synthesis and characterization of photo-responsive carbosilane dendrimers合成和表征photo-responsive carbosilane树枝状分子.pdfVIP

Molecules 2009, 14, 2226-2234; doi:10.3390/molecule OPEN ACCESS molecules ISSN 1420-3049 /journal/molecules Article Synthesis and Characterization of Photo-esponsive endrimers 1, 1 1, 2 1 Tetsuo Koyama *, Ken Hatano , Koji Matsuoka *, Yasuaki Esumi and Daiyo Terunuma 1 Division of Material Science, Graduate School of Science and Engineering, Saitama University, Sakura, Saitama 338-8570, Japan 2 The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan * Authors to whom correspondence should be addressed; E-mails: koyama@fms.saitama-u.ac.jp (T.K.), koji@fms.saitama-u.ac.jp (K.M.); Tel/Fax: +81-48-858-3099 (T.K.), +81-48-858-3099 (K.M.) Received: 2 June 2009; in revised form: 13 June 2009 / Accepted: 17 June 2009 / Published: 18 June 2009 Abstract: Preparation of photo-responsive carbosilane dendrimers bearing 4-phenylazo- benzonitrile units on their molecular surface has been accomplished, and their both photo and thermal behaviors have also been characterized. These functional dendrimers suggest that the apparent molecular sizes of the cis-isomers are smaller than those of the corresponding trans-isomers, since the molecular diameter of these dendrimers would be shorter on the basis of trans→cis photo-isomerization of azobenzene. Keywords: azobenzene; carbosilane dendrimer; heat isomerization 1. Introduction Dendrimers