Thermotropic Mesomorphic Behavior of Surfactant-Encapsulated Polyoxometalate Hybrids

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• 作者：Wen Li ; Shengyan Yi ; Yuqing Wu ; Lixin Wu
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：August 31, 2006
• 年：2006
• 卷：110
• 期：34
• 页码：16961 - 16966
• 全文大小：498K
• 年卷期：v.110,no.34(August 31, 2006)
• ISSN：1520-5207

文摘

We investigate in detail novel organic-inorganic hybrid liquid crystalline materials, the complexes of surfactant-encapsulated polyoxometalate clusters (SECs), using thermal, X-ray diffraction, and FT-IR spectroscopicanalyses. The differential scanning calorimetry measurements reveal four phase transitions under heatingprocesses. We employ FT-IR spectroscopy to understand these phase behaviors. On the basis of vibrationspectral assignments, the evidence suggests that the first two phase transitions are associated with the increaseof gauche conformers and the disruption of alkyl chains packing in the heating run; the third phase transitionis due to the full conformational disorder of alkyl chains covered on the polyoxometalates (PMs); no significantC-H stretching or wagging vibrations are observed with the fourth transition. We find that the fourthendothermic peak is sensitive to the charges of the PMs, and the transition temperature decreases from 185,177, to 164 C with decreasing PM charges from 13, 11, to 9, respectively. Interestingly, the temperatures ofthe first three phase transitions of SECs are essentially independent of the PM charges.