Intramolecular Charge Transfer and Solvation of Photoactive Molecules with Conjugated Push–Pull Structures

Abstract

A comparative investigation on the photophysical properties and solvation-related ICT dynamics of three push-pull compounds containing different donors including carbazole, triphenylamine and phenothiazine, was performed. The steady-state spectra and theoretical calculations show the charge transfers from the central donors to the acceptors at each side. The characterization of the extent of charge transfer was determined by various means, including estimation of the dipole moment, the electron density distribution of HOMO and LUMO, CDD and change in Gibb's free energy, which show the charge transfer strength to be in the order PDHP > BDHT > PDHC. This suggests that the electron-donating ability of the donor groups plays a crucial role in the charge transfer in these compounds. The TA data show the excited-state relaxation dynamics follow a sequential model: FC→ICT→ICT'→S , and are affected by the solvent polarity. The results presented here demonstrate that the compound with a higher degree of ICT characteristic interacts more strongly with stronger polar solvent molecules, which can accelerate the solvation and spectral evolution to lower energy levels. The A-π-D-π-A architectures with prominent ICT characteristics based on carbazole, triphenylamine and phenothiazine might be potential scaffolds for light-harvesting and photovoltaic devices. These results are of value for understanding structure-property relationships and the rational design of functional materials for photoelectric applications.

Synthesis and spectroscopic characterization of novel GFP chromophore analogues based on aminoimidazolone derivatives

“…We also found that the presence of the benzylamino group (9) could not boost further the emission intensity, as it only gave rise to a 7.9 relative intensity referenced to p-HOBDI. Excitation and emission wavelengths are also in the same ranges, which can be attributed to the enhanced intramolecular charge transfer [39], where the electron donating (ED) and conjugative character of the substituted amino group generate a higher electron density at the central imidazolone ring, illustrated in Scheme 2. At the same time, neither non-substituted nor substituted sulfur groups at the same position were successful to provide any significant ED effect, so the increase in relative intensity was much lower for them (Table 1 and 2).…”

“…Protonation of the tertiary amine function drastically alters the electron-donating properties of the tertiary amine group and consequently it is expected to switch off ICT [39]. Consequently, the emission spectrum of 1g was recorded for a series of MeOH solutions in which an increasing HCl concentration was present.…”

The influence of driving force on intramolecular electron transfer: A theoretical study of subphthalocyanine‐AzaBODIPY‐C60 supramolecular triad

“…It is very complicated and expensive for researchers to calculate intramolecular charge transfer (CT) rates by using Marcus theory, and then compare calculated rates to find the dominant intramolecular CT pathway. Some research groups have calculated the intramolecular CT rate constants of small molecular D‐A (D: donor, A‐acceptor) systems (around 100 atoms) with approximations . However, there are still few calculations of intramolecular CT rate constants for supramolecules (>100 atoms) because it is very expensive .…”

Two‐Photon‐Absorption Properties of Pyrene‐Based Dipolar D‐π‐A Fluorophores

“…All compounds exhibit high quantum yields (≥0.75) and considerably short lifetimes (≤15 ns) at room temperature (Figure S17). The same prompt and delayed PL emissions readily reveals the emission state resulting from the lowest singlet excited state …”