The Theory Research On Circular Dichroism Specturm Of Chiral Bis-porphyrin

Chirality is the property of nature, enzymes and receptors in vivo cell surface are chiral,the core part of the plant photosynthesis is also chiral, and even the survival of our planet isalso chiral. Due to the chiral molecules playing such an important role in life events, eventhat the human life itself depends on the chirality.In recent decades, the study of chiral compounds on porphyrin chromophore have beenlargely studied. As reported group, molecule chiral probes, optical and other areas have avery wide range of applications. However,the reported porphyrin system theoreticallystudied systematically is even less. Otherwise, the interaction between the porphyrins andporphyrin is fundamental biological processes, and therefore, most research in this area hasbeen a pressing problem.Circular dichroism (CD) spectroscopy is the effective tool of absolute configuration andconformation for studying molecules. Experimental CD spectra can be a direct response to thepositive and negative cases of chiral compounds, but it have to rely on the theoretical CDspectrum for a detailed analysis of its origins. For these reasons, we have designed andsynthesized a series of binaphthyl bridged bis-porphyrin compounds and experimentalcharacterization of its chiral CD spectra, but also with Devoe polarization theory, using threemodels (effective transition dipole moment model, circular oscillator model, hybrid model)to simulate the CD spectra of each compound separately, and comparison with theexperimental spectrum. Because every kind of model has its applicable conditions, bycomparison with the experimental spectrum, it can obtain which mode is more appropriate toquantitatively simulate CD spectra. we can find that the there exists a kind of relationshipbetween the spectra of the origin and geometry. The results showed that: the para porphyrincompounds is suitable for the hybrid model; the ortho porphyrin suites effective transitiondipole moment model; the meta porphyrin suites circular oscillator model. And the studyfound that the direction of the transition dipole moment is not valid all along5-15direction,there are special circumstances along the10-20direction.Finally, we have also studied the CD spectra of phenylalanine bridged bis-porphyrincompounds which is very flexible, and thus the method is the combination molecular mechanics methods and exciton chirality method. Using this method, the calculated results isthe same with the experimental ones. We have proved that the flexible system is suitable forthe method.