The dawn of polymer chemistry based on multicomponent reactions

Fast and Selective Main-Chain Scission of Vinyl Polymers Using the Domino Reaction in the Alternating Sequence for Transesterification

This communication reports on vinyl polymers capable of selective and fast main-chain scission (MCS). The trick is the domino reaction in an alternating sequence of methyl 2-(trimethylsiloxymethyl)acrylate and 5,6-benzo-2-methylene-1,3-dioxepane, a cyclic ketene acetal for radical ring-opening polymerization. Removal of the trimethylsilyl group using Bu4N+·F- readily led to MCS via irreversible transesterification of the ester backbone, affording a five-membered lactone fragment. The molar mass decreased drastically within 5 min, and no side reactions were observed. Control experiments suggest that the formation of a five-membered ring via a domino reaction is critical for fast and selective MCS. The terpolymers with methyl methacrylate and styrene also exhibited a large decrease in molar mass within 5 min. In addition, MCS was also observed for the heterogeneous reaction system in acidic aqueous media; treatment of the binary copolymer in a 50 wt % acetic acid solution resulted in a significant decrease in molar mass after 30 min. These results suggest efficient construction of degradable sites using a binary monomer system corresponding to the pendant trigger and ester backbone. Because this molecular design using a binary monomer system provides selective and fast MCS for terpolymers containing other vinyl monomers, it can provide various degradable vinyl polymers.

Smart/stimuli-responsive chitosan/gelatin and other polymeric macromolecules natural hydrogels vs. synthetic hydrogels systems for brain tissue engineering: A state-of-the-art review

Currently, there are no viable curative treatments that can enhance the central nervous system's (CNS) recovery from trauma or illness. Bioengineered injectable smart/stimuli-responsive hydrogels (SSRHs) that mirror the intricacy of the CNS milieu and architecture have been suggested as a way to get around these restrictions in combination with medication and cell therapy. Additionally, the right biophysical and pharmacological stimuli are required to boost meaningful CNS regeneration. Recent research has focused heavily on developing SSRHs as cutting-edge delivery systems that can direct the regeneration of brain tissue. In the present article, we have discussed the pathology of brain injuries, and the applicable strategies employed to regenerate the brain tissues. Moreover, the most promising SSRHs for neural tissue engineering (TE) including alginate (Alg.), hyaluronic acid (HA), chitosan (CH), gelatin, and collagen are used in natural polymer-based hydrogels and thoroughly discussed in this review. The ability of these hydrogels to distribute bioactive substances or cells in response to internal and external stimuli is highlighted with particular attention. In addition, this article provides a summary of the most cutting-edge techniques for CNS recovery employing SSRHs for several neurodegenerative diseases.

Functional chromophores synthesized via multicomponent Reactions: A review on their use as cell-imaging probes

This review aims to provide a comprehensive overview of recent advancements and applications of fluorescence imaging probes synthesized via MCRs (multicomponent reactions). These probes, also known as functional chromophores, belong to a currently investigated class of fluorophores that are presently being successfully applied in bioimaging experiments, especially in various living cell lineages. We describe some of the MCRs that have been employed in the synthesis of these probes and explore their applications in biological imaging, with an emphasis on cellular imaging. The review also discusses the challenges and future perspectives in the field, particularly considering the potential impact of MCR-based fluorescence imaging probes on advancing this field of research in the coming years. Considering that this area of research is relatively new and nearly a decade has passed since the first publication, this review also provides a historical perspective on this class of fluorophores, highlighting the pioneering works published between 2011 and 2016.

Superhydrophobic Coatings Composed of Multifunctional Polymers Synthesized Using Successive Modification of Dihydropyrimidin-2(1H)-thione

Polymer synthesis via multicomponent reactions (MCRs) has opened avenues in polymer chemistry and led to the development of various types of functional polymers. Herein, we developed a strategy to prepare multifunctional polymers via the successive modification of dihydropyrimidin-2(1H)-thione (DHPMT), which can be generated by the tricomponent Biginelli reaction. Four hydrophobic polymers were efficiently prepared by using DHPMT derivatives. These polymers can be dip-coated onto the oxidized copper mesh to obtain superhydrophobic meshes because of the strong attractive forces between the DHPMT derivatives and Cu(II). The optimized mesh has self-cleaning properties and outstanding stability in various liquid environments; it has also been successfully applied for oil/water separation with high separation efficiency and good durability. These results demonstrate that successive modification of DHPMT is a promising method for fabricating multifunctional polymers, which may have applications in polymer chemistry and materials science.

