Nitric oxide sensors based on copper(II) complexes of N-donor ligands

Two Cu(II) complexes, 1 and 2, were synthesized with N-donor ligands L-1 and L-2 [L-1 = N-1,N-1-dimethylethane-1,2-diamine, L-2 = N-1,N-1-dimethyl-N-2-{(pyridin-2-yl)methyl}ethane-1,2-diamine], respectively, and were characterized. Complexes 1 and 2 upon reaction with NO, found to show reduction of Cu(II) to Cu(I) in various solvents. Ligands L-3, L-4 and L-5 are the dansyl derivatives of L-1, 2-(pyridin-2-yl)ethanamine and L-2, respectively. Three Cu(II) complexes, 3, 4 and 5 were synthesized with ligands L-3, L-4 and L-5 respectively. The fluorescence intensity of these ligands were found to be quenched significantly on complexation due to the paramagnetism of the Cu(II) center. However, when exposed to NO in methanol or aqueous medium, the fluorescence intensity of the fluorophores has been found to be restored because of reduction of paramagnetic Cu(II) to diamagnetic Cu(I). (C) 2013 Elsevier B. V. All rights reserved.