Chiral Light and the Stokes Parameters

Light is electromagnetic radiation which can be interpreted as wave of an electrical field vector E and a magnetic field vector B, each of them oscillating and perpendicular to the axis of translation and E.LB. For unpolarized light, the electrical field vector has an infinite number of orientations. If one restricts its oscillations to one plane, for example by a linearly polarizing filter, we speak of linearly polarized light. Also here, E L B is valid. This light is used in a polarimeter for...

Adsorption of Chiral Organic Molecules on Enantiomorphous Crystals

We have seen that crystals can be chiral and that such chiral crystals can originate from the crystallization of a racemic solution or melt in laboratory experiments and also in deposits of enantiomorphous crystals on Earth. Locally, high excesses of enantiomorphous crystals have been recorded. The next question will be whether organic molecules such as amino acids can enantioselectively interact on mineral surfaces of enantiomorphous crystals via adsorption or similar processes in order to...

Asymmetric Radiolysis by Polarized Electrons

Our central question will now be whether this asymmetry inherent to the nuclear P-decay can have contributed to the selection of chiral molecules in life's biopolymers. Is it truly reasonable to assume that polarized electrons can interact with racemic or prochiral organic molecules such as amino acids inducing an enantioen-richment In this case, a flux of spin-polarized P-electrons should react in a different and measurable way with R- and S-enantiomers. Here, the interested reader will remark...

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L length, ID inner diameter, LT layer thickness L length, ID inner diameter, LT layer thickness acids were investigated with a derivatization step prior to gas chromatographic analysis. 9.1.3.1 Resolution of Chiral Amino Acids The identification and resolution of chiral amino acids are probably the most fascinating targets for ROSETTA's chirality-module. However, we have to consider that D,L-amino acids are too polar to get direct access to their analysis by gas chromatography. D,L-Amino acids...

When Crystals Deliver Chirality to Life

Chirality Quartz Crystals

We have already outlined that biomolecules like DNA, proteins (enzymes), and also lipids1 are composed of homochiral monomers that do not tolerate any pollution by the wrong enantiomer. In order to understand the decisive asymmetry of evolutionary processes at life's beginning, we have to think of an asymmetric element put into the vicinity of a racemic or prochiral chemical substrate. In this chapter, a crystallization nucleus spontaneously generated in solution will serve as such an...

Difference Matters Energies of Enantiomers

The small, weak, and pseudo-scalar potential V PNC contributes to the attracting forces and the binding energy of molecules in a way, that a tiny amount of energy is added to one enantiomer whereas the same amount is subtracted from the energy of the mirror-image enantiomer giving rise to definite AEPNC values. Usually - and as we have outlined in Chap. 2 - it has been assumed that all scalar values of enan-tiomers, with the exception of its capacity to rotate the plane of linearly-polarized...

Miscellaneous Techniques

Furthermore, the elucidation of chiral structures in the context of the origin of biomolecular asymmetry is influenced and flanked by techniques such as magnetic optical rotation dispersion, magnetic and vibrational circular dichroism, linear dichroism, but also Raman optical activity. These techniques will be briefly introduced interested readers will be referred to the literature. Substances that are optically active in the absence of external influences are said to exhibit natural optical...

Stereochemistry for the Study of the Origin of Life

Before exploring up-do-date theories and cutting-edge research activities on the origin of life's molecular asymmetry, this Chap. 2 will provide a brief, comprehensible, and illustrated introduction on common stereochemical terms like chirality, stereogenic center, enantiomer, racemic mixture, optical activity, and homochiral-ity. Stereochemical descriptors like R S, d l, (+) (-), d l, A A, and P M will be explained. After being familiar with these basic terms, we will focus on techniques often...

The Dark Side of DAmino Acids

Some D-amino acid enantiomers are associated with destructive and toxic effects for living organisms, in contrast to the above-presented desired deviant enantiomers. Consequently, biological organisms try to get rid of these enantiomers using various strategies. First of all, D-amino acids can be detected and eliminated by special proteins, called D-amino acid oxidases. Moreover, D-amino acids can be stored in deposits where they do not interfere with everyday metabolism Rein 1992 . In some...

The Origin of Life

The origin of life is one of the unsolved fundamental mysteries in modern natural science. The endeavour to discover some of its secrets continues to challenge researchers from many different scientific domains such as astrophysics and planetary sciences, geology, mineralogy, geochemistry, organic, inorganic, analytical, and physical chemistry, biophysics, biochemistry, biology, and even mathematics. Not to forget the profound interest of philosophers, writers, theologians, and artists in a...