Synthesis of Ag-Cu-Ni Nanoparticles Stabilized on Functionalized g-C3N4 and Investigation of Its Catalytic Activity in the A3-Coupling Reaction

In the present research, using ethylenediamine and hydrazine hydrate as the capping and reducing agents in this investigation, respectively, Ag-Cu-Ni NPs were immobilized on the functionalized g-C₃N₄ surface. This nanocatalyst was studied in terms of its catalytic activities for the A³-coupling reaction to synthesize propargylamine derivatives. According to the results, in the presence of 1 mL of toluene as the solvent and 20 mg of the g-C₃N₄-TCT-2AEDSEA-Ag-Cu-Ni nanocatalyst, the maximum efficiency of the nanocatalyst occurred at a temperature of 80 °C. Products were purified using thin-layer chromatography plates (silica gel) by employing n-hexane/ethyl acetate with a 90:10 ratio. In addition, the prominent benefits of the synthesized nanocatalyst include its high yields of the product, cost-effectiveness, recyclability, and easy separation. The novelty of the catalyst is due to the presence of Ag-Cu-Ni nanoparticles at the same time in the structure of the functionalized g-C₃N₄ substrate. So, Ag-Cu-Ni can be strongly connected to the substrate. The structure of the synthesized nanocatalyst was characterized using Fourier transformed infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating-sample magnetometry, and transmission electron microscopy.

The Discovery of Novel Antimicrobial Agents through the Application of Isocyanide-Based Multicomponent Reactions

Multicomponent reactions (MCR) have been used to synthesize a wide range of analogs from several classes of heterocyclic compounds, with multifaceted medicinal uses. The synthesis of highly functionalized molecules in a single pot is a unique property of MCR, allowing researchers to quickly assemble libraries of compounds of biological interest and uncover novel leads as possible therapeutic agents. Isocyanide-based multicomponent reactions have proven to be extremely effective at swiftly specifying members of compound libraries, particularly in the discovery of drugs. The understanding of structure-activity correlations that drive the development of new goods and technology requires structural variety in these libraries. In today's world, antibiotic resistance is a major ongoing problem that poses risks to public health. The implementation of isocyanide-based multicomponent reactions upholds a significant potential in this regard. By utilizing such reactions, new antimicrobial compounds can be discovered and subsequently used to fight against such concerns. This study discusses the recent developments in antimicrobial medication discovery using isocyanide-based multicomponent reactions (IMCRs). Furthermore, the article emphasizes the potential of IMCRs (Isocyanide-based multicomponent based reactions) in the near future.

The Synthesis of 2,2-BIS(1-INDOL-3-YL)Acenaphthylene-1(2)-Ones Using Nanocatalysis: Fluorescent Sensing for Cu2+ Ions

2,2-bis(1H-indol-3-yl)acenaphthylene-1(2H)-ones were synthesised by the reaction of acenaphthenequinone and 2 equivalents of indole using Fe3O4@SiO2@Si-Pr-NH-CH2CH2NH2 as the basic magnetic nanocatalyst, assembled under greener and sustainable conditions in high purity and yields. Furthermore, the photoluminescence properties of 2,2-bis(2-methyl-1H-indol-3-yl)acenaphthylene-1(2H)-one were exploited for the sensing of copper ions in the mixed solvent systems comprising H2O and CH3CN in excitation wavelength at 410 nm with a detection limit of 9.5 ∙ 10–6 M.

