Warm/cool-tone switchable thermochromic material for smart windows by orthogonally integrating properties of pillar[6]arene and ferrocene

Highly Potent Transparent Passive Cooling Coating via Microphase-Separated Hydrogel Combining Radiative and Evaporative Cooling

Transparent passive cooling materials can cool targets environmentally without interfering with light transmission or visual information reception. They play a prominent role in solar cells and flexible display cooling. However, achieving potent transparent cooling remains challenging, because light transmission is accompanied by thermal energy. Here we propose to realize effective passive cooling in transparent materials via a microscale phase separation hydrogel film. The poly(N-isopropylacrylamide-co-acrylamide) hydrogel presents light transmittance of >96% and infrared emissivity as high as 95%. The microphase-separated structure affords a higher enthalpy of evaporation. The film is highly adhesive. In field applications, it reduces temperatures by 9.14 °C compared to those with uncovered photovoltaic panels and 7.68 °C compared to those for bare flexible light-emitting diode screens. Simulations indicate that energy savings of 32.76-51.65 MJ m-2 year-1 can be achieved in typical tropical monsoon climates and temperate continental climates. We expect this work to contribute to energy-efficient materials and a carbon-neutral society.

Synthesis and Inclusion Properties of a β-Cyclodextrin Heptaphosphoramidate

In this study, we report a novel per-6-substituted β-cyclodextrin (4) featuring seven phosphoramidate moieties as an innovative host for inclusion. This structurally well-defined host has remarkable water solubility and was isolated in pure form. Analytical techniques such as NMR and ITC were used to probe the molecular interactions with different drug molecules. Our investigations revealed that host 4 can form 2:1 inclusion complexes with various drugs. Further studies showed that the inclusions of drugs by β-CD host (4) are mostly enthalpy driven, highlighting the potential roles played by the phosphoramidate functionalities of the host. Comparatively, a per-O2, O3-acetylated analog (6) of compound 4 was also obtained, which also shows unusual water solubility but diminished inclusion capability.

Optical Phenomena in Molecule-Based Magnetic Materials

Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes. Among them, the broadest attention was devoted to molecule-based ferro-/ferrimagnets, spin transition materials, including those exploring electron transfer, molecular nanomagnets, such as single-molecule magnets (SMMs), molecular qubits, and stimuli-responsive magnetic materials. Their physical properties open the application horizons in sensors, data storage, spintronics, and quantum computation. It was found that various optical phenomena, such as thermochromism, photoswitching of magnetic and optical characteristics, luminescence, nonlinear optical and chiroptical effects, as well as optical responsivity to external stimuli, can be implemented into molecule-based magnetic materials. Moreover, the fruitful interactions of these optical effects with magnetism in molecule-based materials can provide new physical cross-effects and multifunctionality, enriching the applications in optical, electronic, and magnetic devices. This Review aims to show the scope of optical phenomena generated in molecule-based magnetic materials, including the recent advances in such areas as high-temperature photomagnetism, optical thermometry utilizing SMMs, optical addressability of molecular qubits, magneto-chiral dichroism, and opto-magneto-electric multifunctionality. These findings are discussed in the context of the types of optical phenomena accessible for various classes of molecule-based magnetic materials.

Gelatin-based biomaterials and gelatin as an additive for chronic wound repair

Disturbing or disrupting the regular healing process of a skin wound may result in its progression to a chronic state. Chronic wounds often lead to increased infection because of their long healing time, malnutrition, and insufficient oxygen flow, subsequently affecting wound progression. Gelatin-the main structure of natural collagen-is widely used in biomedical fields because of its low cost, wide availability, biocompatibility, and degradability. However, gelatin may exhibit diverse tailored physical properties and poor antibacterial activity. Research on gelatin-based biomaterials has identified the challenges of improving gelatin's poor antibacterial properties and low mechanical properties. In chronic wounds, gelatin-based biomaterials can promote wound hemostasis, enhance peri-wound antibacterial and anti-inflammatory properties, and promote vascular and epithelial cell regeneration. In this article, we first introduce the natural process of wound healing. Second, we present the role of gelatin-based biomaterials and gelatin as an additive in wound healing. Finally, we present the future implications of gelatin-based biomaterials.

Responsive Supramolecular Polymers for Diagnosis and Treatment

Stimuli-responsive supramolecular polymers are ordered nanosized materials that are held together by non-covalent interactions (hydrogen-bonding, metal-ligand coordination, π-stacking and, host-guest interactions) and can reversibly undergo self-assembly. Their non-covalent nature endows supramolecular polymers with the ability to respond to external stimuli (temperature, light, ultrasound, electric/magnetic field) or environmental changes (temperature, pH, redox potential, enzyme activity), making them attractive candidates for a variety of biomedical applications. To date, supramolecular research has largely evolved in the development of smart water-soluble self-assemblies with the aim of mimicking the biological function of natural supramolecular systems. Indeed, there is a wide variety of synthetic biomaterials formulated with responsiveness to control and trigger, or not to trigger, aqueous self-assembly. The design of responsive supramolecular polymers ranges from the use of hydrophobic cores (i.e., benzene-1,3,5-tricarboxamide) to the introduction of macrocyclic hosts (i.e., cyclodextrins). In this review, we summarize the most relevant advances achieved in the design of stimuli-responsive supramolecular systems used to control transport and release of both diagnosis agents and therapeutic drugs in order to prevent, diagnose, and treat human diseases.

