Fluorescence Toggling Mechanism of Photochromic Phenylhydrazones: N–N Single Bond Rotation-Assisting E/Z Photoisomerization Differs from Imine
- 21 July 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 124 (32), 6411-6419
- https://doi.org/10.1021/acs.jpca.0c03525
Abstract
Photochromic phenylhydrazones are one of the most promising candidates for a photoswitchable fluorescent probe with potential applications in various fields, but mechanistic understanding of the origin of this unique behavior is limited. In this work, we explored the emission nature and switching mechanism of a model phenylhydrazone-based fluorescent photoswitch, DMA-PHA, by means of TD-DFT and CASPT2 calculations. The fluorescent emitting Z-configuration of DMA-PHA does not involve an excited-state intramolecular proton transfer process, since resonance effect between the DMA group and the rest of the molecule in excited state strengthens the hydrogen bond and thus stabilizes the emissive state. The light-induced fluorescence toggling results from E↔Z interconversion driven by an out-of-plane C=N bond torsion and assisted by a N−N single bond rotation, which in total lead to a charge-separation process losing the fluorescence activity. The N−N bond rotation in phenylhydrazone further enhances the competitive nonradiative decay and reduces the photoisomerization yields. The theoretical results will provide the guidance for the rational design of novel and improved photoswitchable fluorescent probe with desired performances.Keywords
Funding Information
- State Administration of Foreign Experts Affairs (B14041)
- Ministry of Education of the People's Republic of China (B14041, GK201901007, GK201903032)
- National Natural Science Foundation of China (21473107, 21873060)
This publication has 59 references indexed in Scilit:
- Role of Solvent on Charge Transfer in 7-Aminocoumarin Dyes: New Hints from TD-CAM-B3LYP and State Specific PCM CalculationsJournal of Chemical Theory and Computation, 2013
- A conical intersection model to explain aggregation induced emission in diphenyl dibenzofulveneChemical Communications, 2013
- Single-molecule fluorescence photoswitching: Design and synthesis of photoswitchable fluorescent moleculesJournal of Photochemistry and Photobiology C: Photochemistry Reviews, 2011
- Including quantum decoherence in surface hoppingThe Journal of Chemical Physics, 2010
- Fast Fluorescence Photoswitching in a BODIPY−Oxazine Dyad with Excellent Fatigue ResistanceThe Journal of Physical Chemistry Letters, 2010
- Single-Chromophore-Based Photoswitchable Nanoparticles Enable Dual-Alternating-Color Fluorescence for Unambiguous Live Cell ImagingJournal of the American Chemical Society, 2009
- Digital Photoswitching of Fluorescence Based on the Photochromism of Diarylethene Derivatives at a Single-Molecule LevelJournal of the American Chemical Society, 2004
- Charge equilibration for molecular dynamics simulationsThe Journal of Physical Chemistry, 1991
- The photochemistry of iminesChemical Society Reviews, 1977
- On the Quantum Correction For Thermodynamic EquilibriumPhysical Review B, 1932