Sachin Kumar Singh

Bio: Sachin Kumar 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 11, co-authored 26 publications receiving 274 citations. Previous affiliations of Sachin Kumar Singh include Indian Institute of Technology Guwahati & Schiller International University.

Effect of alkoxy chain density on the mesogenic properties of aroylhydrazone based liquid crystals: synthesis, characterisation, photophysical and gelation behaviour

Abstract: Three series of ester linkage containing aroylhydrazone based compounds have been synthesised where density and length of alkoxy chains are varied sequentially at ester end, keeping amide end of th...

Mesomorphic and DFT studies of terminal ester containing salicylaldimines and their copper (II) complexes

Abstract: In this article, we report synthesis and characterization of a novel homologous series of butyl 4-(4′-(alkoxy)-2-hydroxybenzylideneamino)benzoates, CnLH (n = 6, 8, 10, 12, 14, 16) and their...

Observation of exceptional ‘de Vries-like’ properties in a conventional aroylhydrazone based liquid crystal

Abstract: Smectic liquid crystals with ‘de Vries-like’ properties are characterized by a maximum layer contraction of ≤1% upon transition from the non-tilted SmA phase to the tilted SmC phase. A straight alkoxy chain-terminated conventional aroylhydrazone based liquid crystal N-(4-(tetradecyloxy)-2-hydroxybenzylidene)-4′((4′′(hexadecyloxy)benzyl)oxy)benzohydrazide (BSac-1416) undergoes the SmA–SmC phase transition with a maximum layer contraction of 0.65%. The merits of the de Vries reduction factor, i.e. R and f values for this mesogen, are comparable to, or even lower than, those reported for established perfluorinated and polysiloxane-terminated bona fide de Vries-like materials.

Synthesis, Characterization, and Mesomorphic Investigations of Calamitic Liquid Crystals – methyl 4-(4′-(alkoxy)-2-hydroxybenzylideneamino) benzoates and Their Copper(II) and Nickel(II) Complexes

Abstract: A new series of Schiff's base mesogenic ligands with a polar methyl ester as an end group, methyl 4-(4′-(alkoxy)-2 hydroxybenzylideneamino) benzoates, CnLH (n = 6, 8, 10, 12, 14, 16) and their copper(II) and nickel(II) complexes have been synthesized They were characterized by elemental analyses, Fourier transform infrared (FT-IR), 1H and 13C nuclear magnetic resonance, and UV-VIS spectroscopy The mesomorphic properties of these compounds were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) The ligands exhibit an enantiotropic SmA mesophase with a high-temperature range and thermal stability The square planar copper(II) complexes show enantiotropic SmA mesophase, but the nickel(II) complexes are nonmesogenic in nature The thermal stability of the compounds was also determined by thermo gravimetric analyses Density functional theory (DFT) calculations were performed using GAUSSIAN-03 program at B3LYP level to obtain the stable electronic structure of th

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.

Portable and smart devices for monitoring heavy metal ions integrated with nanomaterials

Abstract: With increasing concerns of ecological environment, safe drinkable water and healthy food, the detection for heavy metal ions (HMIs) becomes an attractive research field. On the basis of optical, electrical and other signals from nanomaterials, many interesting methods and portable devices for detection of HMIs are growing flourishingly. In this review, we focus on the portable and smart devices integrated with nanomaterials for monitoring HMIs. The interesting design of the miniaturization, portability, and commercialization of HMIs detection devices are summarized and introduced comprehensively.