Thermochromic Hydrogels with Opaque-Transparent Gradient Transition for Switchable Window and Temperature Monitor

In recent years, the thermochromic hydrogel was acted as suitable sandwiching material to adjust light transmission. However, to accurately control the thermochromic temperature in a wide range still was a significant challenge. Here, a simple method was explored to prepare hydrogels with gradient opaque-transparent transition thermochromic temperature from 5 °C to 53 °C, which was regulated by the aggregation state of sodium dodecyl sulfate micelles by adding potassium tartrate hemihydrate and cations. Using Li+ , Na+ , and K+ as cations, the accuracy was controlled at 1 °C. Moreover, the transmittance of the hydrogel was not changed when the thermochromic temperature was adjusted. As a result, an intelligent window was fabricated by utilizing thermochromic hydrogel as a sandwiching layer into the outer glass layers, which could effectively and stably regulate the visible and infrared light. The temperature monitors/detectors were also designed, which showed excellent temperature monitoring/detecting ability. Therefore, this low-cost, high-efficient, large-scale prepared thermochromic hydrogel provided more potential for intelligent temperature devices.

Thermosensitive Scattering Hydrogels Based on Triblock Poly-Ethers: A Novel Approach to Solar Radiation Regulation

Energy conservation in buildings is paramount, especially considering that glass accounts for 50% of energy consumption. The solar heat gain coefficient (SHGC) of glass is a critical energy-saving index for transparent structures. However, the fixed SHGC of ordinary glass makes it difficult to provide both summer shading and winter heating. In this study, we synthesized a hydrogel with a thermosensitive scattering (TS) property using triblock polyether and acrylamide. This hydrogel can realize the transition of clearness and atomization based on the temperature. When sealed within a glass cavity, it exhibits a high SHGC of 0.682 in its transparent state and a low SHGC of less than 0.31 when atomized. The lower critical solution temperature (LCST) of the TS glass can be adjusted from 0 to 70 °C to suit different regions. The photothermal properties of the material remained stable after 200 hot and cold cycles and 200 h of ultraviolet irradiation. This glass can prevent solar radiation from entering the room in summer, thereby reducing air conditioning usage and power consumption. In winter, it allows solar heat radiation to enter the room, minimizing the need for artificial heating. Its adaptable temperature design makes it an excellent solution for designers to create energy-efficient building exteriors.

Ferrocene: an exotic building block for supramolecular assemblies

Ferrocene (Fc), a classical organometallic complex, has found potential applications in ligand design, catalysis, and analytical, biological, medicinal and materials chemistry. In recent years, the use of Fc as a building block in supramolecular chemistry has emerged. The molecular shape, size, and hydrophobicity of Fc make it an ideal guest for a variety of macrocyclic host molecules to form stable host-guest complexes. The vertical distance (3.3 Å) between two cyclopentadienyl rings and molecular "ball bearing" property in Fc support the formation of intramolecular π-π stacking, H-bonding and metallophilic interactions between two appropriate substituents in 1,n'-disubstituted ferrocenes. Along with these molecular features, the rigidity along with rotational flexibility, redox reversibility and oxidation-triggered tunable hydrophobicity of Fc have led to its use as an exotic building block for the development of a wide range of supramolecular assemblies such as smart molecular receptors, intricate metal-organic assemblies, supramolecular polymers, and gels including out-of-equilibrium assemblies and metal nanoparticle assemblies. This review highlights the concepts behind the design and development of these assemblies, where the Fc unit has a direct and defined role in their formation and function. The use of Fc in supramolecular assembly is still a relatively young field and set to be the subject of increasing research interest towards the development of fascinating supramolecular structures with tailored properties and programmable functions towards applications in materials and biological sciences.

Water-soluble pillar[6]arene bearing pyrene on alternating methylene bridges for direct spermine sensing

This paper describes the design and synthesis of a conjugate, which is composed of a percarboxylated water-soluble pillar[6]arene and three fluorescent pyrene chromophores on alternating methylene bridges. The optical characteristics are investigated. This conjugate is capable of encapsulating polycationic guest spermine, which results in an enhancement in the fluorescence intensity of pyrene. This host-pyrene conjugate is used for direct sensing of spermine, which shows selectivity towards a variety of biological analytes. The detection of spermine is demonstrated in live cells.

