Unraveling the peculiar modus operandi of a new class of solvatochromic fluorescent molecular rotors by spectroscopic and quantum mechanical methods
König M, Bottari G, Brancato G, Barone V, Guldi DM, Torres T (2013)
Publication Type: Journal article, Original article
Publication year: 2013
Journal
Original Authors: König M., Bottari G., Brancato G., Barone V., Guldi D.M., Torres T.
Publisher: Royal Society of Chemistry
Book Volume: 4
Pages Range: 2502-2511
Journal Issue: 6
DOI: 10.1039/c3sc50290b
Abstract
A prototype for a new class of fluorescent molecular rotors (FMRs), namely 4-(diphenylamino)phthalonitrile (DPAP), was synthesized and its sensitivity towards solvent polarity and viscosity probed using photophysical and computational methods. DPAP is characterized by a pronounced fluorosolvatochromism in polarity-dependent absorption, emission and fluorescent lifetime experiments. At the same time, a strong viscosity response is observed, especially in polar and protic solvents. Quantum mechanical calculations assisted in interpreting the unusual solvent sensitivity of DPAP in terms of its high flexibility, giving rise to solvent-independent, barrier-free rotations. As a matter of fact, the modus operandi in DPAP contrasts that of traditional FMRs involving twisted intramolecular charge transfer (TICT) states. The influence of this unusual flexible character on excitation and emission energies was studied using computational methods upon considering twisting of the molecule in solvents of different polarity. Furthermore, a detailed characterization of the excited state profile was attained using time resolved spectroscopy techniques. In particular, a contrasting deactivation pattern of the intramolecular charge transfer (ICT) state was observed in low and high polar media. Moreover, in low and medium polar solvents strong emission is accompanied by triplet excited state formation, while in high polar and protic solvents the ICT state is highly stabilized and decays primarily non-radiatively. Notably, a viscosity increase in the latter solvents hampers rotations leading to a strong emission enhancement. This latter behavior, coupled to a remarkable solvatochromic character, makes DPAP a promising probe for biological and environmental sensing and imaging applications. © 2013 The Royal Society of Chemistry.
Authors with CRIS profile
Matthias König
Lehrstuhl für Physikalische Chemie I
Dirk Michael Guldi
Lehrstuhl für Physikalische Chemie I
Involved external institutions
Spain (ES)
Italy (IT)How to cite
APA:
König, M., Bottari, G., Brancato, G., Barone, V., Guldi, D.M., & Torres, T. (2013). Unraveling the peculiar modus operandi of a new class of solvatochromic fluorescent molecular rotors by spectroscopic and quantum mechanical methods. Chemical Science, 4(6), 2502-2511. https://doi.org/10.1039/c3sc50290b
MLA:
König, Matthias, et al. "Unraveling the peculiar modus operandi of a new class of solvatochromic fluorescent molecular rotors by spectroscopic and quantum mechanical methods." Chemical Science 4.6 (2013): 2502-2511.
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