MASSIMO BARONCINI, CLAN-Center for Light Activated Nanostructures, ISOF-CNR, Bologna, Italy, and Dipartimento di Scienze e Tecnologie Agro-alimentari, Università di Bologna, Bologna, Italy
The eternal youth of azobenzene: New photoactive hard and soft materials
Host: Jorge Parola
Photochromic units undergo profound changes in their chemical and/or electronic structure upon light excitation, and are highly interesting for the construction of photocontrollable molecular devices, machines and materials. Among photochromic processes, the trans-cis photoisomerization of azobenzene – owing to its high efficiency, excellent reversibility, and significant physico-chemical differences between the two forms – is a highly useful reaction. Azobenzene photoisomerization has been known for almost 80 years and has been exploited to implement light-induced functionalities with a large variety of compounds, biomolecules, nanosystems and materials. Here we present recent investigations undertaken in our laboratories aimed at using azobenzene isomerization for photo-inducing and -controlling properties in hard and soft materials at the nano- and macroscale. The reversible photoisomerization of shape-persistent azobenzene tetramers in the bulk crystalline solid state and at the single molecule level will be described [1,2]. Moreover, we will present research on the spontaneous emulsification of an azobenzene based surfactant and its photo-reversible uptake and release of small molecules in aqueous solution as an example of how this outstanding photochrome can be utilized to develop soft materials with valuable light-induced functionalities .
Fig. 1. (a-b) Crystals of an azobenzene based star-shaped tetramer before (a) and after (b) irradiation with UV light. (c-d) Microemulsion of an azobenzene based surfactant embedding Nile-Red before (c) and after (d) irradiation with UV-light.
 Baroncini M.; d’Agostino S; Bergamini G.; Ceroni P.; Comotti A.; Sozzani P.; Bassanetti I.; Grepioni F.; Hernandez T. M.; Silvi S.; Venturi M.; Credi A. Nat. Chem. 2015, 7, 634.  Nacci C.; Baroncini M.; Credi A.; Grill L. Angew. Chem. Int. Ed. 2018, 57, 15034.  Villa C.; Bergamini G.; Ceroni P.; Baroncini, M. Chem. Comm., 2019, under revision.
Massimo Baroncini received both his BSc and PhD in Chemical Sciences from the University of Bologna. He is currently assistant professor of Chemistry at the University of Bologna and associate researcher at the Institute of Organic Synthesis and Photochemistry (CNR-ISOF).
He has coauthored over 50 scientific publications and one monograph. His main research activity deals with the synthesis and investigation of supramolecular systems with tailored physico-chemical functionalities.