Controlled encapsulation of photoresponsive macromolecules in porous coordination polymer

A photoresponsive controlled adsorption system based on a porous coordination polymer (PCP) was fabricated, using azobenzene tethered with poly(ethylene glycol) (PEG-AB) as macromolecular guests. Specific adsorption behavior of trans-PEG-AB into the nanochannels of a PCP was observed in an EtOH medium. When this composite was irradiated with UV light in EtOH, isomerization of PEG-AB from the trans to the cis form resulted in release of PEG-AB because of the large changes in the molecular shape and solubility of PEG-AB. Subsequent visible light irradiation induced photoisomerization of PEG-AB, which led to readsorption of PEG-AB into the nanochannels.