Syntheses And Luminescent Properties Of D⁸/d¹⁰ Transition Metal Complexes

The d⁸/d¹⁰ transition metal complexes have been widely studied because of their special electronic orbitals,rich structures,high stability,rich photochemical and photophysical properties.The complexes have rich optical properties due to their multiple types of charge transitions,including intraligand charge transfer（ILCT）,ligand-to-metal charge transfer（LMCT）,metal-to-ligand charge transfer（MLCT）,metal-metal-to-ligand charge transfer（MMLCT）and metal-centered（MC）.The d⁸/d¹⁰ transition metal complexes have abundant stimulus-responsive luminescent properties,such as thermochromism,mechanochromism and vapochromism/solvatochromism,which are widely used in intelligent switches and sensing devices.The purposes of this paper are to design the structure of d⁸/d¹⁰ transition metal complexes and modulate their luminescent properties to obtain sensitive stimulus-responsive and near-infrared luminescent materials.Six d⁸/d¹⁰ transition metal complexes were synthesized by the reaction of d⁸/d¹⁰ transition metal salts and organic ligands containing nitrogen and sulfur elements through the solvothermal and diffusion synthesis methods.First,the binuclear platinum（Ⅱ）complexes,[Pt₂（amt）₄]·2DMF（1）,[Pt₂（mmt）₄]（2）,[Pt₂（mmtt）₄]（3）,were synthesized by the employment of platinate and different ligands containing electron-donating group substituents.The luminescent properties of these complexes can be regulated according to the electron-donating ability of the electron-donating groups.The emission wavelengths of 1-3 are 736 nm,764 nm and 789 nm,respectively,achieving luminescence from deep red to near-infrared.Among them,1 does not reach the ideal near-infrared emission due to the construction of hydrogen bonds in the structure.1 was soaked in 1,4-dioxane,and the emission wavelength is redshifted by breaking the hydrogen bonds to adjust the luminescence properties.Meanwhile,the Pt-Pt distance of 1 can be shortened by cooling the temperature,which regulates the emission wavelength.Secondly,a copper（Ⅰ）thiolate complex[Cu（pot）]_n（4）was synthesized,which is composed of three-dimensional rhomboid channels withπ-πinteractions between the ligands.4 displays orange emission at room temperature and excellent photoluminescent stability to acidic/alkaline conditions and organic solvents.In addition,the luminescence of 4 has stimuli-responsive properties to temperature and mechanical forces.Finally,two copper（Ⅰ）thiolate complexes,[Cu（pyt）]_n（5）and[Cu（pyt）]_n（6）,were synthesized by changing the type of cuprous halide that react with the same ligand Hpyt.The asymmetric unit of 5 is essentially the same as that of 6,but their space groups and coordination modes are different.The biggest structural difference between 5 and 6 is that the nitrogen atom on the pyridyl group of 5 does not coordinate with the copper ion,while that of 6 is involved in coordination.The crystal color of 5 is yellow.5 exhibits a red emission at room temperature and interesting temperature-dependent photoluminescence.The crystal color of 6 is black and it has strong UV-vis absorption.The emission spectrum of 6 is not detected because all the light is absorbed by itself.