Photo-activated metallotherapeutics: copper(I) or silver(I) mixed ligand complexes with 2-mercaptopyrimidine and triphenylphosphine

Coordination-induced emission enhancement in copper(I) iodide coordination polymers supported by 2-(alkylsulfanyl)pyrimidines

First examples of copper(i) complexes with 2-(alkylsulfanyl)pyrimidine ligands have been synthesized. Reactions of copper(i) iodide with 2-(methylsulfanyl)pyrimidine (L1) in various metal-to-ligand molar ratios in MeCN afford a ladder-type coordination polymer [Cu2L1I2]n with polymeric chains built from double-stranded (Cu2I2)n ribbons supported on both sides by μ2-N,S-L1 molecules. Although the second ligand, 2-(ethylsulfanyl)pyrimidine (L2), differs from L1 only by a methylene group, its reactions with copper(i) iodide in MeCN yield not only a congenerous coordination polymer, [Cu2L2I2]n, but also [CuL2I]n, in which a similar (Cu2I2)n ribbon is decorated by N-monodentate L2 molecules. Absorption spectra of all compounds represent an interplay of metal + iodine-to-ligand charge transfer (XMLCT) and ligand-centered (LC) and cluster-centered (CC) transitions, while the emission occurs from the excited states of XMLCT nature. The luminescence of [Cu2L1I2]n and [Cu2L2I2]n is blue-shifted and greatly enhanced in comparison with that of [CuL2I]n (quantum yields: 89% and 68% for [Cu2L1I2]n and [Cu2L2I2]nvs. 23% for [CuL2I]n at 77 K), which can be associated with a more rigid μ2-N,S coordination of 2-(alkylsulfanyl)pyrimidine ligands in [Cu2L1I2]n and [Cu2L2I2]n leading to a less distorted T1 state.

Structural, photolysis and biological studies of novel mixed metal Cu(I)-Sb(III) mixed ligand complexes

Direct reaction of copper(I) halides with triphenylstibine (tpSb) and 2-mercapto-thiazolidine (tzdtH) in 1:1:1 molar ratio, results in the formation of the [CuX(μ2-S)-tzdtH)(tpSb)]2 (X=Cl (1), Br (2) and I (3)) complexes. The complexes have been characterized by melting point, FT-IR, UV-vis, (1)H NMR spectroscopic data and X-ray crystallography. Complexes 1-3 are di-nuclear and they are the first examples of mixed metals (CuSb), mixed ligand (thioamide, stibine and halogen) containing complexes. Two μ2-S (1-3) atoms bridge the two copper(I) ions with tetrahedral geometry. The coordination sphere around copper atoms is completed by one Sb from tpSb and one halogen (chlorine, bromine or iodine) atom. Intermolecular via N-H⋯X (Cl (1) and Br (2)) interactions stabilized the assembly. The short coppercopper bond distances of 3.103 (1), 3.061 (2) and 3.110, 3.108 (3) Ǻ found in 1-3 indicates d(10)-d(10) interaction between metal centers. The complexes exhibit high photo-sensitivity to UVB light. The complexes 1-3 and the already known [Cu(μ2-I)(tpSb)2]2 (4) were tested for their in vitro cytotoxic activity against human cancer cell lines: MCF-7 (breast, estrogen receptor (ER) positive), MDA-MB-231 (breast, estrogen receptor (ER) negative) and MRC-5 (normal human fetal lung fibroblast cells) with sulforhodamine B (SRB) colorimetric assay. Since estrogen receptors (ERs) are located in MCF-7, in contrast to MDA-MB-231 cells, the estrogenic effect of 1-4 on MCF-7 cells was studied by the mean of methylene blue assay. Compound 4 exhibits the highest estrogenic effect. None of 1-4 exceeds the activity of cisplatin against MCF-7 cells, but they are more active than cisplatin towards MDA-MB-231 cells. UVB light increases the effectiveness of complexes on MCF-7 cells which in the case of 4 is up to 28% higher than the corresponding initial complex (without irradiation).

Synthesis, characterization, and binding properties towards CT-DNA and lipoxygenase of mixed-ligand silver(I) complexes with 2-mercaptothiazole and its derivatives and triphenylphosphine

Mixed-ligand silver(I) complexes of formulae [AgCl(TPP)2(MTZD)] (1), {[AgCl(TPP)2(MBZT)]·(MBZT)·2(toluene)} (2), and [AgCl(TPP)2(CMBZT)] (3) were obtained by refluxing toluene solutions of silver(I) chloride with triphenylphosphine (TPP) and the appropriate heterocyclic thioamides 2-mercaptothiazolidine (MTZD), 2-mercaptobenzothiazole (MBZT), and 5-chloro-2-mercaptobenzothiazole (CMBZT). The complexes were characterized by the melting point, vibrational spectroscopy (Fourier transform mid-IR), (1)H-NMR spectroscopy, UV-vis spectroscopy, and X-ray crystallography. DNA binding tests indicate the ability of complexes 1-3 to modify the activity of cells. The binding constants of 1-3 towards calf-thymus DNA (CT-DNA) [(3.5 ± 8.5) × 10(4) M(-1) for 1, (10.0 ± 0.0) × 10(4) M(-1) for 2, and (46.4 ± 7.0) × 10(4) M(-1) for 3] indicate strong interaction of 3. Changes in the fluorescence of ethidium bromide in the presence of DNA suggest intercalation into or electrostatic interactions with DNA. The corresponding apparent binding constants (K app) towards CT-DNA calculated through fluorescence spectra are (3.5 ± 0.7) × 10(4) M(-1) for 1, (10.0 ± 0.0) × 10(4) M(-1) for 2, and (46.4 ± 7.0) × 10(4) M(-1) for 3. Docking studies on DNA complexes confirm the binding of 1 and 2 in the major groove of CT-DNA and of 3 in the minor groove. Moreover, the influence of 1-3 on the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase was studied kinetically and theoretically. The antibacterial effect of 1-3 against the bacterial species Pseudomonas aeruginosa and Escherichia coli was evaluated. Complex 1 exhibits the strongest activity.