Highly Fluorescent π-Conjugated Azomethines and Divalent Metal Complexes as Antibacterial and Antibiofilm Nominees.

π-Conjugated azomethine ligands differing in the naphthalene or phenylmethane-centered core structure and their divalent cobalt, nickel, copper, and zinc metal complexes were prepared and well-characterized by spectral analyses in solid state. Magnetic natures of the complexes were determined by magnetic susceptibility measurements in solid-state. Their remarkable photophysical characteristics were recorded by Uv-vis and Fluorescence spectroscopic techniques. At their excitation wavelenght of 265 nm, all molecules exhibited triple fluorescence emission bands with promising intensities above 673 nm in near infra-red region. Antibacterial and antibiofilm activities of the π-conjugated azomethines are promising for potential applications in medical and healthcare settings. Hence, the antibacterial/antibiofilm activity of the π-conjugated azomethine ligands and their metal complexes against some clinically important bacteria namely Staphylococcus aureus (MSSA), Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Proteus mirabilis was investigated, and the obtained results have shown that the ligands and complexes had a remarkable antibacterial effect, especially on Proteus mirabilis. Metal complexes have been found to have a significant inhibitory effect on biofilm formation by MRSA, MSSA, and P. mirabilis compared to ligands. The copper (II) complex of ligand-2 showed the highest inhibition percentage, significantly reducing biofilm formation for MRSA and MSSA. Furthermore, cobalt (II) complexes of the ligands selectively inhibited the growth of the opportunistic pathogen P. mirabilis biofilms, indicating that metal complexes might be a good choice for future antibiofilm studies.

Carboxamide-Based Tripodal Fluororeceptors for Cations: Preparation, Characterization and Spectroscopic Studies.

Tripodal receptors, N-1,3,5-tris[2-(ethylamino)ethyl]benzene-1,3,5-tricarboxylamide (L1), N-1,3,5-tris[2-(phenylamino)ethyl]benzene-1,3,5tricarboxylamide (L2) and highly fluorescent N-1,3,5-tris[2(naphthalene-2-ylamino)-ethyl]benzene-1,3,5,tricarboxyl-amid)) (L3) were synthesized by the reaction of 1,3,5-benzene-tricarbonylchloride and different amine groups originally. Sensitivity measurements were performed with the addition of Fe(II), Cu(II), Hg(II), Zn(II), Ni(II), Mn(II), Cd(II), Ga(III), Co(II), Yb(III), Cr(III) and Ag(I) metals to the receptor solutions. According to the absorption and emission studies, these receptors show fluorescent property and Fe(II) ion quenches their fluorescence effectively.

Preparation of Different Substitued Polypyridine Ligands, Ruthenium(II)-Bridged Complexes and Spectoscopic Studies.

Novel different substitued polypyridine ligands 4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzaldehyde (BA-PPY), (E)-N-(4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzylidene)-pyrene-4-amine (PR-PPY), (E)-N-(4-((4-(1H-imidazo[4,5-f][1,10] phenanthroline-2-yl)phenoxy)methyl)benzylidene)-1,10-phenanthroline-5amine (FN-PPY), 2-(4-(bromomethyl)phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline (BR-PPY), 2-(4-(azidomethyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (N3-PPY) and triazole containing polypyridine ligand 3,4-bis[(4-(metoxy)-1,2,3-triazole)1-methylphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline)] benzaldehyde (BA-DIPPY) and Ruthenium(II) complexes were synthesized and characterized. Their photopysical properties were investigated. The complexes RuP(PR-PPY), RuB(PR-PPY, RuP(FN-PPY) and RuB(FN-PPY) exhibited a broad absorption bands at 485, 475, 476, and 453 nm, respectively, assignable to the spin-allowed MLCT (dπ-π*) transition. The emission maxima of the pyrene-appended polypyridine ligand PR-PPY was observed at λems = 616 nm and the phenanthroline-appended polypyridine ligand FN-PPY was observed at λems = 668 nm. And the emission maxima of the complexes RuP(PR-PPY), RuB(PR-PPY), RuP(FN-PPY) and RuB(FN-PPY) were observed at λems = 646, 646, 685 and 685 nm, respectively. As seen in fluorescence spectra, the fluorescence intensities of the ligands are higher than their metal complexes. This is because of quenching effect of Ruthenium(II) metal on chromophore groups.

Ruthenium (II) Complexes of Mono-, Di- and Tripodal Polypyridine Ligands: Synthesis, Characterization, and Spectroscopic Studies.

Mono-, di- and tripodal polypyridine ligands 4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenol (L1), 2-(4-(2-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzyloxy)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L2), 2-(4-(4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzyl oxy)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L3), 2-(4-(4,6-bis(4-(1H-imidazo[4,5-f][1,10] phenanthroline-2-yl)phenoxy)-1,3,5-triazine-2-yloxy)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L4), and their Ru (II) complexes have been synthesized and characterized. All the ligands (L1-L4) gave the emissions at three shoulder at 278 nm, 315 nm, and 328 nm and the complexes (C1-C4) exhibit Ru (II) metal centered emission at 265 nm, 288 nm and 328 nm in acetonitrile solution at room temperature. Maximum d-π* transition seen at 462 nm for all the complexes.

Aromatic chromophore-tethered Schiff base ligands and their iron(III)/chromium(III) Salen and Saloph capped complexes.

Aromatic chromophores; pyrene, phenanthrene, anthracene, naphtalene and benzene-tethered Schiff base ligands and their iron(III)/chromium(III) Salen and Saloph capped complexes have been synthesized. Compounds have been characterized by means of FT-IR Spectroscopy, (1)H-NMR Spectroscopy, Magnetic Susceptibility, Elementel Analsis, TG/DTA measurements. Their fluorescence and absorbance properties have been investigated by Luminescence Spectroscopy and UV-vis Spectroscopy. Generally, ligands show an intense excimer fluorescence emissions in acetonitrile-methanol medium while iron(III) and chromium(III) complexes exhibit low fluorescence's. Intensity compared to ligands iron and chromium centers act as an extra chromophore that quench the pyrene, phenanthrene, anthracene, naphtalene and benzene molecules' singlet state. The mechanism of quenching is attributed to a iron (or chromium)-to-pyrene (or phenanthrene, anthracene, naphtalene and benzene) electronic energy transfer process.