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Excimer

About: Excimer is a research topic. Over the lifetime, 3725 publications have been published within this topic receiving 75104 citations.


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Journal ArticleDOI
TL;DR: In this article, the fluorescence properties of inclusion complexes of 2,5-diphenyl-1,3,4-oxadiazole (PPD), 2-phenyl-5-(4-bipenyl)- 1, 3, 4, 4-oxadiadiazoles (PBD), and 2-5-biphioxazole (BBD) in aqueous solutions of cyclodextrins (CDs) were examined and compared.
Abstract: The fluorescence properties of inclusion complexes of 2,5-diphenyl-1,3,4-oxadiazole (PPD), 2-phenyl-5-(4-biphenyl)- 1,3,4-oxadiazole (PBD) and 2,5-biphenyl-1,3,4-oxadiazole (BBD) in aqueous solutions of cyclodextrins (CDs) were examined and compared. Excimer/dimer fluorescence appeared only in the presence of γ-CD but not with the other CDs. The results indicate the formation of extended linear beads emitting excimer fluorescence of 2,5-diphenyloxazole (PPO). Brilliant crysel blue (BCB) is a flourescent terminator molecule which causes shortening of the extended linear beads of PPO and γ-CD. The excimer fluorescence of BBD is reported here for the first time. The difficulties encountered in the detection and identification of the excimer fluorescence of the other oxadiazoles are well known. The identification of the steady state excimer fluorescence of BBD is almost impossible unless it is compared with the excimer fluorescence spectra of PPD and PBD.

36 citations

Journal ArticleDOI
TL;DR: Trimesitylbodipy (TMB) is a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene derivative with bulky side groups as discussed by the authors.
Abstract: Trimesitylbodipy (TMB), a new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene derivative with bulky side groups, was synthesized in order to develop nanostructured fluorescent devices. Fluorescence properties of TMB were studied in dichloromethane, in amorphous films prepared by rapid evaporation of a solution and in micro- and nanocrystals. It was compared to the spectroscopy of Mesitylbodipy (MB) to see if the mesityl groups of TMB modify fluorescence in the solid state. A set-up including a space and time correlated photon-counting photo-multiplier was used to record fluorescence intensity and lifetime images of solids. For both dyes, the formation of fluorescent excimers was observed. There is evidence to suggest energy transfer from monomer to both fluorescent and non-fluorescent excimers. MB fluorescence is still quenched in the crystalline state but in TMB monocrystals the fluorescence comes from only one excimer with a lifetime of 9.5 ns. TMB nanocrystals with a monoexponential fluorescence decay were also prepared.

36 citations

Journal ArticleDOI
TL;DR: In this paper, a mixed excimer fluorescence is observed when any one of a variety of aromatic hydrocarbons is added to solutions of 9−cyanoanthracene or 9, 10−dicyanoanthracene.
Abstract: Mixed excimer fluorescence is observed when any one of a variety of aromatic hydrocarbons is added to solutions of 9‐cyanoanthracene or 9, 10‐dicyanoanthracene. The formation of a mixed excimer appears to be markedly dependent upon the ionization potential of the donor. The emission maxima of the 9, 10‐dicyanoanthracene mixed excimers vary linearly with the polarographic oxidation potentials of the donors, a results corresponding to that found for charge‐transfer absorption bands. It is concluded that charge‐transfer interaction is important in the excimer state.

36 citations

Journal ArticleDOI
TL;DR: Intramolecular excimer formation with 1,5-bis(1-pyrenylcarboxy)pentane, (1PC(5)1PC) is studied as a function of temperature in a series of alkane solvents and in toluene, covering a wide range of solvent viscosities η, from 0.2 to 125 cP.
Abstract: Intramolecular excimer formation with 1,5-bis(1-pyrenylcarboxy)pentane, (1PC(5)1PC) is studied as a function of temperature in a series of alkane solvents and in toluene, covering a wide range of s...

36 citations

Journal ArticleDOI
TL;DR: In this article, the photophysical processes taking place in the excited state of a donor−bridge−acceptor compound (1) in alkane solvents were studied with time-resolved laser-induced optoacoustic spectroscopy.
Abstract: The photophysical processes taking place in the excited state of a donor−bridge−acceptor compound (1) in alkane solvents were studied with time-resolved laser-induced optoacoustic spectroscopy. 1 contains an aniline/cyanonaphthalene D/A pair, separated by a semiflexible saturated hydrocarbon bridge. Excitation at 308 nm leads to efficient long-range charge separation, followed by rapid Coulomb-induced intramolecular exciplex formation. By monitoring the pressure waves generated by the decay of the excited species, three consecutive heat release processes could be discerned. In order to separate the contributions to the observed acoustic signals of structural volume changes (ΔVstr) and enthalpy changes, experiments were carried out in a series of normal alkanes, differing in their photothermal properties. A value of ΔVstr = −40 ± 5 mL/mol was obtained for the difference in reaction volume between the ground state and the exciplex state of 1. This large contraction should be attributed in part to electrostr...

36 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023106
2022253
202142
202045
201959
201847