To understand the fundamental mechanism of aggregation-induced phosphorescent emission(AIPE)and to improve the development of mechanochromic molecules,five new Pt(II)complexes Pt-1–Pt-5 bearing different terminal sub...To understand the fundamental mechanism of aggregation-induced phosphorescent emission(AIPE)and to improve the development of mechanochromic molecules,five new Pt(II)complexes Pt-1–Pt-5 bearing different terminal substituents on 1,3-di(2-pyridyl)benzene(N^C^N)ligands were designed and synthesized.Their photophysical properties have been investigated systematically via a series of spectroscopic methods.Upon excitation,the solid states of these Pt complexes exhibit tunable emissions from yellow to red,and complexes Pt-2 and Pt-3 with a large steric hindrance display remarkable AIPE properties in a tetrahydrofuran/H_(2)O mixture.All complexes,except Pt-5,show evident mechanochromic and vapochromic behaviors.Based on in-depth experimental studies,the reason for the mechanochromic behavior could be the change in the distance of the neighboring Pt complexes,which causes a switching of the emission state from^(3)π,π*/^(3)MLCT(metal-to-ligand charge transfer)to^(3)MLCT.The above results suggest an example of phosphorescence tuning by a switching of the triplet excited state in the solid state,and provide a mechanism of mechanochromic behavior.Furthermore,complex Pt-2 was used as an emission ink in the field of advanced anti-counterfeiting.展开更多
基金support pro-vided in part by the Natural Science Foundation of Jiangsu Province-Outstanding Youth Foundation(BK20170104)the National Natural Science Foundation of China(21602106)+2 种基金the Six Talent Peaks Project in Jiangsu Province(XCL-037)the Strategic Pioneer Program on Space Science,Chinese Academy of Sciences(XDA15013100 and XDA15013101)the Undergraduate Innovation and Entrepreneurship Training Program(201910291053Z).
文摘To understand the fundamental mechanism of aggregation-induced phosphorescent emission(AIPE)and to improve the development of mechanochromic molecules,five new Pt(II)complexes Pt-1–Pt-5 bearing different terminal substituents on 1,3-di(2-pyridyl)benzene(N^C^N)ligands were designed and synthesized.Their photophysical properties have been investigated systematically via a series of spectroscopic methods.Upon excitation,the solid states of these Pt complexes exhibit tunable emissions from yellow to red,and complexes Pt-2 and Pt-3 with a large steric hindrance display remarkable AIPE properties in a tetrahydrofuran/H_(2)O mixture.All complexes,except Pt-5,show evident mechanochromic and vapochromic behaviors.Based on in-depth experimental studies,the reason for the mechanochromic behavior could be the change in the distance of the neighboring Pt complexes,which causes a switching of the emission state from^(3)π,π*/^(3)MLCT(metal-to-ligand charge transfer)to^(3)MLCT.The above results suggest an example of phosphorescence tuning by a switching of the triplet excited state in the solid state,and provide a mechanism of mechanochromic behavior.Furthermore,complex Pt-2 was used as an emission ink in the field of advanced anti-counterfeiting.
