Exciplex fluorescence in heterocycle acceptor complexes

Harman, PJ; Nott, PR; Selinger, BK

doi:10.1071/ch9771875

Cited by 3 publications

(7 citation statements)

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“…Similar results are also obtained for POPOP quenched by TMB. The absence of exciplex emission for POPOP−DEA as well as for POPOP−TMB in propylene glycol can be explained by a solvent polarity effect 52 or by a nonemissive exciplex also shows that the fine structure of the emission spectrum of POPOP does not change even in the presence of the highest concentrations of DEA (0.3 M), suggesting the absence of photodegradation products.…”

Section: Resultsmentioning

confidence: 93%

“…Iodide ion can act as an electron donor. POPOP is a good electron acceptor characterized by a redox potential of -1.77 V. 13 On the basis of the polarographic oxidation and reduction potentials data presented in Table 1, we calculated the free energy ∆G ET of the electron transfer process in the POPOP-donor molecule systems using the Rehm and Weller 4,5 equation…”

Section: Resultsmentioning

confidence: 99%

“…Iodide ion can act as an electron donor. POPOP is a good electron acceptor characterized by a redox potential of −1.77 V . On the basis of the polarographic oxidation and reduction potentials data presented in Table , we calculated the free energy Δ G ET of the electron transfer process in the POPOP−donor molecule systems using the Rehm and Weller 4,5 equation where E 1/2 ox (D/D •+ ) refer to half-wave oxidation potential of the electron donor and E 1/2 red (A •- /A) the reduction potential of the electron-acceptor molecules, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The fluorescence emission of POPOP can be quenched by typical electron-donor molecules like aromatic amines 5,13 or methoxybenzenes. This quenching involves electron transfer and indicates the electron-acceptor character of POPOP molecule.…”

Section: Resultsmentioning

confidence: 99%

“…Collisional quenching of fluorescence has been widely used in physical chemistry and biochemistry. Fluorescence quenching of aromatic and heteroaromatic hydrocarbons by aromatic amines, − aromatic nitriles, haloalkanes, − and halide ions − as well as by nitroxides , and oxygen , has been studied to determine the bimolecular rate constants, to characterize the solvent effects on quenching, and to determine the mechanisms of interaction between the fluorophore and quencher molecules. Moreover, collisional quenching of tryptophan fluorescence by a variety of ionic and neutral quenchers has been used to study the structure and dynamics of proteins − and membranes. , Collisional or dynamic quenching requires contact between the fluorophore and quencher molecules during the lifetime of the excited state.…”

Section: Introductionmentioning

confidence: 99%

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Distance-Dependent Fluorescence Quenching ofp-Bis[2-(5-phenyloxazolyl)]benzene by Various Quenchers

et al. 1996

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We report results of frequency-domain and steady-state measurements of the fluorescence quenching of p-bis-[2-(5-phenyloxazolyl)]benzene (POPOP) when quenched by bromoform (CHBr 3 ), methyl iodide (CH 3 I), potassium iodide (KI), 1,2,4-trimethoxybenzene (TMB), or N,N-diethylaniline (DEA). The quenching efficiency of these compounds decreased in the order DEA, TMB, KI, CH 3 I, CHBr 3 . In the case of DEA and TMB the measurements clearly confirm the applicability of the exponential distance-dependent quenching (DDQ) model, in which the bimolecular quenching rate k(r) depends exponentially on the fluorophore-quencher separation r, k(r) ) k a exp[-(r -a)/r e ], where a is the distance of closest approach. Simultaneous analysis of the frequency-domain and steady-state data significantly improved resolution of the recovered molecular parameters k a and r e . The data for DEA and TMB cannot be satisfactorily fit using either the Smoluchowski or CollinsKimball radiation boundary condition (RBC) model. The quenching behavior of the less efficient quenchers KI, CH 3 I, and CHBr 3 can be adequately described with both the DDQ and RBC models, but this may be a simple consequence of less efficient quenching. The efficiency of quenching is discussed on the basis of the mechanisms of interaction between the fluorophore and quencher molecules, which involves electron transfer and/or heavy atom effects. IntroductionCollisional quenching of fluorescence has been widely used in physical chemistry and biochemistry. Fluorescence quenching of aromatic and heteroaromatic hydrocarbons by aromatic amines, 1-13 aromatic nitriles, 14 haloalkanes, 15-24 and halide ions 25-27 as well as by nitroxides 28,29 and oxygen 30,31 has been studied to determine the bimolecular rate constants, to characterize the solvent effects on quenching, and to determine the mechanisms of interaction between the fluorophore and quencher molecules. Moreover, collisional quenching of tryptophan fluorescence by a variety of ionic and neutral quenchers has been used to study the structure and dynamics of proteins 32-40 and membranes. 41,42 Collisional or dynamic quenching requires contact between the fluorophore and quencher molecules during the lifetime of the excited state. The quenching data can reveal information about accessibility of fluorophores in macromolecules to externally added quenchers and the diffusion of quenchers within proteins and membranes.For many fluorophores in solution, including aromatic and heteroaromatic fluorophores, the intensity decays are often monoexponential. 43 However, in the presence of collisional quenching the monoexponential intensity decays become nonexponential due to transient effects in diffusion. 21,[44][45][46] This effect in collisional quenching of fluorescence is due to a rapid decay of closely spaced fluorophore-quencher pairs, followed by slower diffusion-limited quenching of remaining fluorophores. These effects can be readily detected by using frequency-domain fluorometry. [47][48][49] We have shown for several fl...

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%