Solvatochromic isocyanonaphthalene dyes as ligands for silver(I) complexes, their applicability in silver(I) detection and background reduction in biolabelling

The complexation behavior of reactive and nonreactive N-substituted 1-amino-5-isocyanonaphthalene (ICAN) derivatives was studied in the presence of Ag(I) ions by UV-vis, steady-state and time resolved fluorescence measurements. The effect of ligand, solvent and counterion is covered. The equilibrium constants were found to be K-Agt similar to 10(6) M-1 in dioxane and water. Complex formation results a significant, solvent dependent (30-59 nm) batochromic shift of the emission maximum. This shift is accompanied by a switch-off effect in the case of the unreactive ligands, while in the case of the acrylated derivative (ACAIN) significant intensity enhancement was detected. Based on spectroscopic results only 1:1 AgL complex could be detected in solution at low concentrations c(AgL) < 10(-4) M, while at higher concentrations pure 1:2 AgL2 formed which was characterized by ESI-MS, IR and NMR methods The structure and optical behavior of the complexes are discussed based on high-level quantum chemical calculations. It is shown that the complexation of ACAIN can be used for the selective detection and quantification of silver(I) ions from aqueous media. In addition, the fluorescene switch-off in the case of MICAN yields a significant contrast enhancement in biolabeling applications as is shown on fixated HaCat cells.s (C) 2017 Elsevier B.V. All rights reserved.