Asymmetric Synthesis

Another strategy to circumvent the problem of excessive photodecomposition during induction of an enantiomeric enhancement by asymmetric photolysis reactions is the spontaneous asymmetric photoformation, i.e., asymmetric synthesis, of amino acid structures, which is particularly interesting under interstellar conditions with circularly polarized light. In contrast to asymmetric photolysis and asymmetric photoisomerization, the pure synthesis of optically active molecules in non-racemic yields...

The Asymmetry of Life

This book is aimed at catching this fingerprint and discovering its evolutionary origin. We will not review all the general aspects of the origin of life,2 but we will focus on one particularly fascinating and crucial period therein, namely the emergence of chirality. More scientifically spoken it is the emergence of biomolecular homochirality. I will present cutting edge research on the elucidation of the ultimate cause of the homochirality phenomena on Earth and the possible correlation with...

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Fig. 2.1 Two three-dimensional non-superimposable molecular structures of the amino acid a-alanine. The structures are unsymmetrical and chiral each of them is called an enantiomer constitution of all chemical bonds connecting the functional groups of a-alanine. The central carbon atom, called a-carbon, holds the amino group and the carboxylic function as well as a methyl group. Consider that the structure is given in three dimensions The methyl group at the bottom of the left structure points...

Chiral Fields Light Magnetism and Chirality

In this chapter we will ask the inspiring question Can the asymmetry of a chiral field - such as a specifically oriented magnetic field, radiation field, or the combination of both - be transferred to racemic or prochiral organic molecules in a manner that an enantiomeric enhancement is induced, that is to say, transferred from the mass-less chiral field into the organic molecule And indeed, the answer to this question is yes. In order to understand systematically such phenomena, we will...

Circularly Polarized Bremsstrahlung in the VU Process

It is known that if electrons pass matter they are decelerated, due to which they emit electromagnetic radiation that is called Bremsstrahlung indeed, this German term describes the particular kind of electromagnetic radiation also in English language . In the context of the VU process it is important to note that Bremsstrahlung produced by spin-polarized electrons is equally polarized Goldhaber et al. 1957 3 The helicity of the spin-polarized electron is transferred to the helicity of the...

Photochirogenesis

Is it reasonable to wonder if a collection of 'chiral photons' -sometimes loosely referred to as 'chiral light' - is capable of inducing enantioenrichments into prochiral or racemic molecules Or, in other words, can one imagine a migration of chiral information from pure and mass-less electromagnetic radiation to matter In theory, the effect of circularly polarized light represents indeed a true-chiral influence on racemates of organic molecules MacDermott 1993 Barron 1994a, 1994b and hence...

Determinate Mechanisms

Determinate mechanisms create predictable non-random enantiomeric enhancements. They involve the interaction of either internal or external physical driving forces - cogencies - with racemic or prochiral substances that are causing prevalence of one enantiomer. Examples of such deterministic scenarios include the adsorption of organic molecules on the enantiomorph surface of quartz Karagunis and Coumoulos 1938 Soai et al. 1999 , or calcite Hazen et al. 2001 as we will discuss later. Here, the...

List of Symbols and Abbreviations

Symbols and abbreviations were used according to the list below. In some cases, such as a or Z, one symbol has more than one meaning. The proper meaning becomes clear from the context in which the symbol is used. a Separation factor and optical rotation angle a Prefix of an amino acid carrying the amino function at the carbon atom in a-position and amplitude for asymmetry a Stereodescriptor for axial chirality and semimajor axis of a0 Non-helical term in Moffit-Young equation P Prefix of an...

Do DAmino Acids Affect Grey Matter

Coming now to mammalians and human beings, we note that the identification of free D-amino acids has been reported for various mammalian tissues. Free impressively high activity. The d-enantiomer in the peptide structure is thus essential for the biological activity of dermorphin. 3 Achatin I was isolated in tissues of the African giant snail Achatina fulica and is described to enhance cardiac activity. Achatin II is the epimer peptide using l-phenylalanine. It was also isolated from the...

Amino Acids in Peptides

Bacteria are known to make use of D-amino acids in several peptide antibiotics in which the wrong amino acids D-glutamate, D-phenylalanine, D-aspartate, and D-valine were found to be incorporated. It is important to note that the classical biosynthetic pathway in which DNA codes for the twenty L-amino acids of proteins cannot produce these exceptional D-amino acid-containing peptides. DNA does not code for D-amino acids. D-Amino acid containing peptides, on the contrary, are formed by specific...