Organocatalytic chiral polymeric nanoparticles for asymmetric aldol reaction

Chiral polymeric particles (CPPs) were studied extensively in recent years due to their importance in pharmaceutical applications. Here, nanosized CPPs were synthesized and applied as catalysts for direct asymmetric aldol reaction. The CPPs were prepared by miniemulsion or inverse miniemulsion based on various chiral amino acid derivatives and characterized by dynamic light scattering and scanning electron microscopy. The nanoparticles with spherical structure between 250 and 400 nm and high chiral surface area were used as catalysts in the aldol reaction at room temperature without additional solvent. l-tryptophan gave the highest enantiomeric excess, >86% with similar catalytic performance four times.

A Guideline for the Synthesis of Amino-Acid-Functionalized Monomers and Their Polymerizations

Amino acids have emerged as a sustainable source for the design of functional polymers. Besides their wide availability, especially their high degree of biocompatibility makes them appealing for a broad range of applications in the biomedical research field. In addition to these favorable characteristics, the versatility of reactive functional groups in amino acids (i.e., carboxylic acids, amines, thiols, and hydroxyl groups) makes them suitable starting materials for various polymerization approaches, which include step- and chain-growth reactions. This review aims to provide an overview of strategies to incorporate amino acids into polymers. To this end, it focuses on the preparation of polymerizable monomers from amino acids, which yield main chain or side chain-functionalized polymers. Furthermore, postpolymerization modification approaches for polymer side chain functionalization are discussed. Amino acids are presented as a versatile platform for the development of polymers with tailored properties.

Synthesis of well-defined heteroglycopolymers via combining sequential click reactions and PPM: the effects of linker and heterogeneity on Con A binding

A versatile post- polymerization modification strategy to synthesize well-defined glycopolymers via the combination of RAFT polymerization and sequential CuAAC and thiol–ene click reactions was developed.

d-, l- and d,l-Tryptophan-Based Polyamidoamino Acids: pH-Dependent Structuring and Fluorescent Properties

Chiral polyamidoamino acids were obtained by polyaddition of N,N'-methylenebisacrylamide with d-, d,l- and l-tryptophan (M-d-Trp, M-d,l-Trp and M-l-Trp). l-tryptophan/glycine copolymers, M-G-l-Trp₅, M-G-l-Trp10, M-G-l-Trp20 and M-G-l-Trp40, were prepared from l-tryptophan/glycine mixtures. These polymers were amphoteric, with acid-base properties similar to those of the parent amino acids. The l-tryptophan/glycine copolymers with high glycine content were water soluble in the pH range 2-12. M-G-l-Trp40 showed a solubility gap centred at pH 4.5 and all tryptophan homopolymers were soluble only at pH > 7. Dynamic light scattering measurements performed in their solubility ranges, namely 2-11 M-G-l-Trp₅, M-G-l-Trp10 and M-G-l-Trp20 and 7-11 for M-G-l-Trp40, M-d-Trp, M-l-Trp and M-d,l-Trp, showed that the size of all samples did not significantly vary with pH. Both M-l-Trp and M-G-l-Trp copolymers showed pH-dependent circular dichroism spectra in the wavelength interval 200⁻280 nm, revealing structuring. All samples were fluorescent. Their emission spectra were unstructured and, if normalized for their tryptophan content, almost superimposable at the same pH, providing evidence that only tryptophan governed the photoluminescence properties. Changing pH induced in all cases a slight shift of the emission wavelength maximum ascribed to the modification of the microenvironment surrounding the indole ring induced by different protonation degrees.

Tryptophan-based styryl homopolymer and polyzwitterions with solvent-induced UCST, ion-induced LCST and pH-induced UCST

A multi-stimuli responsive tryptophan-based styryl homopolymer and polyzwitterions with solvent-induced UCST, ion-induced LCST and pH-induced UCST under different conditions are presented.

The synthesis of poly(arylthiols) and their utilization in the preparation of cross-linked dynamic covalent polymer nanoparticles and hydrogels

Poly(arylthiols) can reversibly cross-link to form nanoparticles and hydrogels.

Amino Acid Functional Polymers: Biomimetic Polymer Design Enabling Catalysis, Chiral Materials, and Drug Delivery

Amino acids are the natural building blocks for the world around us. Highly functional, these small molecules have unique catalytic properties, chirality, and biocompatibility. Imparting these properties to surfaces and other macromolecules is highly sought after and represents a fast-growing field. Polymers functionalized with amino acids in the side chains have tunable optical properties, pH responsiveness, biocompatibility, structure and self-assembly properties. Herein, we review the synthesis of amino acid functional polymers, discuss manipulation of available strategies to achieve the desired responsive materials, and summarize some exciting applications in catalysis, chiral particles, and drug delivery.

Temperature-responsive molecular recognition chromatography using phenylalanine and tryptophan derived polymer modified silica beads

The separation system with dual temperature-response and molecular recognition characteristics leads to selective separation using only aqueous solution.

Amino-acid-based chiral nanoparticles for enantioselective crystallization

Chiral polymer nanoparticles based on amino acids are prepared by miniemulsion polymerization and are demonstrated to serve as nucleating agents for the enantioselective crystallization of racemic mixtures of amino acids. The synthesized chiral nanoparticles are suited for the development of enantioselective processes and also contribute to a better understanding of chiral recognition on polymer surfaces.