Patent ID: 6919324

Claim:
A compound of the formula: wherein: R 1 , R 4 and R 5 is independently H, OH, lower alkoxy, NH 2 , NO 2 , N 3 , NH—R 6 , halogen, a phosphate ester salt moiety of the general formula (—O—P(O)(O − M + ) 2 or (—OP(O)(OR 9 )(O − M + ); or —OPO 3 R 7 R 8 ; R 2 is H, OH, lower alkoxy, NH 2 , NO 2 , NH—R 6 , or phosphate ester salt moiety of the general formula (—O—P(O)(O − M + ) 2 or (—OP(O)(OR 9 )(O − M + ); or —OPO 3 R 7 R 8 , wherein NH 2 or OH may cyclize with R 1 ; R 3 is H, lower alkoxy, or phosphate ester salt moiety of the general formula (—O—P(O)(O − M + ) 2 or (—OP(O)(OR 9 )(O − M + ); or —OPO 3 R 7 R 8 ; R 6 is an acylamino group; R 7 is an ammonium salt (NH 4 + ); R 8 is lower alkyl, cycloalkyl, or aryl; R 9 is an alkyl or branched alkyl substituent, or a benzyl or aryl group; and M is a metal cation or salt, wherein at least one of R 1 , R 2 , R 3 R 4 or R 5 is a phosphate ester salt moiety of the general formula (—OP(O)(OR 9 )(O − M − ).