Synlett 2020; 31(15): 1435-1442
DOI: 10.1055/s-0040-1707180
synpacts
© Georg Thieme Verlag Stuttgart · New York

Electronically Governed ROMP: Expanding Sequence Control for Donor–Acceptor Conjugated Polymers

Stephen J. Koehler
,
Jinzhen Hu
,
The authors gratefully acknowledge financial support from Pennsylvania State University.
Further Information

Publication History

Received: 20 April 2020

Accepted after revision: 20 May 2020

Publication Date:
14 July 2020 (online)


Abstract

Controlling the primary sequence of synthetic polymers remains a grand challenge in chemistry. A variety of methods that exert control over monomer sequence have been realized wherein differential reactivity, pre-organization, and stimuli-response have been key factors in programming sequence. Whereas much has been established in nonconjugated systems, π-extended frameworks remain systems wherein subtle structural changes influence bulk properties. The recent introduction of electronically biased ring-opening metathesis polymerization (ROMP) extends the repertoire of feasible approaches to prescribe donor–acceptor sequences in conjugated polymers, by enabling a system to achieve both low dispersity and controlled polymer sequences. Herein, we discuss recent advances in obtaining well-defined (i.e., low dispersity) polymers featuring donor–acceptor sequence control, and present our design of an electronically ambiguous (4-methoxy-1-(2-ethylhexyloxy) and benzothiadiazole-(donor–acceptor-)based [2.2]paracyclophanediene monomer that undergoes electronically dictated ROMP. The resultant donor–acceptor polymers were well-defined (Đ = 1.2, Mn > 20 k) and exhibited lower energy excitation and emission in comparison to ‘sequence-ill-defined’ polymers. Electronically driven ROMP expands on prior synthetic methods to attain sequence control, while providing a promising platform for further interrogation of polymer sequence and resultant properties.

1 Introduction to Sequence Control

2 Sequence Control in Polymers

3 Multistep-Synthesis-Driven Sequence Control

4 Catalyst-Dictated Sequence Control

5 Electronically Governed Sequence Control

6 Conclusions