Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand h i g h l i g h t s A new Co(II) complex with formula [Co(tptz)(CH 3 OH)Cl 2 ]ÁCH 3 OHÁ0.5H 2 O has been prepared. Using tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine as ligand. The antibacterial activity of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) with tptz have been evaluated. The DFT studies consistent with experimental results. g r a p h i c a l a b s t r a c tThe crystal structure of Co(II) with formula [Co(tptz)(CH 3 OH)Cl 2 ]ÁCH 3 OHÁ0.5H 2 O, (tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) was determined by single-crystal X-ray diffraction. The DFT studies consistent with experimental results. Then, the in vitro antibacterial activity of ligand and tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) have been evaluated. a b s t r a c t A cobalt complex was prepared from CoCl 2 Á6H 2 O and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in methanol and designated as [Co(tptz)(CH 3 OH)Cl 2 ]ÁCH 3 OHÁ0.5H 2 O (1). It was characterized by several techniques including TGA analysis and FT-IR, UV-Vis and 1 H NMR spectral studies. The crystal structure of 1 was determined by single-crystal X-ray diffraction. The Co(II) metal center in 1 is six coordinated with a distorted octahedral geometry. The tptz ligand is tridentate and coordinates to the cobalt through coplanar nitrogen atoms from the triazine and two pyridyl rings. Two chloride anions and a methanol molecule complete the inner coordination sphere of the metal ion. The optimized geometrical parameters obtained by DFT calculation are in good agreement with single XRD data. The in vitro antibacterial activity of various tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) were evaluated against Gram-positive (Bacillus subtilis, Staphylococcus aureus and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Whereas all complexes exhibited good activity in comparison to standard antibacterial drugs, the inhibitory effects of complexes were found to be more than that of the parent ligand. Overall, the obtained results strongly suggest that the cobalt(II) complex is a suitable candidate for counteracting antibiotic resistant microorganisms.

The 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) undergoes hydrolysis in the presence of VO(SO4) in an alkaline solution, affording mainly the bis(2‐pyridyl carbonyl)amid) VO2 complex, designated as [VO2(bpca)]. Single‐crystal X‐ray crystallography revealed that the coordination of V in complex is a distorted square‐pyramid coordinated with three nitrogen of bis(2‐pyridyl carbonyl)amid) ligand and two binding oxygen atoms. The prepared complex which successfully supported on modified Fe3O4 nanoparticles using tetraethylorthosilicate (TEOS) and (3‐aminopropyl)trimethoxysilane(APTMS)was designated as Fe3O4@SiO2@APTMS@[VO2(bpca)] complex (nanocatalyst). The complex and nanocatalyst were characterized by means of FT‐IR, XRD, VSM, SEM and TEM. The catalytic activity of [VO2(bpca)] complex and Fe3O4@SiO2@APTMS@complex as catalysts 1 and 2 were evaluated by the epoxidation of geraniol, 3‐methyl‐2‐buten‐1‐ol, trans‐2‐hexen‐1‐ol and 1‐octen‐3‐ol with 70–98% conversions and 95–100% selectivities. Based on the obtained results, the heterogeneity and reusability of the catalyst seems promising. In addition, the in vitro antibacterial activity of [VO2 (bpca)] complex have also been evaluated and compared to the activities of other vanadium complexes, tptz ligand and two standard antibacterial drugs, Nalidixic acid and Vancomycin.

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The new binuclear organotin(basis of these data, acyldihydrazone supplies two tridentate dianionic ONO domains and is coordinated to two diphenyltin(IV) moiety through the imine nitrogen and phenolic and enolic oxygen atoms. All complexes are binuclear and the coordination number of each tin is five. The in vitro antibacterial activity of ligands and complexes has been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria and compared with standard drugs. All complexes exhibit more inhibitory effects than the parent ligands and have a potential to be used as drugs.

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