Synthesis and Characteristics of Some Transition Metal Complexes with O N O and O O Donor Ligands

Abstract

Coumarins, or benzo--pyrones, are a very large and important family of compounds. The coumarins structure consists of fused pyrone and benzene rings, with the pyrone carbonyl group at position. The study of coumarins began more than 100 years ago. Coumarins owe their class name to Coumarou . Coumarin is a widely found as secondary metabolite that occurs naturally in most of the plant families and essential oils. Coumarin were used in flavoring food and in cosmetic products as a fragrant.The coumarin nucleus corresponds to benzo--pyrone (2H-1- benzopyran-2-one). Coumarins are used as natural products mainly isolated from umbelliferae, rutaceae and leguminous plant. Several compounds are isolated from micro-organisms or animals. The well known novobiocin and aflatoxin are also coumarin derivatives. Interestingly, micro-organisms usually produce. isocoumarin derivatives. Majority of coumarins. isolated from plants contain an oxygen substituent. Few of the coumarins contain an isoprenoid side chain and some of these are condensed with another oxygen heterocyclic (eg: furano coumarin). Few substituted coumarins and their derivatives has been developed artificially. newline