Why and how could an aliphatic bridge allow for a long- range photoinduced charge separation in Tröger’s bases derivatives

LANZA, PRISCILA A.; DIEGO DUSSO; MENA, LEANDRO; ALEJANDRO R. PARISE; E. LAURA MOYANO; CARLOS A. CHESTA; D. MARIANO A. VERA *

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2023 vol. 441 p. 114699 - 114699

1010-6030

Tröger’s bases (TBs) have shown greatpotential to be used in different fields of science, such as biology,organic synthesis, photoelectronic applications, among others. As wehave recently shown, a series of asymmetrically substitutedTröger’s base derivatives showed unexpected pull-push behavior.The aliphatic diazocine heterocycle which connect an electron donorand an electron acceptor moiety efficiently couples both electronicsubsystems as if it were a typical π-conjugated linker. A thoroughcomputational study was intended to shed light on the origin of theobserved photophysical properties. A modified version of theCAM-B3LYP functional yielded an accurate prediction of the absorptionand emission spectra of these species. In contrast, range-correctedand classical hybrid approaches showed too high and remarkably toolow excited states energies, respectively. Unlikethe typical π-linked donor/acceptor systems, a threshold was foundin the redox gap of the centers in order to obtain a full chargeseparation. The role of the aliphatic bridge was found to be relatedto the unusual topology of the frontier orbitals involved, to thetension and particular molecular shape of the Tröger bicycle and toa contribution due to homoconjugation as well. Calculations on theactual Tröger derivatives and specific models were able to quantifythe magnitude of the different contributions that make possible thecharge separation.p { margin-top: 0.15cm; margin-bottom: 0.15cm; direction: ltr; line-height: 150%; text-align: justify; orphans: 2; widows: 2; background: transparent }p.western { font-family: "Times New Roman", serif }a:link { color: #000080; text-decoration: underline }