Model compounds for evaluating the reactivity of amphetamine-type stimulants

The use of controlled precursors for reaction optimisation is not always practical. One approach to limiting the use of controlled substances is to instead use 'model compounds'. Herein, two model compounds resembling norephedrine and ephedrine were selected based on their (i) structural similarity (i.e., presence of key functional groups) and (ii) availability from multiple suppliers without restriction. Model compounds 2-amino-1-phenylethanol and 2-(methylamino)-1-phenylethanol (halostachine), were compared to norephedrine and pseudoephedrine by firstly subjecting them to transformations known in the synthesis of amphetamines, and secondly, comparing the compounds using colourimetric spot tests, FTIR and NMR.

Regioselective Palladium-Catalyzed Chain-Growth Allylic Amination Polymerization of Vinyl Aziridines

Organometallic-mediated chain growth polymerization of readily accessible chemical building blocks is responsible for important commercial and technological advances in polymer science, but the incorporation of heteroatoms into the polymer backbone through these mechanisms remains a challenge. Transition metal π-allyl complexes are well-developed organometallic intermediates for carbon-heteroatom bond formation in small-molecule catalysis yet remain underexplored in polymer science. Here, we developed a regioselective palladium-phosphoramidite-catalyzed chain-growth allylic amination polymerization of vinyl aziridines for the synthesis of novel nitrogen-rich polymers via ambiphilic π-allyl complexes. The polymerization accessed a linear microstructure with four carbons between each nitrogen, which is challenging to achieve through other chain-growth polymerization approaches. The highly regioselective allylic amination polymerization demonstrated the characteristics of a controlled polymerization and was able to achieve molar masses exceeding 20 kg mol-1 with low dispersities (D̵ < 1.3). The identification of the polymer structure and well-defined chain ends were supported by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and chain extension experiments demonstrate opportunities for building more complex materials from this method. A Hammett study was performed to understand the role of the catalyst and monomer structure on regioselectivity, and the data supported a mechanism wherein regioselectivity was primarily controlled by the ligand-metal complex. Postpolymerization desulfonylation provided access to a novel polyamine that demonstrated broad anticancer activity in vitro, which highlights the benefits of unlocking novel polyamine microstructures through regioselective chain-growth allylic amination polymerization.

Development of a Continuous Flow Baldwin Rearrangement Process and Its Comparison to Traditional Batch Mode

A new and highly efficient continuous flow process is presented for the synthesis of aziridines via the thermal Baldwin rearrangement. The process was initially explored using traditional batch synthesis techniques but suffered from moderate yields, long reaction times, and moderate diastereoselectivities. Here we demonstrate that the process can be greatly improved upon its transfer to continuous flow, which afforded the aziridine targets in high yields, short reaction times, and consistently high diastereoselectivities, with the high-throughput process rendering multigram quantities of product in short periods of time. In addition, flow processing extended the substrate scope including several examples that had failed in batch mode, thus demonstrating the value of this overlooked entry into valuable aziridine species.

Stereoregular poly(2-phenylthiirane) via cationic ring-opening polymerization

Herein, we describe an effective strategy for synthesizing polythioethers with a well-defined structure through the cationic polymerization of thiirane with electron-withdrawing substituents. This strategy allows for precisely controlling the regio- and stereochemistry of the ring-opening polymerization of 2-phenylthiirane, thus allowing for producing poly(2-phenylthiirane) with high stereoregularity using enantiomeric pure thiirane.

