Metal-Containing Polymers as Light-Emitting and Light-Responsive Materials and Beyond

Terpyridine-Decorated Polymer Nanosphere Latex: Template Nanocarriers for the Synthesis of Cu-CeO2 Hollow Spheres

Water-soluble polymers with the ability to complex metal ions through complexing ligands have attracted significant interest in diverse domains, such as optical or catalyst applications. In this paper, we successfully synthesized, through a one-pot process combining polymerization-induced self-assembly and reversible addition-fragmentation chain transfer polymerization, aqueous dispersions of terpyridine-decorated poly[poly(ethylene glycol)methyl ether methacrylate]-b-poly(methyl methacrylate) (tpy-PPEGMA-b-PMMA) amphiphilic block copolymers. The in-situ formation of well-defined amphiphilic block copolymers and their self-assembly led to nanosphere latex with the hydrodynamic diameters increasing from 17 to 52 nm and the length of the copolymers increasing from 21,000 to 51,000 g·mol-1. These aqueous dispersed tpy-PPEGMA-b-PMMA nanospheres effectively complex metal ions, such as Cu2+, in a stoichiometric ratio of 2:1. Subsequently, these metal-complexed nanospheres were employed as soft template nanocarriers to control, on the nanometer scale, the dispersion of metal on a nanostructured support. This is exemplified by the synthesis of copper supported on cerium oxide hollow spheres (Cu-CeO2) using Cu2+-tpy-PPEGMA-b-PMMA as template nanocarriers and CeO2 nanoparticles. This novel assembly engineering strategy for the preparation of atomically dispersed metal on a nanostructured support was highlighted through the utilization of Cu-CeO2 hollow spheres as an electrocatalyst for the nitrate reduction reaction (NO3RR) to NH3. These encouraging outcomes emphasize the potential of metal-metal oxide-nanostructured materials to treat contaminated water sources with nitrate while allowing the green production of ammonia.

Barbier single-atom polymerization induced emission as a one-pot approach towards stimuli-responsive luminescent polymers

A one-pot strategy for the design of stimuli-responsive luminescent polymers has been demonstrated through Barbier PIE, where the N,N-dimethyl moiety endows the polymers with both stimuli-responsive and red-shifted nonconjugated emission properties.

Synthesis and Characterization of Metallo-Supramolecular Polymers Based on Benzodipyrrolidone

A simple route to the preparation of benzodipyrrolidone (BDP) based monomeric building blocks containing 2,2':6',2″-terpyridines is reported from a common precursor 4'-(4-pinacolatoboronphenyl)-2,2':6',2″-terpyridine via Suzuki coupling reaction. Self-assembly polymerization with ruthenium (II) ions under mild conditions yielded a series of novel metallo-supramolecular polymers with weak donor-acceptor (D-A) structures based on benzodipyrrolidone. The structure of the bridge connected BDP with terpyridine have a significant impact on the wavelength and intensity of the intramolecular charge transfer (ICT) absorption peak. The resulting metallo-polymers exhibited strong double absorption bands around 315 nm and 510 nm involved in π-π* transitions and ICT or metal to ligand charge transfer (MLCT) absorption bands. The forming of D-A structure and coordination with ruthenium (II) ions is favorable to narrow the energy gap and the energy gaps of the resulting metallo-supramolecular polymers are 2.01 and 1.62 eV, respectively.

Syntheses, characterization, multi-acid fluorescence sensing and electroluminescence properties of Cr(ii)-based metallopolymers

Cr(ii)-Based multifunctional fluorescent metallopolymers with different degrees of backbone rigidity were synthesized and applied as multi-acid sensors and electroluminescent ON–OFF switches.

Recent advances in metallopolymer-based drug delivery systems

Metallopolymers (MPs) or metal-containing polymers have shown great potential as new drug delivery systems (DDSs) due to their unique properties, including universal architectures, composition, properties and surface chemistry. Over the past few decades, the exponential growth of many new classes of MPs that deal with these issues has been demonstrated. This review presents and assesses the recent advances and challenges associated with using MPs as DDSs. Among the most widely used MPs for these purposes, metal complexes based on synthetic and natural polymers, coordination polymers, metal-organic frameworks, and metallodendrimers are distinguished. Particular attention is paid to the stimulus- and multistimuli-responsive metallopolymer-based DDSs. Of considerable interest is the use of MPs for combination therapy and multimodal systems. Finally, the problems and future prospects of using metallopolymer-based DDSs are outlined. The bibliography includes articles published over the past five years.

