentioned as a probable simultaneous source of organic molecules.Among the various carboneous products, radioastronomy has identified some specific unsaturated aliphatics, worthy of particular attention: the cyanopolyines.(7)The fact that types, so reactive on Earth survive in space is surprising, but can be understood considering the temperature, rarefaction and photoprotection exercised by the grains and by the black particles.The cyanopolyines are linear homologues of acetylene CHº CH added onto a nitrile radical -Cº N. Their being found in space finds agreement in the presence of free acetylene and cyanhydric acid HCN. These very reactive compounds can cyclize in determined conditions, forming nitrogen heterocyclic and, from these, their black polymers.

 

 

HCnN

HC º C º N HC3N

HC º C - C º C - C º N HC5N

HC º C - C º C - C º C - C º N HC7N

HC º C - C º C - C º C - C º C - C º N HC9N

HC º C - C º C - C º C - C º C - C º C - C º N HC11N

 

Figure 2 - Cyanopolyines determined in interstellar space

 

Acetylene itself can polymerise in the laboratory, giving rise to linear chains (acetylene blacks) or cyclic products (aromers, oligomers, aromatics of benzene). These are variously coloured products with electrical conductivity (8) (Figure 3)

 

 

 

 

 

Figure 3 - Aromatic polycondensed hydrocarbons

 

The aromers (C6H4)n are not very common on Earth because of their poor stability. During the formation process of polycyclic hydrocarbons those with a non-linear structure are preferred. On this theme it should be noted that in the series of aromers, the aromatic character diminishes with an increase in molecular weight, while the olephinic and instability properties increase. For example, it has not been possible to isolate the terminal heptacene in the pure state. The acetylene black (35) formed by a linear aliphatic chain (radical-polarone system) and, having excellent electrical conductivity in the doped state, can be considered a prototype of the black organic polymers (melanins). Acetylene forms easily from hydrogen and carbon at high temperatures and is present in space. It seems probable, therefore, that one also finds its direct transformation product, acetylene black, in the clouds. This black polymer could play a relevant role in electric charge transfer in the clouds and contribute to causing their dark colour. It also represents a potential store of carbon, from which to take fragments, by photolysis, for the synthesis of biogene molecules.

The combustion of acetylene and other products has been amply studied in the laboratory(9), confirming that in these conditions one has the formation of aromatic polycondensated types, fullerenes and fuligines. Therefore it is credible that similar polycondensated materials form in the extreme conditions of the "stellar laboratory". The polyarenes, derived from combustion, are very common on Earth (10,11) but fortunately at low concentrations (cancerogenes).(12)

It has been estimated that 2% of the carbon present in the interstellar clouds is in the form of polyarenes(13), which represent the prevalent organic molecules in the universe.(14)

These estimates could be redimensioned if the presence of black nitrogenated polymers in space is confirmed.

Unlike the aromers, the PAH are not very reactive and have very high fusion points (one may observe that during the determination of the fusion point the thick glass capillary melts before the product). They belong to complex cyclic systems and the number of the possible composites is truly enormous. The physico-chemical and biological properties, like stability and reactivity, vary according to the steric positioning of the rings and the grade of alkylation.

Both the polyarenes and the aromers are virtual polymers of acetylene and it is probable that they are formed in the giant stars by dimerization of dienes and polycondensation of acetylene derivatives. Besides, on Earth they are found in the tars from the distillation of carbon and in the residues of petroleum refining.(15) In these sources they are accompanied by the analogous polycyclics with one or more nitrogen, oxygen or sulphur atom. In the stellar and terrestrial synthesis, the preference towards one composite rather than another is determined by thermodynamic parameters and not only by chance. A confusion of highly reactive compounds (radical methynics HCº ; methylenics H2C=; acetylene HCCH; dienes CH2=CH-CH=CH2; ethylenes CH2=CH2; etc) in competition among themselves, takes chemistry back to the first dawn, when, under the influx of very high temperatures, powerful radiation and the absence of oxygen, prebiotic reactions were the norm. Among the many possible structures those which are more stable (and more aromatic) and with a higher probability of surviving in the conditions of space have been proposed for the interstellar PAH (Fig 4), in agreement with radioastronomy measurements.

 

 

 

Fig 4 - Structures of polycondensated aromatic hydrocarbons (PAH, polyarenes) identified in space by radiospectroscopy.

 

The polyarenes are sensitive to light and oxygen. Under the combined action of these two agents they form highly mutagenic oxygenated products (e.g. benzopyrene) in the Earth’s atmosphere. With organic molecules and salts, they can form charge transfer complexes: these are excellent conductors of electricity and could catalyse various reactions in interstellar clouds.

From what has been described one has the picture of a space "crowded" with various organic molecules. It has also been postulated that many photoreactions occur in the grains, forming oxygenated aliphatic composites (aldehydes, alcohols, acids, etc) which are key products for the synthesis further of biomonomers and polymers.(16)

The nitrate products, except for a few exceptions (N H3, HCN, cyanopolyines, etc), have been given little importance, to date, despite their representing one of the main chapters in the chemistry of living forms (proteins, polypeptides, alkaloids, etc). Considering that most of the biomonomers undoubtedly have their origins in space, it would seem logical to find the roots of those nitrates in space too.

We turn therefore our attention to this topic and try to find a reply to three fundamental questions:

1. Is there a valid scientific basis for the presence of nitrated organic products in space?

2. In what forms is it probable that they are found in space?

3. What relationship is there between the cosmic products and the terrestrial ones?

 

***

 

Inside giant stars all the chemical elements starting from hydrogen and helium are formed by nuclear fusion.

Carbon, hydrogen, oxygen, nitrogen, C, H, O, N, are the four elements key of living organisms: "for there to be life" they must be found close together and in the appropriate forms.(17)

The carboneous stars, during the last stages of their evolution, are rich in C, H, N. It is easy to imagine that in these conditions various nitrogenated heterocycles (pyrrol, indol, pyridine, quinoline, isoquinoline, etc) are formed from acetylene and nitrogen. Similarly, oxygenated or sulphated polycycles (furane, benzofurane, benzothiophene, etc) are generated from acetylene and oxygen or sulphur .

