A Class Of Pt(?) Complexes With Long-wavelength Near-infrared Luminescence Properties

The definition of near-infrared light(NIR)refers to electromagnetic waves between visible light(VIS)and mid-infrared light(MIR).Near-infrared refers to the electromagnetic spectrum in the range of 700-2526 nm according to the American Society for Testing and Materials(ASTM).Due to its versatile advantages such as strong penetrating ability,biological safety,NIR has found wide applications in many fields including optical communication and optical information processing,environmental testing,chemical sensing,analytical quality inspection,medical military and other fields.A series of square-planar platinum(II)complex,based on 4,4-dichloro-2,2?-bipyridine and a series of phenylethylene with different substituents ligands,were developed and characterized.The composition,structure and photophysical properties of the complexes were measured by 1H-NMR,IR,fluorescence spectroscopy,UV-Vis absorption spectroscopy,XRD,X-ray single crystal diffraction and so on.And their luminescence switching property and long-wavelength NIR luminescence were systematically studied.The results reveal that all of the complexes except for 6 and 8 have luminescence switching property and the complexes 1,2,5,11 and 12 exhibit long-wavelength NIR luminescence with their emission wavelength beyond 950 nm in the solid-state.The results show that once the complex stacks in the 1-D “platinum wire” structure with strong Pt-Pt interactions,the energy of 3MMLCT excited state could be reduced greatly,leading to the long wavelength NIR luminescence of the complex.And square-planar,electron-donating and electron-withdrawing substituents,substituent position and stimulus play the key roles in the formation of the 1-D “platinum wire” stacking structure and long-wavelength near-infrared luminescence properties of the complex.