| Institution: | 1. Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062 P. R. China
These authors contributed equally to this work.;2. Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062 P. R. China;3. Department of Chemistry, National (Taiwan) University, Taipei, 10617 Taiwan R.O.C. |
| Abstract: | The origin of the positive temperature effect in fluorescence emission of a newly designed perylene bisimide (PBI) derivative with two naphthyl units containing ortho-methoxy group (NM) at its bay positions (PBI-2NM) was elucidated. A key point is the finding of a weak hydrogen bond (<5.0 kcal mol−1) between the methoxy group of the NM unit and a nearby hydrogen atom of the PBI core. It is the bonding that drives co-planarization of the different aromatic units, resulting in delocalization of the π-electrons of the compound as synthesized, inducing fluorescence quenching via intramolecular charge transfer (ICT). With increasing temperature, the co-planar structure could be distorted in part, resulting in a decreased degree of ICT, and hence leading to enhanced fluorescence emission. The unique positive temperature effect in emission induced by H-bond-driven co-planarization may pave a new avenue in designing functional molecular systems complementary to conventional methods. |
