A General Approach to Sequence-Controlled Polymers Using Macrocyclic Ring Opening Metathesis Polymerization

Abstract

A new and general strategy for the synthesis of sequence-defined polymers is described that employs relay metathesis to promote the ring opening polymerization of unstrained macrocyclic structures. Central to this approach is the development of a small molecule “polymerization trigger” which when coupled with a diverse range of sequence-defined units allows for the controlled, directional synthesis of sequence controlled polymers.

Coding and decoding libraries of sequence-defined functional copolymers synthesized via photoligation

“…Generating an ensemble of perfectly sequence-defined identical macromolecules containing exactly the same chemical information at the molecular scale—in contrast to existing avenues to disperse and irregularly coded species when compared with natural analogues—via a simple process constitutes a key technological gate for data storage, biological and material applications, yet requires reaction concepts that provide perfect yields and orthogonality under equimolar reaction conditions. Although solid-state peptide synthesis was introduced by Merrifield6—the first example of a true synthetic sequence-defined peptide—macromolecular chemists have initially focused on and developed a diverse number of solution-based polymerization strategies for imparting a certain level of control over statistical polymerization processes and exploited these for controlling the order of the building blocks (sequence-controlled polymers)7891011121314151617181920. In addition, the advent of modular synthetic strategies21222324 has contributed significantly towards achieving a high level of control over macromolecular formation processes.…”

Biosynthetic Polymers as Functional Materials

“…67 Prior to this work, efforts to synthesize sequence-controlled polymers via multisubstituted cyclooctadienes using ROMP have been limited in number and types of incorporated functionalities. 68,69 During chain extension, the growing polymer sequence obtained ordered repeats of ABCDE units along a polyester backbone.…”

“…Monomers are composed of a ROMP polymerization trigger attached to a series of glycolate (Gly), ( S )-lactate (Lact), ( S )-phenyllactate (PhLact), and β-alanine ( β Ala). Reproduced with permission from ref (67). …”

Poly(arylenevinylene)s through Ring‐Opening Metathesis Polymerization of an Unsymmetrical Donor‐Acceptor Cyclophane

“…In our studies to attain D-A materials,w ed eveloped an interest in using "electronically-ambiguous" pCpd frameworks.W ed efine electronically ambiguous as comprising both electronically activated and electronically deficient ring systems,w hich is likely to unpredictably influence ROMP efficiency.W hereas ROMP has been exploited to achieve sequence-defined polymers, [21,22] the scope of monomers remains centered on norbornenes (and related bicyclic derivatives), cyclooctadienes,cyclopentenes,and other cyclo-alkanes that do not generally feature substitutions proximal to the reactive alkenes, [23] allowing the initiator to approach the monomer in an ubiquitous fashion. In our studies to attain D-A materials,w ed eveloped an interest in using "electronically-ambiguous" pCpd frameworks.W ed efine electronically ambiguous as comprising both electronically activated and electronically deficient ring systems,w hich is likely to unpredictably influence ROMP efficiency.W hereas ROMP has been exploited to achieve sequence-defined polymers, [21,22] the scope of monomers remains centered on norbornenes (and related bicyclic derivatives), cyclooctadienes,cyclopentenes,and other cyclo-alkanes that do not generally feature substitutions proximal to the reactive alkenes, [23] allowing the initiator to approach the monomer in an ubiquitous fashion.…”