《cm903121n 由偶氮苯树枝液晶聚合物所带来的超分子手性的光控制》.pdf

1714 Chem. Mater. 2010, 22, 1714–1723 DOI:10.1021/cm903121n Photocontrol of the Supramolecular Chirality Imposed by Stereocenters in Liquid Crystalline Azodendrimers † † † ‡ ~ † Jesus del Barrio, Rosa M. Tejedor, Luiz S. Chinelatto, Carlos Sanchez, Milagros Pinol, and Luis Oriol*,† † ´ ´ ´ ‡ ´ Departamento de Quımica Organica y Quımica Fısica and Departamento de Fısica de la Materia Condensada, Facultad de Ciencias-Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain Received October 9, 2009. Revised Manuscript Received December 15, 2009 A series of liquid crystalline dendrimers have been synthesized by peripheral functionalization of PPI dendrimers (generations having 16 or 32 functional groups) with photochromic azobenzene units that contain stereocenters at the terminal alkyl chains. Complete functionalization was checked by NMR and MALDI-TOF mass spectrometry. The mesomorphic properties were analyzed by optical microscopy, DSC, X-ray diffraction and AFM. The dendrimers exhibit a smectic phase that can be frozen at room temperature depending on the thermal history of the sample. Dendrimers did not exhibit a CD response in solution. However, chiroptical properties were detected in films and these