Luminescent sensor for copper(II) ion based on imine functionalized monometallic rhenium(I) complexes

Novel imine functionalized monometallic rhenium(I) polypyridine complexes (1-4) comprising phenol moiety with 2,2'-bipyridine ligands L1-L4 have been synthesized and characterized by various spectroscopic techniques. These complexes function as selective and sensitive sensor towards the copper(II) ion demonstrated by UV-vis absorption, luminescence and time-resolved spectroscopic techniques. An enormous enhancement is observed in emission intensity, quantum yield and luminescence lifetime with the addition of copper(II) ion due to the restriction of C=N isomerization in the Re(I) complexes. The strong binding between copper(II) ion and these complexes can be inferred from the binding constant values, which are in the range of 1.1 x 10(4)-2.4 x 10(4) M-1. Furthermore, the structural and the absorption features of the complexes have been supported by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. (C) 2016 Elsevier B.V. All rights reserved.