The Impact of C2 Insertion into a Carbazole Donor on the Physicochemical Properties of Dibenzo[a,j]phenazine‐Cored Donor–Acceptor–Donor Triads

• Published in: Chemistry : a European journal 2021-09, Vol.27 (53), p.13390-13398
• Main Authors: Zimmermann Crocomo, Paola, Kaihara, Takahito, Kawaguchi, Soki, Stachelek, Patrycja, Minakata, Satoshi, Silva, Piotr, Data, Przemyslaw, Takeda, Youhei
• Format: Article
• Language: English
• Subjects: charge transfer; donor–acceptor; fluorescence; organic light-emitting diodes; triplet–triplet annihilation
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202101654

Novel electron donor–acceptor–donor (D‐A‐D) compounds comprising dibenzo[a,j]phenazine as the central acceptor core and two 7‐membered diarylamines (iminodibenzyl and iminostilbene) as the donors have been designed and synthesized. Investigation of their physicochemical properties revealed the impact of C2 insertion into well‐known carbazole electron donors on the properties of previously reported twisted dibenzo[a,j]phenazine‐core D‐A‐D triads. Slight structural modification caused a drastic change in conformational preference, allowing unique photophysical behavior of dual emission derived from room‐temperature phosphorescence and triplet–triplet annihilation. Furthermore, electrochemical analysis suggested sigma‐dimer formation and electrochemical polymerization on the electrode. Quantum chemical calculations also rationalized the experimental results. Plus 2: C2 insertion into well‐known electron‐donating carbazole unit brought about a drastic change in the physicochemical properties of dibenzo[a,j]phenazine‐core twisted donor–acceptor–donor triad compounds. The slight structural modification at the donor unit led to a thermodynamic preference for quasi‐axial conformations, dual emission comprising room‐temperature phosphorescence and triplet–triplet annihilation, and unique electrochemical behavior.