The possibility of reactions between the carbon and the other simple elements like hydrogen, sulphur, oxygen and nitrogen have been amply studied and now belong to the repertoire of classical chemistry.

The hydrocyanic acid HCN, obtained in the pure state by Gay Lussac in 1881, can be synthesised from the elements by making a gaseous mixture of hydrogen and nitrogen run across a voltaic arch with high temperature (1800°C) carbon electrodes.

Passing acetylene C2H2 across red-hot glass tubes, Berthelot demonstrated the formation of benzene C6H6 obtained by trimerization and cyclization.

If one makes a flow of acetylene, heated to at least 300°C, pass over pyrite, one can isolate thiophene H4C4S (Steinkopf) in high yields.

In a completely analogous way, using ferrous oxide as a catalyst and an oxygen donor, the furane H4C4O forms from acetylene.

In favourable conditions (high temperature, metals, nitrogen) acetylene and butadiene cyclize giving rise to the pyrrol H5C4N, which represents an important component of various animal and vegetable products like polypeptides and proteins, haemoglobin, chlorophyll, nicotine, atropine, cocaine and many others.

Therefore, we can give a positive reply to the first question of the above section: On a theoretical plane, it seems probable that nitrogenated organic products and in particular nitrogenated heterocycles (also sulphurated and oxygenated) form in the course of the stellar chemical reactions and are erupted into sidereal space.

 

***

 

The nitrogenated heterocycles like pyrrole and indole, like also their sulphurated or oxygenated isosters (thiophene, furane) and their derivatives tend to polymerise. This phenomenon is accentuated in the presence of certain catalysts and is highly favoured by temperature and light. The polymerisation yields amorphous black materials, conductors of electricity and characterised by a graphite(18) or a giant fullerene type structure.

It is therefore probable that simple heterocyclics, once formed in the stars, are quickly transformed into the corresponding black polymers (polycyclic heterocyclic blacks), and as such are released into space (Fig. 5).

 

 

Acetylene + Nitrogen

CHº CH N2

 

Pyrrole H5C4N Indole H7C8N Pyridine H5C5N Quinoline H7C9N Isoquinoline H7C9N

Pyrrole-black Indole-black Pyridine-black Quinoline-black Isoquinoline-black

(HC4N)n (HC8N)n (HC5N)n (HC9N)n (HC9N)n

 

 

Fig. 5 - Total synthesis of some heterocyclics and their black polymers from acetylene and nitrogen

 

Graphite is a stable product, even though sensible to the action of LASER rays. These manage to explode its structure giving rise to smaller fragments with the characteristic cage conformation of fullerenes (to take on this new closed form, the plane of the open structure of the graphite, formed by a net of hexagonal parallels, curves, restricting a certain number of hexagons into pentagons).

In interstellar space, the graphite and the black polymers (indole black, pyrrole black, acetylene black, etc) undergo bombardment by high energy electromagnetic and corpuscular radiation able to demolish them into smaller fragments. With similarity to what happens in the laboratory on Earth, it is probable that these are transformed also into fragments with nitrogenated fullerene - graphite structures. In these, the pentagons necessary for the closure of the cage are represented by the pyrrol rings, isosters of the cyclopenthane.

The substitution of some carbon atoms with nitrogen in a computerised model of C60 leads to the formation of a nitrogenated fullerene, C53N7, in which quinoline units are present. The calculated geometric optimisation does not produced deformations of the initial soccer-ball type structure. The model shows how a giant fullerene structure is possible for synthetic and natural blacks. For the giant fullerenes one predicts diffraction spectra of X-rays similar to those predicted for graphite structures. For this reason we believe it probable that black pigments and their fragments from photodemolition are found in space. These conclusions give an answer to the second of the questions we asked at the beginning of the section. The black polymers are excellent electrical conductors, an important property for the evolution of molecular clouds, and the dark colour may also be caused by the presence of black material.

The experimental verification of these claims may be possible in a short time, (first decade of the 21st century) when it may be possible to put our hands on samples of interstellar material (19).

In the meanwhile, it would be worth verifying the spectroscopic properties of the black pigments in the laboratory, and comparing them with what has been collected from radioastronomy to date.

The presence of nitrogenated molecules of the base form HCnN in space has also been shown. These have been attributed a cyanopolynic structure.

It is interesting to note how this same base formula corresponds to some black pigments, derived by polycondensation of heterocycles (pyridine black HC5N, quinoline and isoquinoline HC9N).

At this point it is possible to draw a further conclusion, confirming that in space (besides the well known polyarenes, graphite, fuligines and aromers) there are most probably also:

- acetylene black

- blacks of heterocyclic polycyclics (pyrrol black, indol, pyridine, quinoline, isoquinoline etc,)

- nitrogenated and non-nitrogenated fragments, deriving from photodemolition of the heterocyclic blacks.

Most of these heterocyclic materials form charge transfer complexes able to move electrical charges towards the inside of molecular clouds and vice versa to catalyse further chemical reactions.

These materials are all black (acetylene black, pyrrole, indole, pyridine etc). This helps to explain the dark colour of the interstellar clouds.

The black polymers can be considered as compact molecules with which it is possible to transport ternary mixtures with bases of carbon, hydrogen and nitrogen simultaneously in space. In the right place and at the right moment it is possible to have simple nitrogenated and/or oxygenated organic molecules, identical to those which compose living organisms, from these modules, through photodisassociation and recombination. (Fig. 6) ( www,tightrope.it/nicolaus/13.htm ) and Link 5.