A polyacrylamide gel containing an engineered hexameric hemoprotein as a cross-linking unit toward redox-responsive materials

Hydrogels containing synthetic polymers and supramolecular cross-linking units are expected to exhibit unique functions and properties. The heme-heme pocket interaction in hemeproteins may be useful for development of a cross-linking unit because heme binding depends on the redox states of the iron center. In this work, hexameric tyrosine-coordinated hemoprotein (HTHP) is employed as a cross-linking unit in a polyacrylamide gel to create redox-responsive hydrogels. First, redox-dependent stability of the heme-heme pocket interaction in HTHP was evaluated, and it was found that the heme affinity dramatically decreases in the Fe(ii) state. Second, the polymerization of acrylamide and engineered HTHP possessing acryloyl group-tethering heme moieties provided a polyacrylamide gel containing HTHP as a cross-linking unit. A reduction-triggered gel-sol transition in the presence of apomyoglobin was observed. Furthermore, the mechanical properties of the gels containing the engineered HTHP and methylene bisacrylamide were evaluated by a tensile test, and the Young's modulus value was determined to be 14 kPa, which is higher than that of the control gel containing only methylene bisacrylamide (8.5 kPa). Compression tests of the gels revealed redox-responsive mechanical behavior, resulting in a decrease in the compressive modulus upon the addition of a reductant. This behavior is qualitatively consistent with the redox-responsive heme binding of HTHP in a solution state. This finding is expected to contribute to the development of redox-responsive materials for biomedical and biological applications.

Direct Conversion of Phase-Transition Entropy into Electrochemical Thermopower and the Peltier Effect

A thermocell generates thermopower from a temperature difference (ΔT) between two electrodes. The converse process of thermocells is an electrochemical Peltier effect, which creates a ΔT on the electrodes by applying an external current. The Seebeck coefficient (Se ) of the electrochemical system is proportional to the entropy change of the redox reaction; therefore, a redox system having a significant entropy change is expected to increase the Se . In this study, a thermoresponsive polymer having a redox-active moiety, poly(N-isopropyl acrylamide-co-N-(2-acrylamide ethyl)-N'-n-propylviologen) (PNV), is used as the redox species of a thermocell. PNV2+ dication undergoes the coil-globule phase transition upon the reduction to PNV+ cation radical, and a large entropy change is introduced because water molecules are freed from the polymer chains. The Se of PNV thermocell drastically increased to +2.1 mV K-1 at the lower critical solution temperature (LCST) of PNV. The entropy change calculated from the increment of Se agrees with the value evaluated by differential scanning calorimetry. Moreover, the electrochemical Peltier effect is observed when the device temperature is increased above the LCST. This study shows that the large entropy change associated with the coil-globule phase transition can be used in electrochemical thermal management and refrigeration technologies.

Nanowire-based smart windows combining electro- and thermochromics for dynamic regulation of solar radiation

Smart window is an attractive option for efficient heat management to minimize energy consumption and improve indoor living comfort owing to their optical properties of adjusting sunlight. To effectively improve the sunlight modulation and heat management capability of smart windows, here, we propose a co-assembly strategy to fabricate the electrochromic and thermochromic smart windows with tunable components and ordered structures for the dynamic regulation of solar radiation. Firstly, to enhance both illumination and cooling efficiency in electrochromic windows, the aspect ratio and mixed type of Au nanorods are tuned to selectively absorb the near-infrared wavelength range of 760 to 1360 nm. Furthermore, when assembled with electrochromic W₁₈O₄₉ nanowires in the colored state, the Au nanorods exhibit a synergistic effect, resulting in a 90% reduction of near-infrared light and a corresponding 5 °C cooling effect under 1-sun irradiation. Secondly, to extend the fixed response temperature value to a wider range of 30-50 °C in thermochromic windows, the doping amount and mixed type of W-VO₂ nanowires are carefully regulated. Last but not the least, the ordered assembly structure of the nanowires can greatly reduce the level of haze and enhance visibility in the windows.

A novel nonreversible heat-induced low-molecular-weight gel based on naturally-occurring self-assembled fupenzic acid for tumor therapy

Herein, a nonreversible heat-induced supramolecular gel based on natural products was reported for the first time. This natural triterpenoid, fupenzic acid (FA), isolated from the roots of Rosa laevigata, was discovered to be capable of forming supramolecular gel spontaneously in 50 % ethanol-water solution induced by heating. Distinguished from the common thermosensitive gels, the FA-gel showed a distinctive nonreversible phase transition from the liquid to gel state upon heating. In this work, the entire gelation process of FA-gel induced by heating was recorded digitally by microrheology monitor. And a unique heat-induced gelation mechanism based on self-assembled FA has been proposed by using various experimental methods and molecular dynamics (MD) simulation. Its excellent injectability and stability were also demonstrated. Furthermore, the FA-gel had been evaluated to exhibit better anti-tumor activity and higher biosafety comparing with its equivalent free-drug, which opened up a new possibility to reinforce antitumor efficacy by using natural product gelator originated from traditional Chinese medicine (TCM) without any complicated chemical modifications.

