New Insight into the Origin of the Red/Near-Infrared Intense Fluorescence of a Crystalline 2-Hydroxychalcone Derivative: A Comprehensive Picture from the Excited-State Femtosecond Dynamics
| Autor: | Balamurugan Subramanian, N. Idayu Zahid, Osama K. Abou-Zied, Suhana Mohd Said, Mohamad Syafie Mahmood |
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| Rok vydání: | 2017 |
| Předmět: |
010405 organic chemistry
010402 general chemistry Photochemistry 01 natural sciences Enol Tautomer Fluorescence Photon upconversion 0104 chemical sciences chemistry.chemical_compound chemistry Excited state Ultrafast laser spectroscopy General Materials Science Physical and Theoretical Chemistry Ground state Spectroscopy |
| Zdroj: | The Journal of Physical Chemistry Letters. 8:5603-5608 |
| ISSN: | 1948-7185 |
| DOI: | 10.1021/acs.jpclett.7b02601 |
| Popis: | Fluorescence upconversion and transient absorption techniques are used to explain the source of the intense red/near-infrared emission of crystalline 4-dimethylamino-2'-hydroxychalcone. We found that the initially excited enol form undergoes tautomerization in 3 ps to form the keto tautomer. The latter is stable in the ground state as a consequence of J-type aggregation in the crystal packing and is manifested in an absorption peak at 550 nm that spectrally overlaps with the short-lived enol emission, leading to self-reabsorption and adding a factor to the complete depletion of the enol emission. Relaxation of the keto tautomer takes place in the form of intense fluorescence (600-750 nm) with 1.7 ns lifetime. The different spectroscopy in solution is due to vibrational cooling (300 fs), followed by solvation dynamics (5 ps in methanol) and twisting of the hydroxyphenyl ring (16 ps), before relaxation of the enol tautomer in the form of weak green fluorescence with 350 ps lifetime. |
| Databáze: | OpenAIRE |
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