a dendritic compound of the following structure : pd n - z - l is disclosed . in the structure above , p is x — r —, r is an integer ranging from 1000 to 4000 , x is oh , nh 2 , or or , r is c 1 to c 10 alkyl , d n is a residue of branched c 3 to c 30 polyol compounds , n is the quantity of layers of the residue of branched compounds and is an integer equal to or greater than 1 , l is a metal cation , z is the residue of a c 3 to c 30 compound with multi functional groups . the functional groups illustrated above can be carboxylic groups , amino groups , amide groups , or chelating groups . the carboxylic groups , ester groups , amino groups , or amide groups bind to d n , and the chelating groups bind to the metal cations .