Research About Luminescence Switch Materials Based On Platinum(?) Complexes

Luminescence switch material is a kind of material which will change color and (or) luminescence upon external stimulus. This material shows the important application value in many fields including information storage and encryption, medical imaging, energy storage, poisonous gas monitoring, etc. Nowadays, platinum complexes become the ideal research object attributing to its good stability, rich luminescence properties and the mutable lowest excited energy levels upon external stimulus.In this paper, we designed and synthesized nine platinum complexes by using 5,5'-bis(trimethylsilylethynyl)-2,2'-bipyridine as main ligand and different benzene acetylene ligands as auxiliary ligands. The structures and luminescence properties of these platinum complexes were studied deeply by 1HNMR, IR spectra, fluorescence spectra, X-ray single crystal diffraction, UV-vis spectra, powder XRD spectra, etc. It turned out that complexes 1,3, 4,5,7 and 9 only response to mechanical force, demonstrating mechanoluminescence; meanwhile, complexes 6 and 8 show two luminescence switch properties, containing vapoluminescence and mechanoluminescence. In particular, complex 2 has three luminescence switch properties upon bearing mechanical force, vapor and heat. On the other hand, complex 2 exhibits multiple characters when it accepts the same stimulus, which can be used for storing information safely. Based on the research data, the properties of the luminescent switch platinum complexes are ascribed to the change of molecular stacking patterns by external stimulus, which is correlated with the transformation of intermolecular Pt-Pt interaction, hydrogen-bond interaction and n-n stacking interaction. The lowest excited states have a transformation between MLCT/LLCT and MMLCT/LLCT, resulting in different luminous energies.