The 4,5‐{Ph2(HO)C}2‐1,2,3‐triazole ligand (2) with two bulky Ph2C(HO) substituents was synthesized and used in the preparation of coordination compounds with selected group 1 metals. In the solid state, the high Lewis acidity of lithium caused the formation of di‐ and tetrametallic L2Li2thf4·2THF and L4Li4thf2(Et2O)2·2Et2O (L = monoanionic form of 2) species, while only the dimetallic derivative L2Na2thf4·2THF was observed for sodium. The larger size of potassium caused the formation of L6K6(H2O)thf2·2THF with a hexagonal drumlike inorganic core. 1H DOSY NMR spectroscopic studies confirmed the presence of multimetallic species also in solution. The molecular structures of the compounds were determined by single‐crystal X‐ray diffraction. In a comparative study, magnesium derivatives of 2 were prepared to evaluate the effect of a higher covalent character of the M–O bond leading to multimetallic polycyclic systems with up to 29 rings. Finally, the lithium compounds showed catalytic activity in the polymerization of ε‐caprolactone.
Four copper(II) coordination compounds from 2-benzimidazole propionic acid (Hbzpr) and 4-(benzimidazol-2-yl)-3-thiobutanoic acid (Hbztb) were synthesized and fully characterized by elemental analyses, electronic spectroscopy, FT-IR and mass spectrometry. The molecular structure for the four complexes was confirmed by single-crystal X-ray crystallography. The DNA-interacting properties of the two trinuclear and two mononuclear compounds were investigated using different spectroscopic techniques including absorption titration experiments, fluorescence spectroscopy and circular dichroism spectroscopy. Trinuclear [Cu(bzpr)(HO)](NO)·3HO·CHOH (2) and [Cu(bzpr)Cl]·3HO (3) bind to DNA through non-intercalative interactions, while for mononuclear [Cu(bzpr)(HO)]·2HO (1) and [Cu(bztb)]·2HO (4), at minor concentrations in relation to the DNA, a groove binding interaction is favored, while at higher concentrations an intercalative mode is preferred. The nuclease properties of all complexes were studied by gel electrophoresis, which showed that they were able to cleave supercoiled plasmid DNA (form I) to the nicked form (form II). Compound 4 is even capable of generating linear form III (resulting from double-strand cleavage). The proposed mechanism of action involves an oxidative pathway (Fenton-type reaction), which produces harmful reactive species, like hydroxyl radicals.
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