2015. 56, 2 – UDC 541.6:547.13:546.56 N,N-DIPYRIDOXYL(1,2-DIAMINOCYCLOHEXANE) AND ITS Cu(II) COMPLEX: SYNTHESIS, EXPERIMENTAL AND THEORETICAL STUDIES S.A. Beyramabadi, A. Morsali, A. Shams Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran E-mail: beiramabadi6285@mshdiau.ac.ir; beiramabadi@yahoo.com (Beyramabadi) Received June, 27, 2013 Revised — September, 17, 2013 In this work, the N,N-dipyridoxyl(1,2-diaminocyclohexane) [=H2L] Schiff-base ligand and its square complex [Cu(L)] are newly synthesized and characterized by IR, mass spectroscopy, 1H NMR, and elemental analysis. <...> The ful optimization of geometries, the 1H NMR chemical shifts (for the H2L) and their vibrational frequencies are calculated using the density functional theory (DFT) method. <...> The optimized geometry of the ligand is not planar, but each of two pyridine rings and the cyclohexane moiety are in the separate planes. <...> INTRODUCTION Due to a variety of applications, including the analytical [ 1 ] and industrial use as catalysts [ 2, 3 ], the Schiff-base ligands and their complexes are of great importance. <...> Pyridoxal is a close analogue of pyridoxine (vitamin B6) [ 7 ], and its deficiency in a human body can lead to serious complications. <...> Manganese dipyridoxyl diphosphate is a contrast agent for the magnetic resonance imaging of the liver [ 8 ] and a copper(II) complex of pyridoxal is used in the treatment of diabetic complications [ 9 ]. <...> Coordination of Schiff-base ligands to metal ions improves their biological activities [ 10 ]. <...> In continuation of our studies [15—19 ] and hopping to biological and catalytic applications, we report here the synthesis and spectroscopic characterization of the H2L Schiff-base of pyridoxal and its Cu(II) complex, where H2L is N,N-dipyridoxyl(1,2-diaminocyclohexane). <...> Also, the optimized geometries of the ligand and the Cu complex, the theoretical assignment of the IR and 1H NMR spectra has been performed using the DFT method. <...> The determined structural parameters of the ligand and its Cu(II) complex, and the assignment of the IR bands and 1H NMR chemical shifts can be used as databases for the identification of similar compounds. . 259 – 265 © Beyramabadi S.A., Morsali A., Shams A., 2015 260 S.A. BEYRAMABADI <...>