Closing the Gap between Experiment and Simulation─A Holistic Study on the Complexation of Small Interfering RNAs with Polyethylenimine

Rational design is pivotal in the modern development of nucleic acid nanocarrier systems. With the rising prominence of polymeric materials as alternatives to lipid-based carriers, understanding their structure-function relationships becomes paramount. Here, we introduce a newly developed coarse-grained model of polyethylenimine (PEI) based on the Martini 3 force field. This model facilitates molecular dynamics simulations of true-sized PEI molecules, exemplified by molecules with molecular weights of 1.3, 5, 10, and 25 kDa, with degrees of branching between 50.0 and 61.5%. We employed this model to investigate the thermodynamics of small interfering RNA (siRNA) complexation with PEI. Our simulations underscore the pivotal role of electrostatic interactions in the complexation process. Thermodynamic analyses revealed a stronger binding affinity with increased protonation, notably in acidic (endosomal) pH, compared to neutral conditions. Furthermore, the molecular weight of PEI was found to be a critical determinant of binding dynamics: smaller PEI molecules closely enveloped the siRNA, whereas larger ones extended outward, facilitating the formation of complexes with multiple RNA molecules. Experimental validations, encompassing isothermal titration calorimetry and single-molecule fluorescence spectroscopy, aligned well with our computational predictions. Our findings not only validate the fidelity of our PEI model but also accentuate the importance of in silico data in the rational design of polymeric drug carriers. The synergy between computational predictions and experimental validations, as showcased here, signals a refined and precise approach to drug carrier design.

Step-growth Polymerization of Aziridines with Elemental Sulfur: Easy Access to Linear Polysulfides and Their Use as Recyclable Adhesives

The bulk radical polymerization of bis(aziridine) with molten elemental sulfur resulted in brittle, cross-linked polymers. However, when the bis(aziridine) was treated with elemental sulfur in the presence of an organobase, the ring-opening reaction of aziridine with oligosulfide anions occurred, leading to the formation of linear polymers by step-growth polymerization. These newly synthesized polymers possess repeating units containing a sulfonamide or amide functional moiety and oligosulfide bonds with an average sulfur segment of about two. A small molecular model reaction confirmed the nucleophilic addition reaction of elemental sulfur to aziridine. It was verified that S-S dynamic bond exchange takes place in the presence of an organic base within the linear chains. The mixture of the synthesized polysulfides with pyridine exhibits exceptional adhesive properties when applied to steel, and aluminum substrates. Notably, these prepared adhesives displayed good reusability due to the dynamic S-S exchange and complete recyclability due to their solution processability. This elemental sulfur-involved polymerization approach represents an innovative method for the synthesis of advanced sulfur-containing polymers, demonstrating the potential for various applications in adhesives and beyond.

Copolymerization Involving Sulfur-Containing Monomers

Incorporating sulfur (S) atoms into polymer main chains endows these materials with many attractive features, including a high refractive index, mechanical properties, electrochemical properties, and adhesive ability to heavy metal ions. The copolymerization involving S-containing monomers constitutes a facile method for effectively constructing S-containing polymers with diverse structures, readily tunable sequences, and topological structures. In this review, we describe the recent advances in the synthesis of S-containing polymers via copolymerization or multicomponent polymerization techniques concerning a variety of S-containing monomers, such as dithiols, carbon disulfide, carbonyl sulfide, cyclic thioanhydrides, episulfides and elemental sulfur (S8). Particularly, significant focus is paid to precise control of the main-chain sequence, stereochemistry, and topological structure for achieving high-value applications.

Acid Gas Capture by Nitrogen Heterocycle Ring Expansion

Acid gases including CO2, OCS, CS2, and SO2 are emitted by industrial processes such as natural gas production or power plants, leading to the formation of acid rain and contributing to global warming as greenhouse gases. An important technological challenge is to capture acid gases and transform them into useful products. The capture of CO2, CS2, SO2, and OCS by ring expansion of saturated and unsaturated substituted nitrogen-strained ring heterocycles was computationally investigated at the G3(MP2) level. The effects of fluorine, methyl, and phenyl substituents on N and/or C were explored. The reactions for the capture CO2, CS2, SO2, and OCS by 3- and 4-membered N-heterocycles are exothermic, whereas ring expansion reactions with 5-membered rings are thermodynamically unfavorable. Incorporation of an OCS into the ring leads to the amide product being thermodynamically favored over the thioamide. CS2 and OCS capture reactions are more exothermic and exergonic than the corresponding CO2 and SO2 capture reactions due to bond dissociation enthalpy differences. Selected reaction energy barriers were calculated and correlated with the reaction thermodynamics for a given acid gas. The barriers are highest for CO2 and OCS and lowest for CS2 and SO2. The ability of a ring to participate in acid gas capture via ring expansion is correlated to ring strain energy but is not wholly dependent upon it. The expanded N-heterocycles produced by acid gas capture should be polymerizable, allowing for upcycling of these materials.

