Metallo-supramolecular Polymers Research Articles

25‐4: Electrochromic Display Devices with Metallo‐Supramolecular Polymers

Metallo‐supramolecular polymers (MSPs) show reversible electrochromic (EC) properties by electrochemical redox of metal ions included in the polymers. This presentation introduces recent three research achievements on EC devices (ECDs) using MSPs: (1) fabrication of highly durable ECDs with cycle stability more than 100,000 times, (2) a new electro‐polymerization method of a thin MSP layer on an ITO‐coated glass or PET‐film, and (3) rewritable multicolor EC paper using MSPs.

Triple-Band Electrochromic Switching Among Visible (400–750 nm), NearIR-I (750–1000 nm), and NearIR-II (1000–1600 nm) Regions with Triple-Redox-Active Metallosupramolecular Polymers

Triple-Band Electrochromic Switching Among Visible (400–750 nm), NearIR-I (750–1000 nm), and NearIR-II (1000–1600 nm) Regions with Triple-Redox-Active Metallosupramolecular Polymers

Retrospective Analysis of Structure-Property Relationship of Emergent Metallo-Supramolecular Polymer Networks.

Metallo-supramolecular polymer networks (MSPNs) are fabricated from the crosslinking of polymers by discrete supramolecular coordination complexes. Due to the availability of various coordination complexes, e.g., 2D macrocycles and 3D nanocages, the MSPNs have been recently developed with broadly tuned visco-elasticity and enriched functions inherited from the coordination complexes. The coordination complexes possess enriched topologies and unique structural relaxation dynamics, rendering them the capability to break the traditional tradeoffs of polymer systems for the design of materials with enhanced mechanical performance. The structure-property relationship studies are critical for the material-by-design of MSPNs, while the spatiotemporal investigations are desired for the exploration of dynamics information. The work summarizes recent studies on the unique ligand-exchange kinetics and the multi-level structural relaxation dynamics of MSPNs. The MSPNs' mechanical properties can be quantitatively correlated with the dynamics for understanding the structure-property relationship. This concept will not only serve to attract more researchers to engage in the study of the structure-activity relationship of MSPNs but also inspire innovative research findings pertaining to the application of MSPNs.

An All-In-One Integrating Strategy for Designing Platinum(II)-Based Supramolecular Polymers for Photocatalytic Hydrogen Evolution.

Organic polymer photocatalysts have achieved significant progress in photocatalytic hydrogen evolution, while developing the integrated organic polymers possessing the functions of photosensitizer, electron transfer mediator, and catalyst simultaneously is urgently needed and presents a great challenge. Considering that chalcogenoviologens are able to act as photosensitizers and electron-transfer mediators, a series of chalcogenoviologen-containing platinum(II)-based supramolecular polymers is designed, which exhibited strong visible light-absorbing ability and suitable bandgap for highly efficient photocatalytic hydrogen evolution without the use of a cocatalyst. The hydrogen evolution rate (HER) increases steadily with the decrease in an optical gap of the polymer. Among these "all-in-one" polymers, Se-containing 2D porous polymer exhibited the best photocatalytic performance with a HER of 3.09mmolg-1h-1 under visible light (>420nm) irradiation. Experimental and theoretical calculations reveal that the distinct intramolecular charge transfer characteristics and heteroatom N in terpyridine unit promote charge separation and transfer within the molecules. This work could provide new insights into the design of metallo-supramolecular polymers with finely tuned components for photocatalytic hydrogen evolution from water.