 

***

 

According to various research, the interstellar grains are composed of a nucleus of silica oxide covered by a mantle of H2O ice and NH3 ice. Polyarenes and other simple molecules are trapped in this icebox. As already mentioned, we believe that other non-identified carboneous materials should also be found in the grains. These including the black pigments of polycondensed heterocycles, acetylene black and their fragmentation products. These black materials, undergoing high energy cosmic radiation are fragmented and recombined, up to obtaining, with the help of H2O ice, simple oxygenated organic molecules CH2O, CH3OH, C2H5OH, etc and nitrogenated molecules HCN, CH3CN, etc. These molecules in turn are trapped and will take part in further fragmentations and combinations. According to this model, the grains act as a support for the chemical reactions in the solid phase. These will happen at temperatures near absolute zero, under the action of cosmic radiation comparable in intensity to terrestrial LASER rays. In these conditions one can make selective reactions at photosensible molecular sites (targets) eliminating the background noise of vibrations and thermic movements. The forced fragmentation of the black material will bring a myriad of radicals, able to react with the water molecules in ice, captating the oxygen. This will give rise to oxygenated nitrogenated and mixed compounds, keys for forming biomonomers and polymers. In the grains aliphatic products, aromatic products and oxygenated heterocyclics form, Among these are : CH3OH, C2H5OH, HCHO, CH3CHO, HCOOH, CH3COOH, NH3, CH3NH2, C2H5NH2, HCN, CH3CN, HC(NH2)COOH, CH3CH(NH2)COOH.

 

 

 

 

 

Fig. 6 - Explosive photodemolition of the black particles.

 

Parting from a few simple products the stream of the organic molecules will follow like a flood, and from this will come life. In the biological synthesis of biopolymers (polysaccarids, proteins, lipids and others), solar energy is transformed into chemical energy.

Consuming these products, the organisms acquire the building blocks of living material and recover part of the accumulated energy. The macromolecules therefore play a triple role of:

- Support structures for the organisms,

- Accumulators of energy,

- Stores (reservoirs) of building blocks of living material.

Life on earth was built on these simple principles.

Something similar happens in the cosmos. When the stars synthesise the base elements, and from then on, the organic polymers, in fact they transform nuclear energy into chemical energy.

After the expulsion from the stars the organic polymers navigate in space also playing a triple role, as:

- Support materials using their mechanical electrical and optical properties (charge transfer, diffraction of radiation, transformation of light into electrical charge);

- Accumulators and distributors of energy (chemical);

- Stores of molecular fragments, (simple and complex molecules).

The reactions in the stars occur at very high temperatures and pressures, in reducing environments. This is the ideal site for the chemistry of carbon, and nitrogen. The oxygen, instead, where it is formed, is soon trapped in water molecules.

The chemistry of interstellar space is the chemistry of cold. It occurs in the grains at temperatures near to absolute zero, in solid systems (ice), under the action of cosmic rays and in the presence of oxygen in the water molecules of H2O ice. It is a chemistry in which the bonds break and reform with great precision.

The screen of dark material, the low temperature, the absence of free oxygen gas and of gravity allow the survival of radicals and even highly reactive molecules.

The chemistry of the biotic era, instead, is of a refined sophistication. It is the chemistry of enzymes in antiradical functions. It is a chemistry which loves moderate temperatures, watery environments, atmospheres rich in oxygen. It is the chemistry which has tamed oxygen, the most aggressive of the terrestrial elements.

Despite the considerable differences these three chemistries are made similar by the same principles: "natura enim simplex est". Cosmic order has stamped the biological world, has moulded the living world according to a unique architectonic principle. Wherever one turns ones eyes in the living world there are chemical reactions. Plants and certain bacteria fix the solar energy synthesising complex substances from simple materials. Other organisms decompose these materials into simpler structures, using the energy they contain. In every cell there are intense chemical processes (reduction, oxidation, hydrolysis, synthesis, etc).

The chemical composition of plants is simple. The biochemical architecture of living things is based on a few pillars C, H, O, N, S, P, etc. This sparse array ramifies into a myriad of molecular composites: binary with a base of only carbon hydrogen (the hydrocarbons), ternary with a base of carbon, oxygen and hydrogen (carbohydrates, fats etc), quaternary with a base of carbon, hydrogen, oxygen, nitrogen (the amminoacids, the peptides, polypeptides, proteins, nucleic acids, alkaloids, lipoproteins, etc) and so on.

Living beings possess a unique characteristic, reproducibility. Another salient property is the specificity of the single structures and the relationship between the structures and a biological role.

The surprising variety of living forms and the individuality of the various organisms can be conducted to the individuality of some macromolecules, the proteins. However, these are nothing but combinations and permutations of a few amminoacids, invariant for various millions of years.

In all the organisms, fuel is transformed into carbonic dioxide CO2 and water H2O through few reactions. The production and use of energy, on the part of the cells, has the same mechanism in many animal species, from protozoons to mammals.

Returning to the star at this point a spontaneous question arises, about the role of interstellar smog, that black tinted garbage of the space which is among the most deadly of cocktails. At first sight it may seem erupted from gigantic forges. At a closer look it demonstrates a design and a target.

 Light emerges, from lifting the veil on the great mystery. It is no longer completely secret. the dark clouds 

Light emerges from the dark clouds lifting.....

 

***

 

4 - From a black tinted firmament to the skin and the brain

On Earth nature is painted in many colours. Transcending purely aesthetic values, the colours play a unique role in the communication between different worlds (animal, vegetable and mineral).

Colour is an instrument of communication. The mechanism with which colour is formed is physical. It happens through the change of the state of the electrons in material.

Colour is an electrical phenomenon. Light and electricity are easily transformed from one to the other. They are two aspects of the same nature.

A grating, a prism or a drop of dew all decompose the light into colours of the rainbow and each of these colours corresponds to a frequency of an electromagnetic wave. A body appears white because it reflects all the light, black if instead it absorbs it. In sunlight white seems fresh, while black burns. Black is not, therefore, a colour, on a par with the others. There is a precise relationship between the colours and the structures of colourants, and the pigments are classified on the basis of their structure: carontinids, pteridins, porphyrines and so on.

The black pigments are an exception. They are regrouped according to their colour which is not a colour, neglecting the extreme differences of many of them. This is black tinted chaos. The terrestrial black materials, unlike those in space of a binary (C, H) or ternary (C, H, N) nature, are in general oxygenated. They are easily obtained by polymerising simple molecules and are named after the substances which have generated them: acetylene black, benzene black, aniline, pyrrole, thiophene, indole, pyridine, quinoline, isoquinoline, etc.