Poly(2-oxazoline)/saRNA Polyplexes for Targeted and Nonviral Gene Delivery

RNA delivery has been demonstrated to be a potent method of vaccine delivery, as demonstrated by the recent success of the COVID-19 vaccines. Polymers have been shown to be effective vehicles for RNA delivery, with poly(ethylene imine) (PEI) being the current gold standard for delivery. Nonetheless, PEI has toxicity concerns, and so finding alternatives is desirable. Poly(2-oxazoline)s are a promising alternative to PEI, as they are generally biocompatible and offer a high degree of control over the polymer structure. Here, we have synthesized an ionizable primary amine 2-oxazoline and combined it with a double bond containing oxazoline to synthesize a small library of charged statistical and block copolymers. The pendant double bonds were reacted further to decorate the polymers with glucose via a thiol-ene click reaction. All polymers were shown to have excellent cell viability, and the synthesized block polymers showed promising complexation efficiencies for the saRNA, demonstrating a clear structure-property relationship. The polymer transfection potential was tested in various cell lines, and a polymer composition with an amine/glucose ratio of 9:27 has demonstrated the best transfection potential across all cell lines tested. Overall, the results suggest that block polymers with a cationic segment and high levels of glycosylation have the best complexation efficiency and RNA expression levels.

Polyethylenimine (PEI) in gene therapy: Current status and clinical applications

Polyethlyenimine (PEI) was introduced 1995 as a cationic polymer for nucleic acid delivery. PEI and its derivatives are extensively used in basic research and as reference formulations in the field of polymer-based gene delivery. Despite its widespread use, the number of clinical applications to date is limited. Thus, this review aims to consolidate the past applications of PEI in DNA delivery, elucidate the obstacles that hinder its transition to clinical use, and highlight potential prospects for novel iterations of PEI derivatives. The present review article is divided into three sections. The first section examines the mechanism of action employed by PEI, examining fundamental aspects of cellular delivery including uptake mechanisms, release from endosomes, and transport into the cell nucleus, along with potential strategies for enhancing these delivery phases. Moreover, an in-depth analysis is conducted concerning the mechanism underlying cellular toxicity, accompanied with approaches to overcome this major challenge. The second part is devoted to the in vivo performance of PEI and its application in various therapeutic indications. While systemic administration has proven to be challenging, alternative localized delivery routes hold promise, such as treatment of solid tumors, application as a vaccine, or serving as a therapeutic agent for pulmonary delivery. In the last section, the outcome of completed and ongoing clinical trials is summarized. Finally, an expert opinion is provided on the potential of PEI and its future applications. PEI-based formulations for nucleic acid delivery have a promising potential, it will be an important task for the years to come to introduce innovations that address PEI-associated shortcomings by introducing well-designed PEI formulations in combination with an appropriate route of administration.

