The fluorescence spectra and photodimerization of anthrylmethyl a,w-alkanedioates (A-Mn-A) both in organic and in aqueous organic mixed solvents have been studied.In aqueous organic mixed solvents strong intramolecula...The fluorescence spectra and photodimerization of anthrylmethyl a,w-alkanedioates (A-Mn-A) both in organic and in aqueous organic mixed solvents have been studied.In aqueous organic mixed solvents strong intramolecular excimer emission is detected and the quantum yield for the intramolecular photodimerization is significantly greater than those in organic solvents.These observations suggest that hydrophobic interactions force A-Mn-A molecule to self-coil.The ratio of the head-to-head to head-to-tail products in the intramolecular photodimers of A-Mn-A depends on the length of the linking chain.This work presents a successful example of application of hydrophobic interactions to enhancement of large-ring formation.展开更多
Effects of self-coiling of organic molecules on intramolecular exciplexformation of compound Ⅰ, in which the carbazole chromophore and terephthalic acid methylesteracceptor group are linked by one (CH_2)_(10) chain, ...Effects of self-coiling of organic molecules on intramolecular exciplexformation of compound Ⅰ, in which the carbazole chromophore and terephthalic acid methylesteracceptor group are linked by one (CH_2)_(10) chain, and the decrease of the fluorescence intensitiesof compounds Ⅱ, Ⅲ, and Ⅳ, in which the carbazole chromophore and 3, 5-dinitrobenzoate areconnected by one aliphatic chain of (CH_2)_(10) (Ⅱ), (CH_2)_(12) (Ⅲ), or (CH_2)_4 (Ⅳ), have beenstudied in the dioxane(DX)-H_2O binary system. The results show that self-coiling of organicmolecules in DX-H_2O facilitates intramolecular exciplex formation of Ⅰ and induces the decrease offluorescence intensities of Ⅱ, because of the proximity effect brought about by self-coiling oforganic molecules under hydrophobic-lipophilic interaction (HLI) between the excited carbazolechromophore and the acceptor. Since the similar effects are observed even when the concentrations ofthe probes are less than their CAgCs (critical aggregate concentrations) in the DX-H_2O mixturewith the same φ values, formation of the intermolecular exciplex has been excluded. The effects arefound to be strongly depended on φ values, indicating that they are mainly driven by HLI. Theproperties of the acceptors can also affect the intramolecular exciplex formation. With terephthalicacid methylester moiety as the acceptor, the carbazole chromophore exhibits the fluorescencespectra of the exciplex, while with 3, 5-dinitrobenzoate moiety as the acceptor, only thefluorescence spectra of excited carbazolyl chromophore are observed.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘The fluorescence spectra and photodimerization of anthrylmethyl a,w-alkanedioates (A-Mn-A) both in organic and in aqueous organic mixed solvents have been studied.In aqueous organic mixed solvents strong intramolecular excimer emission is detected and the quantum yield for the intramolecular photodimerization is significantly greater than those in organic solvents.These observations suggest that hydrophobic interactions force A-Mn-A molecule to self-coil.The ratio of the head-to-head to head-to-tail products in the intramolecular photodimers of A-Mn-A depends on the length of the linking chain.This work presents a successful example of application of hydrophobic interactions to enhancement of large-ring formation.
基金theNationalNaturalScienceFoundationofChina (No .2 9972 0 5 2 ) theMinistryofScienceandTechnologyChineseAcademyofSciences
文摘Effects of self-coiling of organic molecules on intramolecular exciplexformation of compound Ⅰ, in which the carbazole chromophore and terephthalic acid methylesteracceptor group are linked by one (CH_2)_(10) chain, and the decrease of the fluorescence intensitiesof compounds Ⅱ, Ⅲ, and Ⅳ, in which the carbazole chromophore and 3, 5-dinitrobenzoate areconnected by one aliphatic chain of (CH_2)_(10) (Ⅱ), (CH_2)_(12) (Ⅲ), or (CH_2)_4 (Ⅳ), have beenstudied in the dioxane(DX)-H_2O binary system. The results show that self-coiling of organicmolecules in DX-H_2O facilitates intramolecular exciplex formation of Ⅰ and induces the decrease offluorescence intensities of Ⅱ, because of the proximity effect brought about by self-coiling oforganic molecules under hydrophobic-lipophilic interaction (HLI) between the excited carbazolechromophore and the acceptor. Since the similar effects are observed even when the concentrations ofthe probes are less than their CAgCs (critical aggregate concentrations) in the DX-H_2O mixturewith the same φ values, formation of the intermolecular exciplex has been excluded. The effects arefound to be strongly depended on φ values, indicating that they are mainly driven by HLI. Theproperties of the acceptors can also affect the intramolecular exciplex formation. With terephthalicacid methylester moiety as the acceptor, the carbazole chromophore exhibits the fluorescencespectra of the exciplex, while with 3, 5-dinitrobenzoate moiety as the acceptor, only thefluorescence spectra of excited carbazolyl chromophore are observed.
