Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt?
J Phys Chem Lett
; 13(35): 8221-8227, 2022 Sep 08.
Article
in En
| MEDLINE
| ID: mdl-36007139
ABSTRACT
Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed toâpurportedlyârigidify the structure and improve the emission performance of these materials. However, direct evidence for these intramolecular interactions is often lacking or ambiguous, leading to assertions that are largely speculative. Here we investigate a series of TADF-active materials incorporating pyridine, which bestows the potential ability to form intramolecular H-bonding interactions. Despite possible indications of H-bonding from an X-ray analysis, an array of other experimental investigations proved largely inconclusive. Instead, after examining computational potential energy surfaces of the donor-acceptor torsion angle we conclude that the pyridine group primarily alleviates steric congestion in our case, rather than enabling an H-bond interaction as elsewhere assumed. We suggest that many previously reported "H-bonding" TADF materials featuring similar chemical motifs may instead operate similarly and that investigation of potential energy surfaces should become a key feature of future studies.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Phys Chem Lett
Year:
2022
Document type:
Article
Affiliation country:
United kingdom