Those produced by living organisms are well represented both in the animal (eyes, skin, hair, etc) and the vegetable (seeds, flowers, fruit, woods, etc) kingdoms. They were called melanins(20) and often derive from aromatic systems and polyhydroxylated heterocyclics.(21)

Leaving aside the precursor which has generated them and for this reason also their substitutes, the melanins present properties typical of black materials and these can be conducted to the nature of the solid state. Black materials are spread in all the universe and is almost always amorphous and non-crystalline. From the lithosphere and biosphere to the cosmos, they possess interesting chemical and physical properties both for the implications for the vital processes and for the study of astrochemistry. These properties include:

- EPR (Electronic Paramagnetic Resonance);

- Electrical and sound waves conductivity (36);

- Modification of surface properties under the action of electrical and magnetic fields;

- X-ray diffraction spectra (22)

- Sensitivity to radiation which produces ionisation and lysis of the covalent bonds (23)

- Fragmentation of the structure on fast atomic bombardment, LASER rays, pyrolisis, oxidation

- Formation of charge transfer complexes

- Permeability to gas and liquids.

The melanins are "fruits of the Earth" and for this reason almost always oxygenated The earth is the planet of oxygen; oxygen is life. The melanins are ternary (C, H, O) or quaternary (C, H, N, O) or more complex (C, H, N, O, S, ...) composites. Life, complexity and the melanins are the fruit of living organisms.

The black polycyclic heterocycles are the offspring of the stars and navigate in space. We can call them "space melanins". They are almost always ternary composites (C, H, N). They are constructed according to the same principle and this relationship is given away by their structure. The oxygen distinguishes the two classes without changing, though, some fundamental properties.

Similar or different structure, similar or different role?

 

***

 

A guiding concept is recognised in the structure of all the pigments. They all have an extended polyconjugated radical-polaronic system called the Little spine (24), in which unpaired electrons create conduction bands. The black particles are amorphous semiconductors and have electrical conductability, which can be modified by doping. Under X-rays the melanins present a diffraction spectrum which is similar to that of graphite, or of the giant fullerenes.

The strict relationship between melanins and graphite is expressed in the colour black, in the EPR signal, in the electrical conductability and in the sensibility to oxygen, to name some of the parameters. The relation is so strict as to be able to consider graphite in some sense the simplest natural melanin or the "Protomelanin" of the prebiotic era.

Like other black particles, the melanins are sensitive to light (photoionization and photolysis) and to LASER rays (Light Amplification by Stimulated Emission of Radiation), which provokes a real explosion of the structure. This property finds multiple practical uses: in dermatology (25) for the transformation of black skin into white, in cleaning of monuments and art works.

The collapse of the black particles has been studied for the purpose of cosmo-chemistry, among other things, by bombarding graphite with LASER (the experiment brought about the discovery of the famous C60 (26).

It does not seem that there has been further investigation to see whether a similar reaction occurs in the interstellar black dust. Despite this it seems reasonable that electromagnetic fragmentation plays a not indifferent role in the photolysis of the black heterocyclic polymers present in space. Effectively the small organic molecules associated to the black material indicate that there is fragmentation in course.

The melanins have origins in the hydroxylated (orthodiphenoles) of aromatic systems like benzene, indol, pyrrol, pyridine, quinoline.

DOPA, Dopachrome, DHI (5,6-Dihydroxyindole), DHICA (5,6-Dihydroxyindol-2-carboxylic acid), dopamine, adrenaline, serotonine, 5,6-dihydroxytriptamine, 5,6-dihydroxy-7-methyl-tetrahydroxyquinoline (linole salt) (27), are some of the substances, which play a role in neurotransmission in living organisms, and which have the properties of producing black particles (melanogenesis) in turn having a biological role.

Melanogenesis is a complex reaction of an enzymatic and radical type. The first phase consists of the formation of the oligomers, in which polyconjugated chains assembled according to the scheme of the Little spine (acetylene-black) are present. The second phase is characterised by the self-assembly of the various units up to reaching graphite structures. This model is universal and is valid for the melanins on Earth and those in space (in the former case it is useful to consider the role of oxygen and of the enzymes operating on Earth).

The melanins are able to bond various substances and ions both by salification (carboxyls, nitrogen bases) and by coordination in typical porphyrine complexes or thanks to interstitial processes. Also the various gasses and water can be trapped by the melanins (absorption) as happens in the case of active carbon and the small fullerenes (C60 and C70) with some noble gasses. The entrapment of oxygen and water can suggest new biological roles for the melanins as matrixes for guided reactions.

The porphyrine system allows the formation of various complexes, helping to explain the affinity for ions and metals, the peroxydase activity, the absorption of gas, the coordination of the water molecules and the electrical conductivity.

These properties and the fact that the melanins (even if different from the currently studied molecules because of the lack of oxygen) must have already been present on the Earth in the prebiotic era, has led to the hypothesis of their having a role in the self-assembly of the first organic molecules.

Acting as a matrix these materials would offer many advantages, besides the simple absorption of reagents on the part of the minerals. In contrast with the monotonous symmetry of a mineral lattice, the black particles can offer a vast diversity of steric configurations, both with their own external surfaces and with their porous internal parts. If you look for a given combination of stereo-specific sites and relative functional groups, also having the capacity to bond metallic ions, the melanin particles seem more adapted than minerals like clay and pyrites to be prototypes of a structure of enzymatic behaviour. In this same environment it should be recalled that the melanins possess structural characteristics similar to molecular sieves and to resins with ionic exchange. More explicitly, the enzyme is a matrix which traps reagents and is provided with a metallic centre (catalyst). The melanins correspond to this model of a primigeneous enzyme. The electrical and sound wave conductivity of the melanins, the fullerenic cages, the surface properties, the unpaired electrons, the hydration, the interstitial activity and charge reversibly applying an electrical potential, that is, the electroactivity of the melanins, thus reveal the other side of their nature. This is flexible and mutable, completely unexpected from the rigidity of the structure.

Under the action of heat, powerful radiation and electrical discharges the melanin matrices take us to the prebiotic era, when carbon derivatives are organised into simple molecules which become more and more complex eventually yielding living organisms.

