An electrochemical sensor, comprising: a working electrode; a composition disposed on the working electrode, the composition formulated to reversibly associate with a target analyte, the composition having a first redox potential in the absence of a target analyte, and having a second redox potential different than the first redox potential in the presence of the target analyte; a reference electrode; an electrical circuit electronically coupled to the working electrode and the reference electrode; wherein the composition comprises a salt of any one of formulas I, II, III, IV, V, Va, VI, VII and VIII or comprises a compound having a structure of any one of formulas (P-2) to (P-10), (P-13), (P-16), (P-18) and (P-19): where: X is an anion; R and R' are independently -(CH 2 ) p -R 1 ; R 1 is C 1 -C 6 alkyl-B(OR 2 )(OR 3 ), aryl-B(OR 2 )(OR 3 ), heteroaryl-B(OR 2 )(OR 3 ), or heterocyclyl-B(OR 2 )(OR 3 ); R 2 and R 3 are independently H, C 1 -C 6 alkyl or R 2 and R 3 can combine with the B atom to form a ring system; L and L' are independently H, halogen, OH, CN, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, aryl, heteroaryl, heterocyclyl, cycloalkyl, alkylthio, arylthio, alkoxy, aryloxy, -COOR 4 , NH 2 , -C(O)N(H)-(CH 2 ) p -N(H)C(O)-R 4 , -C(O)NH(R 4 ), or -N(H)C(O)R 4 ; R 4 is independently at each occurrence H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, aryl, heteroaryl, heterocyclyl, cycloalkyl; n is 2, 3, 4, 5, or 6; and p is independently 0, 1, 2, 3, 4, 5, or 6. a working electrode; a composition disposed on the working electrode, the composition formulated to reversibly associate with a target analyte, the composition having a first redox potential in the absence of a target analyte, and having a second redox potential different than the first redox potential in the presence of the target analyte; a reference electrode; an electrical circuit electronically coupled to the working electrode and the reference electrode; wherein the composition comprises a salt of any one of formulas I, II, III, IV, V, Va, VI, VII and VIII or comprises a compound having a structure of any one of formulas (P-2) to (P-10), (P-13), (P-16), (P-18) and (P-19): where: X is an anion; R and R' are independently -(CH 2 ) p -R 1 ; R 1 is C 1 -C 6 alkyl-B(OR 2 )(OR 3 ), aryl-B(OR 2 )(OR 3 ), heteroaryl-B(OR 2 )(OR 3 ), or heterocyclyl-B(OR 2 )(OR 3 ); R 2 and R 3 are independently H, C 1 -C 6 alkyl or R 2 and R 3 can combine with the B atom to form a ring system; L and L' are independently H, halogen, OH, CN, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, aryl, heteroaryl, heterocyclyl, cycloalkyl, alkylthio, arylthio, alkoxy, aryloxy, -COOR 4 , NH 2 , -C(O)N(H)-(CH 2 ) p -N(H)C(O)-R 4 , -C(O)NH(R 4 ), or -N(H)C(O)R 4 ; R 4 is independently at each occurrence H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, aryl, heteroaryl, heterocyclyl, cycloalkyl; n is 2, 3, 4, 5, or 6; and p is independently 0, 1, 2, 3, 4, 5, or 6. X is an anion; R and R' are independently -(CH 2 ) p -R 1 ; R 1 is C 1 -C 6 alkyl-B(OR 2 )(OR 3 ), aryl-B(OR 2 )(OR 3 ), heteroaryl-B(OR 2 )(OR 3 ), or heterocyclyl-B(OR 2 )(OR 3 ); R 2 and R 3 are independently H, C 1 -C 6 alkyl or R 2 and R 3 can combine with the B atom to form a ring system; L and L' are independently H, halogen, OH, CN, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, aryl, heteroaryl, heterocyclyl, cycloalkyl, alkylthio, arylthio, alkoxy, aryloxy, -COOR 4 , NH 2 , -C(O)N(H)-(CH 2 ) p -N(H)C(O)-R 4 , -C(O)NH(R 4 ), or -N(H)C(O)R 4 ; R 4 is independently at each occurrence H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, aryl, heteroaryl, heterocyclyl, cycloalkyl; n is 2, 3, 4, 5, or 6; and p is independently 0, 1, 2, 3, 4, 5, or 6. <EOS>