Multiple-Bridged Bis-Tetrathiafulvalenes: New Synthetic Protocols and Spectroelectrochemical Investigations

Synthetic strategies for preparing dimeric tetrathiafulvalenes (TTFs) linked by either one, two, or four bridges have been developed. In particular, we report efficient few-step protocols for the preparation of face-to-face overlapped quadruple-bridged bis-TTFs. The ready interconversion of cis and trans TTFs in the presence of catalytic amounts of acid was implemented in one synthetic protocol as a way to control the isomeric outcome. The compounds were characterized by NMR spectroscopy, mass spectrometry, and elemental analysis. Moreover, the X-ray crystal structure of the macrocycle 4b is presented and compared to semiempirical (PM3) geometry optimizations. Cyclic voltammetry and spectroelectrochemistry were used to describe the interactions established between two TTF units upon oxidation, that is, their ability to form mixed-valence complexes and π-dimers either intra- or intermolecularly. The length, flexibility, and number of bridging units in a bis-TTF, as well as the specific TTF positions being connected, determine the extent of these interactions. Thus, rigid linkers enhance the formation of intermolecular mixed-valence complexes. For 4b, the absorption spectrum of this mixed-valence state of TTF in solution has been recorded for the first time. Finally, preliminary complexation experiments with different electron-deficient molecules are described

Calcium electroporation and electrochemotherapy for cancer treatment:Importance of cell membrane composition investigated by lipidomics, calorimetry and in vitro efficacy

Abstract Calcium electroporation is a novel anti-cancer treatment investigated in clinical trials. We explored cell sensitivity to calcium electroporation and electroporation with bleomycin, using viability assays at different time and temperature points, as well as heat calorimetry, lipidomics, and flow cytometry. Three cell lines: HT29 (colon cancer), MDA-MB231 (breast cancer), and HDF-n (normal fibroblasts) were investigated for; (a) cell survival dependent on time of addition of drug relative to electroporation (1.2 kV/cm, 8 pulses, 99 µs, 1 Hz), at different temperatures (37 °C, 27 °C, 17 °C); (b) heat capacity profiles obtained by differential scanning calorimetry without added calcium; (c) lipid composition by mass spectrometry; (d) phosphatidylserine in the plasma membrane outer leaflet using flow cytometry. Temperature as well as time of drug administration affected treatment efficacy in HT29 and HDF-n cells, but not MDA-MB231 cells. Interestingly the HT29 cell line displayed a higher phase transition temperature (approximately 20 °C) versus 14 °C (HDF-n) and 15 °C (MDA-MB231). Furthermore the HT29 cell membranes had a higher ratio of ethers to esters, and a higher expression of phosphatidylserine in the outer leaflet. In conclusion, lipid composition and heat capacity of the membrane might influence permeabilisation of cells and thereby the effect of calcium electroporation and electrochemotherapy

Fingerprints for Structural Defects in Poly(thienylene vinylene) (PTV): A Joint Theoretical–Experimental NMR Study on Model Molecules

In the field of plastic electronics, low band gap conjugated polymers like poly(thienylene vinylene) (PTV) and its derivatives are a promising class of materials that can be obtained with high molecular weight via the so-called dithiocarbamate precursor route. We have performed a joint experimental- theoretical study of the full NMR chemical shift assignment in a series of thiophene-based model compounds, which aims at (i) benchmarking the quantum-chemical calculations against experiments, (ii) identifying the signature of possible structural defects that can appear during the polymerization of PTV's, namely head-to-head and tail-to-tail defects, and (iii) defining a criterion regarding regioregularity