A Theoretical Investigation of Novel Sila- and Germa-Spirocyclic Imines and Their Relevance for Electron-Transporting Materials and Drug Discovery

A new class of spirocyclic imines (SCIs) has been theoretically investigated by applying a variety of quantum chemical methods and basis sets. The uniqueness of these compounds is depicted by various peculiarities, e.g., the incidence of planar six-membered rings each with two imine groups (two π bonds) and the incorporation of the isosteres carbon, silicon, or germanium spiro centers. Additional peculiarities of these novel SCIs are mirrored by their three-dimensionality, the simultaneous occurrence of nucleophilic and electrophilic centers, and the cross-hyperconjugative (spiro-conjugation) interactions, which provoke charge mobility along the spirocyclic scaffold. Substitution of SCIs with strong electron-withdrawing substituents, like the cyano group or fluorine, enhances their docking capability and impacts their reactivity and charge mobility. To gain thorough knowledge about the molecular properties of these SCIs, their structures have been optimized and various quantum chemical concepts and models were applied, e.g., full NBO analysis and the frontier molecular orbitals (FMOs) theory (HOMO-LUMO energy gap) and the chemical reactivity descriptors derived from them. For the assessment of the charge density distribution along the SCI framework, additional complementary quantum chemical methods were used, e.g., molecular electrostatic potential (MESP) and Bader's QTAIM. Additionally, using the aromaticity index NICS (nuclear independent chemical shift) and other criteria, it could be shown that the investigated cross-hyperconjugated sila and germa SCIs are spiro-aromatics of the Heilbronner Craig-type Möbius aromaticity.

Rapid synthesis of functional poly(ester amide)s through thiol-ene chemistry

Poly(ester amide)s (PEAs) bearing various side chains were synthesized by post-polymerization modification of PA-1, a vinylidene containing PEA. The thiols 1-dodecanethiol (1A-SH), 2-phenylethanethiol (1B-SH), 2-mercaptoethanol (1C-SH), thioglycolic acid (1D-SH), furfuryl mercaptan (1E-SH) and sodium-2-mercaptoethanesulfonate (1F-SH) were reacted with PA-1 to form PEAs PA-1A through PA-1F respectively. PEAs containing non-polar thiol side chains (PA-1A, PA-1B, PA-1E), showed little change in solubility compared to PA-1, while PEAs with more polar side chains improved solubility in more polar solvents. PA-1F, functionalized with sodium-2-mercaptoethanesulfonate, became water-soluble. The introduction of pendant functional groups impacted the thermal behaviors of PEAs in a wide range. The PEAs were thermally stable up to 368 °C, with glass transition temperatures (T_g) measured between 117 to 152 °C. Moreover, to demonstrate the versatility of the PEAs, thermal reprocessable networks and polyurethanes were successfully fabricated by reacting with a bismaleimide (1,6-bis(maleimido)hexane, 1,6-BMH) and a diisocyanate (4,4'-diphenylmethane diisocyanate, 4,4'-MDI), respectively. This study paves the way for the facile synthesis of functional poly(ester amide)s with great potential in many fields.

Cross-Linking of Oxidized Hydroxypropyl Cellulose in Paper: Influence of Molecular Weight and Polymer Distribution on Paper Wet Strength Development

With the overarching aim for the development of sustainable, nontoxic wet strength agents for paper, a novel polymer gel system based on oxidized hydroxypropyl cellulose (keto-HPC) cross-linked with polyamines was investigated in detail to gain a deeper insight into the wet strength mechanism. When applied to paper, this wet strength system significantly increases the relative wet strength by using only low amounts of polymer, and it is therefore comparable with established wet strength agents based on fossil resources, such as polyamidoamine epichlorohydrin resins. With the help of ultrasonic treatment, keto-HPC was degraded with respect to its molecular weight and further cross-linked in paper using polymeric amine-reactive counterparts. The resulting polymer-cross-linked paper mechanical properties were analyzed with respect to the dry and wet tensile strength, respectively. In addition, we analyzed the polymer distribution using fluorescence confocal laser scanning microscopy (CLSM). If high-molecular-weight samples are being used for cross-linking, we do find accumulation of the polymer mainly on the surface of the fibers and at fiber crossing points, accompanied with enhancing strong effects on paper’s wet tensile strength. In contrast, if low-molecular-weight (i.e., degraded) keto-HPC is being applied, the macromolecules are capable of entering the inner porous structure of the paper fibers, and almost no accumulation at the fiber crossing points is observed, which also results in a lowered wet paper tensile strength, respectively. This insight into wet strength mechanisms of the keto-HPC/polyamine system can thus lead to new opportunities for the development of alternative biobased wet strength agents where molecular weight dependence of the wet tensile properties allows for a fine tuning of mechanical properties in the wet state.

