Connick W B, Miskowski V M, Houlding V H, Gray H B
Beckman Institute 139-74, California Institute of Technology, Pasadena, California 91125, USA.
Inorg Chem. 2000 Jun 12;39(12):2585-92. doi: 10.1021/ic991369w.
Absorption and emission spectra of Pt(diimine)L2 complexes (diimine = 2,2'-bipyridine (bpy) or 4,4'-dimethyl-2,2'-bipyridine (dmbpy); L = pyrazolate (pz-), 3,5-dimethylpyrazolate (dmpz-), or 3,4,5-trimethylpyrazolate (tmpz-)) have been measured. Solvent-sensitive absorption bands (370-440 nm) are attributed to spin-allowed metal-to-ligand charge-transfer (1MLCT) transitions. As solids and in 77 K glassy solution, Pt(bpy)(pz)2 and Pt(dmbpy)(pz)2 exhibit highly structured emission systems (lambda max approximately 494 nm) similar to those of the diprotonated forms of these complexes. The highly structured bands (spacings 1000-1400 cm-1) indicate that the transition originates in a diimine-centered 3(pi-->pi*) (3LL) excited state. The intense solid-state and 77 K glassy solution emissions from 3MLCT[d(Pt)-->pi*(bpy)] excited states of complexes with dmpz- and tmpz- ligands occur at longer wavelengths (lambda max = 500-610 nm), with much broader vibronic structure. These findings are consistent with increasing electron donation of the pyrazolate ligands, leading to a distinct crossover from a lowest 3LL to a 3MLCT excited state.
已测量了Pt(diimine)L2配合物（diimine = 2,2'-联吡啶（bpy）或4,4'-二甲基-2,2'-联吡啶（dmbpy）；L = 吡唑盐（pz-）、3,5-二甲基吡唑盐（dmpz-）或3,4,5-三甲基吡唑盐（tmpz-））的吸收光谱和发射光谱。溶剂敏感吸收带（370 - 440 nm）归因于自旋允许的金属到配体的电荷转移（1MLCT）跃迁。作为固体以及在77 K玻璃态溶液中，Pt(bpy)(pz)2和Pt(dmbpy)(pz)2表现出高度结构化的发射体系（λmax约为494 nm），类似于这些配合物的双质子化形式的发射体系。高度结构化的谱带（间距为1000 - 1400 cm-1）表明跃迁起源于以二亚胺为中心的3(π→π*)（3LL）激发态。具有dmpz-和tmpz-配体的配合物从3MLCT[d(Pt)→π*(bpy)]激发态产生的强烈固态和77 K玻璃态溶液发射出现在更长波长（λmax = 500 - 610 nm），具有更宽的振动结构。这些发现与吡唑盐配体电子给予能力的增加相一致，导致从最低的3LL激发态到3MLCT激发态的明显转变。
