Language：English  

DOI： 10.1021/acs.bioconjchem.6c00298

Web of Science

PubMed

Language：English   Publisher：ACS Macro Letters  

The preparation of discrete and stereochemically defined polymers is essential for establishing reliable structure–function relationships and enabling the rational design of functional synthetic macromolecules. Discrete oligomers with precisely defined molar mass and sequence can be accessed by combining controlled polymerization with purification; however, the functional diversity of such oligomers remains limited, because both polymerization and high-resolution separation are typically compatible only with selected functionalities. Herein, we report a versatile route to discrete oligoacrylamides bearing diverse functional groups via postpolymerization amidation of discrete oligo(N-succinimidyl acrylates) (oligo(NSA)) as common activated-ester precursors. Discrete di-, tri-, and tetra-NSA were prepared on a subgram scale by reversible addition–fragmentation chain-transfer (RAFT) polymerization followed by normal-phase flash chromatography and subsequently converted into 16 discrete oligoacrylamides bearing seven different functional groups. As an additional demonstration of stereochemical control, all four stereoisomers of di(NSA) were isolated by chiral chromatography and transformed to the corresponding stereochemically defined acrylamide dimers. This postpolymerization diversification strategy expands the structural diversity accessible for discrete oligomers and provides a practical platform for constructing well-defined oligomer libraries for downstream molecular design.

DOI： 10.1021/acsmacrolett.6c00050

Web of Science

Scopus

PubMed

Language：English   Publisher：Chemical Science  

The construction of stereoisomer libraries is essential for designing, maximizing, and tuning the biological, self-assembly, and photoelectromagnetic properties of optically active molecules. In this study, a stereoisomer library consisting of all eight stereoisomers of a vinyl oligomer, a trimer of phenyl acrylamide (tri(PAAm)), was prepared by a one-pot controlled radical polymerization reaction followed by two-step column chromatography. Tacticity of each isomer, i.e., the relative stereochemistry of three chiral centers within tri(PAAm), was assigned using proton nuclear magnetic resonance (¹H-NMR) and circular dichroism (CD) spectra. Interestingly, one stereoisomer self-assembled and formed an organo-gel. The control experiments revealed that the assembly was driven via configuration-dependent intermolecular hydrogen bonding and π-π interaction. The absolute structure of the gelled tri(PAAm) was identified by combining the tacticity data with the CD spectra and an electronic CD spectrum calculated by density functional theory (DFT). Stereoisomer libraries easily prepared via one-pot radical polymerization are promising modalities for supramolecular chemistry, pharmaceuticals, and photoelectromagnetic materials.

DOI： 10.1039/d5sc00612k

Web of Science

Scopus

PubMed