Polymethacrylic zinc porphyrin: A new approach to chiral recognition

A methacrylic homopolymer bearing in the side-chain achiral zinc tetraarylporphyrin moieties, has been studied as macromolecular chromophoric host to determine the absolute configuration of ,-diamines. The polymeric material resulted able to bind the chiral guest through amine nitrogen/zinc coordination to form a complex which exhibits exciton-coupled bisignate Circular Dichroism (CD) spectra, due to stereodifferentiation leading to a preferred porphyrin helicity. The sign of CD signal reflects the absolute configuration of diamine and the method turns out very sensitive, requiring only few microgram quantities of guest compound. To our knowledge this is the first example of absolute configuration assignment to chiral molecular compounds by means of a polymeric derivative containing in the side-chain metallo-porphyrins moieties.