Synthesis of (E)-2-(1H-tetrazole-5-yl)-3-phenylacrylenenitrile derivatives catalyzed by new ZnO nanoparticles embedded in a thermally stable magnetic periodic mesoporous organosilica under green conditions

ZnO nanoparticles embedded in a magnetic isocyanurate-based periodic mesoporous organosilica (Fe₃O₄@PMO–ICS–ZnO) were prepared through a modified environmentally-benign procedure for the first time and properly characterized by appropriate spectroscopic and analytical methods or techniques used for mesoporous materials. The new thermally stable Fe₃O₄@PMO–ICS–ZnO nanomaterial with proper active sites and surface area as well as uniform particle size was investigated for the synthesis of medicinally important tetrazole derivatives through cascade condensation and concerted 1,3-cycloaddition reactions as a representative of the Click Chemistry concept. The desired 5-substituted-1H-tetrazole derivatives were smoothly prepared in high to quantitative yields and good purity in EtOH under reflux conditions. Low catalyst loading, short reaction time and the use of green solvents such as EtOH and water instead of carcinogenic DMF as well as easy separation and recyclability of the catalyst for at least five consecutive runs without significant loss of its activity are notable advantages of this new protocol compared to other recent introduced procedures.

Chitosan-EDTA-Cellulose network as a green, recyclable and multifunctional biopolymeric organocatalyst for the one-pot synthesis of 2-amino-4H-pyran derivatives

In this research, cellulose grafted to chitosan by EDTA (Cs-EDTA-Cell) bio-based material is reported and characterized by a series of various methods and techniques such as FTIR, DRS-UV–Vis, TGA, FESEM, XRD and EDX analysis. In fact, the Cs-EDTA-Cell network is more thermally stable than pristine cellulose or chitosan. There is a plenty of both acidic and basic sites on the surface of this bio-based and biodegradable network, as a multifunctional organocatalyst, to proceed three-component synthesis of 2-amino-4H-pyran derivatives at room temperature in EtOH. The Cs-EDTA-Cell nanocatalyst can be easily recovered from the reaction mixture by using filtration and reused for at least five times without significant decrease in its catalytic activity. In general, the Cs-EDTA-Cell network, as a heterogeneous catalyst, demonstrated excellent catalytic activity in an environmentally-benign solvent to afford desired products in short reaction times and required simple experimental and work-up procedure compared to many protocols using similar catalytic systems.

MNP-cellulose-OSO3H as an efficient and biodegradable heterogeneous catalyst for green synthesis of trisubstituted imidazoles

Cellulose is an eco-friendly, efficient, and suitable substrate for use as a coating material and support in the preparation of catalysts. Herein, MNP–cellulose–OSO₃H was prepared as an efficient heterogeneous catalyst composed of Fe₃O₄ nanoparticles covered with cellulose–OSO₃H and used for the synthesis of trisubstituted imidazoles. The catalyst was characterized by FT-IR, CHNS, ICP, PXRD, EDAX, elemental mapping, SEM, TEM, zeta potential, TGA, and VSM techniques. The catalytic activity was evaluated in the one-pot three-component synthesis of trisubstituted imidazole derivatives using benzil or 9,10-phenanthrenequinone, different aldehydes, and ammonium acetate in EtOH solvent at 80 °C over 30 min. The yields of products were excellent, in the range 83–97%. The catalyst showed outstanding catalytic performance toward heating conditions and good reusability. Also, this methodology had several advantages, such as simple procedures, short reaction time, excellent yield, simple workup, and mild reaction conditions.

Cellulose is an eco-friendly, efficient, and suitable substrate for use as a coating material and support in the preparation of catalysts.

Exhaustive Baeyer–Villiger oxidation: a tailor-made post-polymerization modification to access challenging poly(vinyl acetate) copolymers

The discovery of exhaustive (nearly quantitative) post-polymerization modifications (PPM) relies heavily on the efficiency of their corresponding small-molecule protocols. However, the direct translation of existing small-molecule protocols into PPM methods has never been guaranteed due to the intrinsic differences between small-molecule substrates and polymers. Herein, we introduce the direct optimization on polymers (DOP) as a complementary approach to developing exhaustive PPM reactions. As proof of the DOP concept, we present an exhaustive Baeyer–Villiger (BV) post-modification which cannot be accessed by conventional approaches. This user-friendly methodology provides general access to synthetically challenging copolymers of vinyl acetate and more activated monomers (MAMs) including both statistical and narrow-dispersed block copolymers. Furthermore, a scalable one-pot copolymerization/exhaustive BV post-modification procedure was developed to produce such materials showing improved performance over regular PVAc.

