Redox-Active M8L6 Cubic Hosts with Tetraphenylethylene Faces Encapsulate Organic Dyes for Light-Driven H2 Production

• Published in: Chemistry : a European journal Vol. 22; no. 50; pp. 18107 - 18114
• Main Authors: Yang, Linlin, Jing, Xu, He, Cheng, Chang, Zhiduo, Duan, Chunying
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 12.12.2016; Wiley Subscription Services, Inc
• Subjects: Chemical reduction; Chemistry; Confined spaces; Dyes; Electrochemistry; Hydrocarbons; Iron; metal-organic frameworks; photoinduced electron transfer; Polycyclic aromatic hydrocarbons; Redox potential; supramolecular chemistry; tetraphenylethylene
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201601447

The design of artificial systems that mimic highly evolved and finely tuned natural enzymes is a promising subject of intensive research. The assembly of O‐symmetric cubic structures with an Fe8L6 formula was reported through the direct combination of a C4‐symmetric tetraphenylethylene‐based ligand with a C3‐symmetric tris(bipyridine)iron node. The robust metal–organic cubes are rich in π‐electron density and provide favorable interactions with planar polycyclic aromatic hydrocarbons. Within the confined space of the host, the aromatic hydrocarbons molecules are forced closer to the redox active host, and the photoinduced electron transfer (PET) is modified into a pseudo‐intramolecular pathway. These iron vertices within the cubes exhibit suitable redox potential for electrochemical reduction of protons and the well‐modified PET is further tailored to create artificial systems for light‐driven hydrogen evolution from water through the encapsulation of fluorescein dyes. Control experiments based on a mononuclear compound resembling the iron corner of the octahedron suggest an enzymatic dynamic behavior. The new, well‐elucidated reaction pathways and the increased molarity of the reaction within the confined space render these supramolecular systems superior to other relevant systems. Thinking inside the cube! Two redox active Fe8L6 cubic cages were created by metal–ligand‐directed self‐assembly and tailored to create artificial systems by encapsulation of organic dyes (see scheme). The robust cubes are rich in π‐electron density and provide favorable interactions with the planar polycyclic aromatic hydrocarbons. The well‐modified photoinduced electron transfer, the unique redox properties, and increased molarity of the reaction in the confined space render the supramolecular systems superior to relevant ones.