Excitation-Dependent Multiple Fluorescence of a Substituted 2-(2'-Hydroxyphenyl)benzoxazole.

Excitation-dependent multiple fluorescence of a 2-(2'-hydroxyphenyl)benzoxazole (HBO) derivative (1) is described. Compound 1 contains the structure of a charge-transfer (CT) 4-hydroxyphenylvinylenebipy fluorophore and an excited-state intramolecular proton transfer capable (ESIPT-capable) HBO component that intersect at the hydroxyphenyl moiety. Therefore, both CT and ESIPT pathways, while spatially mostly separated, are available to the excited state of 1.

5-Arylvinyl-2,2'-bipyridyls: Bright "push-pull" dyes as components in fluorescent indicators for zinc ions.

This article reviews the zinc(II)-dependent photophysical properties of arylvinylbipyridines (AVBs), a class of fluoroionophores in which 2,2'-bipyridyl and an aryl moiety are electronically conjugated. Zinc(II) binding of an AVB may lead to an emission bathochromic shift of the fluoroionophore without diminishing its fluorescence quantum yield. This observation can be explained using the excited state model of electron donor-π bridge-electron acceptor "push-pull" fluorophores, in which the bipy moiety acts as an electron acceptor, and zinc(II)-coordination strengthens its electron affinity.

Enhancing the Photostability of Arylvinylenebipyridyl Compounds as Fluorescent Indicators for Intracellular Zinc(II) Ions.

Arylvinylenebipyridyl (AVB) ligands are bright, zinc(II)-sensitive fluoroionophores. The applicability of AVBs as fluorescent indicators for imaging cellular zinc(II), however, is limited by low photostability, partially attributable to the photoisomerization of the vinylene functionality. Two configurationally immobilized (i.

Absorption and Emission Sensitivity of 2-(2'-Hydroxyphenyl)benzoxazole to Solvents and Impurities.

2-(2'-Hydroxyphenyl)benzoxazole (HBO) is known for undergoing intramolecular proton transfer in the excited state to result in the emission of its tautomer. A minor long-wavelength absorption band in the range 370-420 nm has been reported in highly polar solvents such as dimethylsulfoxide (DMSO). However, the nature of this species has not been entirely clarified.

Tunable dual fluorescence of 3-(2,2'-bipyridyl)-substituted iminocoumarin.

3-(2,2'-Bipyridyl)-substituted iminocoumarin molecules (compounds 1 and 2) exhibit dual fluorescence. Each molecule has one electron donor and two electron acceptors that are in conjugation, which leads to fluorescence from two independent charge transfer (CT) states. To account for the dual fluorescence, we subscribe to a kinetic model in which both CT states form after rapid decays from the directly accessed S(1) and S(2) excited states.

Electronic structural dependence of the photophysical properties of fluorescent heteroditopic ligands - implications in designing molecular fluorescent indicators.

Two fluorescent heteroditopic ligands (2a and 2b) for zinc ion were synthesized and studied. The efficiencies of two photophysical processes, intramolecular charge transfer (ICT) and photoinduced electron transfer (PET), determine the magnitudes of emission bathochromic shift and enhancement, respectively, when a heteroditopic ligand forms mono- or dizinc complexes. The electron-rich 2b is characterized by a high degree of ICT in the excited state with little propensity for PET, which is manifested in a large bathochromic shift of emission upon Zn(2+) coordination without enhancement in fluorescence quantum yield.

Fluorescence of 5-arylvinyl-5'-methyl-2,2'-bipyridyl ligands and their zinc complexes.

The photophysical properties of 5-arylvinyl-5'-methyl-2,2'-bipyridyls (AVMBs, 1-9, 11) and their zinc complexes were studied. Similar 2,2'-bipyridyl-based ligands have been applied as optical sensors for metal ions and sensitizers for solar energy conversion. The goal of this investigation is to reveal the factors that determine the emission band shift and fluorescence quantum yield change of the title ligand system upon zinc binding.

Synthesis and photophysical properties of ruthenium-based dendrimers and their use in dye sensitized solar cells.

First- and second-generation dendrimers (Ru3 and Ru6) have been synthesized, and their photophysical properties were investigated in solution and when adsorbed on the nanocrystalline TiO2 surface. The performance of Ru3 and Ru6 as charge transfer photosensitizers in nanocrytalline TiO2 based solar cells was also investigated. The best photovoltaic performance was obtained by the Ru3 based solar cell yielding a short circuit current of J sc = 5.