Excited-State Dynamics in Rigid Media: Evidence for Long-Range Energy Transfer

Abstract

In semirigid PEG-DMA550 films with the added anthracene derivatives PEG-An and Acr-An, energy transfer quenching of the metal-to-ligand charge transfer excited state Ru(bpy)3(2+)* to give -(3)An occurs by both rapid, static, and slow, diffusional quenching processes. The appearance of -(3)An was verified by transient absorption measurements. The kinetics of the two quenching processes have been analyzed by a Stern-Volmer kinetic analysis. The data for static quenching are consistent with energy transfer quenching with a distance dependence consistent with Dexter (exchange) energy transfer. On the basis of this analysis Bohr radii were found to be 26 and 11 Å for PEG-An and Acr-An, respectively. Evidence for triplet-triplet annihilation between triplet anthracene excited states in the films was obtained from the concentration dependences of excited-state decay. These results provide evidence for long-range energy migration between derivatized anthracenes in rigid, cross-linked PEG-DMA550 films.

Photon-upconverting chiral liquid crystal: significantly amplified upconverted circularly polarized luminescence

“…As expected, D LC > D sol , L LC > L sol , that is to say, the capability of triplet diffusion in a liquid crystal is stronger, correspondingly the triplet diffusion length of the acceptor in the liquid crystal is longer than in the solution state. Moreover, the average nearest-neighbor distance between two sensitizers was calculated to be 115 nm 50. These results indicate that even better triplet diffusion and migration could be observed in the liquid crystal; due to the extremely high viscosity, molecular collision was severely suppressed which resulted in the relatively weak UC emission efficiency.…”

Ir(iii) complexes designed for light-emitting devices: beyond the luminescence color array

“…In eqn ( 15), E em is approximately equal to the energy gap between the zeroth vibrational levels in the ground and excited states (E 0 ), S M is the electron-vibrational coupling constant associated with ħω M ,v ˜1/2 is the fwhm for an individual vibronic line and V k is the vibrationally induced electronic coupling matrix element. Their values are obtained by Franck-Condon (FC) emission spectral fittings 29,40,103,104 and the application of the Golden Rule, as reported by Ito and Meyer. 44 Eqn ( 14) predicts increased non-radiative decays for lowerenergy T 1 states, hence red-emissive compounds (lower E em ) are usually less efficient as emitters.…”

The Golden Rule. Application for fun and profit in electron transfer, energy transfer, and excited-state decay

“…These states are antibonding with regard to the metal-ligand bonding framework, 61,136 contribute to nonradiative decay, 53,56,60,130,[132][133][134][135] and lead to ligand-loss photochemistry and decomposition. 137,138 …”