Self-Adhesive Self-Healing Thermochromic Ionogels for Smart Windows with Excellent Environmental and Mechanical Stability, Solar Modulation, and Antifogging Capabilities

Current thermochromic materials used in smart windows still face challenges, such as poor mechanical and environmental stability, unsatisfactory solar modulation capacity, and low transparency. Herein, the first self-adhesive self-healing thermochromic ionogels with excellent mechanical and environmental stability, antifogging capability, transparency, and solar modulation capability by loading binary ionic liquids (ILs) into rational-designed self-healing poly(urethaneurea) with acylsemicarbazide (ASCZ) moieties that have reversible and multiple hydrogen bonds are reported and their feasibility as smart windows with reliability and long service life is demonstrated. The self-healing thermochromic ionogels can switch between transparent and opaque without leakage or shrinkage, by the constrained reversible phase separation of ILs within the ionogels. The ionogels have the highest transparency and solar modulation capability among reported thermochromic materials and such excellent solar modulation capability can be well maintained after undergoing 1000 transitions, stretches, and bends, and storage at -30 °C, 60 °C, 90% RH, and vacuum environment for 2 months. The formation of high-density hydrogen bonds among the ASCZ moieties contributes to the excellent mechanical strength of the ionogels and allows the thermochromic ionogels to spontaneously heal their damages and be fully recycled at room temperature without the loss of thermochromic capabilities.

Printable Thermochromic Hydrogel-Based Smart Window for All-Weather Building Temperature Regulation in Diverse Climates

Thermochromic smart windows are widely developed to modulate building energy exchange to save building energy consumption. However, most smart windows have fixed working temperatures, moderate energy-saving efficiency, and are not suitable for diverse (cold and hot) climates. Here smart windows with strong temperature modulation over a broad range of hydrogels with adjustable transition temperatures for all-weather building temperature regulation in different climates are reported. Thermochromic poly(N-isopropylacrylamide-co-N, N-dimethylacrylamide) hydrogels, with lower critical transition temperatures ranging from 32.5 to 43.5 °C, are developed for smart windows with solar modulation up to 88.84% and intrinsic transmittance up to 91.30% over full spectrum without energy input. Simulated indoor investigations are performed in different cities from 23 °N to 39 °N from winter to summer. The results indicate that smart windows have a strong solar modulation in summer to reduce indoor temperature up to 7.3 °C and efficient heat conservation in winter to save energy up to 4.30 J m^-3 , in comparison to glass windows. Smart windows with grid patterns and Chinese kirigami are fabricated by using 3D printing of the hydrogels to achieve both solar modulation and light incidence. The strategy offers an innovative path for thermochromic smart windows for low carbon economy.

Thermochromic Energy Efficient Windows: Fundamentals, Recent Advances, and Perspectives

Thermochromic energy efficient windows represent an important protocol technology for advanced architectural windows with energy-saving capabilities through the intelligent regulation of indoor solar irradiation and the modulation of window optical properties in response to real-time temperature stimuli. In this review, recent progress in some promising thermochromic systems is summarized from the aspects of structures, the micro-/mesoscale regulation of thermochromic properties, and integration with other emerging energy techniques. Furthermore, the challenges and opportunities in thermochromic energy-efficient windows are outlined to promote future scientific investigations and practical applications in building energy conservation.

High Mechanical Strength and Multifunctional Microphase-Separated Supramolecular Hydrogels Fabricated by Liquid-Crystalline Block Copolymer

The development of multifunctional supramolecular hydrogels with high mechanical strength and multifunction is in high demand. In this work, the diblock copolymer poly(acrylamide-co-1-benzyl-3-vinylimidazolium bromide)-block-polyAzobenzene is synthesized through reversible addition-fragmentation chain transfer polymerization. The dynamic host-guest interactions between the host molecule cucurbit[8] uril and guest units are used to fabricate a 3D network of supramolecular hydrogels. Investigations on the properties of the supramolecular hydrogels show that the tensile stress of the sample is 1.46 MPa, eight times higher than that of hydrogel without liquid-crystalline block copolymer, and the self-healing efficiency of the supramolecular hydrogels at room temperature is 88.3% (fracture stress) and 100% (fracture strain) after 24 h. Results show that microphase-separated structure plays a key role in the high-strength hydrogel, whereas the host-guest interaction endows the hydrogel with self-healing properties. The supramolecular hydrogels with high mechanical strength, photo-responsivity, injectability, and biocompatibility can be used in various potential applications.

Handcuff-like metallo-pseudorotaxanes consisting of tiara[5]arene wheels and dimeric silver trifluoroacetate axles

The complexation between tiara[5]arene (T[5]) and silver trifluoroacetate affords a binuclear metallo-pseudorotaxane on account of multiple endo-cavity Ag^I η²-arene interactions. Furthermore, two such enantiomeric [(CF₃CO₂Ag)₂⊂T[5]] complexes are bridged by an extra (CF₃CO₂Ag)₂ dimer through exo-wall Ag^I η²-arene coordination, resulting in a unique handcuff metallo-bis-pseudorotaxane structure in the solid state.