Cationic ring-opening polymerization of N-benzylaziridines to polyamines via organic boron

This communication reports the synthesis of cyclic polyamines via the cationic ring-opening polymerization (CROP) of N-benzylaziridines initiated by tris(pentafluorophenyl)borane. The debenzylation of these polyamines afforded water-soluble polyethylenimine derivatives. The electrospray ionization mass spectrometry and density functional theory results revealed that the CROP proceeded via the activated chain end intermediates.

Recent Advances in Sequence-Controlled Ring-Opening Copolymerizations of Monomer Mixtures

Transforming renewable resources into functional and degradable polymers is driven by the ever-increasing demand to replace unsustainable polyolefins. However, the utility of many degradable homopolymers remains limited due to their inferior properties compared to commodity polyolefins. Therefore, the synthesis of sequence-defined copolymers from one-pot monomer mixtures is not only conceptually appealing in chemistry, but also economically attractive by maximizing materials usage and improving polymers' performances. Among many polymerization strategies, ring-opening (co)polymerization of cyclic monomers enables efficient access to degradable polymers with high control on molecular weights and molecular weight distributions. Herein, we highlight recent advances in achieving one-pot, sequence-controlled polymerizations of cyclic monomer mixtures using a single catalytic system that combines multiple catalytic cycles. The scopes of cyclic monomers, catalysts, and polymerization mechanisms are presented for this type of sequence-controlled ring-opening copolymerization.

Rational Tuning of the Reactivity of Three-Membered Heterocycle Ring Openings via SN 2 Reactions

The development of small-molecule covalent inhibitors and probes continuously pushes the rapidly evolving field of chemical biology forward. A key element in these molecular tool compounds is the "electrophilic trap" that allows a covalent linkage with the target enzyme. The reactivity of this entity needs to be well balanced to effectively trap the desired enzyme, while not being attacked by off-target nucleophiles. Here we investigate the intrinsic reactivity of substrates containing a class of widely used electrophilic traps, the three-membered heterocycles with a nitrogen (aziridine), phosphorus (phosphirane), oxygen (epoxide) or sulfur atom (thiirane) as heteroatom. Using quantum chemical approaches, we studied the conformational flexibility and nucleophilic ring opening of a series of model substrates, in which these electrophilic traps are mounted on a cyclohexene scaffold (C₆ H₁₀ Y with Y=NH, PH, O, S). It was revealed that the activation energy of the ring opening does not necessarily follow the trend that is expected from C-Y leaving-group bond strength, but steeply decreases from Y=NH, to PH, to O, to S. We illustrate that the HOMO_Nu -LUMO_Substrate interaction is an all-important factor for the observed reactivity. In addition, we show that the activation energy of aziridines and phosphiranes can be tuned far below that of the corresponding epoxides and thiiranes by the addition of proper electron-withdrawing ring substituents. Our results provide mechanistic insights to rationally tune the reactivity of this class of popular electrophilic traps and can guide the experimental design of covalent inhibitors and probes for enzymatic activity.

