Luminescent assemblies based on surface active transition metal complexes and supramolecular host-guest systems

Miniaturisation of devices and components is becoming increasingly important in the field of molecular devices. The design of multicomponent supramolecular systems that undergo photoinduced energy or electron transfer processes has been well recognised in view of its potential for development of nanosized molecular devices for solar energy conversion and components in photonic devices. Consequently research has expanded to the properties of monolayers formed from rather simple organic molecules to biological systems and metal complexes. In the present approach, surface active Ru(II) and Os(II) complexes have been designed. Their attachment to surfaces and their photophysical properties in solution, as powders and as self-assembled monolayers have been investigated. The complexes present relatively high quantum yields and long lifetimes in solution, as powders and in monolayers. The complexes have been developed further to carry \(\beta\)-cyclodextrin recognition sites in their structure. This new group of molecules opens a window into guest-host chemistry on surfaces, with the view to examining photophysical properties of supramolecular functional surface-active systems. The surface active Ru(II) and Os(II) complexes bearing \(\beta\)-cyclodextrin exhibit formation of emissive monolayers. Later Ir(III) and Ru(II) metalloguests with a specific design to bind to \(\beta\)-cyclodextrin cavity have been synthesised and the photo-induced communication between metals were investigated both in solution and on gold surface. Finally, we propose a new and efficient method of sensitising Nd(III) NIR emission by non-covalent attachment of a BODIPY dye attached to \(\beta\)-cyclodextrin (BODIPY-CD). The BODIPY-CD has been proved to be a good sensitizer for neodymium complexes. This is the first time that NIR lanthanides have been sensitised through non-covalent host-guest approach using cyclodextrin. The inclusion of the hydrophobic biphenyl and phenyl tails in the cyclodextrin has been proved by the NMR studies