Structure–Activity Relationship and Stimuli-Responsiveness Behavior of Metallosupramolecular Polymers

The widespread discourse on the circular economy has fueled a growing demand for polymeric materials characterized by mechanical robustness, sustainability, renewability, and the ability to mend defects. Such materials can be crafted using dynamic covalent bonds, albeit rarely or more efficiently through noncovalent interactions. Metal–ligand interactions, commonly employed by living organisms to adapt to environmental changes, play a pivotal role in this endeavor. Metallosupramolecular polymers (MSPs), formed through the incorporation of metal–ligand interactions, present a versatile platform for tailoring physicochemical properties. This review explores recent advancements in MSPs achieved through the assembly of (macro)monomers via reversible metal–ligand interactions. Various strategies and pathways for synthesizing these materials are discussed, along with their resulting properties. The review delves into the stimuli-responsive behavior of coordination metal–ligand polymers, shedding light on the impact of the core employed in MSPs. Additionally, it examines the influence of parameters such as solvent choice and counter-ions on the supramolecular assemblies. The ability of these materials to adapt their properties in response to changing environmental conditions challenges the traditional goal of creating stable materials, marking a paradigm shift in material design.

Microwave‐Assisted Quick Synthesis of Ru(II)‐Based Metallosupramolecular Polymer for Improved Electrochromic Properties

Microwave‐Assisted Quick Synthesis of Ru(II)‐Based Metallosupramolecular Polymer for Improved Electrochromic Properties

Microwave‐Assisted Quick Synthesis of Ru(II)‐Based Metallosupramolecular Polymer for Improved Electrochromic Properties

AbstractMetallosupramolecular polymers (MSPs) have reversible electrochromic (EC) characteristics. Transition metal ions and ditopic organic ligands are complexed 1:1 to form MSPs, but the complexation conditions depend on the metal species ions. Herein, a microwave‐assisted (MWA) quick synthesis of a Ru(II)‐based MSP (polyRu–MWA) as a novel preparation method for MSPs is reported. PolyRu–MWA is synthesized under microwave irritation for 60 min using 770 W and 2.45 GHz frequency, whereas a conventionally synthesized Ru(II)‐based MSP (polyRu–CS) is obtained using oil‐bath at 160 °C for 24 h. PolyRu–MWA is found to show much better EC properties than polyRu–CS. A film of polyRu–MWA prepared on an indium tin oxide glass exhibits higher optical contrast (transmittance change, ΔT: 81.39%) than polyRu–CS (67.73%). Coloration efficiency(CE, η) of polyRu–MWA (425.7 cm2 C−1) is also higher than that of polyRu–CS (318.3 cm2 C−1). Interestingly, the charge and discharge current ratio for bleaching and coloring in polyRu–MWA is ≈1.7 times higher than that for polyRu–CS, probably because of the high molecular weight polymer formation in polyRu–MWA. A polyRu–MWA film also displays a longer EC optical memory than polyRu–CS.

Mechanistic Insights into Anion-Induced Electrochromism of Ru(II)-Based Metallo-Supramolecular Polymer.

The metallo-supramolecular polymer (MSP) is considered one of the most promising electrodes for electrochromic devices due to its intrinsically stable redox properties. Nevertheless, despite extensive work focusing on improving the electrochromic and electrochemical properties of MSPs, little experimental evidence exists from in-depth investigations on the anion-induced electrochromism of MSPs. Herein, Ru-based metallo-supramolecular polymer (polyRu) films with excellent electrochromic performance were fabricated through a novel electrochemical deposition method, and the electrochromic mechanism was further understood. The polyRu films possess fast reaction kinetics with a short switching time of 4.0 s (colored) and 2.8 s (bleached) and highly reversible redox properties due to the resulting impacts on the capacitive behaviors (containing surface, near-surface and intercalation pseudo-capacitance) of the perchlorate ions in the electrochromic process. Moreover, the electrochromic degradation of the polyRu films is considered to stem from the numerous nanopores in the film induced by ClO4- transport and the exchange of counter anions from Cl- to ClO4-. In addition, a physical model, revealing the transport of conduction ions and the evolution of the structure and properties of the polyRu film during the electrochromic process, is presented. It is observed that the charge balance of Ru3+ and Ru2+, achieved through the adsorption/desorption of ClO4- on the film, provides electrochromic and electrochemical reversibility to the polyRu film under positive/negative bias. Correspondingly, a transformation from polyRu·(Cl-)2n to polyRu·(ClO4-)x(Cl-)2n-x in the polyRu film is induced by a counter anion exchange from Cl- to ClO4-. Revealing the detailed perchlorate ion transfer kinetics and electrochromic mechanism in this film can offer new insights into the application of metallo-supramolecular polymers in electrochromic devices.

