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The synthesis, antibacterial screening and mode of action copper pyridyl complexes towards drug resistant bacteria. [Display omitted] • Novel series of copper complexes with pyridyl-based ligands were successfully synthesized using mechanochemical methods, resulting in favorable yields of 80–90%. • Characterization data confirmed the successful synthesis of the complexes and the electronic spectra and magnetic susceptibility data indicated that the copper complexes were d9 tetrahedral complexes with parallel spin electrons. • The copper complexes exhibited promising antibacterial activity, with higher efficacy against Gram-positive bacteria, particularly CuL4 , which showed exceptional activity against MRSA and S. aureus. • Time-kill kinetics analysis indicated that the copper complexes displayed bacteriostatic activity at their minimum inhibitory concentrations (MIC) but exhibited bactericidal tendencies after 24 h. • Cell membrane disruption studies revealed that CuL4 , the nitro group complex, was the most effective in disrupting the cell membrane of S. aureus , followed by Cu4PY-H and the control AgSD , indicating potential modes of action. A series of four new copper complexes containing pyridyl-based ligands of the type [Cu(Cl) 2 (L) 2 ] were prepared by solid-state methods and evaluated for antibacterial activity. Their elemental analysis showed that the grinding method produced pure complexes. FTIR spectroscopy confirmed the coordination of ligands to copper ions by identifying shifts in vibrational frequencies. Furthermore, their successful synthesis was confirmed by the coordinating bonds being shifted to lower frequencies. Electronic spectra and magnetic susceptibility data proved the complexes to be d9 tetrahedral complexes. Thermal studies of the copper complexes indicated that they had good thermal stability. In the thermal analysis, a recurring pattern emerges as each copper complex experiences multiple mass losses and exhibits characteristic transitions in DSC profiles, shedding light on their distinct thermal behaviors. The mass spectra of the copper complexes showed that the data agreed with the elemental analysis and other elucidation techniques. The complexes displayed characteristic molecular ion peaks and adducts consistent with their calculated masses, substantiating the successful synthesis of these complexes and enhancing understanding of their composition and stability. The copper complexes also displayed solubility in highly polar and heavy solvents thus reduced the chances of forming good-quality crystals. The copper complexes were more effective against Gram-positive bacteria, with CuL4 performing best, notably against MRSA and S. aureus. All of the active complexes were bacteriostatic against MRSA and S. aureus based on the time kill kinetics. Additionally, it was shown that the CuL4 and Cu4PY-H disrupted the S. aureus cell membrane more effectively than the AgSD control. Finally, the CuL4 membrane disruption studies were not significantly different to the AgSD control on MRSA. The results of cell membrane disruption were supported by molecular docking scores, where CuL4 outperformed the other active compounds, and the trends corroborated the experimental results. [ABSTRACT FROM AUTHOR]

The Lewis base–Lewis acid adducts with the Lewis bases pyrazine, triphenyphosphine, neocuproine (2,9-dimethyl-1,10-phenanthroline), cuproine (2,2′-diquinolyl) and triphenylborane as Lewis acid were prepared. Their electronic spectra are characterized by low-energy electronic transitions which are attributed to phenyl (BPh 3 ) to Lewis base, ligand to ligand charge transfer (LLCT) transitions. These Lewis base-BPh 3 complexes display a distinct blue to green fluorescence in solution which originates from the lowest-energy LLCT singlets. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cyclometalated Rh(III) complex was synthesized. • It was characterized by CHN analysis, UV–Vis, FT-IR and NMR spectra. • Its molecular structure was confirmed by X-ray crystallography. • The comparison of the experimental and calculated data (DFT) was carried out. • Compound exhibited significant antibacterial activity. • Phosphorescent emissions were observed at 508 and 538 nm in solvent and solid state, respectively. In this work, structural and spectroscopic properties of the cyclometalated Rh(III) complex, [Rh(ppy) 2 (Mdtc)]·H 2 O with ppy = 2-phenylpyridine and Mdtc = morpholine-4-dithiocarbamate were studied by X-ray crystallography and IR, 1H and 13C NMR, electronic absorption and Fluorescence spectroscopy. The title complex crystallized in triclinic, space group P-1 , Z = 2, a = 9.7173(19) Å, b = 11.399(2) Å, c = 12.398(3) Å and α = 107.63(3)˚, β = 100.76 (3)°, γ = 90.84(3)˚. Electronic spectrum of the complex show that ligand-centered (LCT) transitions and ligand-to-metal charge transfer (LMCT). Geometric structure, frontier orbital and electronic absorption spectrum property of the compound were investigated by using density functional theory (DFT) and compared with the experimental data. Calculated geometric parameters agree with the experimental data. Then the agar disc diffusion method was used to determine the antibacterial activity of the ligands and complex on the growth profile of Four Gram-negative bacteria, i.e., Pseudomunas aeroginosa , Salmonella typhai , Proteus mirabilis and Yersinia enterocolitica and two Gram-positive bacteria, i.e., Staphylococcus aureus and Enterococcus faecalis. The activity of the Rh (III) complex against bacteria was considerably stronger than the ligands. [ABSTRACT FROM AUTHOR]

A series of mixed-ligand heterobimetallic complexes of the form MM′(C7H4NS2)4(py)2 and MM′(C7H4NS2)4(N–N) and complex heterobimetallic salts [M(N–N)3][M′(C7H4NS2)4] [M=Co(II) or Ni(II); M′=Zn(II) or Hg(II); N–N=ethylenediamine(en) or 1,10-phenanthroline(phen)] has been prepared and characterized by IR and UV–visible spectroscopy, microanalysis and conductivity techniques. Except with NiZn(C7H4NS2)4(py)2 which is insulator all of the compounds exhibit σrt in the 10−12–10−5 S cm−1 range and semiconduct over 303–393 K. [Copyright &y& Elsevier]

Iron(III) complexes with phenolate ligands (m-cresolate and tyrosinate) undergo a redox photolysis in aqueous solution upon phenolate → Fe(III) ligand-to-metal charge transfer excitation. At λirr=577 nm the quantum yields of Fe(II) formation are approximately φ=10−4. [Copyright &y& Elsevier]

Light pink crystal of composition [Co(4-CH2OH-5-CH3im)4](NO3)2 (where 4-CH2OH-5-CH3im denotes 4-hydroxymethyl-5-methylimidazole) were obtained from 2-propanol. The complex has been characterized by single-crystal X-ray as well as by electronic and vibrational spectroscopy. The immediate surrounding of the central ion is made up of four nitrogen atoms of the heterocyclic rings and two oxygen atoms of the hydroxymethyl group (CoN4O2 chromophore) The shape of the coordination polyhedron of the cobalt(II) ion is that of a slightly distorted octahedral. [Copyright &y& Elsevier]

The photolysis of gold azide complexes in CH3CN leads to the formation of colloidal gold and [AuI(CN)2]−. The gold atoms which are initially formed do not only agglomerate to colloidal particles but also react with the solvent. It is suggested that CH3CN adds oxidatively to atomic gold and [AuI(CN)2]− is generated in subsequent reactions. [Copyright &y& Elsevier]