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.