Photoprocesses in Bis-Diethylamino Derivatives of 1,4- and 1,3-Distyrylbenzene.

The photoprocesses of diethylamino derivatives of 1,4- and 1,3-distyrylbenzenes in MeCN were studied using absorption, luminescence, H NMR, and laser kinetic spectroscopy. Compounds and undergo intersystem crossing to the triplet state and exhibit delayed fluorescence. It was concluded that dye radical anions and radical cations are formed upon dismutation of the triplet state in the presence of an electron donor or acceptor.

Photoprocesses in Derivatives of 1,4- and 1,3-Diazadistyryldibenzenes.

Photoprocesses in 1,4-diazadistyrylbenzene () and 1,3-diazadistyrylbenzene derivative () diperchlorates in MeCN were studied by absorption, luminescence, and kinetic laser spectroscopies. For compound , -photoisomerization and intersystem crossing to a triplet state are observed. For compound , photoelectrocyclization is suggested.

Cyanine-based J-aggregates as a chirality-sensing supramolecular system.

J-aggregates are formed for 3,3'-disulfopropyl-5,5'-dichlorothiacyanine (Tc) and 3,3'-disulfobutyl-5,5'-diphenyl-9-ethyloxacarbocyanine (Oc) in aqueous solution in the presence of NaCl, Mg(NO(3))(2), d/l-tartaric acids, asparagine, proline, DNA, and proteins, such as lysozyme, trypsin, RNase, and gelatin. J-aggregates, which are formed in the presence of chiral additives, are optically active and characterized by sigmoidal kinetics with half-times of 10-1000 s, resonance fluorescence, and large CD amplitudes being up to 2° for Tc. Generally, the induced CD signals of the J-aggregates of both dyes are bisignate and the sign corresponds to that of the additive.

Kinetics of spontaneous formation of chiral J-aggregate of N-sulfobutyl oxacarbocyanine.

An oxacarbocyanine with N-sulfobutyl substituents, dye 1, exhibits an ability to form optically active J-aggregates in aqueous solution in the absence of chiral auxiliaries or templates. Optically active J-aggregates are formed in the absence (self-association) and presence of mono- and divalent metal ions. The time course of formation of J-aggregates is described by a sigmoidal time dependence and further characterized by an induction period.

J-aggregation of anionic ethyl meso-thiacarbocyanine dyes induced by binding to proteins.

The effects of ribonuclease A (RNase), lysozyme, trypsin, and bovine serum albumin (BSA) on the J-aggregation behavior of 3,3'-bis[sulfopropyl]-5-methoxy-4',5'-benzo-9-ethylthiacarbocyanine (1), 3,3'-bis[sulfopropyl]-4,5,4',5'-dibenzo-9-ethylthiacarbocyanine (2), and 3,3'-bis[sulfopropyl]-5,5'-dimethoxy-9-ethylthiacarbocyanine (3) were studied in aqueous solution. The formation of J-aggregates at pH 6 is induced by RNase for 1-3, by lysozyme for 1 and 2, and by trypsin for 2. The formation of J-aggregates correlates with decay of the dimers and is supported by induced circular dichroism spectra.

Kinetics of salt-induced J-aggregation of cyanine dyes.

The addition of monovalent, divalent, and trivalent metal ions to three anionic ethyl meso-thiacarbocyanine dyes, an ethyl meso-oxacarbocyanine, and an imidacarbocyanine in aqueous solution at room temperature results in the production of J-aggregates within the range of tens to hundreds of seconds. The rate of formation of J-aggregates correlates with the rate of decay of dimers or monomers and is dependent on the type of metal ion, dye structure, and temperature. The rate of formation of J-aggregates increases as the temperature decreases and the dye and salt concentrations increase, and the rate is highest for trivalent ions and smallest for monovalent ions, independent of the type of anion.

Kinetics of J-aggregation of cyanine dyes in the presence of gelatin.

The kinetics of formation of J-aggregates for 3,3'-bis[sulfopropyl]-R-4',5'-dibenzo-9-ethylthiacarbocyanines (R=5-methoxy; R=4,5-dibenzo) and 3,3'-bis[sulfopropyl]-5,5'-diphenyl-9-ethyloxacarbocyanine were studied in aqueous solution in the presence of gelatin at different pH values and at room and elevated temperatures. Addition of gelatin at concentrations of 0.0005-0.