含二甲亚枫配体锇配合物的溶剂化显色效应

The Solvatochromism Effect on a Series of Os Complexes with the DMSO Ligand

采用HF/DFT的混合泛函PBE0和UPBE0优化了配合物[Os(DMSO)2(CN)2(N^N)](其中N^N=2,2'-吡啶)的基态和激发态结构.在基态和激发态结构的基础上,利用含时密度泛函理论(TD-DFT)方法,结合极化连续介质(PCM)模型分别计算了它在gas(1)、CH2Cl2(2)、CH3OH(3)和H2O(4)溶液中的吸收和发射光谱.研究结果表明:优化得到的几何结构参数和相应的实验值符合得非常好.在极性较大的溶剂中Os-S1、Os-C1键较长,Os-N3键较短,表明溶剂的极性会影响配合物的电子云分布.配合物在1-4溶剂中的最低能吸收和发射均来自分子轨道93→95的激发,该激发被指认为[d(Os)+π(CN)+π(N^N)→π*(N^N)]的跃迁具有混合的金属到配体和配体到配体的电荷转移跃迁(MLCT/LLCT)特征.配合物在1-4溶剂中的最低能吸收和发射分别在519、501、494、485和654、631、622、610 nm,表明随着溶剂极性的逐渐增大(1<2<3<4),最低能吸收和发射发生明显的蓝移.这显示出通过改变溶剂极性可以调节配合物的发光颜色.

The geometries of ground and excited states of[ Os （DMSO） 2 （CN） 2 （N^N） 1 （ N^N = 2,2＇-bipyridine ） were optimized by a hybrid Hartree-Fock/density functional model approach based on the Perdew-Burke- Erzenrhof （PBE0） and UPBE0 functional, respectively. Time-dependent density functional theory （TD-DFT） method together with the polarized continuum model （PCM） were used to obtain their absorption and phosphorescent emission spectra in gas （ 1 ）, CH2 C12 （2）, CH3 OH （3） and H2O （4） media based on their optimized ground and excited-state geometries. The results revealed that the optimized structural parameters agreed well with the corresponding experimental results. In more polar solvent, the bond length of the Os-S1 and Os-C1 were longer, the bond length of the Os-N3 was shorter, the polarity of solvent could affect the distribution of electron cloud of complexes. The lowest-lying absorptions and emissions of complexes at 1-4 solvent are contributed by the e- lectron excitation from 93→95（LUMO） ,and the transitions are all attributed to[ d（OS） ＋ π（CN） ＋ π（N^N） →π （N^N） ] transition with MLCT/LLCT character. At the TD-DFT and PCM levels, 1-4 solvent give rise to lowest-lying absorptions at 519,501,494 and 485 nm and phosphorescent emissions at 654,631,622 and 610 nm, respectively. The calculation results show that the lowest-energy absorptions and emissions are blue-shifted with the increasing of the polarity of solvent in the order of 1 〈 2 〈 3 〈 4. It is shown that the phosphorescent color can be tuned by changing the polarity of solvent.