Scien. Tech. Bull-Chem. Food Sci. Eng., Vol. 14(XV), 2017, 17-23 FLUORESCENCE AND THERMAL STUDY OF 3D METAL COMPLEXES CONTAINING HEXADENTATE SCHIFF BASE LIGAND Carmen CRETU, Viorel SASCA, Elisabeta I. SZERB, Liliana CSEH * , Otilia COSTISOR Institute of Chemistry Timisoara of Romanian Academy, Bv. Mihai Viteazu, No.24, RO-300223 Timisoara, Romania; * e-mail: lili_cseh@yahoo.com Abstract: New binuclear Zn2(ZOPP-2H)(CH3COO)2 complex (where ZOPP = N,N’-bis[(4-decyloxy- salicylideneamino)-propyl)-piperazine]) has been synthesized and characterized by elemental analysis, 1 H- NMR, FT- IR, UV-Vis and fluorescence spectroscopy. The non-electrolyte character of the complex was evidenced by conductivity measurement. The zinc ions are penta-coordinated by the N2O donor sets namely one phenolate oxygen atom, one imine nitrogen and one piperazine nitrogen atoms of Schiff base and two oxygen atoms of the acetate group. The Zn(II) complex displayed fluorescence from the intra-ligand emission excited state in N, N-dimethylformamide (DMF) solution at room temperature. The thermal behaviour of Zn(II) complex and other Ni(ZOPP-2H) complex previously reported suggested a high stability of these compounds compared to ZOPP ligand. Keywords: 3d Schiff base complexes; fluorescence; thermal analysis INTRODUCTION Schiff base metal complexes have been extensively studied for years due to their selectivity and sensitivity towards the transition metal ions (Hernández-Molina et al. 2004, Andruh et al. 2005). Schiff bases derived from the salicylaldehydes and diamine are known as polydentate ligands with synthetic flexibility, which are often used as chelating ligands in the field of coordination chemistry leading to stable metal complexes (Kuma et al. 1980). Additionally, their 3d metal complexes turned out to be interesting in the fields of liquid crystals (Donnio et al. 1999, Paul et al. 2015), biological such as antimicrobial (Golcu et al. 2005), antibacterial (Chohan et al. 2010, Esmadi et al. 2016) and antifungal agents (Creaven et al. 2010), optoelectronic materials (Hai et al. 2011, Che et al. 2010) and sensors (Gebreyesus et al. 2015, Sakthinathan et al. 2017). Moreover, zinc(II) complexes containing Schiff base ligands are known as fluorescent material or candidates for biological use having intense emission at room temperature (Wen et al. 2012, Qin et al. 2009). Also, thermal behaviour of Schiff base metal complexes has been widely investigated (Ates et al. 2010, Lemos et al. 2004, Durmus et al. 2006, Bartyzel 2017), their metal oxides being used as photoconductors (Mishra et al. 2012), catalysts for a number of reactions like hydrogenation (Osawa et al. 2005), oxidation (Nichio et al. 1996, Abbasi et al. 2014) and decomposition (Deraz et al. 2009, Harraz et al. 2010). Previously, we reported on the synthesis and characterisation of a new Schiff base ligand (ZOPP) and its coordination complexes with Cu(II) and Ni(II) metal centres (Cretu et al. 2008). In Chart 1 is presented the chemical structure of one of these metal complexes, based on Ni(II) metal centre. Chart 1. Chemical structure of complex 1 In this paper we present the synthesis and physico-chemical characterization of a new binuclear zinc(II) complex of general formula Zn2(ZOPP-2H)(CH3COO)2 based on the Schiff base ligand ZOPP. Also, the thermal stabilities of the previously reported Ni(ZOPP-2H) (1) and the herein synthesised Zn2(ZOPP- 2H)(CH3COO)2 (2), compared with ZOPP ligand are evaluated. 17