Photoisomerization of Azobenzenes Inserted Into A Supramolecular Aggregate


Photoisomerization of Azobenzenes Inserted Into A Supramolecular Aggregate



Caroline O Piekarski


This poster reflects research conducted as part of a course project designed to give students experience in the research process.



The purpose of this research project was to develop photomolecular systems that contain photoresponsive properties. Light provides a convenient and sustainable source of “green” energy for manipulating and powering nano materials and biomaterials. The primary molecules focused on in this experiment were two azobenzene derivatives: azobenzene 4,4’-dicarboxylic acid (ADA) and 4-dimethylaminoazobenzene-4’-carboxylic acid (M0423). Some azobenzene chromophores undergo cis-trans isomerization when irradiated with UV and visible light. Of the derivatives chosen, only ADA showed photoisomerization capability in its non-aggregated form. A series of dilutions and titrations were performed in order to induce and observe the formation of homo-aggregates of ADA and M0423, and hetero-aggregates containing both molecules. Aggregate formation was monitored using both UV-Vis absorption and circular dichroism spectroscopy. The experiment showed that both ADA and M0423 form aggregates in acidic conditions. Moreover, both ADA and M0423 are achiral but their 1:2 aggregate showed a quite intense CD signal indicating the formation of a chiral assembly despite the absence of any chiral template. The azobenzene-based systems were irradiated with UV and visible light in order to investigate their photodynamic properties. Irradiation experiments showed that the homo-aggregate of ADA is not able to photo-switch while the hetero-aggregate shows some photo-switching capabilities. Future studies will involve the analysis of additional derivatives and an array of hetero-aggregate to better understand their structure and its correlation with photo-isomerization.

Publication Date


Project Designation

Course Project

Primary Advisor

Angela Mammana

Primary Advisor's Department



Stander Symposium project

Photoisomerization of Azobenzenes Inserted Into A Supramolecular Aggregate