Metallo-Supramolecular Assemblies With Photoresponsive Functionality

This thesis concerns the design of metallosupramolecular architectures incorporating a specific function, namely light-responsive properties, for potential applications in molecular recognition, molecular electronics and as stimuli-responsive materials. This is achieved by employing established geometrically directing metallotectons in combination with novel light-responsive tripodal hosts based on the cyclotriveratrylene scaffold. A novel library of light-responsive molecular hosts have been prepared via novel asymmetrical azobenzene precursors. These light-responsive ligands undergo self-assembly with a variety of Ir(III) metallotectons to give a family of M3L2 metallocryptophanes, thus implanting the light-responsive functionality into these systems. Solution-state analysis indicates these metallocages contain a significant internal space for potential applications in molecular recognition. The photoresponsive properties of both the novel ligands and metallocryptophanes has been explored utilising light of UV and visible wavelengths to toggle between the trans/cis conformations of the embedded azobenzene units, resulting in dramatic structural perturbations in solution, pointing the way to sophisticated applications in molecular recognition. Photophysical analysis of these metallocryptophanes reveals deep blue emission properties, characteristically uncommon for Ir(III) complexes. A series of non-discrete coordination polymers have also been prepared and crystallographically elucidated from the combination of a light-responsive ligand with various Cu(II) and Ag(I) salts. Although light-responsive behaviour is yet to be demonstrated in these systems, a solvent-induced structural rearrangement is observed in one example, potentially promising further sophisticated host-guest properties

Data to support study "2D networks of metallo-capsules and other coordination polymers from a hexapodal ligand"

Data to support study of coordination polymers of hexakis(isonicotinoyl)cyclotricatechylene (L) including those of [M3L2] composition with M = Re, Co, Cu or N

Homochiral self-sorted and emissive IrIII metallo-cryptophanes

We thank the EPSRC (DTG award 1238852, EP/K039202/1, EP/M02105X/1, EP/J001325/1), Leverhulme Trust (RPG-2014-148), University of St Andrews, and the MEXT/JSPS Grants in Aid for Scientific Research (JP25102005 and JP25102001) for funding; Simon Barrett for assistance with NMR; Martin Huscroft for assistance with HPLC, and Stephen Boyer for elemental analysis measurements.The racemic ligands (±)-tris(isonicotinoyl)-cyclotriguaiacylene (L1), or (±)-tris(4-pyridyl-methyl)-cyclotriguaiacylene (L2) assemblewith racemic (Λ, Δ)- [Ir(ppy)2(MeCN)2]+, in which ppy = 2-phenylpyridinato to form [{Ir(ppy)2}3(L)2]3+ metallo-cryptophane cages. The crystal structure of [{Ir(ppy)2}3(L1)2]∙3BF4 has MM-ΛΛΛ nd PP-ΔΔΔ isomers, and homochiral self-sorting occurs in solution, a processaccelerated by a chiral guest. Self-recognition between L1 and L2 within cagesdoes not occur, and cages show very slow ligand-exchange. Both cages are phosphorescent,with [{Ir(ppy)2}3(L2)2]3+ havingenhanced and blue-shifted emission when compared with [{Ir(ppy)2}3(L1)2]3+ .PostprintPeer reviewe

Data to support study "Structure-switching M3L2 Ir(III) coordination cages with photo-isomerising azo-aromatic groups"

Spectroscopic raw data, crystal strcutures and other characterisation for study of 'Structure-switching M3L2 Ir(III) coordination cages with photo-isomerising azo-aromatic groups'

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

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).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.Publisher PDFPeer reviewe