Covalently bridged pillararene-based polymers: structures, synthesis, and applications

Covalently bridged pillararene-based polymers (CBPPs) are a special class of macrocycle-based polymers in which multiple pillararene monomers are attached to the polymer structures by covalent bonds. Owing to the unique molecular structures including the connection components or the spatial structures, CBPPs have become increasingly popular in applications ranging from environmental science to biomedical science. In this review, CBPPs are divided into three types (linear polymers, grafted polymers, and cross-linked polymers) according to their structural characteristics and described from the perspective of synthesis methods comprehensively. In addition, the applications of CBPPs are presented, including selective adsorption and separation, fluorescence sensing and detection, construction of supramolecular gels, anticancer drug delivery, artificial light-harvesting, catalysis, and others. Finally, the current challenging issues and comprehensive prospects of CBPPs are discussed.

Introduction of Ferrocene as a Facilitator for the Construction of Supramolecular Polymers

Proper monomer design is the key to enhancing the strength of noncovalent interactions between the molecules toward the efficient formation of supramolecular polymers (SPs). We have designed and synthesized 1,n'-disubstituted ferrocene-azobenzene-long alkyl chains, Fc(CONH-Azo-TDP)₂ , to afford SPs with a high probability. The design exploits the ''molecular ball-bearing'' property of the ferrocene core, which allows two azobenzene arms to rotate in the planes of cyclopentadienyl rings, generating the most suitable molecular conformation required for SP formation. This ferrocene monomer formed a supergel consisting of SPs supported by strong intermolecular (H-bonding and π-π stacking) interactions and higher enthalpy gain than the reference molecules, where the central ferrocene core was replaced by flexible aliphatic as well as rigid benzene linkers. The molecular conformation involved in SPs, the strength of noncovalent interactions, and the process of supramolecular polymerization were investigated through NMR, UV-Vis, XRD and TEM studies. The results demonstrate that ferrocene may act as a good modulator for constructing efficient SPs.

Dual-Responsive Hydrogels with Three-Stage Optical Modulation for Smart Windows

Since room temperature management consumes a large amount of building energy, thermochromic smart windows have been extensively used for temperature regulation and energy management. However, the development of the smart window is still limited by its simple thermochromic performance, unreasonable thermochromic temperature, and the lack of additional stimulation conditions. In this work, a dual-responsive hydrogel was developed by introducing sodium dodecyl sulfate (SDS) and sodium chloride into the cross-linking network of poly(N-isopropylacrylamide) (PNIPAM) and polyacrylamide (PAM) for energy-saving and privacy protection. By controlling the temperature from low (<15 °C) to medium (15-28 °C) to high (>28 °C), the dual-responsive hydrogel achieved a reversible three-stage transition of opaque-transparent-translucent. The hydrogel exhibited a satisfactory solar modulation ability (T_lum = 80.3%, ΔT_sol,15-18°C = 72.9%, ΔT_sol,18-35°C = 42.7%) and effective IR and UV shielding at high (or low) temperatures. Moreover, compared with traditional windows, smart windows made of dual-responsive hydrogels could offer better thermal insulation and heat preservation. The electrochromic properties of the dual-responsive hydrogel presented a facile strategy to meet the needs of different situations. The dual-responsive hydrogel features energy-saving, privacy protection, three-stage optical modulation, and multistimulus responsiveness, making it an ideal smart window candidate.

A Biocompatible Liquid Pillar[n]arene-Based Drug Reservoir for Topical Drug Delivery

Advanced external preparations that possess a sustained-release effect and integrate few irritant elements are urgently needed to satisfy the special requirements of topical administration in the clinic. Here, a series of liquid pillar[n]arene-bearing varying-length oligoethylene oxide chains (OEPns) were designed and synthesized. Following rheological property and biocompatibility investigations, pillar[6]arene with triethylene oxide substituents (TEP6) with satisfactory cavity size were screened as optimal candidate compounds. Then, a supramolecular liquid reservoir was constructed from host-guest complexes between TEP6 and econazole nitrate (ECN), an external antimicrobial agent without additional solvents. In vitro drug-release studies revealed that complexation by TEP6 could regulate the release rate of ECN and afford effective cumulative amounts. In vivo pharmacodynamic studies confirmed the formation of a supramolecular liquid reservoir contributed to the accelerated healing rate of a S. aureus-infected mouse wound model. Overall, these findings have provided the first insights into the construction of a supramolecular liquid reservoir for topical administration.

