01609nas a2200193   4500008004100000022001400041245011900055210006900174260012500243300001100368490000700379520078800386100001601174700002001190700002101210700002301231700003001254856013101284       2010                        eng d  a0003-695100aEnhancement of anisotropic conductivity, elastic, and dielectric constants in a liquid crystal-gold nanorod system0 aEnhancement of anisotropic conductivity elastic and dielectric c  aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScOCT  a1519130 v973 a<p>We report electrical conductivity (sigma), dielectric constant (epsilon) and the elastic constant measurements in a nematic liquid crystal (LC) doped with small concentrations of gold nanorods. This LC-nanoparticle complex, shows not only orders of magnitude higher sigma, but also stabilizes its anisotropy. The epsilon data suggests an increased ordering in the nematic phase, and an improved antiparallel correlation of the molecules in the isotropic phase. Surprisingly, an anisotropic enhancement of the Frank elasticity is also seen. We suggest a possible electro/magnetomechanical conductivity switch and also provide explanations based on the aspect ratio of the nanoparticles vis-a-vis the LC molecules. (c) 2010 American Institute of Physics. [doi:10.1063/1.3499744]</p>1 aSridevi, S.1 aPrasad, Krishna1 aNair, Geetha, G.1 aD'Britto, Virginia1 aPrasad, Bhagavatula L. V.  uhttps://library.ncl.res.in/content/enhancement-anisotropic-conductivity-elastic-and-dielectric-constants-liquid-crystal-gold-002442nas a2200277   4500008004100000022001400041245010600055210006900161260010600230300001200336490000800348520141600356653003001772653001701802653001401819653001601833653002201849100002401871700003001895700001701925700002901942700002101971700002001992700002402012856012802036       2016                        eng d  a0277-538700aPhotoluminescent tetrahedral d(10)-metal Schiff base complexes exhibiting highly ordered mesomorphism0 aPhotoluminescent tetrahedral d10metal Schiff base complexes exhi  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcFEB  a150-1580 v1053 a<p>A series of four-coordinate d(10)-metal complexes of the type [ML2] {M = Zn, Cd, Hg; L = 4-nitro-2-((octadecylimino)methyl)phenol}, incorporating a new N-alkylated bidentate [N,O]-donor salicylaldimine Schiff base ligand, has been synthesized and characterized by elemental analyses, FT-IR, UV-Vis, H-1 NMR and FAB-mass spectroscopies. The ligand is non-mesomorphic and devoid of any photoluminescence. The zinc(II) and cadmium(II) complexes displayed highly ordered mesophases reminiscent of soft crystals. The phases have been characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) studies. The complex of mercury(II) decomposed prior to melting. An orthogonal symmetry with a `herringbone' array for the zinc complex and a primitive triclinic symmetry (p(1)) for the cadmium complex, respectively, has been proposed. The complexes exhibited fluorescence at room temperature, both in the solution and in the solid state, with emission maxima in the blue region. Density functional theory (DFT) calculations carried out using the GAUSSIAN 09 program at the B3LYP level revealed a distorted tetrahedral geometry around the metal center in all the complexes. Natural bond orbital (NBO) analysis suggested appreciable charge transfer from the ligand to the metal center in the complexes. (C) 2015 Elsevier Ltd. All rights reserved.</p>10aDensity functional theory10aLuminescence10aMesophase10aSchiff base10aX-ray diffraction1 aChakraborty, Sutapa1 aPurkayastha, Debraj, Dhar1 aDas, Gobinda1 aBhattacharjee, Chira, R.1 aMondal, Paritosh1 aPrasad, Krishna1 aRao, D., S. Shankar  uhttps://library.ncl.res.in/content/photoluminescent-tetrahedral-d10-metal-schiff-base-complexes-exhibiting-highly-ordered-102808nas a2200277   4500008004100000022001400041245012400055210006900179260000900248300001100257490000800268520186200276653002402138653001802162653001802180653001602198653002602214100002102240700002402261700002202285700002302307700001902330700003002349700002002379856013102399       2020                        eng d  a0167-732200aInfluence of gold nanorods on the structure and photonic bandgap in a twist grain boundary phase with smectic C* blocks0 aInfluence of gold nanorods on the structure and photonic bandgap  cFEB   a1121170 v2993 a<p>We describe the first report