SYNTHESIS AND APPLICATIONS OF β- FUNCTIONALIZED METALLOPORPHYRINOIDS

Abstract

Fully β-substituted electron deficient porphyrins are widely explored in literature due to their unique photochemical, stereochemical and tunable redox properties. Further, these sterically crowded porphyrins have shown interesting catalytic application. The modification of macrocyclic ring results into altered altered electronic and acid base properties. In particular, modification at β-pyrrolic position exert pronounce effect on the electronic and redox properties. Substitution with electron deficient sterically hindered groups onto the macrocyclic system leads to nonplanar conformation of the macrocyclic core. To gain insight into the electronic changes of macrocyclic systems, we have synthesized π-expanded dodeca phenylethynyl substituted porphyrins which have observed multiple reductions due to combined effect of electron withdrawing and highly nonplanar nature of this macrocycilc core. Further, the reduction of one or more β-pyrrolic bonds results into the formation of reduced macrocyclic core namely chlorin and bacteriochlorins which have distinguish electrochemical and photophysical properties. In present thesis, we have utilized free base dicyanomethyl trans-chlorin into skeleton rearrangement of the macrocyclic core which led to the formation of mono dicyanomethyl appended porphyrin NiTPP(MN). Due to strong electron withdrawing nature of cyano groups the malononitrile appended porphyrinoids have proven very useful for anion sensing applications. Thus, we also utilize the NiTPP(MN) for basic anion sensing. In addition to that porphyrin with formyl substituents are also useful for sensing application by subjecting them with different active methylene compounds to obtain vinylic group at β-pyrrolic position. Thus, to get selective sensing of cyanide and fluoride ion we have utilized the cyanoacetic acid appended porphyrin attached through vinylic bond. The exhaustive substitution with electron deficient groups for example chloro and bromo are of particular interest since the electronic properties of the macrocyclic core can be easily alter and are very useful for catalytic application. In this context, we have synthesized octabromo vanadyl porphyrin for selective epoxidation of Olefins.