 

***

The age of our planet is written in its rocks and its birth, connected with the explosion of a supernova, was certainly traumatic.

This is testified by the radioactive uranium (235U) still present and by its fission products, as well as by the endless deposits of heavy metals, these being elements which do not form during normal stellar evolution, but rather, following violent fusions.

From the geological stratification and the radioactivity of the rocks the start of the Earth as an independent planet in space, is dated at 4.5 billion years ago.

From this one deduces, that anaerobic life started 3.6 billion and aerobic 2.5 billion years ago or a little less; therefore there are about 900 million years between the birth of the planet and that of life the prebiotic era (28).

The atmosphere today is dominated by nitrogen and oxygen, with small percentages of carbon dioxide CO2, H2, H2S, CH4, NH3, NO2, NO, SO2, O3 ( 29).

The atmospheres of Venus and Mars are instead dominated by CO2 with small percentages of oxygen and nitrogen.(30) Making a comparison with something from everyday life, our atmosphere is like the mixture of burning gasses which makes a motor car work, those of Venus and Mars like the exhaust gasses of the same motor. The first case it is synonymous with life, in the second is exhausted and sterile. We do not know precisely what the primogeneous atmosphere of the Earth was like. We can only make guesses. One imagines that it was reducing and for this reason had the capacity of binding oxygen and impeding its appearance in the pure state. The oxygen appeared much later, freed by photosynthesis or micro-organisms. It is a gift from the sun and from life.

From the reaction of the ferrous ion (Fe++) with water (H2O), copious amounts of hydrogen gas (H2) formed which was dispersed in the atmosphere. At the same time hydrogen was also erupted in great quantities by volcanoes together with carbon dioxide (CO2).

All this contributed to making the air and the oceans highly reducing. A totally different picture to today’s. If today, for example, we threw the carcass of a car into the sea, soon we would have little more than a pile of rust. The oxygen oxidises the iron without pity. In those times, the car, would, instead, have dissolved without leaving a trace.

In the first five hundred million years of its formation, it seems that the Earth was bombarded by small planets, asteroids, comets and other residue of the cloud of the sun. The traces of these apocalyptic collisions are still obvious in the many small, large and immense, craters so far discovered in various regions.(31)

Besides the mechanical damage caused by this cosmic "rain", it is probable that many simple and complex organic molecules accompanied the downpour, stored in the grains of the interstellar clouds. These contributed to the creation of a "protomix" of reagents ready for further combinations, from biomonomers to biopolymers, on the Earth’s crust, in the sea and in lake waters.

In the prebiotic era chemical reactions already sketched out in space occurred on the Earth and others adequate to the profoundly changed environmental conditions also developed. The temperature passed from almost absolute zero of space to 20-30° on Earth. The molecules no longer frozen in the grains became mobile and superactive with great possibility of remixing in the agitated waters with strong tides. The kinetic possibility of collisions and reactions with different partners notably increased.

The now liquid reactions and the weakening acid favoured the dissolving of basic (amines) substances and reactions of addition and condensation with other functions (e.g. aldehydes + nitryls ----> amminoacids), while the reducing environment kept sensitive products (aldehydes, alcohols, phenols, etc) safe from oxidation.

The water screened the UV rays and actively participated in hydrolysis and hydration. New possibilities of assembling complex structures were created at the solid/liquid, solid/gas interfaces between dissolved reagents or gaseous with inorganic (clay, pyrites) and organic (melanins) matrices.

Following the decomposition of water (H2O) highly reactive oxygenated radicals formed giving the start to new reactions and new compounds. The era of oxygen would soon come about. The notable increase in the temperature stimulated reactions which were previously blocked for the lack of activating energy, in the new terrestrial environment.

A mass of metallic ions, free and chelated in fortunate matrices (melanins) mingled in the marine and lake environments, determining the chemical cataclysm which gave the biotic era the start of enzymes.

The "prebiotic test-tube" became bigger and bigger, expanding enormously, taking in by now, lakes, seas and oceans: the biological soup was ready for cooking.

 

***

 

Given that the pot is ready a spontaneous question arises: Will the soup be the simple outcome of chance or is it, instead, preordained and to some extent guided? The question is valid, giving an answer is difficult. In nature there is a continual conflict between the game of chaos and the tendency to self-organisation. The study of the sciences and of chemistry in particular moves in the direction of order, seeking an ordering principle of every phenomenon. We shall examine two concrete examples, one coming from physics the other from biology.

We have a universe made of hydrogen. In this universe carbon is the element on which life is based. It is still difficult to understand why such enormous quantities of this element have formed.(32)

The synthesis of carbon is a sequence of improbable events favoured by energy. It starts with the fusion of two atoms of helium which form beryllium, an isotope which is so unstable that it must disintegrate quickly and regenerate helium. But, instead, the beryllium fuses with another atom of helium and produces carbon. This last reaction is improbable but is favoured since the combined energy of beryllium + helium (7.370 MeV) is in fact a little less than that of carbon (7.656 MeV). Reacting with helium the carbon should, in turn, form oxygen. However, this reaction is not favoured since the energy level of oxygen (7.1187 MeV) is lower than that of the two reagents (C+He = 7.1616 MeV) even if only by a little. There is a low, but sufficient, probability that the energy levels of the sequence He, Be, C, O are in correspondence with the necessary levels. The energy balance prevails over the game of chance. Therefore we have a universe coloured black, as black as coal. According to Darwin, the first forms of complex life (blue algae, bacteria) developed in the span of 500 million years, parting from a casual molecular soup. A short length of time, frankly, for obtaining such complexity through the game of fortunate chemical reactions and casual mutations. Chemistry follows precise laws. The molecules, even though free to oscillate, vibrate, and move randomly and tend to become organised according to predetermined lines. The very concepts of chemical valence or of affinity are deterministic. The atoms are not free to pair up randomly They obey the laws of chemical bonding, of valence and affinity. The same is true for molecules which are groupings of atoms, pairing according to a precise design. The degrees of freedom of atoms and molecules are not infinite. Little is left to luck.

