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Graphical abstract Equimolar reactions of copper(I) halides with PPh 3 and pyridine-2-carbaldehyde-N-substituted thiosemicarbazone (C 5 H 4 N)HC2 N3N2(H)-C1(S)N1HR has yielded complexes, [CuX 2 (κS1-H 2 L1-R)(PPh 3)] 1–5 (X = halogen, R = Me, Et) with pyridine protonated thio-ligand. Similar reactions of copper(I) halides with benzaldehyde-N1-substituted thiosemicarbazones (C 6 H 5)HC2 N3-N2(H)-C1(S)-N1HR and Ph 3 P halogen bridged dinuclear complexes, [Cu 2 (μ-X) 2 (κS1-HL2-R) 2 (Ph 3 P) 2 ] 6–10 (X = halogen, R = Me, Et) or sulfur-bridged dinucelar complexes [Cu 2 (μ-S-HL2-Ph) 2 (κS1-HL2-Ph) 2 X 2 ] 11–13 with no Ph 3 P coordination. The substitutions at N1, C2 and order of reactants with change in solvent appear to have yielded three types of products. Abstract Equimolar reaction of copper(I) iodide with PPh 3 in acetonitrile formed compound of empirical composition, {CuI(Ph 3 P)} and its further reaction in chloroform with pyridine-2-carbaldehyde-N-methyl thiosemicarbazone {(C 5 H 4 N)HC2 N3-N2-(H)-C1(S)N1HR; R = Me; HL1-Me} formed crystals of complex, [CuICl(Ph 3 P)(κS1-H 2 L1-Me] 1a , tetramer [Cu 4 I 4 (Ph 3 P) 4 ] 1b and free HL1-Me 1c , separated from the same reaction vessel. The formation of product 1a involved abstraction of chlorine from chloroform and has pyridine-N-protonated thio-ligand. Copper(I) bromide/chloride with Ph 3 P and HL1-Me or HL1-Et also formed pyridyl protonated, [CuBr 2 (Ph 3 P)(κS1-H 2 L1-Me)] 2 , [CuCl 2 (Ph 3 P)(κS1-H 2 L1-Me)] 3 , [CuBr 2 (Ph 3 P)(κS1-H 2 L1-Et)] 4 and [CuCl 2 (Ph 3 P)(κS1-H 2 L1-Et)] 5. The products similar to 1b and 1c were also identified in these reactions. In these four coordinated complexes the pyridine protonated thio-ligands are coordinating through sulfur only. Copper(I) halides with benzaldehyde-N1-substituted thiosemicarbazones {(C 6 H 5)HC2 N3-N2(H)-C1(S)-N1HR ; R = Me, Et; HL2-Me; HL2-Et} and Ph 3 P have yielded halogen bridged dinuclear complexes, [Cu 2 (μ-X) 2 (κS1-HL2-R) 2 (Ph 3 P) 2 ] (X, R: I, Me, 6 ; Br, Me, 7 ; I, Et, 8 ; Br, Et, 9 ; Cl, Et, 10). For R = phenyl at N1 atom, copper(I) halides with two m moles of HL2-Ph have formed sulfur–bridged dinucelar complexes, namely, [Cu 2 (μ-S-HL2-Ph) 2 (κS1-HL2-Ph) 2 X 2 ] (X = I, 11 , Br, 12 , Cl, 13). Complexes have been characterized using analytical data, IR, proton NMR and single crystal X-ray crystallography (1–5, 7, 9, 11 and 12). The coordination environment of the Cu in complex 1a contains both Cl and I, but both sites are disordered. [ABSTRACT FROM AUTHOR]

Anti-tubercular activity of oxindole semicarbazones increased to much larger extent on complexation with Cu(II). Binding studies and molecular modeling are in well agreement with experimental data. [Display omitted] Copper (II) acetate reacted with 2-oxindole semicarbazone (2-Hoxsc, H1L), 3-methyl 2-oxindole semicarbazone (3-MeHoxsc, H2L) and 6-Chloro-2-oxindole semicarbazone (6-ClHoxsc, H3L) in 1:2 (M:L) molar ratio to form complexes of general formula, [Cu(L 2)] (1L, 1 ; 2L 2 ; 3L 3. Stoichiometric ratio of complexes was established using UV–Vis spectroscopy. All the complexes were characterised by the CHN analysis, IR, ESR spectroscopy and Mass spectrometry. From the ESR spectrum, g values obtained (g ‖ = 2.20; g ⊥ = 2.05) for complex 2 confirms axial symmetry for this complex, whereas a broad isotropic signal in 1 and 3 (g iso = 2.060, 1 ; 2.057, 3) indicates extensive exchange coupling. All the synthesized compounds (ligands and complexes) complexes were examined for