Published in: Journal, Article, Research Support, Non-U.S. Gov’t, Volume : 82, Issue : 1, Pages : 312-318
Author : Upadhyay, K. K.; Mishra, Rakesh K.; Kumar, Virendra; Chowdhury, P. K. Roy
Abstract : A new coumarin based hydrazone (receptor 1) synthesized by modifying one of our earlier reported receptor detected fluoride ion selectively through naked eye in aqueous DMSO (5:95, volume/volume). It was also able to detect fluoride through naked eye in a toothpaste sample. The addition of 1 equivalent of fluoride as its tetrabutylammonium salt to the 5 × 10-5 M aqueous DMSO solution of the receptor 1 produced red color while the similar addition of acetate produced faint pink color. The dihydrogen phosphate and a variety of other anions were not able to produce any significant color change with receptor 1 under similar exptl. conditions. The corresponding UV-vis measurements showed a bathochromic shifting of 455 nm band of receptor 1 to 514 and 484 nm for fluoride and acetate, resp. The non-linear fittings of corresponding UV-vis titration data in 1:1 binding equation yielded association constants in 105:1 ratio for fluoride and acetate, resp. The 1H NMR titrations studies shade further light on their mode of binding with receptor 1. The quantum mech. calculations through time dependant d. functional theory (TD-DFT) using basis set b3lyp/6-311g** supported our exptl. findings nicely.