Raj Kamal

Spectroscopic and Computational Study of a Naphthalene Derivative as Colorimetric and Fluorescent Sensor for Bioactive Anions

The anion recognition property of a naphthalene based receptor (L) was investigated by naked-eye, UV-Vis, fluorescence, 1H NMR and computational methods. The receptor L showed fluoride selective naked-eye detectable colorimetric and UV-Vis spectral changes over other tested anions due to the formation of hydrogen bonding complex in 1:1 stoichiometry and/or deprotonation between fluoride and the receptor. Interestingly, the fluorescence of L was quenched by fluoride but enhanced by acetate.

Schiff base bis(5-nitrosalycilaldehyde)ethylenediamine as colorimetric sensor for fluoride

Schiff bases are widely investigated to develop novel chemosensors for selective identification and determination of anions. In this communication, we have taken an old but novel Schiff base, bis(5-nitrosalycilaldehyde)ethylenediamine (5-NO2-Salen, L), as a receptor to investigate the binding interaction with different anions such as F−, I−, Cl−, and Br− using spectrophotometric and computational approaches. Addition of anions accelerated the tautomerization process of L. The enolimine form of L interacts through the phenolic-OH by intermolecular hydrogen bond that intensified the color of the receptor, and a significant hyperchromic shift was observed due to the fluoride anion.

Hypervalent-Iodine(III)-Mediated Oxidative Methodology for the Synthesis of Fused Triazoles.

The organic chemistry of hypervalent organoiodine compounds has been an area of unprecedented development. This surge in interest in the use of hypervalent iodine compounds has mainly been owing to their highly selective oxidizing properties, environmentally benign character and commercial availability. Hypervalent iodine reagents have also been used as an alternative to toxic heavy metals, owing to their low toxicity and ease of handling. Hypervalent organoiodine(III) reagents are versatile oxidants that have been successfully employed to extend the scope of selective oxidative transformations of complex organic molecules in synthetic chemistry. This Focus Review concerns the tandem in situ generation and 1,5-electrocyclization of N-heteroaryl nitrilimines into fused triazoles. We describe the importance of recently developed hypervalent-organoiodine(III)-catalyzed oxidative cyclization reactions, building towards the conclusion that hypervalent iodine chemistry is a promising frontier for oxidative cyclization, in particular of hydrazones, for the synthesis of fused triazoles.

Synthesis, characterization and in vitro antimicrobial evaluation of some novel hydrazone derivatives bearing pyrimidinyl and pyrazolyl moieties as a promising heterocycles

In the present investigation, ten new 2-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-1-(4,6-dimethylpyrimidin-2-yl)hydrazine (3a–j) having pyrimidinyl and pyrazolyl moieties were synthesized. Structures of all compounds were confirmed by their spectral and elemental data. Most of the tested compounds were found to be significantly more effective against bacterial strains Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa than the reference drug ciprofloxacin. All the newly synthesized compounds were found to be more potent antifungal agents than reference drug against Candida albicans, whereas except 3e all other compounds also shown good activity against Saccharomyces cerevisiae.

An economic, simple and convenient synthesis of 2-aryl/heteroaryl/styryl/alkylbenzothiazoles using SiO2–HNO3

The present work was undertaken to develop an economic method for the synthesis of 2-aryl/heteroaryl/styryl/alkylbenzothiazoles mediated by SiO2–HNO3. In this report, we have demonstrated the catalytic potential of SiO2–HNO3 for the oxidative condensation of 2-aminothiophenol and aldehydes. Instant reaction at room temperature under solvent-free condition, high substrate to catalyst ratio 50:1 (by weight), practical application by large-scale synthesis, and excellent yields are the main advantages of the present protocol.Graphical Abstract

Design, Synthesis, and Screening of Triazolopyrimidine-Pyrazole Hybrids as Potent Apoptotic Inducers: Pro-Apoptotic Potential of Triazolopyrimidines

An efficient synthesis of novel 3‐(3‐aryl‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐5,7‐dimethyl‐[1,2,4]triazolo[4,3‐a]‐pyrimidines was accomplished by the oxidation of pyrimidinylhydrazones by using organoiodine(III) reagent. All new triazolopyrimidine derivatives bearing the pyrazole scaffold were screened to evaluate them as a reproductive toxicant in the testicular germ cells of goat (Capra hircus). This study aimed at assessing the cytological and biochemical changes in testicular germ cells after the exposure to triazolopyrimidines in a dose‐ and time‐dependent manner. Histomorphological analysis, fluorescence assays, apoptosis quantification, and terminal deoxynucleotidyl transferase dUTP‐mediated nick‐end labeling (TUNEL) assays were performed to determine cytological changes, whereas thiobarbituric acid‐reactive substance (TBARS) and ferric reducing antioxidant power (FRAP) assays were carried out to measure the oxidative stress in triazolopyrimidines treated germ cells. The parallel use of these methods enabled us to determine the role of triazolopyrimidines in inducing apoptosis as a consequence of cytogenetic damage and oxidative stress generated in testicular germ cells of goat.