Ligands useful for promoting copper-catalyzed azide-alkyne cycloaddition reactions comprise a compound represented by structural Formula (I) as described in the specification, wherein in Formula (I) Z1 is a nitrogen-containing heterocyclic group or a group represented by the formula: Y1—(CH2)c—Y2—(CH2)d—Y3—CH2—N(CH2Z4)(CH2Z5), where Y1 is -E1-C(O)O—, -E1-C(O)NH—, -E1-, or a covalent bond; Y2 is a covalent bond, —CH═CH—, or a 1,4-(1,2,3-triazolyl) group; Y3 is —OC(O)-E2-, —NHC(O)-E2-, -E2-, or a covalent bond; each of E1 and E2 is a benzimidazolyl group attached at the 1 and 2 positions; each of c and d is independently 1, 2, 3, 4, or 5; each of Z2, Z3, Z4 and Z5 is a nitrogen-containing heterocyclic group including a substituent X1 and optionally including a substituent (CH2)n—R1, and Y1, Y2, Y3, X1, R1, c, d and n are each as defined in the specification.