Patent ID: 7101909

Claim:
A compound of the formula: L-X-L or a pharmaceutically-acceptable salt thereof; wherein one L is a ligand of formula (A): and the other L is a ligand independently selected from the group consisting of formulae (A), (C), (D), (E), (F), (G), and (H): X is a linker of the formula: —X′-Z-(Y″-Z) m -Y″-Z-X′— in which: m is an integer of from 0 to 20; X′ at each separate occurrence is —O—, —S—, —S(O)—, —S(O) 2 —, —NR—, —N + RR′, —C(O)—, —C(O)O—, —C(O)NH—, —C(S)—, —C(S)O—, —C(S)NH— or a covalent bond, where R and R′ at each separate occurrence are as defined below for R′ and R″; Z is at each separate occurrence selected from alkylene, substituted alkylene, alkylalkoxy, cycloalkylene, substituted cycloalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, substituted arylene, heteroarylene, heterocyclene, substituted heterocyclene, crown compounds or a covalent bond; Y′ and Y″ at each separate occurrence are selected from —S—S—, a covalent bond or a structure selected from the following group: in which: n is 0, 1 or 2; and R′ and R″ at each separate occurrence are selected from hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl or heterocyclic.