Chirooptical properties

Chirooptical properties give more subtle information on the conformational behavior of biopolymers and peptides in solution. In early experiments, optical rotation and optical rotatory dispersion (ORD) have been recognized as valuable techniques, followed more recently by significant progress and refinements in the equipment which have resulted in the routine measurements of applied circular dichroism (CD). 

From electronic back to optical properties, in the final Chapter 15, Rajca and Miyasaka provide an overview of the synthesis of molecules with highly anne-lated, chiral, 3t-conjugated systems, primarily of the helicene-type. Tremendous progress has been made in the synthesis of helicenes however, the corresponding helical, ladder-type polymers remain a significant and attractive challenge. In addition to the synthesis, the configurational stability (barriers for racemization) and chirooptical properties are described and discussed in depth in this chapter. In this context, perspectives for isotropic materials with molecule-based chirooptical properties are outlined. 

Optically active poly(y-ketosulfi(ie)s have also been the subject of detailed studies. Different routes to both ahphatic (66,67) and aromatic (68-70) polymers and their chirooptical properties have been described. 

The value for the most isotactic fraction is -1-160 against the value -h240 calculated for a left handed helical chain of poly(4-methyl-l-pentene).2i Cooperativity is a critical feature of macromolecular behavior. Studies of the dependence of chirooptical properties on the degree of tacticity in homopolymers and the mole fraction of chiral monomers in copolymers has shed considerable light on the nature of cooperativity in linear macromolecules. 

A study has been made of the diastereotopy of the methylene and methyl protons in ethyl and isopropyl esters of purine nucleoside uronates. Anisochromism of the diastereotopic protons was conditional upon both close spatial proximity and fixed orientation of the heterocycle vis-a-vis the alkoxycarbonyl group. 139 Unsaturated nucleoside uronates such as (89) have been prepared by p-elimination and their chirooptical properties investigated, i ... 

Autschbach, J., Ziegler, T., van Gisbergen, S.J.A., Baerends, E.J. Chirooptical properties from time-dependent density functional theory. I. Circular dichroism of organic molecules. J. Chem. Phys. 116, 6930-6940 (2002)... 

Polavarapu PL (2006) Quantum mechanical predictions of chirooptical vibrational properties. Int J Quantum Chem 106 1809-1814... 

Over the last three decades, chiral carbon-rich compounds have evolved into an interesting and useful class of materials due to the many unique properties that result from the installation of conjugated chromophores within a chiral framework. Chiral carbon-rich materials possess distinct chirooptical and electronic properties that may prove useful for a number of intriguing applications ranging from optically active liquid crystals to nonlinear optical materials. Chiral carbon-rich compounds also represent a potentially valuable scaffold for use in asymmetric reactions and catalysis. 

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