Precision synthesis, structure and function of helical polymers

Abstract

Helical structures are chiral, which means that if we can synthesize a polymer having a stable one-handed helicity, the polymer is optically active. In 1979, we succeeded in the synthesis of a one-handed helical polymer from an optically inactive achiral monomer, triphenylmethyl methacrylate (TrMA). This is the first example of the asymmetric synthesis of an optically active one-handed helical polymer. The polymer (PTrMA) exhibited an unexpected high chiral recognition ability and afforded a practically useful chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) by coating it on silica gel. In addition, we also succeeded in the development of very useful CSPs for HPLC using the phenylcarbamate derivatives of polysaccharides, cellulose and amylose. These CSPs can efficiently resolve a broad range of chiral compounds, and have been used all over the world for separating and analyzing chiral compounds.

Stereochemical enhancement of polymer properties

“…197 For example, a hydrogel developed by imprinting chiral sites with helical polymers displayed prominent enantioselective adsorption behaviour. 198 Moreover, chiral recognition can be exploited in the case of static helical polymers such as polyisocyanide 196,199 and poly(triphenylmethyl methacrylate) (PTrMA) [200][201][202] which have also found utility as chiral stationary phases (CSPs) for HPLC columns. The dynamic and helical memory properties of polyacetylene have been leveraged for the same application but with the added advantage of a switchable chirality to potentially alter the elution order of the enantiomers.…”

Discrete and Stereospecific Oligomers Prepared by Sequential and Alternating Single Unit Monomer Insertion

“…For most naturally-occurring polymers, helical structures are essential for exerting their sophisticated functions in nature. [5][6][7] Reproducing the chemical structures of these functional biomacromolecules and mimicking their natural processes to understand the underlying mechanisms has been a great challenge for more than half a century. There has been limited success, and for instance, scientists have duplicated these structurally perfect polymers from their natural monomers (nucleotides and amino acids) using chemical approaches, such as solid-phase peptide synthesis and oligonucleotide synthesis, to create new macromolecules for a range of biomedical and pharmacological applications.…”

Chromatographic enantioseparation by poly(biphenylylacetylene) derivatives with memory of both axial chirality and macromolecular helicity

“…It is well known that the direct resolution of enantiomers by high‐performance liquid chromatography (HPLC) using chiral stationary phases (CSPs) is one of the most useful methods for both analytical and preparative purposes, and a large number of CSPs for HPLC have been developed so far . Particularly since the discovery of one‐handed helical poly(triphenylmethyl methacrylate) (PTrMA) and polysaccharide derivatives, showing an excellent resolution ability as CSPs, a variety of helical polymers have been prepared for using them as CSPs …”

“…More special articles will be found in this issue as well as in those to come.] (PTrMA) [13][14][15][16][17] and polysaccharide derivatives, [18][19][20][21] showing an excellent resolution ability as CSPs, a variety of helical polymers have been prepared for using them as CSPs. 12,[22][23][24] We recently discovered a quite unique helical polymer, a poly(biphenylylacetylene) derivative (poly-MOM-a) bearing methoxymethoxy (MOM) groups at the 2-and 2′-positions and an n-dodecyloxy group at the 4′-position of the biphenyl pendant, which folds into a preferred-handed helical conformation through noncovalent weak interactions with (R)-or (S)-1-phenylethanol ((R)-or (S)-1) in the solid state as well as in solution, through which the axial chirality of the biphenyl pendants is also biased.…”