Exhaustive Baeyer–Villiger (BV) oxidation, which was developed by a direct optimization on polymers (DOP) approach, provides a general solution for preparing synthetically challenging poly(vinyl acetate) statistical and block copolymers.

Tandem polymerization consisting of cyclotrimerization and the Tishchenko reaction: synthesis of acid- and alkali-degradable polymers with cyclic acetal and ester structures in the main chain

Tandem polymerization consisting of cyclotrimerization and the Tishchenko reaction was developed, which yielded acid- and alkali-degradable polymers.

Three-Component Dynamic Covalent Chemistry: From Janus Small Molecules to Functional Polymers

A new multicomponent reaction involving 2-hydroxybenzaldehyde, amine, and 2-mercaptobenzaldehyde (HAM reaction) has been developed and applied to multicomponent polymerization and controlled radical polymerization for the construction of random and block copolymers. This chemistry features mild reaction conditions, high yield, simple isolation, and water as the only byproduct. With the advantages of the distinct nucleophilicity of thiol and hydroxyl groups, the chemistry could be used for stepwise labeling and modifications on primary amines. The Janus chemical joint formed from this reaction exhibits degradability in buffers and generates the corresponding starting reagents, allowing amine release. Interestingly, the chemical joint exhibits thermally activated reversibility with water as the catalyst. This multicomponent dynamic covalent feature has been applied to the metamorphosis of random and block copolymers, generating polymers with diverse architectures. This chemistry is expected to be broadly applicable to synthetic polymer chemistry and materials science.

Materials diversity of hydrogel: Synthesis, polymerization process and soil conditioning properties in agricultural field

BACKGROUND

The cumulative influence of global warming, climate abrupt changes, growing population, topsoil erosion is becoming a threatening alarm for facing food challenges and upcoming global water issues. It ultimately affects the production of food in a water-stressed environment and slows down the production with more consumption of fertilizers by plants. The superabsorbent hydrogels (SAHs) have extensive applications in the agricultural field and proved very beneficial for plant growth and soil health. These polymeric materials are remarkably distinct from hygroscopic materials owing to their multidimensional network structure. It retains a lot of water in its 3D network and releases it slowly along with nutrients to plant in stressed environment.

AIM OF REVIEW

A soil conditioner boosts up the topology, compactness, and mechanical properties (swelling, water retention, and slow nutrient release) of soil. The superabsorbent hydrogel plays an astonishing role in preventing the loss of nutrients during the heavy flow of rainwater from the upper surface of soil because these SAHs absorb water and get swollen to keep water for longer time. The SAHs facilitate the growth of plants with limited use of water and fertilizers. Beyond, it improves the soil health and makes it fertile in horticulture and drought areas.

KEY SCIENTIFIC CONCEPT OF REVIEW

The SAHs can be synthesized through grafting and cross-linking polymerization to introduce value-added features and extended network structure. The structure of superabsorbent hydrogel entirely based on cross-linking that prompts its use in the agricultural field as a soil conditioner. The properties of a SAHs vary due to its nature of constituents, polymerization process (grafting or cross-linking), and other parameters. The use of SAHs in agricultural field comparatively enhances the swelling rate up to 60-80%, maximum water retaining, and slowly nutrient release to plants for a longer time.

Recent Advances in Diversity-Oriented Polymerization Using Cu-Catalyzed Multicomponent Reactions

Diversification of polymer structures is important for imparting various properties and functions to polymers, so as to realize novel applications of these polymers. In this regard, diversity-oriented polymerization (DOP) is a powerful synthetic strategy for producing diverse and complex polymer structures. Multicomponent polymerization (MCP) is a key method for realizing DOP owing to its combinatorial features and high efficiency. Among the MCP methods, Cu-catalyzed MCP (Cu-MCP) has recently paved the way for DOP by overcoming the synthetic challenges of the previous MCP methods. Here the emergence and progress of Cu-MCP, its current challenges, and future perspectives are discussed.

Passerini Multicomponent Reactions Enabling Self-Reporting Photosensitive Tetrazole Polymers

We introduce the synthesis of photosensitive tetrazole monomers via Passerini multicomponent reactions (MCRs). We exploit the MCR's tolerance toward various functional groups under mild, catalyst-free conditions in a one-pot reaction setup to generate tetrazole-containing monomers featuring a methacrylic moiety, which enables their subsequent reversible addition-fragmentation chain transfer (RAFT) polymerization. By employing tetrazoles with either a 4-methoxy phenyl or a pyrene substituent, further modifications of the polymers in a wavelength-orthogonal, self-reporting fashion upon irradiation with either UV or visible light become possible.

