Affiliation:
1. Institute of Organic Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
2. Empa Swiss Federal Laboratories for Materials Science and Technology Laboratory for functional polymers CH-8600 Dübendorf Switzerland
3. Institute of Physics Polish Academy of Sciences Al. Lotników 32/46 02-668 Warsaw Poland
Abstract
AbstractStrongly polarized donor‐acceptor‐donor′ diketopyrrolopyrroles, differing in the type of key donor moiety, were designed and synthesized to examine how this affects the non‐radiative decay. Dyes possessing less electron‐rich N‐carbazolyl substituents are characterized by strong yellow emission from a locally excited (LE) state, whereas replacing this donor with more electron‐rich N‐phenothiazinyl substituent changes the relative position of charge‐transfer (CT) and LE states, leading to weaker, reddish‐orange fluorescence. As a result, there is solvent‐dependent charge‐transfer emission shifted to as far as 700 nm. The opening of the intersystem crossing channel to the triplet state possessing CT character is the most likely cause of the fluorescence quantum yield variation in some cases. These results reveal that the fate of molecules in their excited state can be fine‐tuned by very small structural changes.
Funder
Fundacja na rzecz Nauki Polskiej
Subject
Organic Chemistry,Physical and Theoretical Chemistry,Analytical Chemistry