ubstituents and each of two of the substituents of the substituted aryl group of R4 are independently coupled to the adjacent nitrogen of the ???NR3???R2??? moiety or the ???N+R3 2???R2??? moiety of the structure (Ib) or when R4 is a substituted aryl group the substituted aryl group of R4 has at least one substituent such that at least two moieties forming an aryl group of the substituted aryl gro