Photothermal Hydrogel Encapsulating Intelligently Bacteria-Capturing Bio-MOF for Infectious Wound Healing

Chronic wounds are characterized by long-term inflammation and persistent infection, which make them difficult to heal. Therefore, an urgent desire is to develop a multifunctional wound dressing that can prevent wound infection and promote wound healing by creating a favorable microenvironment. In this study, a curcumin-based metal-organic framework (QCSMOF-Van), loaded with vancomycin and coated with quaternary ammonium salt chitosan (QCS), was prepared. Multifunctional composite hydrogels were conveniently synthesized by combining methacrylic anhydride modified gelatin and methacrylic anhydride modified oxidized sodium alginate with QCSMOF-Van through radical polymerization and Schiff base reaction. It is important to note that the QCSMOF-Van could capture bacteria through the positive charges on the surface of QCS. In this process, due to the synergistic effect of broad-spectrum antibacterial Zn²⁺ and vancomycin, the metabolism of bacteria was well inhibited, and the efficient capturing and rapid killing of bacteria were achieved. The QCSMOF-Van hydrogels could precisely regulate the balance of M1/M2 phenotypes of macrophages, thereby promoting the regeneration of nerves and blood vessels, which promotes the rapid healing of chronic wounds. This advanced cascade management strategy for tissue regeneration highlights the potential of multifunctional composite hydrogels in chronic wound dressings.

Cucurbit[10]uril-Based Orthogonal Supramolecular Polymers with Host-Guest and Coordination Interactions and Its Applications in Anion Classification

A novel orthogonal supramolecular polymer (Q[10]-TPDPB-Lu³⁺) in a host-guest ratio of 2:1 was successfully constructed utilizing the specificity and excellent cavity matching of Q[10] with the tripyridine derivatives (TPDPB). Significantly, non-covalent interactions between Q[10]'s hydrophobic cavities and Lu³⁺ were used to induce charge transfer of TPDPB to TPDPB and TPDPB to Lu³⁺, resulting in the construction of structurally interesting orthogonal assemblies with excellent fluorescence properties. Finally, the Q[10]-TPDPB-Lu³⁺ assemblies were shown to have good recognition and classification of strong and weak acid anions as well as iodide anions, and the classification was accompanied by a clear fluorescence emission change allowing visual observation.

Recent progress in 2D hybrid heterostructures from transition metal dichalcogenides and organic layers: properties and applications in energy and optoelectronics fields

Atomically thin transition metal dichalcogenides (TMDs) present extraordinary optoelectronic, electrochemical, and mechanical properties that have not been accessible in bulk semiconducting materials. Recently, a new research field, 2D hybrid heteromaterials, has emerged upon integrating TMDs with molecular systems, including organic molecules, polymers, metal-organic frameworks, and carbonaceous materials, that can tailor the TMD properties and exploit synergetic effects. TMD-based hybrid heterostructures can meet the demands of future optoelectronics, including supporting flexible, transparent, and ultrathin devices, and energy-based applications, offering high energy and power densities with long cycle lives. To realize such applications, it is necessary to understand the interactions between the hybrid components and to develop strategies for exploiting the distinct benefits of each component. Here, we provide an overview of the current understanding of the new phenomena and mechanisms involved in TMD/organic hybrids and potential applications harnessing such valuable materials in an insightful way. We highlight recent discoveries relating to multicomponent hybrid materials. Finally, we conclude this review by discussing challenges related to hybrid heteromaterials and presenting future directions and opportunities in this research field.

"Rim-Differentiated" Pillar[6]arenes

A "rim-differentiated" pillar[6]arene (RD-P[6]) was obtained successfully, with the assistance of a dimeric silver trifluoroacetate template, among eight different constitutional isomers in a direct and regioselective manner. The solid-state conformation of this macrocycle could switch from the 1,3,5-alternate to a truly rim-differentiated one upon guest inclusion. This highly symmetric RD-P[6] not only hosts metal-containing molecules inside its cavity, but also can form a pillar[6]arene-C₆₀ adduct through co-crystallization on account of donor-acceptor interactions. The development of synthetic strategies to desymmetrize pillararenes offers new opportunities for engineering complex molecular architectures and organic electronic materials.

Facile Fabrication of Transparent and Opaque Albumin Methacryloyl Gels with Highly Improved Mechanical Properties and Controlled Pore Structures

For porous protein scaffolds to be employed in tissue-engineered structures, the development of cost-effective, macroporous, and mechanically improved protein-based hydrogels, without compromising the original properties of native protein, is crucial. Here, we introduced a facile method of albumin methacryloyl transparent hydrogels and opaque cryogels with adjustable porosity and improved mechanical characteristics via controlling polymerization temperatures (room temperature and −80 °C). The structural, morphological, mechanical, and physical characteristics of both porous albumin methacryloyl biomaterials were investigated using FTIR, CD, SEM, XRD, compression tests, TGA, and swelling behavior. The biodegradation and biocompatibility of the various gels were also carefully examined. Albumin methacryloyl opaque cryogels outperformed their counterpart transparent hydrogels in terms of mechanical characteristics and interconnecting macropores. Both materials demonstrated high mineralization potential as well as good cell compatibility. The solvation and phase separation owing to ice crystal formation during polymerization are attributed to the transparency of hydrogels and opacity of cryogels, respectively, suggesting that two fully protein-based hydrogels could be used as visible detectors/sensors in medical devices or bone regeneration scaffolds in the future.

