Dual Fluorescence of Phenyl and Biphenyl Substituted Pyrene Derivatives

Abstract

The photophysical properties of several acceptor substituted 1-arylpyrene derivatives were investigated. The fluorescence spectra strongly depend on the nature of the aryl moiety and the position and number of methoxycarbonyl acceptor groups. Dual fluorescence, originating from a locally excited and a charge transfer state, was observed for the diester derivatives. The solvent dependence of the dual fluorescence and the slightly curved solvatochromic plots indicate a change of the character of the excited states from solvents of low to high polarity. The rate constants for fluorescence and nonradiative decay were calculated to reveal the nature of the excited-state relaxation, that is, the increase of the mesomeric interactions by geometrical flattening or stabilization of the CT state by further twisting toward perpendicularity. Flattening is the major relaxation pathway of the diester phenylpyrene derivative in nonpolar solvents whereas in highly polar solvents the low value for the fluorescence transition dipole moment (M f ) indicates stabilization of the charge transfer state by further twisting. The fluorescence of the diester biphenylpyrene derivative originates from a locally excited state (LE) in nonpolar solvents. The low value for M f in polar solvents and the change of the relative intensity of the dual fluorescence signals with the temperature indicate that the red-shifted fluorescence can be assigned to a twisted intramolecular charge transfer state.

Characterization by flow cytometry of fluorescent, selective agonist probes of the A3 adenosine receptor

“…Here, MRS5704 contains attached adenine and ethynyl moieties that may be able to interact with the π-system of pyrene, especially in polar solvents [35]. …”

Excited-state relaxation of bridged and unbridged anilino-pyridinium dyes

“…The instrument response function was obtained by detection of Rayleigh scattered light in pure solvents and had a width of around 60 ps. The equipment is described in detail elsewhere [15]. The decay times were fitted using the iterative reconvolution procedure (Marquard algorithm) which allowed a time resolution down to about 50 ps.…”

Recent progress on intramolecular charge-transfer compounds as photoelectric active materials

“…Upon photoexcitation of the D fragment in molecules, the local excited (LE) state undergoes ICT from D to A, accompanying with structural relaxation to form a stabilized dipolar state (namely, charge-transfer state) [18]. For the excited state geometry, several models have been proposed [20]. For example, Grabowski et al [21,22] proposed a twisted ICT (TICT) state, where a perpendicularly twisted structure between the D species and the A moieties is suggested.…”