Pundlik Rambhau Bhagat

Recent developments of metal N-heterocyclic carbenes as anticancer agents

Metal based anticancer drugs have demonstrated their crucial role in preventing all types of cancers whereas their effectiveness is selective with respect to the cancer cells rather than the normal cells. Recently metal N-heterocyclic carbenes have established their selective performance for cancer cells excluding normal healthy cells based on which they are widely utilised for targeting cancer cells specifically which leads to cell death or cell growth inhibition. This is mainly due to their ionic character which helps them to localise in cancer cells with the help of enhanced expression of Organic Cation Transporters (OCT). Also their unique mechanism of action involving DNA binding, less recognizable by DNA repair machinery, mitochondria targeting gives them a new area for anticancer drug development. This review summarises the medicinal as well as pharmacological approach to the anticancer properties of metal NHC complexes.

Highly dispersible graphene oxide reinforced polypyrrole/polyvinyl alcohol blend nanocomposites with high dielectric constant and low dielectric loss

In the present study, we report the fabrication and characterizations of flexible dielectric nanocomposites consisting of water soluble polypyrrole (WPPy)/polyvinyl alcohol (PVA)/graphene oxide (GO) at different GO loadings (0.5–3 wt%). The WPPy/PVA/GO nanocomposites were characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-vis spectroscopy (UV), X-ray diffraction (XRD), thermogravimetric analysis (TGA), polarized optical microscopy (POM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). FTIR studies indicate the strong chemical interaction between GO and polymer systems. SEM results confirm that GO was homogeneously dispersed within the polymer matrix. The nanocomposites exhibit significant enhancement in the dielectric constant with low dielectric loss values as a function of GO loading which resulted from the fine dispersion of GO in the polymer matrix. The dielectric constant increases from (e = 27.93, 50 Hz, 150 °C) for WPPy/PVA (50/50) blend to (e = 155.18, 50 Hz, 150 °C) for nanocomposites with 3 wt% GO loading and the dielectric loss increases from (tan δ = 2.01, 50 Hz, 150 °C) for WPPy/PVA (50/50) blend to (tan δ = 4.71, 50 Hz, 150 °C) for nanocomposites with 3 wt% GO loading. Thus, these high-κ WPPy/PVA/GO nanocomposites are potential flexible high-performance dielectric materials for electronic devices such as high-frequency capacitors or embedded capacitors.

Influence of K2CrO4 Doping on the Structural, Optical and Dielectric Properties of Polyvinyl Alcohol/K2CrO4 Composite Films

ABSTRACT Polyvinyl alcohol/potassium chromate (K2CrO4) composite films were prepared by solution casting technique using distilled water as a solvent, and were further investigated using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction, thermogravimetric analysis, optical microscopy, scanning electron microscopy, and dielectric measurements. Microscopic studies reveal that K2CrO4 was homogenously mixed with polyvinyl alcohol matrix due to interfacial interaction between polyvinyl alcohol and K2CrO4. The composite films showed very high dielectric constant and relatively low dielectric loss. Hence, such composite materials with improved dielectric properties could be useful for fabrication of electrical charge storage device. GRAPHICAL ABSTRACT

A novel amino acid functionalized ionic liquid promoted one-pot solvent-free synthesis of 3,4-dihydropyrimidin-2-(1H)-thiones

An environmentally benign, cheap and reusable L-amino acid functionalized ionic liquid [L-AAIL]/AlCl3 was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-thione derivatives in good to excellent yield under solvent-free condition. Compared with the classical Biginelli reactions, this method consistently enjoys the advantages of mild reaction conditions, easy work-up, and short reaction time. These one-pot three-component Biginelli products could be separated easily from the catalyst–water system, and the catalyst could be reused at least five times without noticeably reducing catalytic activity.

Polymer-supported benzimidazolium based ionic liquid: an efficient and reusable Brønsted acid catalyst for Biginelli reaction

A polymer-supported benzimidazolium based ionic liquid (PSBIL) was synthesized by reaction of poly(vinylbenzyl chloride) and benzimidazole followed by ring opening of 1,4-butane sultone and acidification with sulphuric acid. The resulting Bronsted acid heterogeneous organocatalyst is very competent for the Biginelli reactions under mild conditions in high yields of 3,4-dihydropyrimidine-2(1H)-one/thiones (DHPMs). Since poly(vinylbenzyl chloride) makes the catalyst bed, the sulphonic acid catalyst will have high loading level of acidic groups compare to other heterogeneous acid catalysts. In spite of conventional heterogeneous ionic liquid catalysts, current PSBIL shows thermal stability up to 334 °C and recyclability up to 5 cycles. This PSBIL signifies a new class of heterogeneous catalyst which is particularly noticeable in green chemistry. The present protocol highlights the easy separation of products without further purification. Furthermore, the effectiveness of this protocol has demonstrated by synthesis of mitotic Kinesin EG5 inhibitor, “Monastrol” under optimized conditions.

