Bachcha Singh

Bio: Bachcha Singh is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Mesophase & Liquid crystal. The author has an hindex of 13, co-authored 89 publications receiving 545 citations.

Studies on 4-(2-thiazolyl)-1-(2,6-diacetylpyridine)thiosemicarbazone complexes of some bivalent metal ions

Abstract: Complexes of 4-(2-thiazolyl)-1-(2,6-diacetylpyridine)-thiosemicarbazone, H2C3NSCNH(S)NHNCMeC5H3N-C(O)Me (Htdaptsc) of the compositions [M(Htdaptsc)2Cl2] [M=MnII, CoII, NiII or ZnII] [M(Htdaptsc)Cl2] [M=ZnII, CdII or HgII] and [M(tdaptsc)2] [M=MnII, CoII, NiII, CuII, or ZnII] have been prepared and characterized by elemental analyses, molar conductance, magnetic susceptibility, electronic, e.s.r. and i.r. studies, and their stereochemistries are discussed.

Metal Containing Liquid Crystalline Polymers

Abstract: Design and synthesis of multifunctional single molecules stabilizing liquid-crystalline phases are significant from both fundamental research and application point of views. This task seems to be fulfilled, in part, by metallomesogenic polymers or metal containing liquid crystal polymers (MLCPs) due to two promising elements- liquid crystallinity and metal centre in a single molecular unit with the processability of polymers. The variety of readily available metals incorporated into these mesogenic polymers introduces new physical properties and, consequently, new applications in the field of polymeric materials traditionally based on a few elements (C, H, N, O, halogens, S, P). In recent years enormous growth has occurred in the field of science and technology of metallomesogenic polymers as evident from a large number of publications on these materials.

Synthesis, Characterization and Mesomorphic Properties of Unsymmetrical N-[4-(Alkoxy)-2-Hydroxybenzylidene]-N′-(4-Alkoxybenzylidene) Azines and Their Copper (II) Complexes

Abstract: A new series of mesogenic unsymmetrical azines, N-[4-(alkoxy)-2-hydroxybenzylidene]-N′-(4-n-alkoxybenzylidene) azines, ROC6H4CH˭N‒N˭CHC6H3OHOR, where R˭CmH2m+1 (m = 6, 8, 10, 12, and 14), and their copper (II) complexes has been synthesized. They were characterized by elemental analyses, Fourier transform infrared (FT-IR), 1H and 13C nuclear magnetic resonance (NMR) spectra, ultraviolet (UV)-visible, and magnetic susceptibility measurements. The copper (II) complexes are square planar. The mesomorphic properties of these compounds were investigated by differential scanning calorimetry and polarizing microscopy. The unsymmetrical azines with m = 6, 12, and 14 exhibit monotropic nematic, enantiotropic, and monotropic smectic A phases, whereas azines with m = 8 display enantiotropic nematic and m = 10 display both enantiotropic smectic A and nematic mesophases in the heating and cooling cycles. The copper (II) complexes of the azines are nonmesomorphic in nature with high clearing temperatures and displayed ...

Synthesis and Structural Studies of 1,5-Diphenyl 2-S-Benzyl ISO-4-Thiobiuret Complexes With Some Bivalent Metal Ions

Abstract: The complexes of 1,5-diphenyl 2-S-benzyliso-4-thiobiuret, (DPBTB, L) of the empirical compositions VOL2SO4, ML2CL2 [M = Co(II), Zn(II), Ca(II), Hg(II)], ML4CI2 [M = Ni(II), Cu(II)] and M(L-H)2 [M = Co(II), Ni(II), Cu(II)] have been prepared and characterized on the basis of analytical data, molar conductance, molecular weight, magnetic susceptibility, electronic, esr, infrared and X-ray diffraction measurements. Some of these complexes have been tested for antifungal activity.

Structural and physical correlations in the biological properties of transition metal heterocyclic thiosemicarbazone and S -alkyldithiocarbazate complexes

Abstract: The nature of metal complexes of heterocyclic thiosemicarbazones reported in the literature through 1989 have been reviewed with an emphasis on variations in stoichiometry and stereochemistry. A brief introduction is followed by a survey of the biological activity of the uncomplexed thiosemicarbazones. Next is a section on the chemical nature of thiosemicarbazones including a discussion of preparative methods, modes of coordination and isomerism. This is followed by a discussion of structural information and biological activity of the iron(III), iron(II), copper(II), cobalt(III), cobalt(II) and nickel(II) complexes of heterocyclic thiosemicarbazones. Short sections on the biological activity of other chelating thiosemicarbazones and metal complexes are also included.

Low-Temperature In Situ Amino Functionalization of TiO2 Nanoparticles Sharpens Electron Management Achieving over 21% Efficient Planar Perovskite Solar Cells.

Abstract: Titanium oxide (TiO2 ) has been commonly used as an electron transport layer (ETL) of regular-structure perovskite solar cells (PSCs), and so far the reported PSC devices with power conversion efficiencies (PCEs) over 21% are mostly based on mesoporous structures containing an indispensable mesoporous TiO2 layer. However, a high temperature annealing (over 450 °C) treatment is mandatory, which is incompatible with low-cost fabrication and flexible devices. Herein, a facile one-step, low-temperature, nonhydrolytic approach to in situ synthesizing amino-functionalized TiO2 nanoparticles (abbreviated as NH2 -TiO2 NPs) is developed by chemical bonding of amino (-NH2 ) groups, via TiN bonds, onto the surface of TiO2 NPs. NH2 -TiO2 NPs are then incorporated as an efficient ETL in n-i-p planar heterojunction (PHJ) PSCs, affording PCE over 21%. Cs0.05 FA0.83 MA0.12 PbI2.55 Br0.45 (abbreviated as CsFAMA) PHJ PSC devices based on NH2 -TiO2 ETL exhibit the best PCE of 21.33%, which is significantly higher than that of the devices based on the pristine TiO2 ETL (19.82%) and is close to the record PCE for devices with similar structures and fabrication procedures. Besides, due to the passivation of the surface trap states of perovskite film, the hysteresis of current-voltage response is significantly suppressed, and the ambient stability of devices is improved upon amino functionalization.

Nanomaterial-based optical sensors for mercury ions

Abstract: As one of the most toxic heavy metals, mercury ion (Hg 2+ ) has become a concern focus for its severe threats to environment and human health. As a result, it is of great importance to develop novel methods to realize the recognition and quantification of Hg 2+ . The past decades witness the development of nanomaterial-based optical sensors for Hg 2+ detection, showing the benefits of simplicity, rapidity, high sensitivity and selectivity, and cost-effectiveness. The reported methods have allowed the detectability down to nanomolar concentrations or much lower levels, and proved their practical applications for detecting and quantifying Hg 2+ in synthetic solutions or natural water samples. In this review, we summarize the published innovations in nanomaterial-based optical sensors for the detection of Hg 2+ according to different sensing strategies, including colorimetric, fluorescent and surface enhanced Raman scattering detection. Moreover, some challenges and significant attempts related to these methods are also discussed.