Patent ID: 7285518

Claim:
A compound according to formula I: R 1 and R 2 are each independently selected from hydrogen and alkyl from 1 to 20 carbon atoms; X and X′ are independently selected from —CHR 3 —, oxygen, sulfur or NR 4 , wherein R 3 and R 4 are independently hydrogen or alkyl from 1 to 6 carbon atoms, with the proviso that at least one of X or X′ is a heteroatom positioned ortho or para to the bridging ring nitrogen; and Y and Y′ are independently selected from —CHR 5 —, oxygen, sulfur or NR 6 wherein R 5 and R 6 are independently hydrogen or alkyl from 1 to 6 carbon atoms; with the proviso that at least one of Y or Y′ is a heteroatom positioned ortho or para to the bridging ring nitrogen; and m and n are independently integers from 1 to 2.