Synthesis, Spectroscopic and Computational Studies of Some Metals Chelates with Chromene-2-one and Pyrazine-Based Ligands

Abstract

The present paper deals with the synthesis of cobalt(II), nickel(II), copper(II) and cadmium(II) complexes with two bidentate ligands, L1 (3-(quinoxaline-2-yl)-coumarin) and L2 (2-methylene-2H-chromene-3-(methyl carbonimidic)thioanhydride). The L1 ligand was prepared by treating w-bromo-3-acetylcoumarin with 1,2-phenylenediamine whereas the ligand L2 was prepared through substitution reaction ofw-bromo-3-acetylcoumarin with potassium thiocyanate in ethanol medium. The confirmation of the structures for L1 and L2 were done by (C.H.N.S.) elemental analysis, FT-IR, NMR and mass spectra. The metal complexes of cobalt(II), nickel(II), copper(II) and cadmium(II), with L1 and L2, were prepared and isolated in the solid state then characterized by (C.H.N.M) elemental analysis, proton and carbon-13 NMR, FT-IR and mass spectra. Furthermore, the thermal analysis (TG-DSC) for some complexes assisted us in the elucidation of the suggested structures of complexes and confirmed their thermal stability. The results obtained from elemental analysis, magnetic susceptibility and thermal analysis confirmed that all metal complexes were formed in 2:1 molar ratio of ligand to metal with octahedral structures except cadmium(II) complexes which were in a tetrahedron geometry with 1:1 mole ratio. The complexes are found to be soluble in DMF and DMSO. The results obtained from TG-DSC analysis revealed that the metal complexes were thermally stable with point decomposition over 350 °C. The DFT/TDDFT calculations were carried out to provide the electronic structures and spectra of the compounds.

3‐Bromoacetylcoumarin, a Crucial Key for Facial Synthesis of Biological Active Compounds

“…[39] Compound 17 exhibits the best bacterial inhibition against Staphylococcus aureus (ZOI 21 mm, MIC 6.25 mg/mL) and Pseudomonas aeruginosa (ZOI 21 mm, MIC 6.25 mg/mL), which is comparable to the drug standard (streptomycin). [39] The 2H-chromen-thio-nicotinonitriles ( 19) [40] are obtained in good yields when 3-bromoacetylcoumarin (2) reacts with pyridinethione (18) under reflux conditions in ethanol, respectively.…”

“…[16] Over the last two decades, various brominating agents were used containing tetrabutylammonium tribromide (TBATB), bromine, phenyltrimethylammonium tribromide (PhTAPBr3), Nbromosuccinimide (NBS), and copper(II) bromide (CuBr 2 ) (Scheme 2). [17][18][19][20][21][22][23][24][25][26][27] Preparation of potential drug candidates with complex molecular architectures built from simple starting materials is an important concern in modern drug development. Researchers used various approaches for the synthesis of coumarin derivatives.…”

“… [16] Over the last two decades, various brominating agents were used containing tetrabutylammonium tribromide (TBATB), bromine, phenyltrimethylammonium tribromide (PhTAPBr3), N ‐bromosuccinimide (NBS), and copper(II) bromide (CuBr 2 ) (Scheme 2). [17–27] …”

3-(Bromoacetyl)coumarins: unraveling their synthesis, chemistry, and applications

“…Several brominating agents have been reported in the last two decades such as tetrabutylammonium tribromide (TBATB), bromine, phenyltrimethylammonium tribromide (PhTAPBr 3 ), N-bromosuccinimide (NBS), and copper(II) bromide (CuBr 2 ) (Scheme 1). [35][36][37][38][39][40][41][42][43][44][45][46][47]…”