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Updated: Mar 31, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Relay proton transfer triggered twisted intramolecular charge transfer
Santosh Kumar Behera1, G Krishnamoorthy1
1Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India. gkrishna@iitg.ernet.in.
The dual fluorescence of 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-c]pyridine (DMAPIP-c) in protic solvents is triggered by a relay proton transfer mechanism. This process involves a hydrogen-bonded complex with methanol, leading to enhanced TICT emission.
Area of Science:
- Photochemistry
- Supramolecular Chemistry
- Organic Spectroscopy
Background:
- Dual emission in organic molecules is a complex phenomenon.
- Understanding excited-state dynamics in protic solvents is crucial for molecular design.
Purpose of the Study:
- To elucidate the mechanism of dual fluorescence in 2-(4 '-N,N-dimethylaminophenyl)imidazo[4,5-c]pyridine (DMAPIP-c) in protic solvents.
- To investigate the role of hydrogen bonding and proton transfer in excited-state processes.
Main Methods:
- Synthesis and spectral studies of DMAPIP-c and its analogues.
- Investigation in various protic and binary solvent mixtures.
- Theoretical calculations including TDDFT for emission energy prediction.
Main Results:
- DMAPIP-c exhibits dual fluorescence in protic solvents, unlike its methyl derivatives.
- A 1:3 hydrogen-bonded complex between DMAPIP-c and methanol is identified as key to TICT emission.
- Relay proton transfer triggered TICT emission mechanism is proposed.
Conclusions:
- The dual emission of DMAPIP-c is strongly dependent on the protic nature of the solvent.
- Hydrogen bonding and proton transfer play a critical role in the observed photophysical behavior.
- The proposed mechanism provides insights into designing molecules with tailored photoluminescence properties.
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