Spectroscopic investigations of new Cu(II), Co(II), Ni(II) complexes with g-L-glutamyl amide as ligand C. Ba ˆtiu a , C. Jelic b , N. Leopold b , O. Cozar b , L. David b, * a Faculty of Chemistry, ‘Babes ¸-Bolyai’ University, Arany Janos 11, 400028 Cluj-Napoca, Romania b Faculty of Physics, ‘Babes ¸-Bolyai’ University, Koga ˘lniceanu 1, 400084 Cluj-Napoca, Romania Received 9 September 2004; revised 16 November 2004; accepted 16 November 2004 Available online 2 March 2005 Abstract The [Cu(GTA) 2 ]$4H 2 O, [Co(GTA) 2 $(H 2 O) 2 ]$6H 2 O and [Ni(GTA) 2 $(H 2 O) 2 ]$6H 2 O) complexes of S(C)-g-L-glutamyl-(5-ethoxycarbo- nyl-4-methyl-2-thiazolyl)–amide (HGTA) ligand were synthesized and characterized by elemental, thermal, spectroscopic and magnetic investigations. In all these complexes the g-L-glutamyl–amide act as a bidentate ligand with coordination involving the carbonyl oxygen and the nitrogen atom of the second amino group. The thermal stability in the 20–700 8C temperature range of the ligand and complexes were discussed. The local structure around the Cu(II) ions is pseudotetrahedral. In the case of Co(II) and Ni(II) complexes two H 2 O molecules are involved in the metal ion coordination resulting an octahedral stereochemistry. q 2005 Elsevier B.V. All rights reserved. Keywords: g-L-glutamyl–amide; Metal complexes; FT-IR spectroscopy; ESR spectroscopy 1. Introduction The g-L-glutamyl amides and some metal complexes derivatives of their metal complexes have biological and pharmaceutical importance, being immunostimulators [1], anticancer [2,3], antifungical agents [4,5] or a diagnostic reagent [6,7]. The ligand HGTAZS(C)-g-L–glutamyl-(5-ethoxycar- bonyl-4-methyl-2-thiazolyl)–amide (Fig. 1) was obtained by a literature procedure [8] and investigated by spectro- scopic methods. In the present paper new coordination compounds of g-L–glutamyl-(5-ethoxycarbonyl-4-methyl-2-thiazolyl)– amide with 3d transition metal ions [Cu(II), Co(II) and Ni(II)] were synthesized and characterized by their spectral and magnetic properties and thermal investigation. 2. Experimental The metal complexes were synthesized by the following procedure: 1!10 K3 mole of metals [Cu(NO 3 ) 2 $3H 2 O, Co(NO 3 ) 2 $6H 2 O or Ni(NO 3 ) 2 $6H 2 O] were solved in distilled water. 2!10 K3 mole of ligand was solved in Na 2 CO 3 1 M at room temperature and mixed with the metal solution. After stirring and standing overnight at room temperature the formed crystalline products were filtered, washed with Na 2 CO 3 1 M, distilled water and dried in air. The metal complexes are insoluble in usually organic solvents and in water. Some physical–chemical properties of the synthesized metal complexes are given in Table 1. Melting points were recorded with an Electrothermal IA 6304 apparatus and are uncorrected. Elemental analyses were carried out at the Perkin–Elmer 240 analyzer. The thermoanalytical curves were recorded on an OD-103 MOM Derivatograph, in air atmosphere, in the temperature range 20–1000 8C. The samples were hated at a constant rate of 6 8C/min., reference material Al 2 O 3 , and atmosphere: static air. The sensitivity on the galvanometers was: TGZ100 mg, DTGZ1/5, DTAZ1/5. 0022-2860/$ - see front matter q 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2004.11.096 Journal of Molecular Structure 744–747 (2005) 325–330 www.elsevier.com/locate/molstruc * Corresponding author. Tel.: C40 264 405300; fax: C40 264 591906. E-mail address: leodavid@phys.ubbcluj.ro (L. David).