Stimuli-Responsive Resorcin[4]arene Cavitands: Toward Visible-Light-Activated Molecular Grippers.

Resorcin[4]arene cavitands, equipped with diverse quinone (Q) and [Ru(bpy)(2)dppz](2+)(bpy=2,2 '-bipyridine, dppz=dipyrido[3,2-a:2 ',3 '-c]phenazine) photosensitizing walls in different configurations, were synthesized. Upon visible-light irradiation at 420 nm, electron transfer from the [Ru(bpy)(2)dppz](2+)to theQgenerates the semiquinone (SQ) radical anion, triggering a large conformational switching from a flatkiteto avasewith a cavity for the encapsulation of small guests, such as cyclohexane and heteroalicyclic derivatives, in CD3CN. Depending on the molecular design, theSQradical anion can live for several minutes (approximate to 10 min) and thevasecan be generated in a secondary process without need for addition of a sacrificial electron donor to accumulate theSQstate. Switching can also be triggered by other stimuli, such as changes in solvent, host-guest complexation, and chemical and electrochemical processes. This comprehensive investigation benefits the development of stimuli-responsive nanodevices, such as light-activated molecular grippers.