Recent Progress in External-Stimulus-Responsive 2D Covalent Organic Frameworks

Recently, smart 2D covalent organic frameworks (COFs), combining the advantages of both inherent structure features and functional building blocks, have been demonstrated to show reversible changes in conformation, color, and luminescence in response to external stimuli. This review provides a summary on the recent progress of 2D COFs that are responsive to external stimuli such as metal ions, gas molecules, pH values, temperature, electricity, light, etc. Moreover, the responsive mechanisms and design strategies, along with the applications of these stimulus-responsive 2D COFs in chemical sensors and photoelectronic devices are also discussed. It is believed that this review would provide some guidelines for designing novel single-/multistimulus-responsive 2D COFs with controllable responsive behaviors for advanced photoelectronic applications.

Thermoresponsive dendritic oligoethylene glycols

Monodispersed molecules of low molar masses showing thermoresponsiveness are appealing both for mechanism investigation of the thermally-modulated dehydration and aggregation on molecular levels and for designing functional intelligent materials. In the present report, thermoresponsive properties of a homologous series of monodispersed dendritic macromolecules carrying three-, four- or six-fold dendritic oligoethylene glycol (OEG) segments were investigated. These dendritic macromolecules carry either methoxyl or ethoxyl terminals, and have different cores (alcohol, methyl ester or methacryloyl) to exhibit different overall hydrophilicity. They show characteristic thermoresponsive properties with sharp phase transitions when suitable structural units are combined. Three structural factors determine their phase transition temperatures, including the cores, branching density and peripheral terminals. Thermally-induced collapse and aggregation are monitored with temperature-varied NMR spectroscopy at the microscale level and optical microscopy at the macroscale level. At elevated temperature, these dendritic macromolecules undergo fast exchange between the dehydrated and the hydrated states. These dendritic macromolecules afford structure-dependent confinement to guest dyes through their multi-valent interactions.

Self-assembled Fluorescent Nanoparticles with Tunable LCST Behavior in Water

The development of stimuli-responsive fluorescent materials in water based on organic molecule has drawn significant interest. Herein, we designed and synthesized an amphiphilic molecule M containing a fixed tetraphenylethylene moiety (FTPE) as hydrophobic part and tri(ethylene glycol) (TEG) chains as hydrophilic part. Notably, the FTPE moiety is aggregation-induced emission (AIE) active, while the TEG chains are thermo-responsive. M can self-assemble into fluorescent nanoparticles (NPs) in water, which showed lower critical solution temperature (LCST) behavior. Moreover, its clouding point can be reversibly tuned upon the concentration variation. Interestingly, the NPs can be acted as a fluorescence thermometer in aqueous media owing to their unique AIE and LCST behaviors. Our work herein not only provides an integration strategy to construct stimuli-responsive fluorescent materials but also shows great potential in biological applications including bioimaging and biosensors.

Energy Saving and Energy Generation Smart Window with Active Control and Antifreezing Functions

Windows are the least energy efficient part of the buildings, as building accounts for 40% of global energy consumption. Traditional smart windows can only regulate solar transmission, while all the solar energy on the window is wasted. Here, for the first time, the authors demonstrate an energy saving and energy generation integrated smart window (ESEG smart window) in a simple way by combining louver structure solar cell, thermotropic hydrogel, and indium tin oxides (ITO) glass. The ESEG smart window can achieve excellent optical properties with ≈90% luminous transmission and ≈54% solar modulation, which endows excellent energy saving performance. The outstanding photoelectric conversion efficiency (18.24%) of silicon solar cells with louver structure gives the smart window excellent energy generation ability, which is more than 100% higher than previously reported energy generation smart window. In addition, the solar cell can provide electricity to for ITO glass to turn the transmittance of hydrogel actively, as well as the effect of antifreezing. This work offers an insight into the design and preparation together with a disruptive strategy of easy fabrication, good uniformity, and scalability, which opens a new avenue to realize energy storage, energy saving, active control, and antifreezing integration in one device.

Stabilization of Antitumor Agent Busulfan through the Encapsulation within a Water-Soluble Pillar[5]arene

The complexation of antitumor agent busulfan by negatively charged carboxylatopillar[5]arenein water is reported. The encapsulation within carboxylatopillar[5]arenein reduces the hydrolytic degradation of busulfan from 90.7 % to 25.2 % after 24 days and accordingly enhances its stability by providing a hydrophobic shelter for busulfan in water. Moreover, the complexation result in 12 times improvement of water solubility for busulfan. Our result provides a supramolecular approach for stabilizing the anticancer agent busulfan.

An amphiphilic water-soluble biphen[3]arene with a tunable lower critical solution temperature behavior

The first amphiphilic water-soluble thermoresponsive biphen[3]arene with a tunable lower critical solution temperature behavior is reported.

