High-Pressure Studies on the Excited-State Intramolecular Charge Transfer of 4-(N,N-Dimethylamino)triphenylphosphine in Alcohols

Abstract

The influence of solvent viscosity on the intramolecular charge-transfer (CT)-state formation in the excited S 1 state for 4-(N,N-dimethylamino) triphenylphosphine (DMATP) in alcohol solvents has been investigated by measuring the steady-state and time-resolved fluorescence spectra at high pressures. The kinetic mechanism of the intramolecular CT reaction has been examined as a function of solvent shear viscosity. In the lower viscosity region the reaction is controlled by the solvent relaxation. With increasing pressure, the reaction path shifts toward the "high-viscosity regime" in which the molecule moves along the nonrelaxed path on the free energy surface. The viscosity dependence of R = 0.33, where R is the power law parameter, can be interpreted as the extreme value in which the reaction is controlled by the dynamic solvent effect due to intrinsic collisional interaction of barrier crossing. The coupling between the intramolecular CT-state formation dynamics of DMATP and the solvent relaxation dynamics is discussed.

Aggregation-Induced Emission-Based Polymer Materials: Ratiometric Fluorescence Responses Controlled by Hydrostatic Pressure

“…, temperature, solvent, or pH) is of particular significance in current multidisciplinary chemistry from the viewpoint of applied materials. − The reason is that such functional applied materials seem to be hold great promise for application in interfacial imaging, probing, and sensing. − For instance, as representative examples presenting dual fluorescence character, it is well known that the excimer/exciplex, , twisted intramolecular charge-transfer, , excited-state intramolecular proton transfer, , and thermally activated delayed fluorescence , are involved in many cases. The luminescence properties observed through these excited-state processes are generally susceptible to microenvironmental polarity and viscosity in solutions based on more polarized excitons formed upon electronic excitation and also to hydrostatic pressure once in a while. − …”

High Pressure Studies on Excited Intramolecular Charge-Transfer Reactions and Solvation Dynamics.

“…The most important conclusion of this paper is that the discussions about the "pressure tuning effect of the solvent viscosity on the ICT reactions", which have been made by using _C L as a measure of solvent relaxation time in our preceding papers [1][2][3][4], are completely adequate.…”

“…Picosecond time-resolved fluorescence spectra at high pressures were measured by the method of time-correlated single photon counting (TCSPC). The high pressure cell [4] and experimental arrangement of the laser system [5] as well as the method of data analysis [1,3] have been described previously. The second and third harmonic radiation of a mode-locked Ti:sapphire laser were used as the excitation light source.…”

“…Instantaneous electronic excitation in a flexible aromatic molecule may cause a conformational change due to breaking the resonance structure in the ground state, along with the stabilization of charge-transfer state in the exited state. We have been studying the dynamic solvent effect on the excitedstate ICT reactions in a series of linear alcohol solvents [1,2]. For the present purpose, application of high pressure provides a large solventt viscosity change in a single solvent without altering the solvent cage in significant amount.…”

Pressure tuning of solvent viscosity for the formation of twisted intramolecular charge-transfer state in 4,4′-diaminodiphenyl sulfone in alcohol solution

“…The analogous ''pressure tuning effect'' has been observed for the excited intramolecular CT-state formation of 4-͑N,N-dimethylamino͒ triphenylphosphine ͑DMATP͒ in alcohol solution. 29 In order to understand this behavior, it is necessary to consider the viscosity dependence on L . The L values at different viscosities have been obtained by the extrapolation or interpolation of low temperature data, 31 since those at high pressures are not available.…”