Bright, long-lasting and non-phototoxic organic fluorophores are essential to the continued advancement of biological imaging. Traditional approaches towards achieving photostability, such as the removal of molecular oxygen and the use of small-molecule additives in solution, suffer from potentially toxic side effects, particularly in the context of living cells. The direct conjugation of small-molecule triplet state quenchers, such as cyclooctatetraene (COT), to organic fluorophores has the potential to bypass these issues by restoring reactive fluorophore triplet states to the ground state through intra-molecular triplet energy transfer. Such methods have enabled marked improvement in cyanine fluorophore photostability spanning the visible spectrum. However, the generality of this strategy to chemically and structurally diverse fluorophore species has yet to be examined. Here, we show that the proximal linkage of COT increases the photon yield of a diverse range of organic fluorophores widely used in biological imaging applications, demonstrating that the intra-molecular triplet energy transfer mechanism is a potentially general approach for improving organic fluorophore performance and photostability.
Development of new organic synthetic methods fascinating the researchers which facilitating the increasing demands of the modern society, environmental friendly with high efficiency and low cost. The introduction of chromophores in an organic molecules facilitating intersystem crossing (ISC) to harvest both singlet and triplet excitons is also currently demanding field. We report a facile synthesis of symmetrical azines from carbonyl compounds and hydrazine hydrate with carboxylic acid esters as catalyst in methanol.
Progress in single molecule fluorescence experiments have enabled an in-depth characterization of fluorophores, ranging from their photophysical rates to the orientation of their emission dipole moments in three dimensions. However, one crucial spatial information remains elusive: the molecule orientation relative to its emission dipole moment. One can retrieve the latter only by the use of another non-colinear transition dipole moment.
Ultrafast non-adiabatic dynamics of the small heteroaromatic compound 2-thiopyridone has been studied with surface hopping simulations based on multi-configurational quantum chemistry. Initial excitation of the bright state is found to promptly relax to ) through in-plane motion. The subsequent dynamics are oppositely driven by out-of-plane motion, which results in both complex population transfers among all the available states and intersystem crossing predominantly through the "El-Sayed forbidden" ) to ) channel, through significant mixing of electronic excitation characters.
In the title com-pound, CHNO, the carbazole system forms a dihedral angle of 68.45 (3)° with the mean plane of the bi-pyridine ring system. The bi-pyridine ring system, with two meth-oxy substituents, is approximately planar (r.
Type I photo-oxidation generates Trp-(TrpN) and Tyr-derived (TyrO) radicals in proteins which can dimerize producing cross-links, or alternatively react with O. It was therefore hypothesized that the O concentration may have a significant effect on dye-photosensitized reactions. We studied photo-oxidation of α- and β-caseins induced by riboflavin (RF), a photosensitizing vitamin present in milk, under aerobic and anaerobic conditions.
