Patent ID: 8389538

Claim:
A compound represented by the general Formula I shown or salt thereof: wherein, R 1 and R 2 are independently selected from the group consisting of straight or branched, alkyl groups wherein positions of R 1 O and R 2 are selected from: R 1 O is in the para position with respect to X 2 , and R 2 is in the meta position with respect to X 1 and X 2 ; or R 1 O is in the meta position with respect to X 1 and X 2 , and R 2 is in the para position with respect to X 2 ) W is NR 3 or CR 3 ; wherein R 3 is selected from a hydrogen, straight or branched, or cyclic group, X 1 is CH, X 2 is selected from CH, CR 4 or N, R 4 is selected from straight, branched or cyclic, unsubstituted or substituted alkyl, alkenyl, alkynyl, alkoxy groups, a halogen, a nitro group and an amino group, Y 1 and Y 2 are independently selected from CH or N, and Z is selected from —COOH, —CH═CH—COOH, —CONHOH, or —CH═CH—CONHOH, and Z is in the meta position with respect to Y 1 and Y 2 .