Vinyl-triphenylamine dyes, a new family of switchable fluorescent probes for targeted two-photon cellular imaging: from DNA to protein labeling

On the basis of our previous work on vinyl-triphenylamine derived DNA fluorophores we explored the structure space around this core by coupling it to diverse cationic, anionic and zwitterionic groups in the aim of targeting different classes of biomolecules. In parallel core modifications were performed to optimize the photophysical properties (quantum yield, two-photon absorption). The resulting water soluble π-conjugated molecules are called TP dyes and display an exceptional combination of optical properties: high two-photon absorption cross-section, high photostability, no self-quenching, and switchable fluorescence emission when bound to a biopolymer matrix. The linear and nonlinear optical properties of the TP dyes were studied in vitro in presence of DNA and in presence of a model protein (human serum albumin) using complementary absorption and fluorescence spectroscopy characterization tools. Structure modifications enabled to switch from DNA probes (cationic TP-pyridinium series) to protein probes (anionic TP-rhodanine series) without affecting the optical properties. Finally most TP compounds appear cell-permeant and show an intracellular localization consistent with their in vitro target specificity.     

2-Benzyliden-2H-thieto[3,2-b]quinoline: a new heterocycle and its rearrangement to 2-phenylthieno[3,2-b]quinoline

Synthesis of the strained 2H-thieto[3,2-b]quinoline ring system is reported for the first time. Treatment of (Z)-2-benzyliden-2H-thieto[3,2-b]quinoline derivatives of this heterocycle with base, at reflux in ethanol, causes a novel rearrangement to 2-phenylthieno[3,2-b]quinolines. Indeed, the one-pot reaction of 2-aminobenzaldehydes and (Z)-2-benzylidenethietan-3-one in refluxing basic ethanol leads directly to 2-phenylthieno[3,2-b]quinolines in good yields.     

Exohedral chemical functionalization of C48B6N6 with NH3: Binding energies and electronic structures of C48B6N6–(NH3)n=1−6

Theoretical study of exohedral chemical functionalization of C₄₈B₆N₆ with NH₃ molecules has been investigated using DFT. It was found that NH₃ molecule can be chemically adsorbed on boron sites of C₄₈B₆N₆, with a charge transfer from NH₃ to C₄₈B₆N₆. Adsorption energy and the quantity of electron charge transfer from latest adsorbed ammonia to C₄₈B₆N₆ decreased with increasing in the adsorbed NH₃ molecules. Despite the strong adsorption energies, electronic properties of C₄₈B₆N₆ is preserved after modification(s) with NH₃ molecule(s) and chemical modification of C₄₈B₆N₆ with NH₃ molecules can be viewed as some kind of safe modification.