Structure-switching M3L2 Ir(III) coordination cages with photo-isomerising azo-aromatic linkers
Abstract
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.
Citation
Oldknow , S , Martir , D R , Pritchard , V E , Blitz , M A , Fishwick , C W G , Zysman-Colman , E & Hardie , M J 2018 , ' Structure-switching M 3 L 2 Ir(III) coordination cages with photo-isomerising azo-aromatic linkers ' , Chemical Science , vol. 9 , no. 42 , pp. 8150-8159 . https://doi.org/10.1039/c8sc03499k
Publication
Chemical Science
Status
Peer reviewed
ISSN
2041-6520Type
Journal article
Description
This work was supported by The Leverhulme Trust (RPG-2014-148), EPSRC (EP/M02105X/1, 1238852 (VEP), equipment grant EP/K039202/1). This work was carried out with support of Diamond Light Source (MT-10344).Collections
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