Abstract: A pyridinium ester according to Formula I wherein 1/n Xn? is a counterion; wherein n is 1 or 2; wherein one of R2 and R3 is H and the other is selected from the group consisting of Formula II, Formula III and Formula IV wherein * represents the point of attachment to the heteroaryl ring, wherein Formula III is selected from the group consisting of a Z-configuration, an E-configuration, and mixtures thereof, preferably an E-configuration, wherein when R2 is H, R1 is a branched or unbranched, saturated or unsaturated, C4-C12 hydrocarbyl group; when R3 is H, R1 is a branched or unbranched, saturated or unsaturated, C1-C12 hydrocarbyl group, and wherein each R4 is independently selected from hydrogen and a C1-C4 hydrocarbyl group and wherein R5 is a branched or unbranched, saturated or unsaturated, C4-C12 hydrocarbyl group.