Supramolecular hydrogel with luminescence tunablility and responsiveness based on co-doped lanthanide and deoxyguanosine complex

Lanthanide (Ln)-based supramolecular hydrogels are a new category of smart optical materials, which are promising for applications in chemistry sensors, bioimaging agents and light-emitting devices. Herein, we report a supramolecular hydrogel with tunable and responsive luminescence, which is based on the assembly of Ln and deoxyguanosine (dG, one of the units of DNA). ESI-TOF-MS, NMR, FTIR, PXRD and simulation results verify the formation of dG/Ln hydrogels. dG/Tb hydrogel emits strong green luminescence, while dG/Eu hydrogel is nonluminous; when Tb is co-doped into dG/Eu, surprisingly we find that co-doped dG/Tb/Eu hydrogel displays tunable luminescence from green, orange to red by simply regulating the stoichiometric ratio of Tb and Eu. A cascade luminescence resonance energy transfer mechanism (from dG to Tb, and to Eu) is proposed in this co-doped system, which is confirmed by luminescence decay curves and emission spectra. Subsequently, luminescence switch is designed based on reversible responsiveness of hydrogel upon Ag+/L-Cys, temperature and pH stimuli via dynamic supramolecular coordination. Our work provides a new route to construct multicolor functional materials.