Journal ArticleDOI
Effects of molecular structure and hydrogen bonding on the radiationless deactivation of singlet excited fluorenone derivatives
TLDR
In this article, the electron-donating character of the substituent in the excited fluorenone and the hydrogen-bonding power of alcohol play important roles in determining the rate of dynamic quenching by alcohols.Abstract:
Substituent effects on intramolecular radiationless deactivation and hydrogen-bonding-induced quenching have been examined for various fluorenone derivatives. In toluene, triplet formation is the dominant process from the singlet excited state when an electron-withdrawing group is attached to the fluorenone moiety, whereas an electron-donating substituent promotes internal conversion. There is a clear correlation between the internal conversion rate constant and the lowest excited singlet state energy, which can be explained in terms of the energy gap law. It is shown that both the electron-donating character of the substituent in the excited fluorenone and the hydrogen-bonding power of alcohol play important roles in determining the rate of dynamic quenching by alcohols. The intermolecular hydrogen bonding with alcohols in the singlet excited state acts as an effective accepting mode of radiationless deactivation for fluorenones substituted with an electron-donating group. However, 2-NO2− and 2-COOCH3− d...read more
Citations
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Journal ArticleDOI
Role of Intramolecular and Intermolecular Hydrogen Bonding in Both Singlet and Triplet Excited States of Aminofluorenones on Internal Conversion, Intersystem Crossing, and Twisted Intramolecular Charge Transfer†
Guangjiu Zhao,Ke-Li Han +1 more
TL;DR: Time-dependent density functional theory method was performed to investigate the intramolecular and intermolecular hydrogen bonding in both the singlet and triplet electronic excited states of amin ofluorenones AF, MAF, and DMAF in alcoholic solutions as well as their important roles on the excited-state photophysical processes of these aminoflu Lorenones.
Journal ArticleDOI
Green emission from poly(fluorene)s: The role of oxidation
Egbert Zojer,Alexander Pogantsch,Emmanuelle Hennebicq,David Beljonne,Jean-Luc Brédas,Patricia Scandiucci de Freitas,Ullrich Scherf,Emil List +7 more
TL;DR: In this article, the optical properties of poly(fluorene)s containing ketonic defects were analyzed using quantum-chemical techniques, focusing on the influence of excited-state localization effects.
Journal ArticleDOI
Fluorescence lifetime of Nile Red as a probe for the hydrogen bonding strength with its microenvironment
TL;DR: The fluorescence lifetime of Nile Red (NR) is not sensitive to dielectric solvent-solute interactions but markedly decreases with the increase of the hydrogen bond donating ability in alcohols because vibrations associated with hydrogen bonding are involved in the deactivation process as mentioned in this paper.
Journal ArticleDOI
Dual fluorescence and fast intramolecular charge transfer with 4-(diisopropylamino)benzonitrile in alkane solvents
Attila Demeter,Sergey I. Druzhinin,Mathew George,Edwin Haselbach,Jean Luc Roulin,Klaas A. Zachariasse +5 more
TL;DR: In this paper, dual fluorescence and fast intramolecular charge transfer (ICT) is observed with 4-(diisopropylamino)benzonitrile (DIABN) in alkane solvents.
Journal ArticleDOI
Fluorescence quenching phenomena facilitated by excited-state hydrogen bond strengthening for fluorenone derivatives in alcohols
TL;DR: In this article, the time-dependent density functional theory (TD-DFT) method was used to study the excited-state hydrogen bonding of both benzo[b]fluorenone (BF) solvatochromism in several aprotic and alcoholic solvents.
References
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TL;DR: In this paper, the authors derived a modified 1/τ0=2.880×10−9n2/n2-1(gl/gu) ∫ edlnν, which should be valid for broad molecular bands when the transition is strongly allowed.
Journal ArticleDOI
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TL;DR: In this article, a unified treatment of non-radiative decay processes in large molecules which involve either electronic relaxation between two electronic states or unimolecular rearrangeme(s) is presented.
Journal ArticleDOI
Reference materials for fluorescence measurement
TL;DR: This body represents the members of the European Parliament in the following countries: Belgium, Hungary, France, Germany, Italy, Greece, Spain, Portugal, Yugoslavia, and the Republic of Ireland.
Journal ArticleDOI
Spin—Orbit Coupling and the Radiationless Processes in Nitrogen Heterocyclics
TL;DR: In this paper, the matrix elements of the spin-orbit operator between the zero-order (spin-free) (n, π*) states of nitrogen heterocyclics are examined.
Journal ArticleDOI
Application of the energy gap law to nonradiative, excited-state decay
TL;DR: In this paper, it was shown that plots of 1nk/sub nr/ vs E/sub em/ are linear for the metal to ligand charge transfer (MLCT) excited states in the series Re(bpy)(CO)/sub 3/L/sup +/ (bpy is 2,2'-bipyridine; L = PMe/sub 3/, CH/sub3/CN, py,...).