Patent ID: 8143057

Claim:
A chelate comprising: (a) a metal ion M 3+ , wherein the metal is selected from a group consisting of europium, terbium, samarium and dysprosium; (b) two or more pyridyl groups, wherein at least one of said two or more pyridyl groups is substituted with a trialkoxyphenyl group, wherein the alkoxy groups are the same or different, and the pyridyl groups are i) tethered directly to each other to form a 2,2′-bipyridyl or 2,2′:6′,2″-terpyridyl group, respectively, or ii) tethered to each other via hydrocarbon chains, wherein said hydrocarbon chains contain no heteroatoms other than N; (c) at least two carboxylic acid or phosphonic acid groups, or esters or salts of said acid groups, attached to the pyridyl groups at ortho position either directly or via a hydrocarbon chain, wherein said hydrocarbon chain contains no heteroatoms other than N; and optionally (d) a substituent A selected from the group consisting of isothiocyanate, haloacetamido, maleimido, dichlorotriazinylamino, pyridyldithio, thioester, aminooxy, hydrazide, amino, a polymerizing group, a carboxylic acid or acid halide or an active ester thereof; wherein: said substituent A is tethered to i) at least one of said two or more pyridyl groups, or ii) at least one of said hydrocarbon chains, either directly or via a linker x, wherein said linker x is formed from one to ten moieties, each moiety being selected from the group consisting of phenylene, alkylene containing 1-12 carbon atoms, ethynydiyl (—C≡C—), ethylenediyl (—C═C—), ether (—O—), thioether (—S—) amide (—CO—NH—, —CO—NR′—, NH—CO and —NR′—CO—), carbonyl (—CO—), ester (—COO—and —OOC—), disulfide (—SS—), diaza (—N═N—), and tertiary amine, wherein R′ represents an alkyl group containing less than 5 carbon atoms.