About Supramolecular Assemblies of π-Conjugated Systems

CRYSTALLINE MATERIALS Introduction Physical Properties Optical Properties Mechanical Properties Thermal Properties Magnetooptic Properties Electrooptic Properties Elastooptic Properties Nonlinear Optical Properties GLASSES Introduction Commercial Optical Glasses Specialty Optical Glasses Fused Silica Fluoride Glasses Chalcogenide Glasses Magnetooptic Properties Electrooptic Properties Elastooptic Properties Nonlinear Optical Properties Special Glasses POLYMERIC MATERIALS Optical Plastics Index of Refraction Nonlinear Optical Properties Thermal Properties Engineering Data METALS Physical Properties of Selected Metals Optical Properties Mechanical Properties Thermal Properties Mirror Substrate Materials LIQUIDS Introduction Water Physical Properties of Selected Liquids Index of Refraction Nonlinear Optical Properties Magnetooptic Properties Commercial Optical Liquids GASES Introduction Physical Properties of Selected Gases Index of Refraction Nonlinear Optical Properties Magnetooptic Properties Atomic Resonance Filters APPENDICES Safe Handling of Optical Materials Abbreviations, Acronyms, and Mineralogical or Common Names for Optical Materials Abbreviations for Methods of Preparing Optical Materials and Thin Films Fundamental Physical Constants Units and Conversion Factors

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Handbook of Optical Materials

Big is beautiful--"aromaticity" revisited from the viewpoint of macromolecular and supramolecular benzene chemistry.

Dendron-mediated self-assembly, disassembly, and self-organization of complex systems have been investigated. The most ideal building blocks would need to display shape persistence in solution and in the solid state, since only this feature provides access to the use of complementary methods of structural analysis. Most supramolecular dendrimers are chiral even when they are constructed from nonchiral building blocks and are equipped with mechanisms that amplify chirality. This poses additional challenges associated with the understanding of the structural origin of chirality in different supramolecular structures through combinations of structural analysis methods. While many supramolecular structures assembled from dendrimers and dendrons resemble some of the related morphologies generated from block-copolymers, they are much more complex and are not determined by the volume ratio between the dissimilar parts of the molecule.

Dendron-Mediated Self-Assembly, Disassembly, and Self-Organization of Complex Systems

Most associate liquid crystals with their everyday use in laptop computers, mobile phones, digital cameras, and other electronic devices. However, in contrast to their rodlike (calamitic) counterparts, first described in 1907 by Vorlander, disklike (discotic, columnar) liquid crystals, which were discovered in 1977 by Chandrasekhar et al., offer further applications as a result of their orientation in the columnar mesophase, making them ideal candidates for molecular wires in various optical and electronic devices such as photocopiers, laser printers, photovoltaic cells, light-emitting diodes, field-effect transistors, and holographic data storage. Beginning with an overview of the various mesophases and characterization methods, this Review will focus on the major classes of columnar mesogens rather than presenting a library of columnar liquid crystals. Emphasis will be given to efficient synthetic procedures, and relevant mesomorphic and physical properties. Finally, some applications and perspectives in materials science and molecular electronics will be discussed.

Discotic Liquid Crystals: From Tailor-Made Synthesis to Plastic Electronics

Numerous formulae have been proposed by several authors to account for the rapid increase in the rotatory power of quartz with decrease of wavelength. These formulae generally consist of a large number of terms both positive and negative, principally of the Drude type, involving various hypothetical characteristic frequencies. An examination of these formulae shows that they do not possess physical justification and are arbitrary in character. In the present investigation it is shown that the data are well represented by the single term formula
 
$$\rho = \frac{{k\lambda ^2 }}{{(\lambda ^2 - \lambda _0 ^2 )^2 }} or \frac{{a\nu ^2 }}{{(\nu _0 ^2 - \nu ^2 )^2 }},$$

 wherek=7·186 andλ
 0=0·0926283µ. Assuming that ‘a’ is a constant with temperature andν
 0 to vary with it, the thermal variation of the optical rotatory power has been quantitatively accounted for,ν
 0 being found to vary in the same manner with temperature as estimated from the thermal variation of the refractive indices of quartz.

The optical rotatory power of quartz and is variation with temperature

The modified form of the Pople-Karasz theory of melting of inolecualr crystatls in a pervious paper is applied to study the thermodynamics of solid-solid and melting trasitions The results are in substantial agreement with the predictions of the theory in its original form

Theory of Melting of Molecular Crystals II: Solid-Solid and Melting Transitions

The rotatory dispersion of crystals of NaClO3 and NaBrO3 has been measured in the visible and ultraviolet region of the spectrum. Apart from a small infrared contribution, the rotatory dispersion of both crystals can be expressed as a difference of two terms. For NaClO3 the positive term has a greater strength than the negative one, whereas for NaBrO3 the reverse is the case. Thus corresponding configurations of the two crystals have opposite signs of optical rotation. The important point is brought out that calculations of optical activity in terms of atomic refractivities but neglecting rotatory dispersion, such as those carried out recently for these two crystals, arc necessarily inconclusive.

Optical rotatory dispersion of crystals of sodium chlorate and sodium bromate

The theory of melting of molecular crystals developed in Parts I and II is extended to include short range orientational order. The thermodynamic properties are evaluated by the quasi-chemical method, which is mathematically equivalent to Bethe's treatment, and the theory is applied to liquid crystalline transitions. The interesting result is obtained that the nematic-isotropic transition is always first order, and that although the long range orientational order disappears suddenly at this transition point, a certain degree of short range orientational order persists in the isotropic phase. The specific heat exhibits both pre- and post-transition anomalies, in conformity with observations. The thermal expansion and isothermal compressibility show pre-transition anomalies but, contrary to experimental facts, no post-transition anomalies, indicating that even the quasi-chemical approach is not quite adequate for explaining all the properties.

Theory of Melting of Molecular Crystals III: The Effect of Short Range Orientational Order on Liquid Crystalline Transitions

(1960). Extinction in x-ray crystallography. Advances in Physics: Vol. 9, No. 36, pp. 363-386.

S. Chandrasekhar

Papers

The optical rotatory power of quartz and is variation with temperature

Theory of Melting of Molecular Crystals II: Solid-Solid and Melting Transitions

Optical rotatory dispersion of crystals of sodium chlorate and sodium bromate

Theory of Melting of Molecular Crystals III: The Effect of Short Range Orientational Order on Liquid Crystalline Transitions

Extinction in x-ray crystallography