The Anionic Polymerization of a tert-Butyl-Carboxylate-Activated Aziridine

N-Sulfonyl-activated aziridines are known to undergo anionic-ring-opening polymerizations (AROP) to form polysulfonyllaziridines. However, the post-polymerization deprotection of the sulfonyl groups from polysulfonyllaziridines remains challenging. In this report, the polymerization of tert-butyl aziridine-1-carboxylate (BocAz) is reported. BocAz has an electron-withdrawing tert-butyloxycarbonyl (BOC) group on the aziridine nitrogen. The BOC group activates the aziridine for AROP and allows the synthesis of low-molecular-weight poly(BocAz) chains. A 13C NMR spectroscopic analysis of poly(BocAz) suggested that the polymer is linear. The attainable molecular weight of poly(BocAz) is limited by the poor solubility of poly(BocAz) in AROP-compatible solvents. The deprotection of poly(BocAz) using trifluoroacetic acid (TFA) cleanly produces linear polyethyleneimine. Overall, these results suggest that carbonyl groups, such as BOC, can play a larger role in the in the activation of aziridines in anionic polymerization and in the synthesis of polyimines.

Anhydride chemistry based Hexanoylation of polyethylenimine increases transfection efficiency and expression of tagged DNA for therapeutic proteins in cultured cells

Transfection of nucleic acid molecules into mammalian cells can be facilitated using viral vectors, electroporation, or biocompatible cationic materials. However, safety issues and the requirement of specialized equipment limits the use of viral vectors and physical methods of transfection like electroporation and microinjection, respectively. Biocompatible cationic lipids and polymers like branched-polyethyleneimine (bPEI) have a wide transfection range and are user friendly in most applications. However, bPEI exhibits low transfection efficiency in most cell types. In the present work, we have crosslinked the hexanoyl group to bPEI using anhydride chemistry to enhance its efficiency as a transfection reagent. The efficient association of hexanoyl group to bPEI was assessed using Fourier transform infrared spectroscopy and other Physico-chemical methods. Hexanoyl modified bPEI (FA6-bPEI) was found to exhibit significantly enhanced transfection efficiency in both cell lines and cultured primary cells, as compared to native bPEI and the commercially available transfection reagent lipofactamine 3000. Furthermore, our in-vitro studies indicated that FA6-bPEI can be used for robust transfection for increased production of therapeutic proteins in a cell culture based system. These results suggested that hexanoyl modified bPEI can serve as an efficient transfection reagent for studies on hard-to-transfect cells and enhanced production of therapeutic proteins in-vitro. This article is protected by copyright. All rights reserved.

Ring-Opening Polymerization of Triaziridine Compounds in Water: An Extremely Facile Method to Synthesize a Porous Polymer through Polymerization-Induced Phase Separation

Dissolution of trifunctional aziridine compounds, 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] (3AZ) and tetramethylolmethane-tri-β-aziridinylpropionate (3AZOH), in water initiates a ring-opening polymerization and successful yields the corresponding network polymers via cationic polymerization. The polymerization of 3AZ induced phase separation and produced porous polymers under a wide range of monomer concentrations and polymerization temperatures. The phase separation rate in the 3AZ/water system was estimated by quantifying the turbidity by means of light transmission where transmittance decreased with an increase in the content of phase-separated materials. The rate increased with an increase in reaction temperature. The 3AZ porous polymers showed characteristic surface morphologies, which were formed by connected particles with diameters of about 4-5 μm. The porous polymers were not breakable by the compression test under 50 N. The Young's modulus of the 3AZ porous polymers increased with an increase in polymerization temperature, which may be accounted for by cross-linking through the formation of quaternary ammonium salt formed by a termination reaction. The 3AZ porous polymer absorbed various solvents.

Composite Corelated Molecular Orbital Theory Calculations of Ring Strain for Use in Predicting Polymerization Reactions

Strained ring systems play an important role in synthesis and can be characterized by the ring strain energy (RSE). The RSE of 3, 4, 5, and 6 membered saturated and unsaturated ring systems containing N, O, P, and S heteroatoms and H, F, Si(CH 3 ) 3 , and SO 2 (CH 3 ) substituents were calculated at the G3(MP2) composite correlated molecular orbital theory level using up to 5 models to predict the RSE. Generally, the RSE decreased as ring size increased with a substantial decrease from 4 to 5 membered rings. Replacement of a ring CH 2 with P or S reduced the RSE, consistent with less angle strain. The RSE for unsaturated systems were generally greater than for saturated systems due to increased angle strain. No general trends were found with respect to substituent effects. The RSE values suggest that 3-pyrroline and 2-pyrroline may be able to support ring opening metathesis polymerization and warrant further study.

