S. Chandrasekhar

Bio: S. Chandrasekhar is an academic researcher from Raman Research Institute. The author has contributed to research in topics: Liquid crystal & Biaxial nematic. The author has an hindex of 31, co-authored 124 publications receiving 3368 citations. Previous affiliations of S. Chandrasekhar include Royal Institution & University of Mysore.

Simple Model for Optical Activity

Abstract: The paper describes a simple theoretical model for explaining optical activity. The model consists of two anisotropic atoms, each having polarizability α. It is shown that when there is an assembly of such models, the refractive indices for right and left circular light are different, which means that the medium possesses optical rotatory power. By taking α to be complex in the vicinity of an optically active absorption band, the main features of Cotton effect or circular dichroism have also been explained.

Molecular statistical theory of nematic liquid crystals. II. Relation between elasticity and orientational order

Abstract: A relationship is derived between curvature, elasticity and orientational order in nematic liquid crystals on the basis of the molecular statistical theory developed in Part I. Calculations show that the elastic moduli of p-azoxyphenetole should be greater than those of p-azoxyanisole, in quantitative agreement with the values reported by the Orsay Group. The theoretical temperature variation of the elastic moduli is also in accord with the available data.

Structural characteristics of some metallo-organic discogens

Abstract: We have recently analysed the crystal and molecular structures of six metalloorganic13; discogens with substituted {J-diketone ligands. The molecules consist of a rigid 11 atom core and a fringe made up of four phenyl rings substituted with13; alkyl/alkoxy chains. In complex (i),with four octyloxy chains, there are four oxygen atoms around the core. Complex (ii) is asymmetrically substituted with two13; heptyloxy and two heptyl chains and therefore has two oxygen atoms and complexes (iii) to (vi)have only alkyl chains and hence no oxygen atoms around the core. The metal atom used for coordination has been chosen as Cu/Pd/Ni. Determination of the crystal and molecular structures of these discogens has led to the identification of the following similarities: (1) All the six discogens crystallize in the triclinic space group PI. The recurrence of the space group may be correlated with the structural requirements for efficient packing of the molecules in the crystal lattice. (2) The coordination around the metal atom is square planar. (3) The 11 atom core is only nearly planar. (4)The phenyl rings and the chains are tilted with respect to the core. (5) The molecular conformation in the crystal confers a nearly13; rectangular shape to these discogens. (6)The chains are fully extended in an ail trans conformation. (7) The molecular arrangement is tilted columnar except for the13; crystal structure of complex (ii).

Handbook of Optical Materials

Abstract: 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

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

Abstract: 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.

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

Abstract: 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.