Synthesis and characterization of some metal complexes containing the chromone moiety

Abstract

Chromones are the most widespread class of naturally occurring compounds. Chromones have potential beneficial effects for human health. Among the diverse biological properties that these compounds possess are included activities like anti-inflammatory, antibacterial, antitumor, antioxidant, anti-HIV, antiviral and antiallergenic activities. 3-Formylchromone and its substituents have attracted a considerable interest as highly reactive compounds, which can form the metal-heterocyclic complexes with useful properties due to the availability of oxygen as a donor center. In the current work, the chelating behavior of 3-formylchromone towards Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) ions was investigated. Thus, a series of binary and ternary metal complexes have been synthesized by using metal ions with different anions (AcO–, NO3–, SO42–, ClO4–, Cl– and Br–) and secondary ligands including N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline and 2,2'-bipyridyl. The prepared complexes have been characterized by micro analytical, spectral (IR, electronic, ESR and mass spectra), thermal, magnetic and conductivity techniques. The analytical and spectroscopic techniques revealed that the ligand behaves as a neutral bidentate, forming chelates that reflect the non-coordinating or weakly coordinating power of the ClO4– and NO3– anions as compared to the strongly coordinating power of AcO– and SO42– anions. The obtained complexes were formed with different molar ratios according to the anion. In case of AcO–, ClO4– and Cl–(with Ni(II) and Co(II) ions) anions, 1:2; M:L complexes were obtained. However, in case of NO3– anion, 1:3; M:L complexes were obtained. In case of SO42–, Cl– and Br– (with Cu(II) ion) anions, 1:1; M:L complexes were obtained. All ternary complexes showed 1: 2: 1, 1:1:1 and 1:1:2 stoichiometry (metal : ligand : secondary ligand). The results showed that all binary metal complexes exhibited octahedral geometry except the copper(II) complex 6, which exhibited square planar geometrical arrangement. Also, all the ternary metal complexes revealed an octahedral geometry. Thermal gravimetric analysis (TGA) was performed for some complexes of the chromone ligand.