Sequential Post-Polymerization Modification of Aldehyde Polymers to Ketone and Oxime Polymers

A new sequential post-polymerization modification route has been developed for the synthesis of multifunctional polymers from a simple aldehyde polymer. In the first modification step, a template polymer derived from the radical polymerization of 4-vinyl benzaldehyde undergoes Rh-catalyzed hydroacylation with alkenes to furnish a group of ketone polymers. In the second modification step, Schiff base formation with alkoxy ammonium salts introduces a second group-an oxime functionality. Both the steps are highly efficient, introducing evenly distributed dual functionalities at the same position.

Four component Passerini polymerization of bulky monomers under high shear flow

We introduce a four component Passerini polymerization utilizing sterically bulky isocyanide monomers. Under typical Passerini conditions, bulky isocyanides do not react within standard Passerini reaction timescales (hours). We overcome this challenge via the unique physiochemical conditions present in a vortex fluidic device, reducing the reaction time to 2 h on average. Under these high-shear thin-film conditions, bulky isocyanides are readily incorporated into the multicomponent polymerization without the need of high-pressure or temperature. Finally, we demonstrate that the four component approach using functional cyclic anhydrides allows for post-polymerization modification.

A straightforward, environmentally beneficial synthesis of spiro[diindeno[1,2-b:2',1'-e]pyridine-11,3'-indoline]-2',10,12-triones mediated by a nano-ordered reusable catalyst

A library of new spiro[diindeno[1,2-b:2',1'-e]pyridine-11,3'-indoline]-2',10,12-trione derivatives has been prepared in an efficient, one-pot pseudo four-component method mediated by a reusable heterogeneous nano-ordered mesoporous SO3H functionalized-silica (MCM-41-SO3H) catalyst. Excellent yields, short reaction times, as well as convenient non-chromatographic purification of the products and environmental benefits such as green and metal-free conditions constitute the main advantages of the developed synthetic methodology. The obtained fused indole-indenone dyes would be of interest to pharmaceutical and medicinal chemistry. Furthermore, due to their sensitivity to pH changes, they could be used as novel pH indicators.

Engaging Isatins in Multicomponent Reactions (MCRs) - Easy Access to Structural Diversity

Multicomponent reactions (MCRs) are a valuable tool in diversity-oriented synthesis. Its application to privileged structures is gaining relevance in the fields of organic and medicinal chemistry. Isatin, due to its unique reactivity, can undergo different MCRs, affording multiple interesting scaffolds, namely oxindole-derivatives (including spirooxindoles, bis-oxindoles and 3,3-disubstituted oxindoles) and even, under certain conditions, ring-opening reactions occur that leads to other heterocyclic compounds. Over the past few years, new methodologies have been described for the application of this important and easily available starting material in MCRs. In this review, we explore these novelties, displaying them according to the structure of the final products obtained.

Progress, challenges and future directions of heterocycles as building blocks in iterative methodologies towards sequence-defined oligomers and polymers

Heterocyclic building blocks for iterative methodologies leading to sequence-defined oligomers and polymers are reviewed. Solid- as well as solution-phase methods, challenges surrounding these systems and potential future directions are presented.

Cu-Catalyzed four-component polymerization of alkynes, sulfonyl azides, nucleophiles and electrophiles

A four-component polymerization method was reported using diynes, sulfonyl azides, diols, and a variety of electrophiles. Such a strategy facilitated the facile preparation of a series of α-functionalized poly(N-sulfonylimidates)s.

Multicomponent Polymerization for π-Conjugated Polymers

Structurally complex π-conjugated polymers hold great promise as key components in sensor and electronic devices; however, their syntheses have not been a trivial task. From a synthetic efficiency perspective, it would be more attractive to access these materials using convenient and efficient methods from simple building blocks. One such synthetic tool, multicomponent polymerization, can accommodate modularity and provide highly efficient syntheses. This feature article outlines several multicomponent polymerization strategies for the synthesis of various π-conjugated polymers, which are classified based upon how the monomers are aligned during polymerization. Additionally, the challenges and outlooks of this field are highlighted and discussed.

