Structure-switching M3L2 Ir(III) coordination cages with photo-isomerising azo-aromatic linkers

Samuel Oldknow, Diego Rota Martir, Victoria E. Pritchard, Mark A. Blitz, Colin W.G. Fishwick, Eli Zysman-Colman, Michaele J. Hardie*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Cyclotriguaiacylene has been functionalised with 3- or 4-pyridyl-azo-phenyl groups to form a series of molecular hosts with three azobenzene-type groups that exhibit reversible photo-isomerisation. Reaction of the host molecules with [Ir(C^N)2(NCMe)2]+ where C^N is the cyclometallating 2-phenylpyridinato, 2-(4-methylphenyl)pyridinato or 2-(4,5,6-trifluorophenyl)pyridinato results in the self-assembly of a family of five different [{Ir(C^N)2}3(L)2]3+ coordination cages. Photo-irradiation of each of the cages with a high energy laser results in E → Z photo-isomerisation of the pyridyl-azo-phenyl groups with up to 40% of groups isomerising. Isomerisation can be reversed by exposure to blue light. Thus, the cages show reversible structure-switching while maintaining their compositional integrity. This represents the largest photo-induced structural change yet reported for a structurally-integral component of a coordination cage. Energy minimised molecular models indicate a switched cage has a smaller internal space than the initial all-E isomer. The [Ir(C^N)2(NCMe)2]+ cages are weakly emissive, each with a deep blue luminescence at ca. 450 nm.

Original languageEnglish
Pages (from-to)8150-8159
Number of pages10
JournalChemical Science
Issue number42
Early online date6 Sept 2018
Publication statusPublished - 14 Nov 2018


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