Porphyrins and Metalloporphyrins

Porphyrins are one of the vital chemical units essential for several life processes on the earth. Many biological molecules function with prosthetic groups essentially made of these units. Chlorophylls of chloroplasts which drive photosynthesis, heme as a component of hemoglobin that transports oxygen to animal tissues and as the central unit of myoglobin ensures the storage of oxygen-all these have active sites essentially made of porphyrin core'". Over the years, a great deal of concerted efforts have brought to light substantial understanding of the structure-function relationship in these natural porphyrins"'O A large variety of synthetic porphyrins and their metalloderivatives were made over the years to study the porphyrin based natural systems. The search for anti-cancer drugs, useful catalysts, semiconductors and superconductors, electronic materials with novel properties has also made this synthetic porphyrin chemistry a very actively probed one by chemists, biologists and physicists alike. The synthetic meso-substituted porphyrins offer a great advantage to study the physical and chemical properties of the porphyrin nucleus quantitatively by a judicious choice of the substituents that may be attached on the periphery. Metalloporphyrins are widely and intensely investigated in the area of catalysis and also as models and mimics of enzymes l i e catalase, peroxidases, P450 cytochromes or as transmembrane electron 11-13 transport agents. They have also been used as NMR image enhancement agents14, Nonlinear optical materials" and DNA-binding or cleavage agent1". 17. Currently there is interest in using chelated radioactiv diagnostic imaging and therapeutic agents. In that con excellent compounds because of their extremely high s many metal ions.