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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.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors developed a simple, sensitive, label-free and real time detection method for mercuric ions (Hg2+) in water using liquid crystals (LCs).
Abstract: We developed a simple, sensitive, label-free and real time detection method for mercuric ions (Hg2+) in water using liquid crystals (LCs). In this system, newly synthesized amphiphilic potassium N-methyl-N-dodecyldithiocarbamate (MeDTC) was doped in 4-cyano-4′-pentyl biphenyl (5CB) LC, which align LC molecules at aqueous interface and polar head group of the amphiphile acts as mecuric ion specific chelating ligand. When this sensor system was incubated in the aqueous solution containing Hg2+ ions, a dark to bright transition of the image of LCs was observed. This was caused due to rapid and stable complex formation between dithiocarbamate chelating group of MeDTC with Hg2+ ions at aqueous interface, which disrupted the orientation of LCs giving bright texture. The limit of detection of the system for aqueous Hg2+ ion is 0.5 μM. This sensor did not respond to other metal ions like Pb2+, Cd2+, Cu2+, Zn2+, Na+, Mg2+ and Ca2+, which are common environmental interference in water. We also demonstrated that this sensor is capable of detecting Hg2+ ions in real water samples (tap water). The very simple and effective procedure reported here should facilitate the development of real time, portable and reliable LC based sensor for mercury pollution control.

58 citations

Journal ArticleDOI
TL;DR: In this article, metal(II) complexes of N-(thiophene-2-carboxamido)salicylaldimine (H2TCS) of types M(HTCS)-2Cl2 [M = Ni, Cu, Zn, Co, Ni and Zn] have been prepared and different modes of chelation of the ligand and the stereochemistry of the complexes are discussed.

38 citations

Journal ArticleDOI
TL;DR: Spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed and the complex is found to be rigid and stable in its monomeric form at very low concentrations.

24 citations

Journal ArticleDOI
TL;DR: In this paper, a series of Schiff base calamitic liquid crystal; methyl 4-(4′-nalkoxybenzylideneamino)benzoate (MABAB), H2n+1C n OC6H4C(H)=NC6H 4COOCH3 (n = 6, 8, 10, 12, 14, 16) has been synthesized and characterised by elemental analyses, Fourier transform infrared spectroscopy (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectrograph
Abstract: A new series of Schiff base calamitic liquid crystal; methyl 4-(4′-n-alkoxybenzylideneamino)benzoate (MABAB), H2n+1C n OC6H4C(H)=NC6H4COOCH3 (n = 6, 8, 10, 12, 14, 16) has been synthesised and characterised by elemental analyses, Fourier transform infrared spectroscopy (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy. The mesomorphic properties of these compounds were studied by differential scanning calorimetry (DSC) and polarising optical microscopy (POM). All members of the series exhibit enantiotropic smectic A (SmA) mesophase. Temperature-dependent micro-Raman study of one of the members, MABAB-10 has been employed to identify phase transitions and the molecular rearrangement therein. Analysis of Raman marker bands; C–H in-plane bending, C–C stretching of phenyl rings and –C(H)=N– linking group of core confirms the transitions clearly as observed through DSC and POM. An in situ Raman measurement of C–H in-plane bending mode has also been performed to visualise the molecular changes m...

22 citations

Journal ArticleDOI
TL;DR: The mesomorphic properties of newly synthesized homologous series of calamitic liquid crystals containing ester and Schiff base groups as linker and Raman marker bands of phenyl rings, Schiff base and ester groups confirm the phase transitions.

20 citations


Cited by
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Journal ArticleDOI
01 Jan 1889

595 citations

Book ChapterDOI
01 Jan 1991
TL;DR: 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 as discussed by the authors.
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.

435 citations

Journal ArticleDOI
TL;DR: 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 TiO1 NPs.
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.

197 citations

Journal ArticleDOI
TL;DR: In this article, the authors summarized 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.
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.

191 citations

Journal ArticleDOI
TL;DR: The experimental results suggest that the adsorption efficiency of DOX is dominated by the strong complexation, electrostatic interactions between DOX molecules and the Cu-BC samples, which hold the significant potential for enhancing the effectiveness to remove DOX from water.

146 citations