Electron Transfer in Porphyrin Complexes in Different Solvents

Abstract

The electron transfer in different solvents is investigated for systems consisting of donor, bridge and acceptor. It is assumed that vibrational relaxation is much faster than the electron transfer. Electron transfer rates and final populations of the acceptor state are calculated numerically and in an approximate fashion analytically. In wide parameter regimes these solutions are in very good agreement. The theory is applied to the electron transfer in H 2 P − ZnP − Q with free-base porphyrin (H 2 P) being the donor, zinc porphyrin (ZnP) the bridge, and quinone (Q) the acceptor. It is shown that the electron transfer rates can be controlled efficiently by changing the energy of the bridging level which can be done by changing the solvent. The effect of the solvent is determined for different models.

Photoinduced Charge Transfer from Titania to Surface Doping Site

“…Here Ω jk = − D jk ·ℰ 0 / ħ , and Δ jk = Ω − ħ ω jk stand for Rabi and detuning frequencies respectively. Also, ħ ω jk = ε j − ε k , J , $f_{BE}={true(\text{exp}false\{\frac{\mathrm{bold-italicħ}\omega }{k_{B}T}-1false\}true)}^{-1}$, and T are described in 83, 85, 86 and stand for an energy difference, spectral density of bosons, their thermal distribution for vibrational frequencies ω, and temperature, respectively, while ${\gamma }_{jk}^0$ stands for a pure dephasing component, obtained through an autocorrelation of time-dependent KSO energy 〈ε i ( t )ε j (τ)〉. 80, 82 The initial values for the RDM correspond to the system initially at thermal equilibrium and then excited by light, during a very long time.…”

“…Also, ħ ω jk = ε j − ε k , J, f BE , and T are described in 83, 85, 86 and stand for an energy difference, spectral density of bosons, their thermal distribution for frequencies ω, and temperature, respectively, while ${\gamma }_{jk}^0$ stands for a pure dephasing component. 126 The thermal equilibrium state in our electron system is specified by the Fermi-Dirac distribution ${\rho }_{jj}^{eq}=f_{FD}false({\epsilon }_j;Tfalse)$ for the diagonal elements of the density matrix and by zero values for the off-diagonal density matrix, ${\mathrm{\rho ̃}}_{ij}^{eq}=0$, i ≠ j , as follows from the relaxation of our system as it interacts with a medium at temperature T .…”

Synthesis and Spectral Properties of Gem-Dimethyl Chlorin Photosensitizers

“…Porphyrin-chlorin dyad (12). The chlorin core can be modified via several approaches with the most common one being bromination and subsequent palladium-catalyzed cross coupling reactions.…”

“…[8] The photophysical properties of chlorins are solvent dependent and, in some cases, charge transfer (CT) can happen and access the desired triplet state via ISC. [12,13] The singlet oxygen lifetime in different solvents has been determined to be in the μs scale from time-resolved phosphorescence experiments by Ogilby and co-workers. [14] However, singlet oxygen has shorter lifetimes in biological media (∼10 -320 ns in cells) and it can only react with biomolecules in its proximity (10 -55 nm).…”

Spectroscopic properties of Zn‐naphtholimines‐TCNQ charge transfer complexes with variable ligand radicals

“…One of the important features of molecular CT-complexes is the possibility of modifying their electronic properties by virtue of the coupled electronic and structural change of the molecular state. Theoretical studies elucidate the interaction between donor-and acceptor molecules, as well as their geometry, energy and electron distribution [8,9].…”