Archana Mizar

Template Syntheses of Copper(II) Complexes from Arylhydrazones of Malononitrile and their Catalytic Activity towards Alcohol Oxidations and the Nitroaldol Reaction: Hydrogen Bond-Assisted Ligand Liberation and E/Z Isomerisation

A one-pot template condensation of 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonic acid (H(2)L(1), 1) or 2-(2-(dicyanomethylene)hydrazinyl)benzoic acid (H(2)L(2), 2) with methanol (a), ethylenediamine (b), ethanol (c) or water (d) on copper(II), led to a variety of metal complexes, that is, mononuclear [Cu(H(2)O)(2)(κO(1),κN(2)L(1a)] (3) and [Cu(H(2)O)(κO(1),κN(3)L(1b))] (4), tetranuclear [Cu(4)(1κO(1),κN(2):2κO(1)L(2a))(3)-(1κO(1), κN(2):2κO(2)L(2a))] (5), [Cu(2)(H(2)O)(1κO(1), κN(2):2κO(1)L(2c))-(1κO(1),1κN(2):2κO(1),2u2009κN(1)- L(2c))](2) (6) and [Cu(2)(H(2)O)(2)(κO(1),κN(2)- L(1dd))-(1κO(1),κN(2):2κO(1)L(1dd))(μ-H(2)O)](2·) 2H(2)O (7·2H(2)O), as well as polymer- ic [Cu(H(2)O)(κO(1),1κN(2):2κN(1)L(1c))](n) (8) and [Cu(NH(2)C(2)H(5))(κO(1),1κN(2):2κN(1)L(2a))](n) (9). The ligands 2-SO(3)H-C(6)H(4)-(NH)N=C{(CN)[C(NH(2))-(=NCH(2)CH(2)NH(2))]} (H(2)L(1b), 10), 2-CO(2)H-C(6)H(4)-(NH)N={C(CN)[C(OCH(3))-(=NH)]} (H(2)L(2a), 11) and 2-SO(3)H-C(6)H(4)-(NH)N=C{C(=O)-(NH(2))}(2) (H(2)L(1dd), 12) were easily liberated upon respective treatment of 4, 5 and 7 with HCl, whereas the formation of cyclic zwitterionic amidine 2-(SO(3)(−))-C(6)H(4)-N=NC(-C=(NH(+))CH(2)CH(2)NH)(=CNHCH(2)CH(2)NH) (13) was observed when 1 was treated with ethylenediamine. The hydrogen bond-induced E/Z isomerization of the (HL(1d))(−) ligand occurs upon conversion of [{Na(H(2)O)(2)(μ-H(2)O)(2)}(HL(1d))](n) (14) to [Cu(H(2)O)(6)][HL(1d)](2)·2H(2)O (15) and [{CuNa(H(2)O)-(κN(1),1κO(2):2κO(1)L(1d))(2)}K(0.5)(μ-O)(2)]n·H(2)O (16). The synthesized complexes 3–9 are catalyst precursors for both the selective oxidation of primary and secondary alcohols (to the corresponding carbonyl compounds) and the following diastereoselective nitroaldol (Henry) reaction, with typical yields of 80–99%.

Synthesis, characterization and antimicrobial activity of arylhydrazones of methylene active compounds

Novel arylhydrazones of methylene active compounds – 3-(2-(1-ethoxy-1,3-dioxobutan-2-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonic acid (1), 2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-2u2009H-indene-1,3-dione (2), 5-chloro-2-hydroxy-3-(2-(4,4,4-trifluoro-1,3-dioxo-1-(thiophen-2-yl)butan-2-ylidene)hydrazinyl) benzenesulfonic acid (3), 5-chloro-2-hydroxy-3-(2-(2,4,6-trioxo-tetrahydropyrimidin-5(6u2009H)-ylidene)-hydrazinyl)benzenesulfonic acid (4), 5-(2-(2-hydroxyphenyl)hydrazono)pyrimidine-2,4,6(1u2009H,3u2009H,5u2009H)-trione (5), 4-hydroxy-5-(2-(2,4,6-trioxo-tetrahydro-pyrimidin-5(6xa0H)-ylidene)hydrazinyl)benzene-1,3-disulfonic acid (6), 5-(2-(2-hydroxy-4-nitrophenyl)hydrazono)pyrimidine-2,4,6(1u2009H,3u2009H,5u2009H)-trione (7) and 5-chloro-3-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-2-hydroxybenzenesulfonic acid (8) have been synthesized by a reaction between the corresponding methylene active compounds and aryldiazonium salts, and characterized by IR, 1u2009H and 13u2009C NMR spectroscopies and element analysis. The collected information confirms that 2, and 4 – 8 exist in DMSO solution in hydrazone form, being stabilized by an intramolecular hydrogen bond, while 1 and 3 exist in mixed enol-azo and hydrazo tautomeric forms. The antimicrobial activity of 1 – 8, as well as that of known analogs 5-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-4-hydroxybenzene-1,3-disulfonic acid (9), 2-(2-sulfophenylhydrazo)malononitrile (10), 2-(2-carboxyphenylhydrazo) malononitrile (11), 2-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)phenylarsonic acid (12) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2,3-dihydrophthalazine-1,4-dione (13), have been studied. It was found that arylhydrazones of barbituric acid are more active than other methylene active compounds. A whole-cell bacterial luminescence biosensor method was used to detect the antimicrobial activity of the synthesized compounds. The results show that compounds 5 and 9 effectively inhibit the luminescence of Staphylococcus aureus at a minimum inhibitory concentration (MIC50) of 10 and 9xa0μg/ml, respectively. For Staphylococcus epidermidis, compound 11 showed the most potent activity with MIC50 of 17xa0μg/mL; for Pseudomonas aeruginosa, compounds 11 showed the most potent activity at MIC50 of 10xa0μg/mL. Observed results have been verified to be statistically significant using the two-tailed test.