Abstract: Disclosed herein are host or receptor compounds that bind targets of interest. In one embodiment the compounds bind ions, such as metal ions. A compound, or a protonate or salt thereof, having the formula of: Formula IIa wherein R6 is an aminoalkoxy, alkylamino, nitro or —NH2; n is 1 or 2; each R2 is independently selected from an optionally substituted alkyl, halogen, optionally substituted alkoxy, optionally substituted carboxyl, or amide; a is 0 to 4.

Abstract: A compound, or a protonate or salt thereof, having the formula of: wherein R1 is an optionally substituted aromatic group; n is 1 or 2; each R2 is independently selected from an optionally substituted alkyl, halogen, optionally substituted alkoxy, optionally substituted carboxyl, or amide; a is 0 to 4; R3 is H or an optionally substituted alkyl; each R4 and R5 is independently selected from H, optionally substituted alkyl, acyl, optionally substituted aralkyl, optionally substituted aryl, or —C(O)R8; and R8 is H, alkyl, aralkyl or aryl.

Abstract: A compound, or a salt thereof, having the formula wherein Y is n is 1 or 2; each R is independently H, alkyl, substituted alkyl, a polyether moiety, carboxyl, substituted carboxyl, carbamate, substituted carbonate, carbonyloxy, alkoxy, substituted alkoxy, haloalkyl, halogen, nitro, amino, aryloxy, cyano, hydroxyl, or sulfonyl; R1 is H, lower alkyl or aralkyl; R2 is selected from H, acyl, aralkyl, phosphonyl, —SO2R3; —C(O)R5; —C(O)OR7 or —C(O)NR9R10; R3; R5; R7; R9 and R10 independently are selected from H, lower alkyl, aralkyl or aryl; and R20 is selected from alkyl, substituted alkyl, a polyether moiety, carboxyl, substituted carboxyl, carbamate, substituted carbonate, carbonyloxy, alkoxy, substituted alkoxy, haloalkyl, halogen, nitro, amino, aryloxy, cyano, hydroxyl, or sulfonyl.

Abstract: A compound, or a salt thereof, having the formula wherein Y is n is 1 or 2; each R is independently H, alkyl, substituted alkyl, a polyether moiety, carboxyl, substituted carboxyl, carbamate, substituted carbonate, carbonyloxy, alkoxy, substituted alkoxy, haloalkyl, halogen, nitro, amino, aryloxy, cyano, hydroxyl, or sulfonyl; R1 is H, lower alkyl or aralkyl; R2 is selected from H, acyl, aralkyl, phosphonyl, —SO2R3; —C(O)R5; —C(O)OR7 or —C(O)NR9R10; R3; R5; R7; R9 and R10 independently are selected from H, lower alkyl, aralkyl or aryl; and R20 is selected from alkyl, substituted alkyl, a polyether moiety, carboxyl, substituted carboxyl, carbamate, substituted carbonate, carbonyloxy, alkoxy, substituted alkoxy, haloalkyl, halogen, nitro, amino, aryloxy, cyano, hydroxyl, or sulfonyl.