title: cis-Dioxomolybdenum(VI) complexes of a new ONN chelating thiosemicarbazidato ligand; synthesis, characterization, crystal, molecular structures and antioxidant activities.
abstract: 5-Chloro-4-methyl-2-hydroxybenzophenone S-propyl-4-phenyl-thiosemicarbazone (H2L) and its cis-dioxomolybdenum(VI) complexes, in the general formula [MoO2(L)R-OH)] (R: methyl, 1; ethyl, 2; n-propyl, 3; n-butyl, 4; n-pentyl, 5), were synthesized and characterized by micro analysis, electronic, infrared and (1)H and (13)C NMR spectra. The crystal structures of complexes, 1 and 3, have been solved by direct methods (SIR92) and refined to the residual indexes R1=0.098 and R1=0.052 respectively. Complexes 1 and 3 are crystallized in the triclinic space group P-1 with Z=2. The crystal study of complex 1 showed the first example of intermolecular hydrogen bond for this type of molybdenum-thiosemicarbazone complexes. The hydrogen bond is between the hydroxyl proton of attached alcohol and an oxo oxygen (in MoO2(2+) unit) of another complex molecule, and its bond distance (1.767(1)Å) is shorter than from the σ-coordination bonds in complex 1. Antioxidant activities of the compounds were determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Ligand showed 23.61% DPPH radical scavenging activity at 250 mg/L concentration. Cupric Reducing Antioxidant Capacity (CUPRAC) was also evaluated and trolox-equivalent antioxidant capacity (TEAC) values were found for ligand, 1 and 3 as 0.51, 0.33 and 0.30 respectively.
authors: Istanbul University, Faculty of Engineering, Department of Chemistry, Inorganic Chemistry Division, 34320 Avcilar, Istanbul, Turkey. Electronic address: beril@istanbul.edu.tr.
authors: Berat
authors: B
authors: İlhan Ceylan
authors: Istanbul University, Faculty of Engineering, Department of Chemistry, Organic Chemistry Division, 34320 Avcilar, Istanbul, Turkey.
authors: Nahide Gulsah
authors: NG
authors: Deniz
authors: Istanbul Aydın University, Faculty of Engineering, Department of Food Engineering, 34295 Kucukcekmece, Istanbul, Turkey.
authors: Sibel
authors: S
authors: Kahraman
authors: Istanbul University, Faculty of Engineering, Department of Chemistry, Inorganic Chemistry Division, 34320 Avcilar, Istanbul, Turkey.
authors: Bahri
authors: B
authors: Ulkuseven
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D016166:Free Radical Scavengers / Q000737:chemistry; D006860:Hydrogen Bonding; D008024:Ligands; D008968:Molecular Conformation; D008982:Molybdenum / Q000737:chemistry* / Q000494:pharmacology*; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D010851:Picrates / Q000737:chemistry; D013882:Thiosemicarbazones / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D002614:Chelating Agents; D016166:Free Radical Scavengers; D008024:Ligands; D010087:Oxides; D010851:Picrates; D013882:Thiosemicarbazones; C539565:molybdenum dioxide; D008982:Molybdenum; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: Antioxidant activity; Benzophenone; Crystal structure; Dioxomolybdenum(VI); Hydrogen bonding; Thiosemicarbazone