Click-coupling of anthraquinone dyes with β -cyclodextrin: formation of polymeric superstructures

Two novel cyclodextrin-modified anthraquinone dyes were synthesized and investigated for their complexation behaviour and formation of superstructures. Therefore, 1-fluoro-4-N-(propargylamino)anthraquinone and 1,4-bis(propargyloxy)anthraquinone were prepared via nucleophilic aromatic displacement and subsequently covalently ‘click-coupled’ in a copper(I)-catalysed azide–alkyne cycloaddition with β-cyclodextrin monoazide. Both the propargyl-modified precursor and the click-coupled anthraquinone dyes were evaluated as hosts and guests, respectively, in β-cyclodextrin interactions. The anthraquinone dye bearing two cyclodextrins, 1,4-bis((1-β-cyclodextrin-1H-1,2,3-triazol-5-yl)methoxy)anthraquinone, enables the reversible formation of supramolecular crosslinked poly[(N,N-dimethyl acrylamide)-co-(N-(ferrocenoylmethyl)acrylamide)] (11), whereas the monofunctionalized compound 1-fluoro-4-(((1-β-cyclodextrin-1H-1,2,3-triazol-5-yl)methyl)amino)anthraquinone can be supramolecularly linked to 11 resulting in coloured polymers. These features of β-cyclodextrin-linked anthraquinone dyes can be verified with either 1H 1H NMR rotating frame nuclear Overhauser effect spectroscopy or the naked eye. © 2016 Society of Chemical Industry