Tuning the Thermometric Features in 1D Luminescent EuIII and TbIII Coordination Polymers through Different Bridge Phosphine Oxide Ligands.

TbIII and EuIII systems have been investigated as ratiometric luminescent temperature probes in luminescent coordination polymers due to TbIII → EuIII energy transfer (ET). To help understand how ion-ion separation, chain conformation as well as excitation channel impact their thermometric properties, herein, [Eu(tfaa)3(µ-L)Tb(tfaa)3]n one-dimensional (1D) coordination polymers (tfaa- = trifluoroacetylacetonate, and L = [(diphenylphosphoryl)R](diphenyl)phosphine oxide, R = ethyl - dppeo - or butyl - dppbo) were synthesized. The short µ-dppeo bridge ligand leads to a more linear 1D polymeric chain, while the longer µ-dppbo bridge leads to tighter packed chains. As the temperature rises from 80 K, upon direct TbIII excitation at 488 nm, the TbIII emission intensity decreases, while the EuIII emission intensity increases after 160 and 200 K when L = dppeo or dppbo, respectively. The temperature-dependent emission intensities, due to TbIII → EuIII ET, enable the development of ratiometric luminescent temperature probes featuring maximum relative thermal sensitivity up to 3.8% K-1 (250 K, L = dppbo, excitation at 488 nm). On the other hand, the same system displays maximum thermal sensitivity up to 3.5% K-1 (323 K) upon ligand excitation at 300 nm. Thus, by changing the excitation channel and bridge ligand that leads to modification of the polymer conformations, the maximum relative thermal sensitivity can be tuned.

Novel piplartine-containing ruthenium complexes: synthesis, cell growth inhibition, apoptosis induction and ROS production on HCT116 cells.

Piplartine (piperlongumine) is a plant-derived molecule that has been receiving intense interest due to its anticancer characteristics that target the oxidative stress. In the present paper, two novel piplartine-containing ruthenium complexes [Ru(piplartine)(dppf)(bipy)](PF6)2 (1) and [Ru(piplartine)(dppb)(bipy)](PF6)2 (2) were synthesized and investigated for their cellular and molecular responses on cancer cell lines. We found that both complexes are more potent than metal-free piplartine in a panel of cancer cell lines on monolayer cultures, as well in 3D model of cancer multicellular spheroids formed from human colon carcinoma HCT116 cells. Mechanistic studies uncovered that the complexes reduced the cell growth and caused phosphatidylserine externalization, internucleosomal DNA fragmentation, caspase-3 activation and loss of the mitochondrial transmembrane potential on HCT116 cells. Moreover, the pre-treatment with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, reduced the complexes-induced apoptosis, indicating cell death by apoptosis through caspase-dependent and mitochondrial intrinsic pathways. Treatment with the complexes also caused a marked increase in the production of reactive oxygen species (ROS), including hydrogen peroxide, superoxide anion and nitric oxide, and decreased reduced glutathione levels. Application of N-acetyl-cysteine, an antioxidant, reduced the ROS levels and apoptosis induced by the complexes, indicating activation of ROS-mediated apoptosis pathway. RNA transcripts of several genes, including gene related to the cell cycle, apoptosis and oxidative stress, were regulated under treatment. However, the complexes failed to induce DNA intercalation. In conclusion, the complexes are more potent than piplartine against different cancer cell lines and are able to induce caspase-dependent and mitochondrial intrinsic apoptosis on HCT116 cells by ROS-mediated pathway.

Structural and Theoretical Investigation of Anhydrous 3,4,5-Triacetoxybenzoic Acid.

A comprehensive investigation of anhydrous form of 3,4,5-Triacetoxybenzoic acid (TABA) is reported. Single crystal X-ray diffraction, Thermal analysis, Fourier Transform Infrared spectroscopy (FTIR) and DFT calculations were applied for TABA characterization. This anhydrous phase crystallizes in the triclinic [Formula: see text] space group (Z' = 1) and its packing shows a supramolecular motif in a classical [Formula: see text] ring formed by acid-acid groups association. The phase stability is accounted in terms of supramolecular architecture and its thermal behaviour. Conformation search at B3LYP/6-311++G(2d,p) level of theory shows the existence of three stable conformers and the most stable conformation was found experimentally. The reactivity of TABA was investigated using the molecular orbital theory and molecular electrostatic potential. The calculation results were used to simulate the infrared spectrum. There is a good agreement between calculated and experimental IR spectrum, which allowed the assignment of the normal vibrational modes.