Publication detail

Photophysical and Protonation Time Resolved Studies of Donor-Acceptor Branched Systems With Pyridine Acceptors

Year: 2019

Type of publication: článek v odborném periodiku

Name of source: Journal of Physical Chemistry A

Publisher name: American Chemical Society

Place: Washington

Page from-to: 417–428

Titles:

Language	Name	Abstract	Keywords
cze	Fotofyzikální a protonační time-resolved studie donor-akceptorového rozvětveného systému s pyridinovými akceptory	Porovnávací studie fotofyzikálních vlastností oktupolárních pyridin-trifenylaminů s jejich kvadrupolárními a dipodálními analogy pomocí steady-state spektroskopie a femtosekundové až nanosekundové time-resolved fluorescenční spektroskopie při běžné a nízké teplotě. Látky byly studovány v rozpouštědlech s různou polaritou, byl studován také vliv přídavků kyseliny octové vedoucí k protonaci pyridinových skupin. Díky kontrolované protonaci vzorky vykazovaly širokopásovou emisi pokrývající téměř celé viditelné spektrum.	pyridin; trifenylamin; time-resolved fluerescence
eng	Photophysical and Protonation Time Resolved Studies of Donor-Acceptor Branched Systems With Pyridine Acceptors	A comparative study of the photophysical properties of octupolar pyridyl-terminated triphenylamine molecule, with its quadrupolar and dipolar analogues, by means of ambient and low temperature steady state spectroscopy and femtosecond to nanosecond time-resolved fluorescence spectroscopy is reported. The push-pull molecules bear triphenylamine electron donating core, pyridine peripheral electron acceptors, and acetylene pi-bridge. The samples were studied in solvents of varying polarity and also upon addition of small amounts of acetic acid to induce protonation of the pyridine group. All samples exhibit significant positive fluorescence solvatochromism as well as a relaxation of their excited state to a solvent relaxed intramolecular charge transfer state on the picosecond time scale. For the octupolar compound, excited state relaxation occurs simultaneously with excitation energy hopping among the branches. The hopping time is solvent polarity controlled since it becomes slower as the polarity increases. The experimental hopping times are compared to those predicted by Forster and Fermi formulations. The samples are capable of emitting broadband light covering almost the whole visible spectrum by careful control of protonation. Energy transfer from the neutral toward the protonated species on the 1 ps time scale is revealed.	excitation-energy transfer; excited-state dynamics; intramolecular charge-transfer; nonlinear-optical properties; white-light emission; 2-photon absorption; triphenylamine derivatives; fluorescence; chromophores; dipolar

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