The evolution of material, which started with the elementary particles, continued with atoms and molecules inside the stars and interstellar clouds. The planetary ecosystems are made up of populations by diverse organisms and these are made up by cells, the cells by proteins, the proteins by molecules and blocks, the molecules by atoms and these from subatomic particles.

Nature (from quarks to the galaxies and from bacteria to the planetary ecosystems) tends towards complexity, to self-organisation. The subatomic particles join in atoms and molecules, these in biomonomers first and in polymers later, the protobiontics in structures and pluricellular organisms, which in turn make way for social and ecological systems.(33)

The creation of this plurality of organisms and structures in such a short time necessarily reduces the casualness of evolution and alters the probability of variations in favour of ordered and coherent outcomes.

Therefore it appear more and more realistic that there are interactions between the physical, chemical and biological aspects of nature. These interactions which make order prevail over chaos.

 

***

 

5 - The dark secret of life

Our vision of the cosmos and life have changed from the start of civilisation and they have been overturned in the last few years, by the force of science and technology.

Today we know that the space between the stars and planets is not a vacuum as was once believed. It is vibrating with material. There are atoms, ions, simple and complex molecules. Some of these molecules only exist in the stellar regions, many are well known in the terrestrial world. Among these there are various composites necessary for the synthesis of proteins, peptides, carbohydrates, and lipids, the basic macromolecules of living organisms.

The clouds have lost all their magic characteristics and seem more and more like huge black coloured stellar garbage cans, gigantic accumulations of rarefied material, all dust and grains of various size, which live in their own organised "inorganic life". The grains grow, diminish in number and amount, and are in continual evolution. They show important optical properties (diffraction, absorption of electromagnetic and corpuscular radiation), electrical properties (charge transference, photoelectric effect), chemical properties (photolythic reactions, photosynthetic, dissociation and combination). Singular properties which evolve and alter notably.

In the grains, real miniature space laboratories , delicate photochemical reactions occur which are great importance for the future biogenesis at temperatures near absolute zero. Complex materials are fragmented and these recombined into oxygenated and nitrogenated molecules (alcohols, aldehydes, acids, carboxylics, ammines, nitrils, amminoacids, phenols etc).

The black polymers are excellent conductors and show a pronounced photoelectric effect (transformation of light into current). This property is possessed to an even greater measure by charge transfer complexes which form easily from black polymers. It is reasonable to suppose, therefore, that these play a role in the evolution of the stellar clouds. All this assumes particular value considering the stars and planets which form from the gravitational collapse of stellar clouds.

The black polymers, probably created from polymerisation of acetylene and nitrogen in the giant stars, play a triple role in these clouds. They are:

- Support structures: mechanical, electrical and optical properties (charge transference, diffraction and absorption of radiation, transformation of light into current);

- Accumulators and distributors of chemical energy;

- Space storehouses of carbon, hydrogen and nitrogen from which to make simple molecules ("building bricks" for biogenesis).

A similar triad of roles is played by organic biopolymers on Earth, demonstrating how, as material tends to organise, cosmic order gives its imprint to the living world.(34)

Carbon together with hydrogen, oxygen, nitrogen, sulphur and phosphorous, represent the basis of life. For life to be created these elements (besides others in small traces) have to be found together in the right place, at the right time and in the appropriate form. They are extruded from the furnaces of the gigantic stars in elementary and combined forms: the carbon as carbon dust, fuligines, graphite, CO, CH4, C2H2, the hydrogen as H2, H2O; the oxygen as O2, H2O, the nitrogen as N2, NH3, NO etc.. The black polymers represent the most condensed forms of C,H,N. These elements are normally packed in solid structures and can thus start their interstellar voyage without being dispersed (hydrogen and nitrogen, gaseous by nature are trapped in the cage of the solid material). Polymerisation achieves the double scope of compacting the key elements and accumulating chemical energy. In the clouds the polymers are therefore fragmented photoelectrically and their fragments opportunely recombined with oxygenated and nitrogenated radicals (taken from the ices).

Melanogenesis is a complex radical reaction which leads to the formation of cosmic black polymers and terrestrial melanins. The process follows a universal model for the black materials both on Earth and in space (in the case of the terrestrial melanins the role of oxygen and the enzymes present on the Earth is to be accounted for).

Thanks to particular properties (conductivity, graphite-fullerene structure, surface properties, interstitial activity), the terrestrial prebiotic melanins could have played a notable role in the self-assembly of the primogeneous organic molecules acting as prototypes of the enzymatic system.

The carboneous interstellar material formed by polycondensed heterocyclic structures, already known on Earth, explodes into many smaller fragments, under photolysis, which recombine with oxygenated radicals forming biomonomers similar and/or equal to those known on the Earth.

The black polymers play a triple role as:

- support structures thanks to their mechanical, electrical and optical properties;

- accumulators and distributors of chemical energy;

- space storehouses of carbon, hydrogen and nitrogen in the form of "solid compact structures" which yield simple molecular fragments ("building bricks" for biogenesis).

The black materials have a protective action against the effects of cosmic radiation on organic material and regulate the ion/radical/molecule equilibrium in the interstellar clouds.

The black particles can be seen either as assemblers of atoms and molecules or as generators of other species of molecules through their annihilation. A single unique cosmic architectonic principle organises both living material and interstellar material.

 

The full version of this paper with figures ,B.J.R.Nicolaus,R.A.Nicolaus '' Lo scrigno oscuro della vita.Riflessioni sul ruolo chimico-biologico della materia nera interstellare e sulla comparsa della vita nell'universo.'' Atti della Accademia Pontaniana Vol.XLVIII, 355-380,(1999) is available on request.

 

 


 


Appendix

 


 

 

 


NOTES

1) B.R.J. Nicolaus, R.A. Nicolaus, M. Olivieri, Riflessioni sulla materia nera interstellare, Rend. Acc. Sci. Fis. Mat., Vol. LXVI, 1999.

2) S. Hawking, Dal Big Bang ai buchi neri, Rizzoli, Milano 1992; E.J. Lerner, Il Big Bang non c’è mai stato, ediz. Dedalo, 1994. Black holes below to the theory.