Multicomponent Reactions in Polymer Chemistry Utilizing Heavier Main Group Elements

Herein, a concise overview of the use of heavier main group elements in multicomponent reactions and their use in polymer chemistry is provided. Incorporating heavier elements into macromolecular structures via multicomponent reactions allows for the rapid development of materials with unique properties that are not readily achieved using carbon, nitrogen, and/or oxygen. Elements in Group 13, Group 14, Group 15, and Group 16 are specifically covered examining both the familiar and unfamiliar properties of these elements and how they are used in multicomponent chemistry. Furthermore, elements that both take part in the reaction mechanism and remain in the macromolecular structure upon completion are only briefly explored. Some of the state-of-the-art work going into developing these heavier element multicomponent reactions are highlighted and it is hoped to inspire other polymer chemists to explore other parts of the periodic table.

Antioxidant Polymers via the Kabachnik-Fields Reaction to Control Cellular Oxidative Stress

Small molecular antioxidants are almost ineffective in regulating harmful oxidative stress in vivo because of their poor bioavailability. Polymer antioxidants are a promising alternative to address this issue, but their laborious synthetic routes limit their development. In this study, aliphatic and aromatic aldehydes are used to synthesize a family of polymers containing different α-aminophosphonate pendant groups via a facile one-pot method that combines the Kabachnik-Fields (KF) reaction and free radical polymerization. The structure-property relationship study of these polymers reveals the KF moieties in polymer structures confer radical scavenging ability on polymers. The radical scavenging ability and cytotoxicity of these polymers are evaluated in a stepwise manner to identify a biocompatible polymer antioxidant that can effectively protect the cells from H₂ O₂ -induced oxidative damage. This is the first attempt to develop antioxidative polymers by the KF reaction. It highlights the feasibility of synthesizing new functional polymers using multicomponent reactions, which has important implications for organic and polymer chemistry.

Novel magnetic propylsulfonic acid-anchored isocyanurate-based periodic mesoporous organosilica (Iron oxide@PMO-ICS-PrSO3H) as a highly efficient and reusable nanoreactor for the sustainable synthesis of imidazopyrimidine derivatives

In this study, preparation and characterization of a new magnetic propylsulfonic acid-anchored isocyanurate bridging periodic mesoporous organosilica (Iron oxide@PMO-ICS-PrSO3H) is described. The iron oxide@PMO-ICS-PrSO3H nanomaterials were characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and field emission scanning electron microscopy as well as thermogravimetric analysis, N2 adsorption-desorption isotherms and vibrating sample magnetometer techniques. Indeed, the new obtained materials are the first example of the magnetic thermally stable isocyanurate-based mesoporous organosilica solid acid. Furthermore, the catalytic activity of the Iron oxide@PMO-ICS-PrSO3H nanomaterials, as a novel and highly efficient recoverable nanoreactor, was investigated for the sustainable heteroannulation synthesis of imidazopyrimidine derivatives through the Traube-Schwarz multicomponent reaction of 2-aminobenzoimidazole, C‒H acids and diverse aromatic aldehydes. The advantages of this green protocol are low catalyst loading, high to quantitative yields, short reaction times and the catalyst recyclability for at least four consecutive runs.

Cascade polymerizations: recent developments in the formation of polymer repeat units by cascade reactions

Traditionally, most polymerizations rely on simple reactions such as alkene addition, ring-opening, and condensation because they are robust, highly efficient, and selective. These reactions, however, generally only yield a single new C-C or C-O bond during each propagation step. In recent years, novel macromolecules have been prepared with propagation steps that involve cascade reactions, enabling various combinations of bond making and breaking steps to form more complex repeat units. These polymerizations are often challenging, given the requirements for high conversion and selectivity in controlled polymerizations, yet they provide polymers with unique chemical structures and significantly broaden the scope of how polymers can be made. In this perspective, we summarize the recent developments in cascade polymerizations, primarily focusing on single-component cascades (rather than multi-component polymerizations). Polymerization performance, monomer scope, and mechanisms are discussed for polymerizations utilizing radical, ionic, and metathesis-based mechanisms.