The self-coiling behaviors of organic molecules in fluorinated solvents haven’t been explored previously.As one particular type of fluorous solvent,polar fluorinated arenes are widely used in both academia and indust...The self-coiling behaviors of organic molecules in fluorinated solvents haven’t been explored previously.As one particular type of fluorous solvent,polar fluorinated arenes are widely used in both academia and industry.In this report,several modern techniques,including visual observation,concentration-dependent UV-visible spectroscopy,concentration-dependent fluorescence spectroscopy and kinetics measurements,dynamic light scattering(DLS)tests,and theoretical calculations,are employed to examine the self-coiling and aggregation behaviors of two types of organic fluorescent probes with saturated aliphatic chains in three polar fluorinated arenes.In contrast to in aqueous solutions,their behaviors differ significantly:the single-headed probes in polar fluorinated arenes maintain a stretched hatpin conformation,form aggregates at low concentrations,and form excimers at higher concentrations;most double-headed probes tend to self-coil in these solvents,but the optimal conformation depends on the chain length and can form excimers at very low concentrations,while their CAgCs are comparable to those of single-headed probes.As an exciting discovery,the macrolactonization reaction of 8-hydroxyoctanoic acid in trifluorotoluene has been obviously improved by molecular self-coiling.Therefore,our discoveries may provide guidance for the regulation of the synthesis of macrocycles in such solvents in the future.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supported by the National Key Research and Development Program of China(Grant 2022YFB4101800)the National Natural Science Foundation of China(Grants 22171141,22193010,and 22193014)the Fundamental Research Funds for the Central Universities(Grant 020-63233022).
文摘The self-coiling behaviors of organic molecules in fluorinated solvents haven’t been explored previously.As one particular type of fluorous solvent,polar fluorinated arenes are widely used in both academia and industry.In this report,several modern techniques,including visual observation,concentration-dependent UV-visible spectroscopy,concentration-dependent fluorescence spectroscopy and kinetics measurements,dynamic light scattering(DLS)tests,and theoretical calculations,are employed to examine the self-coiling and aggregation behaviors of two types of organic fluorescent probes with saturated aliphatic chains in three polar fluorinated arenes.In contrast to in aqueous solutions,their behaviors differ significantly:the single-headed probes in polar fluorinated arenes maintain a stretched hatpin conformation,form aggregates at low concentrations,and form excimers at higher concentrations;most double-headed probes tend to self-coil in these solvents,but the optimal conformation depends on the chain length and can form excimers at very low concentrations,while their CAgCs are comparable to those of single-headed probes.As an exciting discovery,the macrolactonization reaction of 8-hydroxyoctanoic acid in trifluorotoluene has been obviously improved by molecular self-coiling.Therefore,our discoveries may provide guidance for the regulation of the synthesis of macrocycles in such solvents in the future.
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.