of the influence of gold nanorods (GNR) on the induced twist grain boundary smectic C* (TGBC*) phase in a binary mixture of achiral bent-core and chiral linear liquid crystals. The GNR concentration-dependent phase diagram of these nanocomposites shows that the thermal range of this twist grain boundary phase having smectic C* blocks phase increases by 50% for an intermediate composition compared to that for the host binary mixture without nanorods. The inclusion of the nanorods is seen to have substantial effect on the structural and photonic bandgap features of the TGBC* phase. For example, the helical periodidty gets altered in all the three dimensions: while those within the block undergo a huge increase, the one which is orthogonal to the blocks, shrinks. The spacing of the square grid pattern arising normal to the TGB helix direction increases for the nanocomposites getting even doubled for a certain composition, a feature evidenced by optical microscopy as well as optical diffraction. Xray diffraction clearly brings out the feature that the presence of GNR alters the thermal character of the transition between the TGBC* and the cholesteric phase. Quantitative analysis of the data indicates that the system would remain in the vicinity of a possible tricritical point, a behavior having wider ramifications to understand the underlying critical phenomenon. Based on the experimental observations, and capturing the essence of the reported adaptive defect core targeting mechanism we propose a model wherein GNRs get confined in the grain boundary region. This feature offers a potential to have periodic and anisotropic plasmonic structure arising out of the synergetic interactions between the metal nanorod and the twisted grain boundary structure. (C) 2019 Elsevier B.V. All rights reserved.</p>
10a3D photonic bandgap10aGold nanorods10aInduced phase10aTGBC* phase10aTricritical phenomena1 aSahoo, Rajalaxmi1 aRao, D., S. Shankar1 aHiremath, Uma, S.1 aYelamaggad, V., C.1 aShinde, Pravin1 aPrasad, Bhagavatula L. V.1 aPrasad, Krishna  uhttps://library.ncl.res.in/content/influence-gold-nanorods-structure-and-photonic-bandgap-twist-grain-boundary-phase-smectic-c02223nas a2200241   4500008004100000022001400041245010900055210006900164260000900233490000700242520136600249653003501615653001601650653001201666653002401678653002501702100001501727700002801742700003501770700002001805700003101825856012501856       2025                        eng d  a1439-423500aTailoring of rheological properties through hydrophobic interactions in silica-based liquid crystal gels0 aTailoring of rheological properties through hydrophobic interact  cNOV 0 v263 a<p>
	Modification of the intrinsic hydrophilic character of the pristine silica nanoparticles (SiNP) decorated with silanol moieties into a hydrophobic state has been of substantial interest, owing to the amenability to gelation of desirable liquids. Many reports exist on composites of SiNP with liquid crystals (LCs), an epitome of anisotropic soft matter. The fumed SiNP, unlike its precipitated counterpart, has been the preferred variety. A family of colloidal gel systems is reported, consisting of precipitated SiNP in a nematic LC, formed by substituting some native silanols with methyl, butyl, or dodecane chains. Detailed steady state and oscillatory rheological measurements are performed, along with analyses using the soft glass and other viscoelastic models. The study demonstrates that the sophisticated modified fractional models, Kelvin-Voight and Maxwell, proposed for generalized viscoelastic behavior of soft materials, are quite successful in describing these nematic gels as well. The observed nontrivial relationship between the ligand length and the strength of the gel network is elucidated on the basis of a judicious combination of the van der Waals, hydrogen bonding, and hydrophobic interactions, leading to a detailed understanding of the viscoelastic behavior of the composites and the influence of SiNP surface chemistry.</p>
10afractional viscoelastic models10aHydrophobic10anematic10arheological studies10asilica nanoparticles1 aSumana, S.1 aChakrabortty, Pratyasha1 aKarumuthil, Subash, Cherumanni1 aPrasad, Krishna1 aPrasad, Bhagavatula, L. V.  uhttps://library.ncl.res.in/content/tailoring-rheological-properties-through-hydrophobic-interactions-silica-based-liquid