Turk J Chem (2013) 37: 101 – 110 c  T ¨ UB ˙ ITAK doi:10.3906/kim-1203-67 Turkish Journal of Chemistry http://journals.tubitak.gov.tr/chem/ Research Article Synthesis and characterization of Ni(II) and Cu(II) complexes derived from novel phenolic Mannich bases Nurg¨ un B ¨ UY ¨ UKKIDAN ∗ , Salih ¨ OZER Department of Chemistry, Faculty of Arts and Sciences, Dumlupınar University, 43100 K¨ utahya, Turkey Received: 29.03.2012 • Accepted: 04.12.2012 • Published Online: 24.01.2013 • Printed: 25.02.2013 Abstract: The novel phenolic Mannich bases 2,2’-(2-hydroxy-4,5-dimethylbenzylazanediyl)diethanol (1) and 2-((2-(4- (2-hydroxy-4,5-dimethylbenzyl)piperazin-1-yl)ethylamino)methyl)-4,5-dimethylphenol (2) have been synthesized in good yield by using a microwave-induced technique from 3,4-dimethylphenol and corresponding amines in the presence of formaldehyde. Metal complexes of 1 and 2 for Ni(II) (3 and 5) and for Cu(II) (4 and 6) have also been prepared and all compounds have been characterized by elemental and spectral analyses. Thermal, magnetic, and electronic studies have also been reported for metal complexes. Electronic spectra and magnetic susceptibility measurements suggested tetrahedral geometry for Ni(II) (3), square planar geometry for Cu(II) (4) complexes of 1, and octahedral geometries for both Ni(II) (5) and Cu(II) (6) complexes of 2. Key words: Mannich base, 3,4-dimethylphenol, piperazine, microwave irradiation, metal complexes 1. Introduction Metal complexes of Mannich bases have been studied extensively in recent years due to selectivity and sensi- tivity of the ligands toward various metal ions. 1−3 The new ligand systems for transition metals have drawn considerable interest to chelating amino and hydroxy compounds. The compounds containing phenolic Man- nich base components have a strong tendency to form metal complexes 4−7 and exhibit significant anticancer and antimalarial properties. 8,9 The classical Mannich reaction has limited applications and has a number of serious disadvantages. Therefore, numerous novel Mannich reactions have been developed 10,11 to overcome the drawbacks of the classical method and to avoid environmental problems using catalyst in combination with surfactant in aqueous medium. 12−21 In view of these facts and following the research programs in the field of coordination chemistry, we report here a microwave-assisted convenient and economic method for the synthesis and characterization of new Mannich bases 1 and 2, formed by 3-component condensation in good yield when compared with the classical method. The proposed structures of the synthesized Mannich bases (1 and 2) are given in Scheme 1. It is well known from the literature that these types of ligands have the ability to form metal complexes via the N and O atoms. We also report metal complexes of 1 and 2 with Ni(II) (3 and 5) and Cu(II) (4 and 6). The proposed structures of the synthesized complexes 3–6 are shown in Scheme 2. ∗ Correspondence: nsakarya@dumlupinar.edu.tr 101