In Situ Film Growth of Metallosupramolecular Polymer via Electropolymerization and Its Application as Electrochromic Film

In Situ Film Growth of Metallosupramolecular Polymer via Electropolymerization and Its Application as Electrochromic Film

Flexible Multicolor Rewritable Paper Coated with Metallosupramolecular Polymers for Electrochromic Printing and Natural Erasing by Humidity

Flexible Multicolor Rewritable Paper Coated with Metallosupramolecular Polymers for Electrochromic Printing and Natural Erasing by Humidity

Highly Durable Electrochromic Devices for More than 100,000 Cycles with Fe(II)-Based Metallo-Supramolecular Polymer by Optimization of the Device Conditions

Highly Durable Electrochromic Devices for More than 100,000 Cycles with Fe(II)-Based Metallo-Supramolecular Polymer by Optimization of the Device Conditions

Rational design of the PEBA2533 mixed matrix membrane containing metallo-supramolecular polymers for efficient CO2/H2 separation

Mixed-matrix membranes (MMMs) are an effective method for overcoming the trade-off limitations of conventional polymeric membranes and are attractive for CO2/H2 separation. However, major challenges remain in achieving high gas separation performance and long-term stability owing to undesirable polymer/filler interfaces. In this study, a novel metallo-supramolecular polymer (F127-Tpy-M) was designed and selected to engineer a polymer/filler interface. Benefiting from strong intermolecular interactions, F127-Tpy-M dispersed well in the PEBA2533 matrix with a defect-free interface. By synergistically combining the dipole–quadrupole effect of the ethylene oxide groups in F127 and gas–metal interactions, MMMs could significantly improve the gas separation performance. In comparison with the pristine membrane, the MMM with 60% F127-Tpy-M loading exhibited 175–194% and 215–259% increases in CO2/H2 selectivity and CO2 permeability, respectively, which far surpass the 2008 Robeson upper bound. The molecular dynamics simulations supported the experimental data, confirming that F127-Tpy-M is a promising candidate for designing next-generation high-performance MMMs.

Metallosupramolecular chains of diazananographene and porphyrin: synthesis, characterization and optical properties

A one-dimensional (1D) metallosupramolecular polymer, consisting of diazananographene (C76N2) and porphyrin cobalt(II) (CoTPP), was synthesized through coordination between pyridinic nitrogen and cobalt (II). Its structure was unambiguously characterized by single crystal X-ray diffraction. Revealed by NMR spectroscopy, this complex in solution still adopted a polymeric structure. The steady and transient absorption spectroscopic measurements of metallosupramolecular polymer indicated fast vibrational relaxation of CoTPP and energy transfer from CoTPP to C76N2.

Structure and Properties of Metallosupramolecular Polymers with a Nitrogen-Based Bidentate Ligand.

The solid-state properties of supramolecular polymers that feature metal-ligand (ML) complexes are, in addition to the general nature of the monomer, significantly affected by the choice of ligand and metal salt. Indeed, the variation of these components can be used to alter the structural, thermal, mechanical, and viscoelastic properties over a wide ranges. Moreover, the dynamic nature of certain ML complexes can render the resulting metallosupramolecular polymers (MSPs) stimuli-responsive, enabling functions such as healing, reversible adhesion, and mechanotransduction. We here report MSPs based on the bidentate ligand 6-(1'-methylbenzimidazolyl) pyridine (MBP), which is easily accessible and forms threefold coordination complexes with various transition metal ions. Thus, a poly(ethylene-co-butylene) telechelic was end-functionalized with two MBP ligands and the resulting macromonomer was assembled with the triflate salts of either Zn2+, Fe2+, or Ni2+. All three MSPs microphase separate and adopt, depending on the metal ion and thermal history, lamellar or hexagonal morphologies with crystalline domains formed by the ML complexes. The melting transitions are well below 200 °C, and this permits facile (re)processing. Furthermore, defects can be readily and fully healed upon exposure to UV-light. While the three MSPs display similar moduli in the rubbery regime, their extensibility and tensile strength depend on the nature of the ML complex, which similarly affects the long-range order and dynamic behavior.

