Molecular Dipole-Induced Photoredox Catalysis for Hydrogen Evolution over Self-Assembled Naphthalimide Nanoribbons.
Angew Chem Int Ed Engl
; 61(12): e202117645, 2022 Mar 14.
Article
em En
| MEDLINE
| ID: mdl-35040544
ABSTRACT
D-π-A type 4-((9-phenylcarbazol-3-yl)ethynyl)-N-dodecyl-1,8-naphthalimide (CZNI) with a large dipole moment of 8.49â
D and A-π-A type bis[(4,4'-1,8-naphthalimide)-N-dodecyl]ethyne (NINI) with a negligible dipole moment of 0.28â
D, were smartly designed and synthesized to demonstrate the evidence of a molecular dipole as the dominant mechanism for controlling charge separation of organic semiconductors. In aqueous solution, these two novel naphthalimides can self-assemble to form nanoribbons (NRs) that present significantly different traces of exciton dissociation dynamics. Upon photoexcitation of NINI-NRs, no charge-separated excitons (CSEs) are formed due to the large exciton binding energy, accordingly there is no hydrogen evolution. On the contrary, in the photoexcited CZNI-NRs, the initial bound Frenkel excitons are dissociated to long-lived CSEs after undergoing ultrafast charge transfer within ca. 1.25â
ps and charge separation within less than 5.0â
ps. Finally, these free electrons were injected into Pt co-catalysts for reducing protons to H2 at a rate of ca. 417â
µmol h-1 g-1 , correspondingly an apparent quantum efficiency of ca. 1.3 % can be achieved at 400â
nm.
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2022
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Article