ORGN 750 |
| Porphyrins exhibit a wide range of interesting biological and physiochemical properties. They play an important role in a wide range of applications in the nature, science, and medicine. Their optical and electronic properties are dominated by the distortion of the macrocycle and NH-tautomerism of the respective porphyrin derivates. The change of the conformation of porphyrin core by substituents and central ions can be categorized into twelve in- and out-of-plane distortion modes. We studied the individual influences of peripheral substituents and metal ions to the distortion mode, respectively. For this, we focus on the energy gain/loss by interchange of metal ions and introduction of substituents, calculated by ab-initio methods. With the transfer from a planar ground conformation (D4h) to a distorted porphyrin moiety by, for instance, introduction of peripheral bulky substituents the dimension of the ring current effect of porphin metal ion complexes changes. We examined the influence of distortion mode, amplitude of displacement, and substituent pattern on the ring current effect. Also the calculation of ring current effects of phenyl or anthracene substituents helps to assign the 1H NMR spectra of porphyrins in general and to describe the high field shift of adjacent protons. |
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Combinatorial, Parallel and Process Chemistry, Heterocycles, Aromatics, New Reactions and Methodology
8:00 PM-10:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Organic Chemistry |