their anti-tubercular activity against M. tuberculosis H37RV strain. Compounds were also tested for their anti-bacterial (B. subtilis , K. pneumonia) and antifungal (C. auris , C. albicans) activities. Biological investigations revealed that the antimicrobial activities (anti-TB, antibacterial and antifungal) of ligands get improved on complexation with Cu (II) due to formation of chelate ring, which can make the ligand a more powerful biological agent. Complex 3 has shown excellent anti-TB (MIC = 1.6 g/ml) and antibacterial (ZOI = 26 mm at 5 mg/mL) activities. Strong binding of complex 3 was observed (K b = 24.22 × 105 M−1) with Human Serum Albumin (HSA) using fluorescence spectroscopy. Molecular modelling of complex 3 was also done with the active site of amino acid of M. tuberculosis enoyl reductase. The minimal binding energy of −10.1 kcal/mol indicated significant intermolecular interaction between M. tuberculosis enoyl reductase and complex 3 and is in well agreement with experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] Reaction of copper(II) acetate with cyclohexanoneselenosemicarbazone (Hcysesc), 5-chloro isatinselenosemicarbazone (5-ClHIstsesc), 1-methyl isatinselenosemicarbazone (1-MeHIstsesc), 3-indole selenosemicarbazone (3-HInsesc), 3-acetylindole selenosemicarbazone (3-AcHInsesc and 2-naphthaldehyde selenosemicarbazone (2-Hnaphsesc) in 1:2 (M: L) molar ratio yielded complexes of stiochiometry, [Cu(L) 2 ] 1 – 6 (L = cysesc 1 ; 5-ClIstsesc 2 ; 1-MeIstsesc 3 ; 3-Insesc 4 ; 3-AcInsesc 5 ; 2-naphsesc 6). All the complexes are characterized by IR, Mass and ESR spectroscopy. Two well defined g values (g ‖ and g ⊥) in ESR spectrum of complexes 1 – 4 , 6 indicate axial symmetry, whereas symmetry around copper(II) metal in complex 5 is confirmed by three different g values (g 1 , 2.095; g 2 , 2.15; g 3 , 2.26), which supports rhombic distortion. The value of g ‖ obtained is greater than g ⊥, which is greater than g e, in 1 – 4 , 6 is in well agreement in d x2-y2 ground term of square planar geometry. The value of empirical factor f for complexes 1 – 4, 6 lies in the range, 102–135 cm indicating a square planar geometry with small distortion, where as in complex 5 value (f = 146 cm) is in conformity of tetrahedral geometry with larger distortion. All the compounds (selenosemicabazones and their complexes) are tested for DPPH radical scavenging, ABTS radical scavenging, FRAP ferric reducing and CUPRAC cupric reducing antioxidant capacity assay and all the compounds have shown good antioxidant capacity in general. Best results are obtained for H1L with FRAP, 6.75 ± 0.01 μg TE/ml and CUPRAC, 9.52 ± 0.07 μg TE/ml. All the compounds are also tested for their anti-tubercular activity against M. tuberculosis H37RV strain ATCC27294. Ligands, H1L , H3L , H6L and complex 6 have shown highest anti-TB activity (MIC = 1.6 µg/ml) which is similar to the standard drugs (Isoniazid, Ethambutol). anti-TB activity of H2L and H5L (MIC = 12.5 µg/ml and 25 µg/ml) increased on complexation with copper(II) (MIC = 1.6 µg/ml, 2 ; 12.5 µg/ml, 6). Experimental results are supported by molecular modeling studies, where a considerable intermolecular interaction of these compounds with the active site of amino acid of enoyl reductase from M. tuberculosis has been observed with minimum binding energy −6.2, −7.3, −7.7, −7.4, −7.2, −8.7 Kcal/mol for H1L , H2L , H3L , H4L , H5L , and H6L and −7.2, −9.4, −8.6, −9.3, −9.9, and −10.6 Kcal/mol for copper complexes 1, 2, 3, 4, 5 and 6 exhibited respectively. [ABSTRACT FROM AUTHOR]