Analysis of pharmaceutical drug oligomers by selective comprehensive two-dimensional liquid chromatography-high resolution mass spectrometry

The presence of oligomeric impurities in drugs is often overlooked and less studied due to conventional small molecule analytical methods which are often not capable of capturing these oligomers. In the present work, the oligomer species of a lipophilic active pharmaceutical ingredient (API) containing an azetidine ring was investigated. No separation was observed by reversed-phase liquid chromatography (RPLC) methods, and only a partial separation of oligomer peaks was achieved by a size exclusion chromatography (SEC) method. To improve the resolution of the different oligomers species and understand the root cause of the formation of the oligomers, a selective comprehensive two-dimensional liquid chromatography (2D-LC) method was developed by coupling SEC to RPLC. The selective comprehensive SEC × RPLC method allowed the separation of 16 species and evidenced four main groups of oligomer impurities. The contour plots of 3 API lots helped to visualize the oligomer profiles and quickly compare the difference between these lots. Finally, the oligomer peaks separated by 2D-LC were identified by high-resolution mass spectrometry (HRMS) using a Q Exactive mass spectrometer. The developed 2D-LC/HRMS workflow provides a fast and generic screening approach to quickly examine and visualize the oligomeric impurities in API materials, and direct the impurity control strategy during process development.

Synthesis of bottlebrush polymers based on poly(N-sulfonyl aziridine) macromonomers

We synthesized bottlebrush polymers with polyaziridine brushes and a polynorbornene backbone by a grafting-through approach. The polyaziridine macromonomer aggregates in solution, but these aggregates disperse over the course of the polymerization.

Tributylphosphine-catalyzed aziridine-based cycloaddition polymerization toward thiacyclic polymers

Cycloaddition polymerization of bis(N-sulfonyl aziridine)s with diisocyanates in the presence of tributylphosphine allows the facile synthesis of poly(thiazolidin-2-imine)s.

A facile post-modification strategy for carboxylic acid-functionalized UV-responsive pressure-sensitive adhesives

UV-responsive pressure-sensitive adhesives (PSAs) were achieved through the ring-opening reactions of N-carbonyl aziridine radicals.

Catalyst-free aziridine-based step-growth polymerization: a facile approach to optically active poly(sulfonamide amine)s and poly(sulfonamide dithiocarbamate)s

Step-growth polymerization of chiral bis(N-sulfonyl aziridine)s with diamines or bis(dialkyldithiocarbamate) in the absence of a catalyst allows the facile synthesis of optically active polysulfonamide derivatives.

Design of Polymeric Carriers for Intracellular Peptide Delivery in Oncology Applications

In recent decades, peptides, which can possess high potency, excellent selectivity, and low toxicity, have emerged as promising therapeutics for cancer applications. Combined with an improved understanding of tumor biology and immuno-oncology, peptides have demonstrated robust antitumor efficacy in preclinical tumor models. However, the translation of peptides with intracellular targets into clinical therapies has been severely hindered by limitations in their intrinsic structure, such as low systemic stability, rapid clearance, and poor membrane permeability, that impede intracellular delivery. In this Review, we summarize recent advances in polymer-mediated intracellular delivery of peptides for cancer therapy, including both therapeutic peptides and peptide antigens. We highlight strategies to engineer polymeric materials to increase peptide delivery efficiency, especially cytosolic delivery, which plays a crucial role in potentiating peptide-based therapies. Finally, we discuss future opportunities for peptides in cancer treatment, with an emphasis on the design of polymer nanocarriers for optimized peptide delivery.

