Doddamane S. Shankar Rao

Bio: Doddamane S. Shankar Rao is an academic researcher from Liquid Crystal Institute. The author has contributed to research in topics: Liquid crystal & Mesophase. The author has an hindex of 19, co-authored 30 publications receiving 910 citations.

A Low‐Molar‐Mass, Monodispersive, Bent‐Rod Dimer Exhibiting Biaxial Nematic and Smectic A Phases

Abstract: A "peelable banana" is formed when a bent-core molecule is linked to a rodlike mesogen through a flexible aliphatic spacer. This is an appropriate description of this novel low-molar-mass organic system, which displays a transition from a biaxial nematic (N b ) phase to a biaxial smectic A phase. The illustration gives a schematic representation of the dimeric molecules in the N b phase as well as the corresponding textural and conoscopic patterns obtained.

Blue Phase, Smectic Fluids, and Unprecedented Sequences in Liquid Crystal Dimers

Abstract: Several optically pure liquid crystal dimers with strong molecular chirality, synthesized by covalently linking an achiral bent-core unit with a bulky pro-mesogenic rodlike chiral entity through a flexible spacer, display amorphous blue phase, smectic phases, and new sequences.

Formation of Highly Luminescent Supramolecular Architectures Possessing Columnar Order from Octupolar Oxadiazole Derivatives: Hierarchical Self‐Assembly from Nanospheres to Fibrous Gels

Abstract: The synthesis and study of the liquid crystalline, photophysical, and aggregation behavior of novel octupolar oxadiazole derivatives are reported. These molecules formed columnar mesophases at elevated temperatures which transformed into a glassy state at ambient temperatures wherein the columnar order was retained. Their spontaneous concentration dependent hierarchical self-assembly from spheres to fibrous gels has been investigated using TEM, SEM, and XRD. Retention ofthe hexagonal columnar (Col h ) order was also observed in the fibrous aggregates. Concentration dependent luminescence spectral studies indicated that the change in morphology from spheres to fibrous aggregates was associated with a shift in chromophore packing from predominantly H-type to J-type aggregates. Time resolved anisotropic investigations revealed that the columnar stacking of molecules in the aggregated state provided a pathway for excitation energy migration to the lower energy J-traps.

Self-Assembly of C3h and Cs Symmetric Keto-enamine Forms of Tris(N-salicyl-ideneanilines) into Columnar Phases: A New Family of Discotic Liquid Crystals

Abstract: A new class of discotic liquid crystals derived from tris(N-salicylideneanilines) existing exclusively in their C3h and Cs keto-enamine tautomeric forms is reported. These compounds self-assemble to form columnar liquid crystalline phases with a small core−core separation as evidenced by X-ray diffraction studies.

A novel family of salicylaldimine-based five-ring symmetric and non-symmetric banana-shaped mesogens derived from laterally substituted resorcinol: synthesis and characterization

Abstract: We present the results of our extensive investigations into the phase behavior of several “robust” five-ring banana-shaped compounds. Six homologous series of either symmetric or non-symmetric bent-core molecules, comprising a laterally substituted 1,3-phenylene ring as the central unit covalently linked to thermally and hydrolytically stable rod-like salicylaldimine segments have been synthesized and evaluated for their mesomorphism. The mesophases have been characterized by optical, calorimetric, X-ray diffraction and electro-optical studies. With a methyl group, polarizable chlorine atom or the more polarizable nitro group as the lateral substituent(s) and terminal alkoxy tails of varying length, the structure–property correlation has been determined. Our study clearly demonstrates that these materials, as predicted, display a different behavior compared to the corresponding compounds without the lateral substituents. The phase behavior shows a critical dependence on the nature and position of the lateral substituent(s). The study includes a comparison with the phase behavior of some of the other types of banana-shaped compounds.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

Abstract: In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping ...

Mitsunobu and Related Reactions: Advances and Applications

Abstract: 10. Patented Literature 2616 10.1. Esterification 2616 10.2. Ether Formation 2619 10.2.1. Etherification without Cyclization 2619 10.2.2. Etherification with Cyclization 2624 10.3. N-Alkylation 2625 10.4. Other Reactions 2627 11. Summary and Outlook 2628 12. Note Added in Proof 2628 13. Abbreviations Used in This Review 2629 14. Acknowledgments 2629 15. Supporting Information Available 2630 16. References 2630

Bent-core liquid crystals: polar order, superstructural chirality and spontaneous desymmetrisation in soft matter systems

Abstract: An overview on the recent developments in the field of liquid crystalline bent-core molecules (so-called banana liquid crystals) is given. After some basic issues, dealing with general aspects of the systematisation of the mesophases, development of polar order and chirality in this class of LC systems and explaining some general structure–property relationships, we focus on fascinating new developments in this field, such as modulated, undulated and columnar phases, so-called B7 phases, phase biaxiality, ferroelectric and antiferroelectric polar order in smectic and columnar phases, amplification and switching of chirality and the spontaneous formation of superstructural and supramolecular chirality.