3) Fundamentally radiotelescopes are instruments equipped with enormous directional antennas. The receivers and the amplifiers can be tuned onto even very weak signals. In general a search is made by tuning the radiotelescope to a given frequency (the frequency is usually slightly corrected for the Doppler effect due to the motion of the Earth and the objects under observation). Laboratory studies indicate that by pointing the radiotelescope towards an appropriate interstellar zone and integrating the signal received it is possible to determine whether a molecule emits at that frequency or preferably at a set of frequencies. Occasionally, during these experiments lines not corresponding to the values of known frequencies have been found. Chemical types like ions and radicals are relatively stable and abundant in a rarified environment in non-equilibrium conditions. Therefore, special space conditions stabilize some molecules which are difficult to study in the laboratory: an example in particular of this is the case of the interstellar polyions.

4) It is estimated that the moon and the earth formed 4.5 billion years ago. Later intense bombardment by meteorites occurred, while the first forms of life appear between 4.4 and 3.8 billion years ago. Around 3 billion years ago, it is believed, the first organisms able to carry out the processes of photosynthesis and to liberate oxygen into the atmosphere were formed. And only later (about 2 billion years ago) was there an atmosphere rich in oxygen able to sustain the first heterotropic organisms. From carbon, hydrogen, oxygen and nitrogen (C, H, O, N) present in the primitive atmosphere, formed, under the joint action of radiation electrical discharge and storms, a miriad of organic molecules later washed by the rains and accumulated in the waters.

The presence of organic substances in extraterrestrial objects suggests that the essential components of biopolymers are formed easily in nature and could have been formed about 4 billion years ago, through non-biological reactions (J. Oro, Stage and mechanisms of prebiological organic synthesis, in S.W. Fox, The origins of prebiological systems, Acad. Press. N.Y., 137-171 (1965).

The problem of passing from very simple organic composites to functional proteins and to the informative system at the base of the nucleic acids, which guarantees reproduction and conservation of function, remains open. Even without sufficient proof, one presumes that the primitive catalysts of the first composites were clays and the masses of pyrites (a similar role has been proposed for the melanins, even though at that time their properties were not adequately understood; Blois in loc. cit.). The universality of the genetic code, uniform in all the organisms from viruses to man, is one of the stongest arguments in favour of the uniqueness of the origin of all living beings (La piccola Treccani, vol. XII, pag. 868-869, Ist. Enciclopedia Italiana Roma, 1997.

5) Enciclopedia delle Scienze Fisiche, Istituto della Enciclopedia Italiana founded by G. Trecanni, vol I, 381; vol. III, 629-645 (1992).

6) Like all biogene elements, carbon undergoes a series of cyclic transformations and passes continually from the mineral world to that of living beings and vice versa. The carbon of the living beings comes directly or indirectly from that of carbon dioxide (CO2) in the atmosphere. The stars form by gravitational collapse of the clouds of gas and dust. In the first phases of their lives, these are heated by the gravitational energy liberated in the contraction which transforms into thermic energy. At a certain point the internal temperature becomes high enough to set off nuclear fusion reactions which feed the stars until they exhaust the fuel, forming hydrogen and helium:

4 H+ --> He (+ 26 MeV)

When the available hydrogen is burnt, the fusion of helium into carbon is set off:

4He + 4He ----> 8Be

8Be + 4He ---> 12C + g (+ 7.27 MeV)

At the same time but to a lesser extent the carbon formed captates helium, generating oxygen:

12C + 4He -----> 16O + g

When the helium is exhausted larger nuclear reactions are set off which lead to iron, through various heavy metals: (O ----> Ni ----> Mg ----> 28Si ----> 56Fe) the chain stops with iron since the other fusions are endothermic. The difference of composition of our planets of the solar system depends on the temperature of the original cloud, which is higher nearer the sun than at greater distances ("La Piccola Treccani", loc. cit.).

7) H.W. Kroto, Semistable molecules in the laboratory and in space, Tilden lecture, J. Chem. Soc. Rev. 11, 435-491 (1982); Chemistry between the stars, New Scientist 79, 400-403 (1978).

8) B.R.J. Nicolaus, R.A. Nicolaus, Speculating on the band colours in nature, Atti della Accademia Pontaniana, vol. XLV, 365, ed, Giannini, Napoli (1997); R.A. Nicolaus, Divagazioni sulla struttura a banda del colore in natura: nero, Rend. Acc. Sc. Fis. Mat. Napoli, vol. LXIV, pag. 146-213 (1997); R.A. Nicolaus, Coloured organic semiconductors: melanins, Rend. Acc. Sc. Fis. Mat. Napoli, vol. LXIV, pag. 325-360 (1997); B.R.J. Nicolaus, R.A. Nicolaus, Melanins, biological garbage or jewels, Scientific Communication Presented at the Meeting of the European Society for Pigment Cell Research - Sept. 23-26 (1998), Prague - Pigment Cell Research, 11, 233 (1998).

9) K-H Homann, Fullerenes and soot formation - new pathways to large prarticles in flames, Angew. Chemie ind. Ed. 37, 2434-2451 (1998).

10) R.G. Harvey, Polycyclic aromatic hydrocarbons, Wiley-VCH New York 1997.

11) E. Clar, Polycyclic hydrocarbons, Academic Press, New York 1964.

12) R.G. Harvey, Polycyclic aromatic hydrocarbons, chemistry and carcinogenicity, M. Coombs ed. Cambridge University Press, Cambridge 1991.

13) I. Gutman, S. Cyvin, Introduction to the theory of benzenoid hydrocarbons, Springer Verlag, Berlin, 1989.

14) L.J. Allamandola, A.G. Tielens, J.R. Barker, Astrophys. J., 1985, 290, L25.

