Facile synthesis of end-functionalized regioregular poly(3-alkylthiophene)s via modified Grignard metathesis reaction

A simple method for the synthesis of end-functionalized regioregular poly(3-alkylthiophene)s is presented. Using a modified Grignard metathesis (GRIM) reaction, a series of polymers have been synthesized bearing functional groups on one or both ends of the polymer. This method has been demonstrated to work with a variety of different types of Grignard reagents (i.e., aryl, alkyl, allyl, vinyl, etc.). The reactivity of these depends on their nature, where allyl, ethynyl, and vinyl groups produced monofunctionalized polymers, and all others yielded difunctionalized polymers. The end group composition of the polymers was monitored by a combination of MALDI-TOF and H-1 NMR and approaches 100% in most cases. By utilizing the proper protecting groups -OH, -CHO, and -NH2 groups have been incorporated onto the polymer ends. The main advantage of this method is that it allows for the in situ functionalization of regioregular polythiophene, generating a variety of end-capped polymers in one step. This approach is advantageous in comparison to previously reported methods because it is not only reliable but also highly versatile and highly efficient.