Advances in self-healing supramolecular soft materials and nanocomposites

The ability to rationally tune and add new end-groups in polymers can lead to transformative advances in emerging self-healing materials. Self-healing networks manipulated by supramolecular strategies such as hydrogen bonding and metal coordination have received significant attention in recent years because of their ability to extend materials lifetime, improve safety and ensure sustainability. This review describes the recent advancements in supramolecular polymers self-healing networks based on hydrogen bonding, metal-containing polymers and their nanocomposites. Collectively, the aim of this review is to provide a panoramic overview of the conceptual framework for the interesting nexus between hydrogen bonding and metal-ligand interactions for enabling supramolecular self-healing soft materials networks and nanocomposites. In addition, insights on the current challenges and future perspectives of this field to propel the development of self-healing materials will be provided.

Synthesis and Reactivity of Metallocarbene-Containing Polymers

Metallopolymers are an emerging class of materials with potential utility as semiconductors, catalysts, optical device components, and stimuli responsive networks. While polymer frameworks have been decorated with an array of organometallic moieties, the incorporation of metallocarbenes has been largely overlooked. Here, we report ring-opening metathesis polymerization as a strategy for the synthesis of Fischer carbene-containing polymers. High degrees of polymerization were observed (>800 repeats), and the isolated materials exhibited exceptional solubility and thermal stability. The tungsten carbene subunits were readily incorporated into block copolymers and could be modified through subsequent transformations. Moreover, the metallocarbene polymers were found to release carbon monoxide upon exposure to light or oxygen, which is unusual for tungsten carbene complexes. These metallocarbene-containing polymers could represent new platforms for the development of functional materials.

Chiral Self-Sorting Process with Ditopic Ligands: Alternate or Block Metallopolymer Assembly as a Function of the Metal Ion

We report an extensive study on the coordination behavior of chiral ditopic bridging ligands, which lead to metallosupramolecular polymers in the presence of Zn(II) and Cu(II) in solution. With the help of UV-vis and circular dichroism spectroscopies, we show that the metallopolymer sequence can be controlled by chirality and by the choice of the metal ion. Although the formation of a block metallopolymer proceeds through the assembly of homoleptic complexes, an alternate metallopolymer may be obtained only when heteroleptic complexes are formed. This demonstrates how the prevalent coordination geometries at metal centers may be used to control the sequences of the metallopolymers.

Infinite coordination polymer networks: metallogelation of aminopyridine conjugates and in situ silver nanoparticle formation

Herein we report silver(i) directed infinite coordination polymer network (ICPN) induced self-assembly of low molecular weight organic ligands leading to metallogelation. Structurally simple ligands are derived from 3-aminopyridine and 4-aminopyridine conjugates which are composed of either pyridine or 2,2'-bipyridine cores. The cation specific gelation was found to be independent of the counter anion, leading to highly entangled fibrillar networks facilitating the immobilization of solvent molecules. Rheological studies revealed that the elastic storage modulus (G') of a given gelator molecule is counter anion dependent. The metallogels derived from ligands containing a bipyridine core displayed higher G' values than those with a pyridine core. Furthermore, using single crystal X-ray diffraction studies and ¹H-¹⁵N two-dimensional (2D) correlation NMR spectroscopy, we show that the tetracoordination of silver ions enables simultaneous coordination polymerization and metallosupramolecular cross-linking. The resulting metallogels show spontaneous, in situ nanoparticle (d < 2-3 nm) formation without any additional reducing agents. The silver nanoparticle formation was followed using spectroscopic studies, and the self-assembled fibrillar networks were imaged using transmission electron microscopy (TEM) imaging.

A 3D electropolymerized thin film based on a thiophene-functionalized Ru(ii) complex: electrochemical and photoelectrochemical insights

A 3D electropolymerized Ru(ii) complex film exhibited a rapid redox reaction and an oxygen reduction enhanced photocurrent which increased by 1.5 fold to 2.3 μA cm⁻².

Gel-based soft actuators driven by light

Gels that display light-induced motile, life-like actions are reviewed and their potential applications as light-driven soft actuators are also discussed.