4-(4,5-Diphenyl-1H-imidazole-2-yl)-N,N-dimethylaniline-Cu(II) complex, a highly selective probe for glutathione sensing in water-acetonitrile mixtures
The imidazole derivative 4-(4,5-diphenyl-1H-imidazol-2-yl)-N,N-dimethylaniline (probe 1) formed a highly coloured and non-emissive 1:1 stoichiometry complex with Cu(II) in water-acetonitrile 1:1 (v/v) solutions. Among all the amino acids (Lys, Val, Gln, Leu, His, Thr, Trp, Gly, Phe, Arg, Ile, Met, Ser, Ala, Pro, Tyr, Gly, Asn, Asp, Glu, Cys and Hcy) and tripeptides (GSH) tested, only GSH induced the bleaching of the 1·Cu(II) solution together with a marked emission enhancement at 411 nm (excitation at 320 nm). These chromo-fluorogenic changes were ascribed to a selective GSH-induced demetallation of the 1·Cu(II) complex that resulted in a recovery of the spectroscopic features of probe 1. In addition to the remarkable selectivity of 1·Cu(II) complex toward GSH a competitive limit of detection as low as 2 μM was determined using fluorescence measurements. ; We thank the Spanish Government (MAT2015-64139-C4-1-R) and Generalitat Valenciana (PROMETEOII/2014/047). H. E. O. thanks Generalitat Valenciana for his Grisolia fellowship. Thanks are also due to Fundação para a Ciência e Tecnologia (Portugal) for financial support to the Portuguese NMR network (PTNMR, Bruker Avance III 400-Univ. Minho), FCT and FEDEReCOMPETEQREN-EU for financial support to the research centre CQUM (UID/QUI/0686/2016) and a doctoral grant to R.C.M. Ferreira (SFRH/BD/86408/2012). The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). ...