Phosphorescent nematic hydrogels and chromonic mesophases driven by intra- and intermolecular interactions of bridged dinuclear cyclometalated platinum(II) complexes

A new class of dinuclear cyclometalated platinum(II) complexes with [Pt-II(C boolean AND N boolean AND N)CNR](+) (HC boolean AND N boolean AND N = 6-phenyl-2,2'-bipyridyl, CNR = 2,6-dimethylphenyl isocyanide) motifs covalently connected by oligo(oxyethylene) chains form luminescent lyotropic chromonic liquid crystals or hydrogels in aqueous dispersions with intra- and intermolecular Pt...Pt and pi-pi interactions as the driving force. Their solution behaviour is modulated by the length of the oligo(oxyethylene) chain connecting the two cyclometalated platinum(II) motifs. One of the dinuclear Pt(II) complexes with a long oligo(oxyethylene) bridge and which does not display intramolecular Pt...Pt and pi-pi interactions can act as an effective 'gelling stimulus' for mononuclear [Pt-II(C boolean AND N boolean AND N)CNR](+) complexes in aqueous solutions, resulting in the formation of a nematic hydrogel that is persistent and displays red photoluminescence.