A highly selective turn-on colorimetric and luminescence sensor based on a triphenylamine-appended ruthenium(II) dye for detecting mercury ion

A dual colorimetric and luminescent sensor based on a heteroleptic ruthenium dye [Ru(Hipdpa)(Hdcbpy)(NCS)2]–·0.5H+ 0.5[N(C4H9)4]+ Ru(Hipdpa) {where Hdcbpy = monodeprotonted-4,4′-dicarboxy-2,2′-bipyridine and Hipdpa = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline} for selective detection of Hg2+ is presented. The results of spectrophotometric titrations revealed an evident luminescence intensity enhancement (I/I0 = 11) and a considerable blue shift in visible absorption and luminescence maxima with the addition of Hg2+. The sensitive response of the optical sensor on Hg2+ was attributed to the binding of the electron-deficient Hg2+ to the electron-rich sulfur atom of the thiocyanate (NCS) ligand in the Ru(Hipdpa), which led to an increase in the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Accordingly, the blue shift in the absorption spectrum of Ru(Hipdpa) due to the binding of Hg2+ was obtained. Ru(Hipdpa) was found to have decreased Hg2+ detection limit and improved linear region as compared to di(tetrabutylammonium) cis-bis(isothiocyanato)bis(2,2′-bipyridine-4-carboxylic acid-4′-carboxylate)ruthenium(II) N719. Moreover, a dramatic color change from pink to yellow was observed, which allowed simple monitoring of Hg2+ by either naked eyes or a simple colorimetric reader. Therefore, the proposed sensor can provide potential applications for Hg2+ detection.

A triphenylamine-appended ruthenium(II) complex-based colorimetric and turn-on luminescence sensor with a wide concentration detection range and low detection limit for mercury ion is described.Figure optionsDownload as PowerPoint slide