Samuel Vasanthkumar

NaOH/Et3N-Promoted Stereoselective One-Pot Synthesis of α-Diazo Oxime Ethers via Diazo Transfer Reaction

Abstract For the first time, we have observed a combined effect of two bases NaOH/Et3N to promote the diazo transfer reaction of β-oximino esters. This unusual synergistic effect has been employed to obtain α-diazo oxime ethers directly from β-keto esters by one-pot process. This method is simple and cost-effective and the reagents are readily available. GRAPHICAL ABSTRACT

Cu(OTf)2-catalyzed synthesis of highly substituted 1-methoxy imidazoles via (3 + 2) cycloaddition between imino carbenoids and nitriles

ABSTRACT A Cu(OTf)2-catalyzed simple synthetic approach for highly substituted 1-alkoxy imidazole has been described. This protocol involves (3 + 2) cycloaddition of oximino carbenoids with organo nitriles. This method has wide substrate scope and tolerates alkyl, aryl, substituted aryl, vinyl, and ester nitriles. GRAPHICAL ABSTRACT

Synthesis of heterocyclic naphthoquinone derivatives as potent organic fluorescent switching molecules

Abstract Quinone is well known molecules for not only in the biological applications but which includes electrochemical and fluorescent applications too. In this paper we attempted to synthesize a series of 2-(4-amino-benzosulfonyl)-5H-benzo[b]carbazole-6,11-dione derivatives and these set of compounds were studied for their fluorescent switching properties. The title compounds were synthesized via Michael-like addition and followed by intramolecular C–C coupling. These compounds were studied for their fluorescent switching properties by using UV–vis, photoluminescence and cyclic voltagram techniques. Among all the molecules studied for their fluorescent switching properties the compounds 4a and 6a exhibited good fluorescent switching properties due to the presence of poor and strong electron withdrawing functional groups in the fourth position at the fluorophoric unit. All the synthesized compounds exhibited good fluorescent switching properties which were studied and confirmed by UV–vis, photoluminescence (PL) and cyclic voltagram (CV) techniques.

Synthesis, Characterization and Solvatochromic Studies Using the Solvent Polarity Parameter, ENT on 2-Chloro-3-Ethylamino-1,4-Naphthoquinone

AbstractQuinones are molecules with varied biological activities and electronic properties which are used for important applications [1, 2]. Quinone with a heteroatom substituted, namely 2-chloro-3-ethylamino-1,4-naphthoquinone (N-CAN) was synthesized and characterized by various techniques such as H1-NMR, C13-NMR, Mass spectroscopy and FT-IR spectroscopy. In this study, the solvatochromic effects on the spectral properties of 2-chloro-3-ethylamino-1,4-naphthoquinone have been investigated in different solvents taking into consideration, the solvent parameters like dielectric constant (ε) and refractive index (η) of different solvent polarities. Using Lippert-Mataga, Bakshiev’s, Kawski-Chamma-Viallet and Reichardt equations, the ground state (μg) and excited state (μe) dipole moments were calculated. The angle between the excited state and ground state dipole moments were also calculated. Graphical Abstractᅟ

Synthesis, molecular docking and antibacterial evaluation of 2-(4-(4-aminophenylsulfonyl)phenylamino)-3-(thiophen-2-ylthio)naphthalene-1,4-dione derivatives

AbstractA new series of 2-(4-(4-aminophenylsulfonyl) phenylamino)-3-(thiophen-2-ylthio)naphthalene-1,4-dione derivatives (3a-3n) were synthesized and characterized by spectral techniques. To understand the interaction of binding sites with bacterial protein receptor, the docking study was performed by the GLIDE program and compound N-(4-(4-(1,4-dioxo-3-(thiophen-2-ylthio)-1,4-dihydronaphthalen-2-ylamino)phenylsulfonyl)phenyl)-3-methylbenzamide (3b) exhibited good glide and E model scores of −5.89 and −94.90, respectively. Moreover among all the molecules studied including the standards used, namely Sparfloxacin (4.8 μg/mL) and Norfloxacin (no inhibition observed) for their antibacterial property, compound N-(4-(4-(1,4-dioxo-3-(thiophen-2-ylthio)-1,4-dihydronaphthalen-2-ylamino)phenylsulfonyl)phenyl)-4-nitrobenzamide (3e) exhibited the lowest minimum inhibitory concentration (MIC) value of 1.3 μg/mL against Proteus vulgaris.

Development of tungsten disulfide ZnO nanohybrid photocatalyst for organic pollutants removal

In this study, ZnO and ZnO/WS2 nanohybrid were synthesized by a facile microwave approach. Nanohybrid phase purity and structural features were examined through XRD, SEM–EDS, and EDS color mapping techniques. The optical absorbance and band gap energy of the ZnO/WS2 nanohybrid was measured by the UV–DRS. Functional group features on the ZnO/WS2 nanohybrid was investigated by the FT-IR spectroscopy. Further, the position of the conduction band and conductivity of the prepared ZnO/WS2 nanohybrid was studied by the Mott–Schottky and Nyquist plot techniques. The photocatalytic properties of the ZnO/WS2 nanohybrid were evaluated through the degradation of anionic and cationic organic pollutants such as methylene blue, bromophenol-B and 4-nitrophenol respectively. The organic pollutants degradation efficiency was determined by the UV absorbance spectroscopy and HPLC. Pseudo first order rate constant of the degradation reaction was calculated by the Langmuir–Hazelwood kinetic model. In addition, probe molecule mineralization was evaluated by TOC analysis. The ZnO/WS2 nanohybrid catalysts durability was analyzed by subjecting it to four repeated photocatalytic cycles. After the photocatalysis reaction the catalyst structure distortion was analyzed by the XRD technique.