A bioinspired ionic liquid tagged cobalt-salophen complex for nonenzymatic detection of glucose

The development of efficient and cost effective nonenzymatic biosensors with remarkable sensitivity, selectivity and stability for the detection of biomolecules, especially glucose is one of the major challenges in materials- and electrochemistry. Herein, we report the design and preparation of nonenzymatic biosensor based on an ionic liquid tagged cobalt-salophen metal complex (Co-salophen-IL) immobilized on electrochemically reduced graphene oxide (ERGO) for the detection of glucose via an electrochemical oxidation. The bioinspired Co-salophen-IL complex has been synthesized and immobilized on ERGO, which was previously deposited on a screen printed carbon electrode (SPE) to form the Co-salophen-IL/ERGO/SPE nonenzymatic biosensor. The electrochemical behaviour of this modified electrode was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Notably, the Co-salophen-IL/ERGO/SPE biosensor exhibited excellent electrocatalytic activity towards glucose oxidation in 0.1M NaOH, based on which an amperometric sensor has been developed. The modified electrode has shown prominent performance towards glucose detection over a wide linear range from 0.2µM to 1.8mM with a detection limit and sensitivity of 0.79µM and 62µAmM-1 respectively. The detection was carried out at 0.40V and such a less working potential excludes the interference from the coexisting oxidizable analytes. The role of Co-salophen, IL and ERGO in the electrocatalytic activity has been systematically investigated. Furthermore, the biosensor demonstrated high stability with good reproducibility.

Designing a sulphonic acid functionalized benzimidazolium based poly(ionic liquid) for efficient adsorption of hexavalent chromium

Herein, the facile synthesis of sulphonic acid functioned benzimidazolium based poly(ionic liquid) (SBPIL) is reported for the first time and we investigated its efficacy towards the removal of Cr(VI). SBPIL was synthesized by co-polymerization of styrene and 1-(4-vinylbenzyl)-1H-benzimidazole, followed by reaction with 1,4-butane sultone and subsequent functionalization with sulphonic acid. The prepared SBPIL was characterized by elemental analysis, FT-IR and NMR spectra, SEM-EDAX, TGA and X-ray diffraction techniques. The batch adsorption method was applied for examining the Cr(VI) removal and also to investigate the kinetics and thermodynamics of adsorption. The adsorption process was correlated with the Langmuir and Freundlich adsorption isotherm models and the Langmuir adsorption capacity was estimated to be 40.81 mg g−1. The thermodynamic study concluded that the adsorption process is exothermic and spontaneous and the adsorption kinetics were well fitted by a pseudo-second order kinetic model. Investigation on the effect of counter ions on the adsorption process revealed that Cl− ions had no influence on the adsorption, whereas SO42− and NO3− were found to affect the Cr(VI) adsorption by 3.6% and 19.5% respectively. SBPIL exhibited excellent stability and recyclability and the adsorbent could be easily regenerated using 1 M H2SO4 and examined for Cr(VI) removal from successive batches.

The Efficient Palladium-Catalyzed Selective t Synthesis of Benzenesulfonic Acids

Abstract Palladium-catalyzed synthetic methodology has been developed for the synthesis of 2-aminobenzenesulfonic acids from benzothiazoles in good to excellent yields using chloramine-B in alkaline (pH 12) acetonitrile/water (1:1) at 80 °C.

Biopolymer Composites With High Dielectric Performance: Interface Engineering

In recent years, there is a growing interest in studying the dielectric behavior of biopolymer composites due to their potential application as a dielectric material in various electronic devices such as microchips, transformers, and circuit boards. Conducting electroactive polymer composites have also been investigated for various potential applications which include biological, biomedical, flexible electrodes, display devices, biosensors, and cells for tissue engineering. In this chapter, the preparation and dielectric behavior of various biopolymer composites is presented. These biopolymer composites generally consist of nanoscale metal nanoparticles and carbon-based nanofillers such as carbon nanotubes, graphene, graphene oxide (GO), etc., dispersed into the polymer matrix. The physical and chemical properties of these fillers and their interactions with polymers have a significant effect on the microstructure and the final properties of nanocomposites. The biopolymer composites with excellent dielectric properties show great promise as an energy storage dielectric layer in high-performance capacitor applications such as embedded capacitors. This chapter highlights some of the examples of such biopolymer composites; their processing and dielectric behavior will be discussed in detail.

Novel and efficient method for esterification catalyzed by 1-glycyl-3-methyl imidazolium chloride-iron (III) complex

Abstract1-Glycyl-3-methyl imidazolium chloride-iron (III) complex [[Gmim]Cl–Fe(III)] was found to be a heterogeneous catalyst for an efficient and greener solvent free synthesis of esters by the condensation of carboxylic acids and alcohols with excellent yield at ambient temperature. This operation formulates very interesting, ecological perspective due to simple reaction condition, isolation, and purification of products. In addition, this method features reusability of catalyst, reduced waste, thus making new protocol more environmentally suitable whilst no catalyst leaching was observed.