Syntheses, electrochemical studies and crystal structures of new unsymmetrical tetrathiafulvalene carboxylate derivatives

A redox active proton transfer and hydrogen-bonding system of tetrathiafulvalene-dicarboxylic acid and pyridine bases

Hydrogen bonds are important in supramolecular chemistry and responsible for proton transfer processes. This manuscript reports new hydrogen-bonding systems of redox-active acid-base assemblies consisting of dimethylthio-tetrathiafulvalene dicarboxylic acid (H(2)L) coupled with pyridine (py), 2,2'-bipyridine (2,2'-bpy), and 4,4'-bipyridine (4,4'-bpy). The (1)H NMR chemical shifts of the pyridines and the redox potential shifts of the tetrathiafulvalene moiety indicate that proton-transfer and strong hydrogen-bonding interactions exist between the acid and the bases in aprotic solvents. The results of cyclic voltammetry show a two-step square reaction with a redox and proton transfer coupled mechanism. The nature of the hydrogen bonds was characterized by X-ray single crystal analysis. In contrast to the mono-carboxyl-py system, in this ortho-substituted dicarboxyl-py system one proton of the H(2)L transfers completely from the carboxyl to the py group. The conjugated intramolecular and intermolecular hydrogen bonds are responsible for the proton transfer.

Highly sensitive identification of cancer cells by combining the new tetrathiafulvalene derivative with a β-cyclodextrin/multi-walled carbon nanotubes modified GCE

In this contribution, we have prepared and explored a novel nano-interface based probe for the rapid identification and highly sensitive detection of cancer cells by means of an electrochemical study. The new probe tetrathiafulvalene (TTF) carboxylate salt (TTF-(COONBu(4))(2), ditetrabutylammonium salt for propylenedithio-4',5'-tetrathiafulvalene-4,5-dicarboxylate), which has specific spectral and electrochemical properties, has been synthesized and assembled with carbon nanotubes to form a new type of nanocomposite. A simple method of fabricating the β-CD/MWCNT modified electrodes based on functionalized multi-walled carbon nanotubes (MWCNTs) and β-cyclodextrin (β-CD) has been explored by using glassy carbon electrodes (GCEs), which could remarkably enhance the sensitivity of the biomolecular detection. Our results demonstrate that the combination of the new probe TTF-(COONBu(4))(2) with β-CD/MWCNT modified electrodes could be readily utilized to sensitively detect cancer cells such as liver cancer cells SMMC-7721 and HepG2, drug sensitive leukemia K562/B.W cells and drug resistant leukemia K562/ADM cells, with a detection limit of ~10(3) cells mL(-1). This may provide a novel strategy for the potential and promising application of the new TTF molecular probe in the development of multi-signal responsive biosensors for the early diagnosis of cancers.