Photoinduced Formation of an Azobenzene‐Based CD‐Active Supramolecular Cyclic Dimer1. Issue 18 (12th March 2015)

• Record Type: Journal Article
• Authors: Sogawa, Hiromitsu; Terada, Kayo; Miyagi, Yu; Shiotsuki, Masashi; Inai, Yoshihito; Masuda, Toshio; Sanda, Fumio
• Is Part Of: Chemistry. Volume 21:Issue 18(2015)
• Page Start: 6747
• Page End: 6755
• Publication Date: 2015-03-12
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201406054
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A series of new photo‐responsive amino acid‐derived azobenzenedicarboxylic acid derivatives (<italic>S</italic>)‐<bold>1 a</bold>–<bold>e</bold> were synthesized. Compound (<italic>S</italic>)‐<bold>1 a</bold> in the <italic>trans</italic> form exhibited no circular dichroism (CD) signal in DMF under ambient conditions, whereas intense Cotton effects were observed upon UV irradiation, indicating the formation of a chiral supramolecular structure in the <italic>cis</italic> form. The CD signals disappeared when trifluoroacetic acid (TFA) was added to the solution. The ester counterpart [(<italic>S</italic>)‐<bold>1 a′</bold>] showed no CD signal. Hydrogen bonding between the carboxy groups seemed necessary for constructing the supramolecular structure. The kinetic studies of <italic>cis</italic> to <italic>trans</italic> isomerization of (<italic>S</italic>)‐<bold>1 a</bold> demonstrated that the formation of a chiral supramolecule enhances the stability of the <italic>cis</italic>‐azobenzene structure. The ESI mass spectrum of stilbenedicarboxylic acid (<italic>S</italic>)‐<bold>4</bold>, an analogue of (<italic>S</italic>)‐<bold>1 b</bold>, confirmed the formation of a dimer. A theoretical CD study revealed that (<italic>S</italic>)‐<bold>1 a</bold> in the <italic>cis</italic> form should be present as a cyclic chiral dimer.</p> </abstract>