15) The bituminous residue is made up of mixtures of naural hydrocarbons or obtained by pyrofusion of the crude oil (or mixtures of both) of solid and semi-solid consistencies and with dark colours up to black. Petroleum is made up of fluid mixtures of natural solid, liquid and gaseous hydrocarbons. The nitrogenated composites are quinoline, pyridine, pyrrol, aromatic and derived bases. The origin of petroleum is organic (napthogenesis) The bituminous schists are schists with a high kerogene content. They give liquid petroleum on heating. They are very widespread and have biological origins. Coal is a material composed mainly of carbon, coming from a progressive decomposition of organic substances, mainly of vegetable origin, through a natural process which interests entire geological ages. Graphite is an allotropic form of carbon. It is a soft mineral, oily to touch, a good conductor of electricity and heat. It does not melt before 3000°C. It oxidises only with hot HNO3 and HClO3 with the formation of graphitic acid and metallic residues.

16 The simple organic molecules tend to organise into more complex molecules, the biomonomers (glycerol, fatty acids, amminoacids, sugars and phenols). These in turn tend to organise into macromolecules (biopolymers) with living functions; (lipids, proteins, carbohydrates, lignines and tannins).

17) The living state continues to resist all attempts of physical and philosophical definition. It may be considered as a common state of material which is found on the surface of the Earth and in the oceans. This state sees complex combinations of the elements C, H, O, N, S and P with traces of other elements. It is easier to define the fundamental characteristics of living beings:

a. Living beings are always generated by living beings

b. They have definite and constant forms

c. They are made up of cells, fundamental structural and functional units

d. They have the property of constructing their own bodies at the expense of chemical substances which they receive from the external world

e. They maintain constant relationships with the environment and are able to react to certain stimuli.

f. They are not perrenial, but are destined to disappear after having passed through the various stages of a vital cycle, during which the reproduce; the capacity of evolving over generations is connected to this characteristic cfr. La Piccola Treccani, vol. XLL, pag. 868, Istituto della Enciclopedia Italiana, Roma (1997).

18) G.M. Badger, Prog. Phys. Org. Chem. ,3, 1-40.(1965)

19) M.P. Bernstein, A. Scott, A. Sandford, L.J. Allamandola, Dallo spazio le molecule della vita, Le Scienze 373, 34-42 (1999); E.L.O. Bakes, The astrochemical evolution of the interstellar medium, Twin Press, Astronomy Publishers, 1997; M. Bernstein et al., UV irradiation of polycyclic aromatic hydrocarbons in ices: production of alcohols, quinones and ethers, Science 283, 1135-1138 (1999).

20) Among the melanins one may distinguish the pheomelanins (from sulphurated melanogenesis), the allomelanins (from polyphenols) and the eumelanins (from nitrogenated melanogenesis). These polynuclear and polycyclic derivatives are often called "polymers". This definition, used here in this work for simplicity, is not correct, considering the heterogenic structure of these materials.

21) G. Prota, Melanins and melanogenesis, J. Wiley, New York 1992; W. Montagna, G. Prota, J.A. Kenney Jr., Black skin structure and function, Academic Press inc., New York, 1993.

22) G.W. Zajac, J.M. Gallas, J. Cheng, M. Eisner, S.C. Moss, A.E. Alvarado-Swaisgood, The fundamental unit of synthetic melanin: a verification by tunneling microscopy of X-ray scattering results, BBA 1199, 271 (1994); J. Cheng, S.C. Moss, M. Eisner, P. Zschok, X-ray characterization of melanins-1, Pigment Cell. Res. 7, 255, (1994); J. Cheng, S.C. Moss, M. Eisner, X-ray characterization of melanins-1l, Pigment Cell. Res. 7, 263, (1994); M. Olivieri, R.A. Nicolaus, Sulla DHI melanina, Rend. Acc. Sci. Fis. Mat., Vol. LXVI (1999).

23) B. Kalyanaraman, C.C. Felix, R.C. Sealy, Photoionization and photohomolysis of melanins: an electron spin resonance spin trapping study, J. Am. Chem. Soc. 106, 7327 (1984).

24) On the basis of calculations, according to BCS (Bardeen, Cooper and Schreiffer’s theory of superconductivity). In 1964 W.A. Little proposed a particular chemical structure for the organic superconductors, formed by a polysaturated chain called the "spine" ( acetylene-black, (35) ), substituted in various positions by heterocycles (often hybrids of resonance) with poly cations and counteranions. The term "candidate" is used to indicate composites and materials presumed to be the seeds or semiconductors, on the basis of mere calculations. For example, the polysaturated polymers (spines) above will be conductors or candidates for conductivity, depending on the case. W.A. Little, Possibility of synthesizing an organic superconductor, Phys. Review 134 A, 1416 (1964).

25) S.L. Jacqes, D.J. McAuliffe, The melanosome threshold temperature for explosive vaporization and in thermal absorption coefficient during pulsed laser irradiation, Photochem. Photobiol. 53, 769 (1998).

26) H.W. Kroto, Fullerene cage clusters, Chem. Soc. Faraday Trans. 86, 2465 (1990).

27) L. Mosca, C. Blarzino, R. Coccia, C. Foppoli, M.A. Rosei, Melanins from tetrahydroisoquinoles: spectroscopic characteristics, scavenging activity and redox transfer properties, Free Radical Biol. Med. 24, 161 (1998).

28) D. Freeman, Origins of life, Cambridge Univ. Press, Cambridge 1986.

29) H.D. Holland, The chemical evolution of the atmosphere and the ocean, Princeton Univ. Press, Princeton 1984.

30) J.S. Lewis, R.G. Prinn, The planets and their atmospheres, Academic Press, Orlando 1984.

31) J. Lovelock, Le nuove età di Gaia, Bull. Boringhieri 1992.

32) L. Erwin, Alle radici dell’universo, Sperling Kupfer, Milano 1993.

33) E. Schrödinger, Che cos’è la vita?, Sansoni, Firenze, Nuova ediz. 1988.

34) D.E. Ingber, Tensegrity: the architectural basis of cellular mechanotransduction, Ann. Rev. Physiol. 59 (1997).

35).G.Natta,G.Mazzanti,P.Corradini'' Polimerizzazione stereospecifica della acetilene '' Rend.Acc.dei Lincei,xxv, (1958).

36) R.Kono,T.Yamaoka,H.Yoshizaki,J.McGinness '' Anomalous absorption and dispersion of sound wawes in diethylamine melanin '',J.Appl.Phys.,50,1236-1244 (1979).

Naples June 2000.