室温发光的[2-(3-碘代苯基)吡啶-C^N][2,4-戊二酮]钯(Ⅱ):合成、晶体结构及其光物理性质

Room temperature luminescent cyclometalated palladium(Ⅱ) complex with 2-(3-iodophenyl) pyridine and acetylacetone as ligand:synthesis,crystal structure and photophysical properties

本文以2-（3-碘苯基）吡啶（HIppy）为主配体,乙酰丙酮（acac）为辅助配体合成了[2-（3-碘代苯基）吡啶-C^N][2,4-戊二酮-O^O]钯（Ⅱ）[（Ippy）Pd（acac）]配合物,通过核磁、质谱、单晶衍射等数据确定其结构.为了考察碘原子对配合物的光物理性质影响,合成了非碘代的配合物[（ppy）Pd（acac）].单晶结构表明,金属钯与配体形成变形的平面正方形结构,螯合平面C007Pd01N005与O003Pd01O004之间的二面角为3.72°.室温下,配合物（Ippy）Pd（acac）和（ppy）Pd（acac）都具有明显的光致发光（PL）光谱,在四氢呋喃（THF）溶液中两个配合物最大PL光谱在400 nm处,伴随着一个422 nm的肩峰.发光寿命分别为14.9和18.5 ns,我们将室温发光归属于金属微扰配体的单线态（^1LC）荧光.（ppy）Pd（acac）和（Ippy）Pd（acac）在THF溶液中PL量子效率为0.012和0.18,含碘的配合物和不含碘的配合物量子效率相差15倍.可见在配体中的苯环上引入碘原子有效降低了激发态非辐射衰减,从而显著提升了配合物的PL量子效率.相反,在低温77 K下,两个配合物呈现出相同的具有精细结构的PL光谱,发射峰分别在460、484、495和521 nm处,配合物的寿命分别为0.138和0.162 ms,配合物在低温下的发射光谱归属于^3MLCT和^3LC三线态混合的磷光.（Ippy）Pd（acac）在室温时,PL发射光谱的CIE坐标值为（0.169,0.091）,是一种色纯度较高的蓝光配合物.

In this paper,[2-（3-iodine phenyl） pyridinato-C^N] [2,4-pentanedionato-O^O] palladium（Ⅱ）,（Ippy）Pd（acac）,was synthesized,where 2-（3-iodophenyl） pyridine（HIppy） was used as the main ligand,acetylacetone（acac） as the auxiliary ligand,and the structure of the complex was confirmed by 1H NMR,MS and X-ray crystallography.In order to investigate the photophysical properties caused by iodine atom,[2-phenylpyridinato-C^N] [2,4-pentanedionato-O^O] palladium（Ⅱ）,（ppy）Pd（acac） was also synthesized.Molecule of（Ippy）Pd（acac） has a distorted square planar geometry with dihedral angle of 3.72° between chelate plane C007Pd01N005 and O003Pd-01O004.At room temperature,complexes（Ippy）Pd（acac） and（ppy）Pd（acac） have obvious photoluminescence（PL） spectra with the maximal peak at 400 nm in tetrahydrofuran（THF） solution,accompanied by a shoulder peak of 422 nm,lifetimes are 14.9 and 18.5 ns,respectively,which is attributed to metal-perturbed ligand singlet（LC） fluorescence.The quantum efficiency of（ppy）Pd（acac） and（Ippy）Pd（acac） PL are 0.012 and 0.18 in tetrahydrofuran（THF） solution,respectively.The quantum efficiency of（Ippy）Pd（acac） is more 15 times than（ppy）Pd（acac）,indicating that iodine atom in the main ligand could effectively reduce non-radiation decayed rate of the excited state.On the other hand,at the low temperature（77 K）,two complexes showed the same of the PL spectra with fine structure,emission peak in 460,484,495 and 521 nm,the lifetimes for（ppy）Pd（acac） and（Ippy）Pd（acac） are 0.138 and 0.162 ms,respectively,the emission at low temperature is attributed to ^3LC triplet emission admixed with a certain extent of ^3MLCT component.At room temperature,（Ippy）Pd（acac） shows a saturated blue color with CIE coordinates of（0.169,0.091）.