Construction And Geometric Comparison Of The Saddled And Waved Zinc Porphyrins

The realization of the unique physiological function of metalloenzyme is closely related to the coordination environment of metal,so it is of great significance to study the structural changes of the site of metalloenzyme activity.The relationship between the function and structure of metalloenzyme and the artificial simulation is a complicated process.In this paper,a series of zinc-porphyrin with adjustable distortion degree are designed and synthesized as target simulation compounds.The structure and properties are systematically tracked and analyzed by means of NMR,X-ray,HR-MS,UV-vis as well as DFT theory calculation.By extracting the parameters of single crystal structure,the geometric changes of their N₄nuclei were observed,and the influence and relationship of nuclear changes on metal electronic structure were further explored to reveal the potential contribution of ligand environment to the function of metalloenzymes.This paper uses the binding strategy to control the deformation mode and distortion degree of porphyrin macrocycles,and realizes the high yield synthesis of highly distorted porphyrin by improving the classical Lindsey and Alder-Longo porphyrin synthesis methods.(1)The deformation mode and distortion of the large ring are regulated by changing the binding position of the two straps(-O(CH₂)_xO-)and the number of carbon atoms in each strap.Among them,the deformation modes involved in this paper include saddle-and wave-type.The synthesis yield of non-planar porphyrins with continuous distortion was increased by more than 13%through the synthesis optimization of catalyst(TFA),oxidant(DDQ)and reaction quencher(Et₃N).The variation of the deformation mode and twist degree of porphyrin acts directly on the nucleus of the macrocyclic ring,which makes the central metallic zinc of saddle type and wave type zinc porphyrin have different electronic structure and bonding properties.Through DFT theoretical analysis of the central metal zinc and porphyrin ring,found that:(1)with the increase of saddle-type zinc-porphyrin distortion,the N₄core is compressed from 4.04?to3.78?(L_NNx),which indicates that the direct contribution of macrocyclic deformation is to adjust the nuclear size;(2)the front-line orbital energy difference decreased from 2.57 e V of3-Zn-s to 2.25 e V of 1-Zn-s e V,and the distortion of the porphyrin ring can shorten the gap between HOMO-LUMO;(3)the axial imidazole bonding increases the E_HOMOof 1-Zn-s by about 0.3 e V,indicating that the axial push effect can be transferred to the porphyrin ring,and the axial imidazole bonding expands the difference between them.Both macrocyclic deformation and axial bonding can increase the ground state energy of molecules accordingly.In addition,the similarities and differences between saddle type zinc porphyrin and wave type zinc porphyrin are systematically compared.The results of this paper provide reliable theoretical and experimental support for a better understanding and simulation of the coordination environment of metalloenzymes,especially the role of zincase polyimidazole coordination environment.wave-type and saddle-type metalloporphyrins may be more widely used in the model system of metalloenzymes.