Advances in heterometallic ring-opening (co)polymerisation catalysis

Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts. This review describes advances in heterometallic RO(CO)P catalyst design, highlighting the overarching structure-activity trends and reactivity patterns to inform future catalyst design.

Grafting polysulfonamide from cellulose paper through organocatalytic ring-opening polymerization of N-sulfonyl aziridines

A facile and effective "grafting from" method by ROP of N-sulfonyl aziridines toward cellulose-g-polysulfonamides has been developed for efficient oil/water separation. The cellulose paper was initially succinylated to transform the hydroxyl to carboxyl acid groups, which act as the initiating sites for the ring-opening copolymerization of fluorescent 2-methyl-1-dansylaziridine and 2-methyl-1-tosylaziridine (TsMAz) towards the grafted cellulose. Both steps are catalyzed by the same compound, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). The grafted polysulfonamide ratio was up to 136 wt%, and the surface contact angle up to 147°. A one-pot tandem strategy was applied to produce the grafted cellulose paper with a grafting ratio ranging from 96 to 150 % and a contact angle over 127°. The modified cellulose paper material showed promising properties for efficient oil/water separations.

Sc(OTf)3-catalyzed [3 + 2]-cycloaddition of nitrones with ynones

An efficient approach to access functionalized (2,3-dihydroisoxazol-4-yl) ketones has been developed by reacting nitrones 4 with ynones 7 or terminal ynones 10 in a one-pot fashion. The reaction went through a formal Sc(OTf)3-catalyzed [3 + 2]-cycloaddition process to generate a number of functionalized (2,3-dihydroisoxazol-4-yl) ketones 11aa-11aw, 11ba-11la and 12aa-12ae in moderate to good yields.

Synthesis and Application of Cellulose-Polyethyleneimine Composites and Nanocomposites: A Concise Review

Cellulose/polyethyleneimine composites have increasingly attracted the attention of scientific community, devoted to the design and development of new synthetic strategies and materials for different application fields. In this review, after introducing the main characteristics of the two polymeric components, we provide in the second section a critical overview on the main protocols for the synthesis of these composites, considering both the several cellulose sources and forms, and the different cross-linkers and cross-linking procedures developed for this purpose, outlining advantages and limits for the reported approaches. The last section analyses the principal results obtained in different application fields. A wide discussion is dedicated to the principal use of cellulose/polyethyleneimine composites as sorbents for water remediation from heavy metal ions and organic contaminants. Subsequently, we introduce the literature describing the use of these composites, functionalized appropriately, where necessary, as drug delivery systems, sensors, and heterogeneous catalysts for organic reactions. Finally, after a brief description of other random applications, we furnish a personal analysis of actual limits and potentialities for these systems.

Amine-containing diblock terpolymers via AROP: a versatile method for the generation of multifunctional micelles

We herein report the synthesis and block copolymerization via AROP of three glycidyl amine species (PiGA; OPGA, and MPGA) with different hydrophobicity. Micelles formed from these block copolymers respond to changes in pH and H₂O₂ concentration.

Solvent and catalyst-free modification of hyperbranched polyethyleneimines by ring-opening-addition or ring-opening-polymerization of N-sulfonyl aziridines

Ring-opening (polymerization) of N-sulfonyl aziridines with PEI under solvent/catalyst-free conditions allows the atom-economic synthesis of amphiphilic alkylated PEIs and luminescent PEI-graft-polysulfonamide.

Organocatalytic sequential ring-opening polymerization of cyclic ester/epoxide and N-sulfonyl aziridine: metal-free and easy access to block copolymers

Sequential ring-opening polymerization of ε-caprolactone (ε-CL)/propylene oxide (PO) and N-sulfonyl aziridine switched by tosyl isocyanate (TSI) allows the metal-free synthesis of polysulfonamide-based copolymers.