Patent ID: 8334029

Claim:
A compound of the formula: wherein: R is a hydrophilic group or a charged group; C, if present is a suitable counterion or counterions; q is an integer indicative of the number of X substituents; and each X, independent of other X in the compound, is a non-hydrogen substituent on the aromatic ring system selected from the group consisting of alkyl, alkoxy, alkyl sulfide, alkyl disulfide, cyano, isocyano, thiocyano, isothiocyano, nitro, or halogen, wherein one or more C, CH or CH 2 groups of the alkyl groups or alkoxy groups can be replaced with one or more of an O atom, S atoms, P atoms, a —CO— group, a —O—CO— group, a —SO 3 — group, a —PO 3 — group, an N atom, an NR 1 group, an —NR 1 —CO— group and wherein one or more C of the alkyl or alkoxy group can be substituted with one or more halogens, hydroxyl, thiol, cyano, isocyano, thiocyano, isothiocyano or nitro groups wherein R 1 is an optionally substituted alkyl or aryl group; or a charged substituent where a charged X is accompanied by an appropriate counterion.