Pramod S. Pandey

Synthesis of a bile acid-based click-macrocycle and its application in selective recognition of chloride ion.

A novel method for the synthesis of a bile acid-based macrocycle has been developed using click chemistry. The 1,2,3-triazolium derivative of the macrocycle shows remarkable selectivity in binding of chloride ion.

Synthesis of click bile acid polymers and their application in stabilization of silver nanoparticles showing iodide sensing property.

A novel method for the synthesis of bile-acid-based polymers has been developed using click chemistry. These 1,2,3-triazole-containing polymers have been found to stabilize silver nanoparticles that show selective colorimetric sensing for iodide ion.

Linear tetrapyrrolic intermediates for biosynthesis of the natural porphyrins: Experiments with modified substrates1

Abstract A brief survey is given of earlier researches on the involvement of linear tetrapyrroles in the biosynthesis of natural porphyrins and their relatives. This brings out the importance of probing the effect of chemically modifying the terminal ring of the linear tetrapyrrolic system. Two such modified hydroxymethylbilanes have been synthesised and the way they interact with the enzyme cosynthetase allows conclusions about the enzymic ring-closure step which generates the uroporphynnogen III macrocycle.

Microwave-Assisted Efficient Methylation of Alkyl and Arenesulfonamides with Trimethylsulfoxonium Iodide and KOH

Abstract A solvent-free synthesis of N-methyl and N,N-dimethylsulfonamides has been achieved by treating the primary and secondary sulfonamides with Me3S+OI− and KOH under microwave irradiation on alumina support.

Recognition Properties of Flavin Analogues with Bile Acid-Based Receptors: Role of Steric Effects in Hydrogen Bond Based Molecular Recognition

The recognition properties of 7,8-dimethyl flavin analogues by bile acid-based receptors that contain 2,6-diaminopyridine and the dioctylamide of 2,6-diaminopyridine in CHCl3 were determined. The results show that the bile acid-based receptors bind 7,8-dimethyl flavin analogues less effectively as compared to 7,8-unsubstituted flavins reported earlier, which is contrary to the known fact that the association constants increase with increasing electron-donating capacity of the substituents at the 7 and 8 positions of the flavin analogues.

A novel dansyl-appended bile acid receptor for preferential recognition of Hg2+

We have designed and synthesized a novel dansyl appended bile acid chemosensor using click chemistry. The chemosensor shows selective and efficient recognition of Hg2+ ions by forming a 1:1 complex with Hg2+ with a binding constant of 3.3 × 104 M−1. The limit of detection for Hg2+ was estimated to be 2 μM.

Synthesis and properties of L-valine based chiral long alkyl chain appended 1,2,3-triazolium ionic liquids

The increasing importance of ionic liquids (ILs) in various strata of chemical sciences is largely due to the fact that modification in the architecture of the cation and/or the anion imparts favorable and specific properties to an IL. Consequently, there is a need to develop new ILs with different functionalities. A series of L-valine based alkyl chain-appended 1,2,3-triazolium ILs (alkyl = hexyl, octyl, dodecyl, cetyl and octadecyl) with iodide and hexafluorophosphate anions, respectively, are synthesized and characterized. These new ILs show optical activity and hence are termed chiral ILs (CILs). All ten CILs are room temperature ILs (RTILs) as their melting points, obtained from differential scanning calorimetry (DSC), are found to be below ambient temperature. Thermogravimetric analysis indicates these CILs to have adequate thermal stability. The longer alkyl chain containing CILs exhibit facile self-aggregation when dissolved in ethanol. There is a hint of pre-micellar aggregation by short alkyl chain possessing CILs along with the long alkyl chain containing ones. These CILs demonstrate weak absorbance and emission of UV-Vis radiation and hence can be considered ideal solvents for photochemical applications. These CILs, consisting of different functionalities, possess interesting properties and have potential to be used in many areas of chemistry.

Dual colorimetric sensing of mercury and iodide ions by steroidal 1,2,3-triazole-stabilized silver nanoparticles

Bile acid-based 1,2,3-triazole ligands have been synthesized, which show excellent ability to stabilize silver nanoparticles. These AgNPs have been found to exhibit highly selective dual colorimetric sensing of Hg2+ and I− ions.

Microwave-Assisted Regioselective Synthesis of trans-1-Arenesulfonyl-2-ethoxycarbonyl-3-phenylazetidines

An efficient regioselective synthesis of trans-1-arenesulfonyl-2-ethoxycarbonyl-3-phenylazetidines has been achieved through microwave-assisted reactions of 1-arenesulfonylaziridines with dimethylsulfonium carboethoxymethylide using alumina as solid support.

Recognition of a Flavin Analogue by Novel Bile Acid-Based Receptors: Effects of Hydrogen Bonding and Aromatic π-Stacking Interactions

Molecular recognition properties are reported for novel bile acid-based receptors that incorporate 2,6-diaminopyridine as a recognition unit. Apart from hydrogen-bonding interactions, the bile acid receptors exhibit significant aromatic π-stacking interactions with the aromatic fused ring of the flavin derivative. These studies provide rationalisation for the differences in binding behaviour of bile acid receptors having differing aromatic arm lengths towards a flavin analogue.