Ultrafast Excited-State Dynamics in Biological Environments

Abstract

: We discuss and illustrate by several examples how the ultrafast excited-state dynamics of a chromophore can be altered when changing its environment from a homogenous solution to a biological molecule such as proteins or nucleic acids.

Photo-induced intramolecular electron transfer and intramolecular vibrational relaxation of rhodamine 6G in DMSO revealed by multiplex transient grating spectroscopy

“…The fast component is attributed to PIET from the phenyl ring (I) to the xanthene plane (II), which leads to the formation of the intramolecular charge transfer (ICT) state, [22] while the slow component, with a lifetime of 3.7 ps, is ascribed to the excited-state IVR process. The time constant of IVR is in good agreement with previously reported values of 1.5 ps-4.9 ps obtained from the analysis of fluorescence up-conversion decay kinetics, [2,7,9,21] which cannot be observed in our TCSPC experiment, owing to the limitation of the experimental response function. Figure 3(c) shows that TG intensity decay dynamics at different wavelengths can be reasonably reproduced with at least two exponential functions.…”

“…[1][2][3][4][5][6][7] Information about the dynamics of IVR and PIET on excited-state molecules in solution is essential for understanding the rates, pathways, and efficiencies of chemical reactions because many chemically relevant reactions take place in solution. [4][5][6][7][8][9][10][11] IVR is an intramolecular process where the excess excitation energy initially populating Franck-Condon active state(s) is distributed over the other dark states within the molecule. IVR dynamics occurs on a timescale ranging from hundreds of femtoseconds (fs) to a few picoseconds (ps), depending on solute-solvent interactions, chemical substitution of solute, and whether the system is in the gas or condensed phase.…”

A photo-induced electron transfer study of an organic dye anchored on the surfaces of TiO2 nanotubes and nanoparticles

“…The solvation dynamics inside the nanotubes can be much slower than that in the bulk solvent, like it was found for many confining media (micelles, proteins, zeolites). [55][56][57] If it is slow enough, all of the electrons from the excited TPC1 state can be injected before the relaxed level of the CT state is reached. Thus, the electron injection takes place from the levels that are higher with respect to the conduction band edge than in P25 and P13 and the kinetics are faster.…”

Site‐Dependent Excited‐State Dynamics of a Fluorescent Probe Bound to Avidin and Streptavidin

“…[1][2][3][4][5] Relaxation processes such as the reorganization of the surroundings after photoexcitation, namely solvation, or vibrational cooling, or photochemical processes such as fluorescence quenching via electron transfer, proton transfer, or isomerization are largely dependent on the direct environment of the chromophore. As these processes take place on a time scale of a few tens of femtoseconds up to several nanoseconds, femtosecond-resolved spectroscopy is a powerful tool to investigate the nanoenvironment of a probe.…”

“…As these processes take place on a time scale of a few tens of femtoseconds up to several nanoseconds, femtosecond-resolved spectroscopy is a powerful tool to investigate the nanoenvironment of a probe. [4,5] Whereas the relaxation dynamics of chromophores in bulk solvents is fairly well understood, it is much less the case in heterogeneous environments or at interfaces. The highly organised nature of biological macromolecules such as proteins or nucleic acids makes biomolecular interfaces very special and despite the growing number of reports, [6] the available amount of information is too scarce for a full understanding of the influence of biological environments on the dynamics of excited chromophores to be achieved.…”