期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 15, 期 38, 页码 9824-9835出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.200900732
关键词
fluorescence; gels; self-assembly; sol-gel processes; solvent effects
资金
- Scientific Research Foundation for the Returned Overseas Chinese Scholars
- State Education Ministry [JSPS-P05402]
- Open Project of State Key Laboratory of Supramolecular Structure and Materials [SKLSSM200703]
- National Natural Science Foundation of China (NNSFC) [20874034]
- 973 Program [2009CB939701]
Glutamine derivative 1 with two-photon absorbing units has been synthesized and was found to show gelation ability in some solvents. Its self-assembly in the gel phase could be controlled by the solvent and speed of gelation. For example, in DMSO the organogelator self-assembled into H-aggregates with weak exciton coupling between the aromatic moieties. On the other hand, in DMSO/diphenyl ether (1:9, v/v) the molecules formed ID aggregates, but with strong exciton coupling due to the small distance between the chromophores. Moreover, the formation of these two kinds of aggregates could be adjusted by the ratio of DMSO to diphenyl ether. In DMSO/toluene, DMSO/butanol, DMSO/butyl acetate, and DMSO/acetic acid systems similar results were observed. Therefore, conversion of the packing model occurs irrespective of the nature of the solvent. Notably, a unique sign inversion in the CD spectra could be realized by controlling the speed of gelation in the DMSO/diphenyl ether (1:9, v/v) system. It was found that a low speed of gelation induces the gelator to adopt a packing model with strong pi-pi interactions between the aromatic units. Moreover, the gels, when excited at 800 nm, emit strong green fluorescence and the quantum chemical calculations suggest that intramolecular charge transfer leads to two-photon absorption of the gelator molecule.
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