中位-四[二-(3,4-羧甲氧基)苯基]卟啉及其结合Re=O的初步研究

A preliminary theoretical study on T_(3,4)CPP and its combination with Re=O

用密度泛函理论的B3LYP法,将中位-四[二-(3,4-羧甲氧基)苯基]卟啉及结合Re=O分子的几何构型优化,初步理论研究其前沿轨道和能量等。证明,与单独的卟吩环相比,T_(3,4)CPP的卟吩环平面性良好,环上的结构参数变化很小;Re=O与T_(3,4)CPP卟吩环的结合能明显大于与T_(3,4)CPP侧链羧基的结合能,且前者所形成配合物的稳定性显然高于后者,说明T_(3,4)CPP与^(188)Re=O结合的位点应在卟吩环上,而不在侧链羧基上。T_(3,4)CPP卟吩环结合Re=O而形成配合物的结构参数,与Vicente等Zn-卟啉衍生物的测定值相近。在卟吩环上配位时,T_(3,4)CPP卟吩环上的电荷重新分布,卟吩环碳原子的电子向4个氮原子转移:配位后,卟吩环的几何构型略收缩(0.14 A-0.19 A)和马鞍形扭转(5.7°)。

The molecular structure of meso-tetrakis[3,4-bis（carboxymethyleneoxy）phenyl porphyrin（T_（3,4）CPP） and the combination of Re=O with T34CPP are studied using the DFT（density functional theory） with B3LYP method.Their optimum geometry structures,FMO（foreside molecular orbital） and combination energy are calculated and analyzed.It shows that the porphin ring in T_（3,4）CPP keeps good planarity and exactly similar geometry with separate porphin ring.It also shows that the combination energy of Re=O with T_（3,4）CPP on porphin ring is remarkably higher than that of Re=O with T_（3,4）CPP on carboxymethyleneoxy group of side chain.And stability of the former complex is much higher than that of the latter one. These imply that ^（188）Re=O should be labeled with T_（3,4）CPP on porphin ring while not on carboxymethyleneoxy group of side chain.It still shows that during combination of Re=O with T_（3,4）CPP on porphin ring,electron shifts from carbon atoms to nitrogen atoms.It still shows that after combination of Re=O with T_（3,4）CPP on porphin ring,the porphin ring deviates slightly（5.7 degree） from planarity to Re=O,and four nitrogen atoms slightly expand toward Re=O with the ring diameter deduced by 0.15～0.20 angstrom.