利用DFT方法探究一类自组装[Pt2M4(C≡CH)8](M=Cu，Ag)簇合物的电子结构和光谱性质  

DFT evaluation of the electronic structures and spectroscopic properties of the self-assembled [Pt_2M_4(C≡CH)_8](M=Cu,Ag) clusters

作　　者：白福全[1] 夏宝辉[1,2] 张红星[1] 杨宝珠[1] 王建[1] 孙磊[1] 

机构地区：[1]理论化学计算国家重点实验室、吉林大学理论化学研究所,长春130023 [2]吉林大学化学学院,长春130023

出　　处：《中国科学（B辑）》2009年第11期1494-1500,共7页Science in China(Series B)

基　　金：国家自然科学基金(批准号:20573042,20703015)资助

摘　　要：应用TD-DFT(time-dependent density functional theory)并PCM(polarizable continuum model)模型研究了一类自组装的[Pt2M4(C≡CH)8](M=Cu,Ag)簇合物的电子结构和光谱性质.应用DFT(density functional theory)方法优化了该簇合物的基态及激发态结构.综合计算结果,得到与试验结果相一致的结构与光谱特点.[Pt2Ag4(C≡CH)8]具有呈D4和D4h对称性的两个稳定的基态几何结构.Pt-M距离预示弱相互作用的存在.Cu-Cu距离大于俩个Cu原子的范德华半径和而Ag-Ag间距与俩个Ag原子的范德华半径和差别不大.激发过程使得Pt…M,Ag…Ag作用增强,虽然Cu…Cu距离也相应缩短,但是其仍大于范德华半径之和.[Pt2Cu4(C≡CH)8]、[Pt2Ag4(C≡CH)8](A)和(B)的最低能吸收在450、365和375nm处,发射在611、431和435nm处.红外可见谱范围内,[Pt2M4(C≡CH)8]的吸收波带都有Cu或Ag成分的贡献,所以没有ILCT或MPtLCT跃迁特征出现(ILCT:intraligand chargetransfer;MLCT:metal-to-ligand charge transfer).由于最低能吸收和发射具有不同的跃迁特征,所以发射不是来自于最低能吸收.[Pt2Ag4(C≡CH)8]簇合物的M…M相互作用在激发态增强,发射光谱具有显著的ILCT特点,这也是[Pt2Ag4(C≡CH)8]的发射波长相对于其对应的同配体前躯体[Pt(C≡CH)4]2?有少许蓝移的原因.Electronic structures and spectroscopic properties of self-assembled [Pt2M4（C=CH）8] （M=Cu, Ag） clusters have been studied by the TD-DFT （time-dependent density functional theory） calculations with the polarizable continuum model （PCM）. The ground- and excited-state structures were optimized by the DFT （density functional theory） methods. The calculated structures and spectroscopic properties are in agreement with the corresponding experimental results. The [Pt2Ag4（C≡CH）8] clusters have two stable ground state geometries （D4 and D4h symmetry）. The calculated Pt-M distances suggest only very weak interactions. The Cu-Cu distances are larger than the van der Waals radii of two Cu atoms and the Ag-Ag distances are analogous with the sum of van der Waals radii of two Ag atoms. Upon excitation, the interaction of PtM, AgAg is strengthened, while the CuCu distances are also shortened but they are still larger than the sum of van der Waals radii of two Cu atoms. The lowest-energy absorptions are at 450, 365 and 375 nm and the emissions are at 611, 431 and 435 nm for [Pt2Cu4（C≡CH）8], [Pt2Ag4（C≡CH）s] （A） and （B）, respectively. The transitions are all perturbed by the Cu or Ag composition through the UV-Vis spectra region, there- fore, there are not pure ILCT or MptLCT characters （ILCT： intraligand charge transfer; MLCT： metal-to-ligand charge transfer） in absorptions of heteropolynuclear [Pt2M4（C≡CH）8] clusters. Since the emissions and the lowest-absorptions have different transition characters for each complex, the emissions should not come from the lowest-energy absorptions. Because the MM interactions in excited state of [Pt2Ag4（C≡CH）8] are augmented, the emissions of [PtzAg4（C≡CH）8] clusters bear prominent ILCT character, which is the reason of the emission wavelengths of [Pt2Ag4（C≡CH）8] have a small hypsochromic shift relative to the emission wavelength of homoleptic [Pt（C≡CH）4]^2- precursor.

关 键 词：电子结构 发光性质 杂多核配合物 TDDFT 

分 类 号：O641.1[理学—物理化学]