A compound of the formula or wherein R 1, R 2, R 3, and R 4 each, independently of the others, is (i) a hydrogen atom, (ii) an alkyl group, (iii) an aryl group, (iv) an arylalkyl group, or (v) an alkylaryl group, wherein R 1 and R 2 can be joined together to form a ring, wherein R 3 and R 4 can be joined together to form a ring, and wherein R 1, R 2, R 3, and R 4 can each be joined to a phenyl ring in the central structure; wherein a and b each, independently of the others, is an integer which is 0, 1, 2, or 3, wherein each R 5, and R 6 independently of the other, is (i) an alkyl group, (ii) an aryl group, (iii) an arylalkyl group, (iv) an alkylaryl group, (v) a halogen atom, (vi) an ester group, (vii) an amide group, (viii) a sulfone group, (ix) an amine group or ammonium group, (x) a nitrile group, (xi) a nitro group, (xii) a hydroxy group, (xiii) a cyano group, (xiv) a pyridine or pyridinium group, (xv) an ether group, (xvi) an aldehyde group, (xvii) a ketone group, (xviii) a carbonyl group, (xix) a thiocarbonyl group, (xx) a sulfate group, (xxi) a sulfide group, (xxii) a sulfoxide group, (xxiii) a phosphine or phosphonium group, (xxiv) a phosphate group, (xxv) a mercapto group, (xxvi) a nitroso group, (xxvii) an acyl group, (xxviii) an acid anhydride group, (xxix) an azide group, (xxx) an azo group, (xxxi) a cyanato group, (xxxii) an isocyanato group, (xxxiii) a thiocyanato group, (xxxiv) an isothiocyanato group, (xxxv) a urethane group, (xxxvi) a urea group, or (xxxvii) hydrogen, wherein R 5 and R 6 can each be joined to a phenyl ring in the central structure, is or wherein R 8, R 9, and R 10 each, independently of the other, is (i) a hydrogen atom, (ii) an alkyl group, (iii) an aryl group, (iv) an arylalkyl group, or (v) an alkylaryl group; wherein A - is an anion; wherein CA + is either a hydrogen ion or a cation; wherein R is (i) an alkyl group, (ii) an aryl group, (iii) an arylalkyl group, (iv) an alkylaryl group, (v) an alkoxy group, (vi) an acetate group, or (vii) a co-polymer of maleic anhydride; wherein n is an integer which is 1 to 1,000; and wherein m is an integer which is 1 to 1,000. wherein R 1, R 2, R 3, and R 4 each, independently of the others, is (i) a hydrogen atom, (ii) an alkyl group, (iii) an aryl group, (iv) an arylalkyl group, or (v) an alkylaryl group, wherein R 1 and R 2 can be joined together to form a ring, wherein R 3 and R 4 can be joined together to form a ring, and wherein R 1, R 2, R 3, and R 4 can each be joined to a phenyl ring in the central structure; wherein a and b each, independently of the others, is an integer which is 0, 1, 2, or 3, wherein each R 5, and R 6 independently of the other, is (i) an alkyl group, (ii) an aryl group, (iii) an arylalkyl group, (iv) an alkylaryl group, (v) a halogen atom, (vi) an ester group, (vii) an amide group, (viii) a sulfone group, (ix) an amine group or ammonium group, (x) a nitrile group, (xi) a nitro group, (xii) a hydroxy group, (xiii) a cyano group, (xiv) a pyridine or pyridinium group, (xv) an ether group, (xvi) an aldehyde group, (xvii) a ketone group, (xviii) a carbonyl group, (xix) a thiocarbonyl group, (xx) a sulfate group, (xxi) a sulfide group, (xxii) a sulfoxide group, (xxiii) a phosphine or phosphonium group, (xxiv) a phosphate group, (xxv) a mercapto group, (xxvi) a nitroso group, (xxvii) an acyl group, (xxviii) an acid anhydride group, (xxix) an azide group, (xxx) an azo group, (xxxi) a cyanato group, (xxxii) an isocyanato group, (xxxiii) a thiocyanato group, (xxxiv) an isothiocyanato group, (xxxv) a urethane group, (xxxvi) a urea group, or (xxxvii) hydrogen, wherein R 5 and R 6 can each be joined to a phenyl ring in the central structure, is or wherein R 8, R 9, and R 10 each, independently of the other, is (i) a hydrogen atom, (ii) an alkyl group, (iii) an aryl group, (iv) an arylalkyl group, or (v) an alkylaryl group; wherein A - is an anion; wherein CA + is either a hydrogen ion or a cation; wherein R is (i) an alkyl group, (ii) an aryl group, (iii) an arylalkyl group, (iv) an alkylaryl group, (v) an alkoxy group, (vi) an acetate group, or (vii) a co-polymer of maleic anhydride; wherein n is an integer which is 1 to 1,000; and wherein m is an integer which is 1 to 1,000.