Fluorescent Dendritic Organogels Based on 2-(2′-Hydroxyphenyl)benzoxazole: Emission Enhancement and Multiple Stimuli-Responsive Properties

A new highly efficient and versatile poly(benzyl ether) dendritic organogelator HPB-G(1) with 2-(2'-hydroxyphenyl) benzoxazole (HPB) at the focal point has been designed and synthesized. HPB-G(1) can form stable organogels toward various apolar and polar organic solvents. Further studies revealed that intermolecular multiple pi-pi stacking interactions are the main driving forces for the formation of the organogels. Notably, dendron HPB-G(1) exhibited a significantly enhanced emission in the gel state in contrast to weak emission in solution. Most interestingly, these dendritic organogels exhibited multiple stimuli-responsive behaviors upon exposure to environmental stimuli, including temperature, sonication, shear stress, and the presence of anions, metal cations, acids/ bases, thus leading to reversible sol-gel phase transitions.