Patent ID: 7151191

Claim:
A compound of the formula or a salt thereof, wherein: R 1 is —OH or —OCH 3 ; R 2 , R 3 , R 4 , R 5 are independently selected from hydrogen, halogen, —OH, —OCH 3 , C 1 –C 4 alkyl, —NH 2 , —NH(CH 3 ), —N(CH 3 ) 2 , or —NO 2 ; m is 0, 1, 3 or 4; R 6 is a phenyl substituted with —O—R 7 —COOH at the ortho, meta, or para position; R 6 is optionally substituted with one or more members selected from halogen, —OH, —OCH 3 , C 1 –C 4 alkyl, —NH 2 , NH(CH 3 ), —N(CH 3 ) 2 , and —NO 2 ; and R 7 is C 2 –C 12 n-alkylene, wherein m is 0 when R 1 is —OCH 3 .