Reversible Electrochromic/Electrofluorochromic Dual Switching in Zn(II)-Based Metallo-Supramolecular Polymer Films.

The introduction of novel materials with multifunctional chromogenic properties, such as electrochromic/electrofluorochromic (EC/EFC) properties, has recently attracted prospective interest in the development of various optoelectronic devices and smart windows. In this study, a novel Zn(II)-based metallo-supramolecular polymer (polyZn) has been developed as an ON/OFF switchable EFC application with prominent EC behavior. In this regard, the polymeric chain of polyZn was first synthesized by 1:1 complexation in a zigzag manner with Zn(II) ions at the metal center and 4,4'-[bis(2,2':6',2″-terpyridinyl)benzene]triphenylamine (LTPY-TPA) as the redox-active ditopic ligand. The polyZn exhibits excellent solubility in organic solvents and can form a very good uniform thin film on an indium tin oxide/glass substrate by spin-coating. In a neutral state, transparent polyZn exhibits a bright yellow color to the naked eye (absorption at ∼325 nm). The electroactive triphenylamine (TPA) core of LTPA-TPY, however, undergoes reversible single-electron oxidation when a positive bias of +1.6 V vs Ag/Ag+ is applied, generating radical cations (TPA ↔ TPA•+) with a significant drop in transparency (77%). A noticeable chromic shift in the hue of the film from brilliant yellow to green was observed with the appearance of a near-infrared absorption band at ∼897 nm with a tail of 1300-1600 nm. Interestingly, in addition to this EC phenomenon, the fabricated solid-state polyZn film exhibits intense, high-contrast reddish-orange photoluminescence with λem = 650 nm, which is significantly desired as a molecular probe for bioimaging. Both the TPA core and the redox-inactive Zn(II)-terpyridine core emit orange-red photoluminescence in polyZn, which is significantly quenched upon the oxidation of the film and is re-emitted at 0.0 V vs Ag/Ag+. This ON/OFF EFC transition was sustained for several cycles. This study should motivate to design and create distinctive new unique materials with combined EC/EFC behavior for the fabrication of optoelectronic devices by combining a metal-fluorescent core with a redox-active spacer.

Flexible Multicolor Rewritable Paper Coated with Metallosupramolecular Polymers for Electrochromic Printing and Natural Erasing by Humidity

Flexible Multicolor Rewritable Paper Coated with Metallosupramolecular Polymers for Electrochromic Printing and Natural Erasing by Humidity

Introducing non-conjugated ionic spacer in metallo-supramolecular polymer: Generation of nanofibers for high-performance electrochromic supercapacitor

The use of indicative electrochromic (EC) supercapatteries is gaining significant attention for their ability to indicate their charging and discharging status through optical color changes and their high energy and power densities, making them a promising renewable alternative energy source. In this study, we performed molecular engineering to prepare a non-conjugated pyridinium cation-containing bisterpyridine ligand (TpyNTpy) and its metallo-supramolecular polymer (MSP), Fe-TpyNTpy. The MSP was thoroughly characterized through spectroscopic, morphological, and structural studies, revealing a homogeneous nanofiber morphology with good thermal stability. The gel-state EC devices, fabricated using Fe-TpyNTpy as the active layer, demonstrated EC color changes from purple to dirty white, with a large optical contrast of 47% at 570 nm, fast coloration (1.5 s) and bleaching (2.4 s) times, high coloration efficiency of 312.8 cm2C-1, longer optical memory, and extremely high EC cycle stability. Incorporating nonconjugated and ionic ligands helped address the opposite electrochemical behaviors, such as EC fastness and optical memory. The Fe-TpyNTpy film showed good supercapacitive properties in solution electrolytes, and the energy storage behavior was correlated with EC transmittance/color change. The energy storage properties were evaluated by preparing a hybrid ESD. The Fe-TpyNTpy and Prussian blue containing hybrid ESD exhibited an improved volumetric capacitance of 73 ± 2F/cm3 with low iR drop, high energy storage capacity (energy density 61 mWh/cm3 at a power density of 8.5 W/cm3), and 95% retention of initial volumetric capacitance after 10,000 charge–discharge cycles. The hybrid ESD can illuminate a single LED, demonstrating the practical applicability of the ESD.

