Patent ID: 7410989

Claim:
A compound according to Formula I: wherein: X 1 and X 3 are each independently selected from the group consisting of O, S and NR 9 , wherein R 9 is H or alkyl; X 2 and X 4 are each independently CH or N, wherein when X 1 is O, X 3 is NR 9 and X 4 is N, X 2 is N; A is selected from the group consisting of R 1 , R 2 , R 3 , and R 4 are each independently selected from the group consisting of H, alkyl, alkoxy, halide, alkylhalide, nitro and amino groups; R 6 is H, alkyl or aryl; and R 7 and R 8 are each independently selected from the group consisting of H and alkyl.