Patent ID: 8828678

Claim:
A compound selected from: wherein Z is a reducible nitrogen-containing group selected from the group consisting of a nitro group (NO 2 ), an azo group (—N═N), a hydrazo group (NH—NH), a nitroso group (NO), and a hydroxylamino group (NHOH), or an amino group with an electron-deficient moiety, or Z is amino group with an electron-deficient moiety selected from the group consisting of carbonyl (C═O), phosphoryl (PO 3 2− ) and sulfonyl (SO 3 − ); and wherein L is nothing when Z is a reducible nitrogen-containing group, or L is an unsubstituted straight-chain, branched or cyclic alkyl, alkenyl or alkynyl group, a substituted straight-chain, branched or cyclic alkyl, alkenyl or alkynyl group wherein one or more C, CH or CH 2 groups are substituted by an O atom, N atom, S atom, or NH group, an unsubstituted or substituted aromatic group, or a linear or branched sequence of amino acids.