Synthesis And Properties Of Strapped Nonplanar Metalloporphyrins

Heme containing a typical tetrapyrrole macrocycle has many unique features and the artificial simulation of its structures and functions is a complex process. In this paper, we constructed a series of ruffle-type "netalloporphyrins (metals including iron and cobalt) as model compounds whose distortion degree of their macrocycles can be continuously changed. The structure parameters of them were obtained from their crystal structures to observe the core changes in size. The changes of the energy level, the single electron structure and the redox potential (E) to these model complexes were traced by using differential spectral analyses, electron paramagnetic resonance method and cyclic voltammetry method, espectively, in order to observe the effect of the change of core size of ruffle-shaped porphyrin on the activation of the metallic electrons, and the potential contribution to stabilizing the higher oxidation state of metal ion.In order to adjust the continuous change of the core size, different ength of alkyl was chosen as strapped chains and construct a series of 5,15-meso,meso-strapped phenyl porphyrins. Because there existed 5,15-strapped chain, this kind of porphyrin macrocyclic showed irregular ruffle-type deformation, and because of the continuous change of strapped chains, their N4 core size can be continuously flexible. These porphyrins were selected as model compounds in this paper.We made the aforementioned model compounds metalize(selected netals are Fe, Co and Zn) and took these series of metal porphyrin as the esearch object, tracked the effect of core size change on the electronic structure of central metals, and used zinc porphyrins as reference compounds. The core size of metal porphyrins decreases with the number of carbon atoms decreased. During our research, the central iron ions electronic properties of iron porphyrins were probed using differential spectral analyses, electrochemical and electron spin resonance. These esults indicated that their electronic configuration occurred conversion by compressing the macrocyclic core size, Under the appropriate size, the adjacent electronic configuration can appeared across and form a cross hybrid state which had a potential ability to stabilize high valence of iron ion. Meanwhile, we used the similar method to confirm that the electronic structure of Co (Ⅱ) ion would change when it maintained its low spin state unchanged in core contraction, and we also speculated the electronic transition originate from the exchange of N coordination electrons in d orbit. Furthermore, during the process of study on the strapped porphyrin molecules, we also regarded zinc porphyrin as the research object, tested the variable-temperature NMR (VT-NMR) results, used dynamic NMR (D NMR) to track. We found that the rotation of meso-aryl groups in porphyrins depends on the degree of macrocyclic distortion as well as the surrounding temperature. Moreover, the strapped molecules have potential to be adjustable molecular turnstile by adjusting the macrocyclic distortion and changing the surrounding temperature. Our researches may provide the experimental support to better understand and simulate the potent oxidation ability of heme and give a new material for the design of molecular device.