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 complexes of cobalt(ii), nickel(ii), copper(ii), and cadmium(ii) with acetophenone and 4-hydroxyacetophenone oxaloyldihydrazones

Abstract: The complexes [M(L1)nCl2] and [Cu(L2)SO4(H2O)2] [M= Co(II), Ni(II), Cu(II) and Cd(II); L1=acetophenone oxaloyldihydrazone (CONHN═C(CH3)C6H5)2, n=2 and L2=4-hydroxyacetophenone oxaloyldihydrazone (CONHN= C(CH3)C6H4OH–4)2 have been prepared. Analytical, molar conductance, magnetic susceptibility, electronic, ESR and NMR spectral data have been used to investigate the structure and bonding of the complexes. X-ray powder diffraction data indicate the shape and size of the unit cell of the copper(II) complex. Some of the complexes were screened against E. coli and Aspergillus niger for biological activity.

Synthesis, Characterization and Mesomorphic Properties of Aromatic Acid Dimers

Abstract: In this study, a new series of acid dimers, N-(4′-carboxybenzylidene)-4-alkoxybenzoyloxyaniline [(4′-HOOCC6H4CH˭N)-4-C6H4OCOC6H4OR, where R = CmH2m + 1 and m = 6, 8, 10, 12, 14, and 16], have been synthesized. The compounds have been characterized by elemental analyses and FTIR, UV-visible, 1H, and 13C NMR spectra. The mesomorphic properties of these acid dimers were studied by differential scanning calorimetry and polarizing optical microscopy. The mesomorphic nature of these compounds depends on hydrogen bonding and on the alkoxy chain length. The compounds with m = 6 and 8 show a characteristic enantiotropic nematic mesophase, whereas those with m = 12 and 14 exhibit monotropic behavior. The compounds with m =10 and 16 exhibit non-mesomorphic behavior.

Reaction of Coordinated Ligands. III. Synthesis and Characterization of Some Lanthanide Complexes of 2,6‐Diacetylpyridine‐2‐thenoylpicolinoyl Dihydrazone

Abstract: A new ligand, 2,6‐diacetylpyridine‐2‐thenoylpicolynoyl dihydrazone (H2dapthph), has been prepared. Complexes of the type [Ln(H2dapthph)Cl2]Cl (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) have been synthesized and characterized by analytical, molar conductance, FAB mass, IR, NMR, electronic and emission spectral data. The bonding sites of the hydrazone are deduced from IR and NMR spectra and the ligand is found to bond to the metal ion in a hexadentate fashion. Electronic spectra of the complexes have been analyzed and the spectral parameters viz. nephelauxetic ratio (β), bonding parameter (b1/2), Sinha parameter (δ%), angular overlap covalency (η) and oscillator strength (P) were calculated and discussed. The symmetry around the Ln(III) ions is indicated from emission spectra of the Eu(III) complex.

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.