Synthesis, spectroscopic and fluorescence properties of N,N′-diethylnicotinamide adducts of 2-bromobenzoate Co(II) and Ni(II) metal-organic complexes

Two mixed complexes diaquabis(2-bromobenzoato-κO)bis-(N,N-diethylnicotinamide-κN')cobalt(II) [Co(C7H4BrO2)2(C10H14N2O)(H2O)2] (Complex I) and diaquabis(2-bromobenzoato-κO)bis-(N,N-diethylnicotinamide-κN')nickel(II) [Ni(C7H4BrO2)2(C10H14N2O)(H2O)2] (Complex II) have been synthesized and characterized by elemental analysis, TG/DTA, FT-IR spectra and X-ray powder diffraction(XRPD). In addition, the optical absorption and emission properties of metal-organic complexes were investigated by using UV–vis absorption and fluorescence spectrophotometers, respectively. Complex I showed larger absorption and emission intensities than complex II in the visible region. This behavior was attributed to the numbers of π → π* transitions which are take place in the visible region.