Six new copper(ii) complexes with 2,2':6',2''-terpyridine (4'-R-terpy) [1 (R = furan-2-yl), 2 (R = thiophen-2-yl), and 3 (R = 1-methyl-1H-pyrrol-2-yl)] and 2,6-di(thiazol-2-yl)pyridine derivatives (R-dtpy) [4 (R), 5 (R), and 6 (R)] have been synthesized by a reaction between copper(ii) chloride and the corresponding ligand. The complexes have been characterized by UV-vis and IR spectroscopy, and their structures have been determined by X-ray analysis. The antiproliferative potential of copper(ii) complexes of 2,2':6',2''-terpyridine and 2,6-di(thiazol-2-yl)pyridine derivatives towards human colorectal (HCT116) and ovarian (A2780) carcinoma as well as towards lung (A549) and breast adenocarcinoma (MCF7) cell lines was examined. Complex 1 and complex 6 were found to have the highest antiproliferative effect on A2780 ovarian carcinoma cells, particularly when compared with complex 2, 3 with no antiproliferative effect. The order of cytotoxicity in this cell line is 6 > 1 > 5 > 4 > 2 ≈ 3. Complex 2 seems to be much more specific towards colorectal carcinoma HCT116 and lung adenocarcinoma A549 cells. The viability loss induced by the complexes agrees with Hoechst 33258 staining and typical morphological apoptotic characteristics like chromatin condensation and nuclear fragmentation. The specificity towards different types of cell lines and the low cytotoxic activity towards healthy cells are of particular interest and are a positive feature for further developments. Complexes 1-6 were also tested in the oxidation of alkanes and alcohols with hydrogen peroxide and tert-butyl-hydroperoxide (TBHP). The most active catalyst 4 gave, after 120 min, 0.105 M of cyclohexanol + cyclohexanone after reduction with PPh. This concentration corresponds to a yield of 23% and TON = 210. Oxidation of cis-1,2-dimethylcyclohexane with m-CPBA catalyzed by 4 in the presence of HNO gave a product of a stereoselective reaction (trans/cis = 0.47). Oxidation of secondary alcohols afforded the target ketones in yields up to 98% and TON = 630.

Several 2,2':6',2''-terpyridines substituted in the 4'-position were synthesized and their photophysical properties were investigated by absorption and photoluminescence spectroscopy in dilute solutions and solid state. The studies confirmed that the absorption and emission wavelengths, fluorescence quantum yields and lifetimes of 1-R(1-16) are strongly structure-related, demonstrating a decisive role of the nature of the substituent in determining the photophysical properties of 4'-functionalized terpyridines. Additionally, the density functional theory (DFT) calculations were performed for 1-R(1-16) to get insight into their electronic structure and spectroscopic properties.

Six new Re(i) complexes of the general formula [ReCl(CO)3(4'-R-terpy-κ(2)N)] with 2,2':6',2''-terpyridine-based ligands have been synthesized and characterized by IR, NMR ((1)H and (13)C), UV-Vis spectroscopy and single crystal X-ray analysis. The luminescent properties of [ReCl(CO)3(4'-R-terpy-κ(2)N)] were studied in solution and solid state, at 298 and 77 K, respectively. To obtain detailed insight into the electronic structures and spectroscopic properties of [ReCl(CO)3(4'-R-terpy-κ(2)N)], the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed. Also, the suitability of this class of materials for being applied in organic light emitting diodes (OLEDs) has been preliminarily tested.

Photophysics of [ReCl(CO)3(4′-R-terpy-κ2N)].