Landscape of Network Connectivity in Transient Polymer Networks with Competing Homo- and Hetero-complementary Bonds

Polymer networks expose a wide range of mechanical properties depending on their microstructure and connectivity. Specifically, transient networks based on end-linking of mixed telechelic polymer precursors capable of forming competing homo- and hetero-complementary bonds demonstrate a wide range of network structures and consequently mechanical properties depending on the composition and reactivity of employed precursors. To address this gap, the Miller–Macosko’s recursive model is extended to tetra-arm polymer precursors capable of forming homo- and hetero-complementary bonds. As such, the composition and time evolution of n-fold network connectivities are visualized as a function of precursor composition and bond selectivity. The model potential is highlighted by confronting its predictions with the rheological behavior of transient metallo-supramolecular polymer networks (MSPNs) obtained by mixing tetra-arm poly(ethylene glycol) functionalized with either sterically demanding mesitylene-substituted phenanthroline or unsubstituted slim phenanthroline or terpyridine ligands. The former precursor is incapable of homoleptic complexation; however, in combination with the latter two, they can form a mixture of homo- and heteroleptic complexes, depending on the coordination geometry preference of the utilized metal ion. These results not only visualize the connectivity landscape that can be explored in transient polymer networks, even beyond MSPNs, but can also provide a selectivity index for competing transient bonds based on rheological properties.

Stimuli-Responsive Self-Healing Luminescent Materials Based on Lanthanide Ions and Bipyridine Moieties

Contemporary, luminescent materials possessing rapid stimulus-responsive characteristics demonstrate considerable potential in anti-counterfeiting applications. However, if anti-counterfeiting materials become damaged during use, the integrity of the information will be compromised. Consequently, endowing materials with self-healing ability can ensure the accuracy and integrity of anti-counterfeiting data. In this study, a luminescent metallo-supramolecular polymer is synthesized through the coordination of lanthanide ions (Ln3+) and bipyridine ligands within polyurethane (PU) chains. The PU elastomers created using 4,4′-dicyclohexylmethane diisocyanate display remarkable transmittance and hydrophobic properties following coordination with Ln3+. The dynamic Ln–N coordination imparts self-healing behavior and robust mechanical performance to the PU elastomers. The “antenna effect” imbues the resulting materials with exemplary luminescent properties, and the emission color can be conveniently modulated by adjusting the Eu3+/Tb3+ ratio. Importantly, all luminescent materials exhibit a rapid stimulus-response to acid-base fluctuations through the disruption or restoration of the “antenna effect” between Ln3+ and bipyridine, a critical aspect for the advancement of materials in the anti-counterfeiting and information encryption domains.

Multi-chiral materials comprising metallosupramolecular and covalent helical polymers containing five axial motifs within a helix

Supramolecular and covalent polymers share multiple structural effects such as communication mechanisms among monomer repeating units, which are related to their axial helical structure. Herein, a unique multi-helical material combining information from both metallosupramolecular and covalent helical polymers is presented. In this system, the helical structure described by the poly(acetylene) (PA) backbone (cis-cisoidal, cis-transoidal) guides the pendant groups in a fashion where a tilting degree emerges between a pendant and the adjacent ones. As a result, a multi-chiral material is formed comprising four or five axial motifs when the polyene skeleton adopts either a cis-transoidal or cis-cisoidal configuration: the two coaxial helices—internal and external—and the two or three chiral axial motifs described by the bispyridyldichlorido PtII complex array. These results show that complex multi-chiral materials can be obtained by polymerizing appropriate monomers that combine both point chirality and the ability to generate chiral supramolecular assemblies.