Construction of a pillararene-based supramolecular polymer network and its application in efficient removal of dyes from water

An AB-type monomer based on a pillar[5]arene host and an imidazolium salt guest was successfully synthesized through a facile way. This monomer can self-assemble into linear supramolecular polymers in chloroform. After the addition of silver ions, the imidazolium salt group coordinated with silver ions to crosslink the linear supramolecular polymers at their ends, resulting in the formation of supramolecular polymer networks. Meanwhile, after further adding iodide ions, the supramolecular polymer network changed back to the linear supramolecular polymer. As a result, the topological structure of the system can be reversibly tuned. Furthermore, this supramolecular polymer network can be applied to remove organic dyes in water, suggesting its great potential in the treatment of waste water.

Mechanically Interlocked Vitrimers

Mechanically interlocked networks (MINs) have emerged as an encouraging platform for the development of mechanically robust yet adaptive materials. However, the difficulty in reversibly breaking the mechanical bonds poses a real challenge to MINs as customizable and sustainable materials. Herein, we couple the vitrimer chemistry with mechanically interlocked structures to generate a new class of MINs─referred to as mechanically interlocked vitrimers (MIVs)─to address the challenge. Specifically, we have prepared the acetoacetate-decorated [2]rotaxane that undergoes catalyst-free condensation reaction with two commercially available multiamine monomers to furnish MIVs. Compared with the control whose wheels are nonslidable under applied force, our MIVs with slidable mechanically interlocked motifs showcase enhanced mechanical performance including Young's modulus (18.5 ± 0.9 vs 1.0 ± 0.1 MPa), toughness (3.7 ± 0.1 vs 0.9 ± 0.1 MJ/m³), and damping capacity (98% vs 72%). The structural basis behind unique property profiles is demonstrated to be the force-induced host-guest dissociation and consequential intramolecular sliding of the wheels along the axles. The peculiar behaviors represent a consecutive energy dissipation mechanism, which provides a complement to other pathways that mainly depend on the breaking of sacrificial bonds. Moreover, by virtue of the vitrimer chemistry of vinylogous urethanes, we impart reprocessability and chemical recyclability to the MINs, thereby empowering the reconfiguration of the networks without breaking of the mechanical bonds. Finally, it is disclosed that the intramolecular motions of [2]rotaxanes could accelerate the dynamic exchange of the vinylogous urethane bonds via loosening the network, suggestive of a synergistic effect between the dual dynamic entities.

Lanthanide Luminescence Supramolecular Switch Based on Photoreactive Ammonium Molybdate

Lanthanide supramolecular assemblies as photoswitches have attracted much attention in the fields of cellular imaging and light-emitting materials. However, the regulation of lanthanide luminescence behavior by redox of metal ions is rare. Herein, we constructed a lanthanide luminescence supramolecular switch, that is, a binary assembly constructed by mono-(6-ethylenediamine-6-deoxy)-β-cyclodextrin (ECD) and ammonium molybdate tetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O, Mo₇), and further assembled into ternary assemblies with polyoxometalate Na₉[XW₁₀O₃₆]·32H₂O (X-POM, X = Eu and Dy), which was comprehensively characterized by UV-vis, fluorescence, NMR, Fourier transform infrared, dynamic light scattering, scanning electron microscopy, and ζ potential. Thanks to the oxygen-shielding effect of secondary supramolecular assembly, the photoreduction process of Mo₇ (VI) could occur rapidly and efficiently. Due to the high Förster resonance energy transfer (FRET) efficiency of X-POM and Mo₇ (V) in supramolecular assembly, the photoreduction process is accompanied by fluorescence quenching. In addition, the oxidation process of the Mo₇ (V) could be rapidly promoted by heating, which allowed the X-POM fluorescence to recover. Interestingly, ECD-mediated ternary supramolecular assemblies not only tune the lanthanide luminescence but also strongly increase the lanthanide luminescence behavior, leading to the emission of strong narrow red light at ⁵D₀-⁷F₄, which can be successfully applied to two-dimensional code anticounterfeiting. In this study, a new approach is provided for the construction of lanthanide luminescence supramolecular switches tuned by photoreactive polyoxometalate.

Fuel-Driven and Enzyme-Regulated Redox-Responsive Supramolecular Hydrogels

Chemical reaction networks (CRN) embedded in hydrogels can transform responsive materials into complex self-regulating materials that generate feedback to counter the effect of external stimuli. This study presents hydrogels containing the β-cyclodextrin (CD) and ferrocene (Fc) host-guest pair as supramolecular crosslinks where redox-responsive behavior is driven by the enzyme-fuel couples horse radish peroxidase (HRP)-H2 O2 and glucose oxidase (GOx)-d-glucose. The hydrogel can be tuned from a responsive to a self-regulating supramolecular system by varying the concentration of added reduction fuel d-glucose. The onset of self-regulating behavior is due to formation of oxidation fuel in the hydrogel by a cofactor intermediate GOx[FADH2 ]. UV/Vis spectroscopy, rheology, and kinetic modeling were employed to understand the emergence of out-of-equilibrium behavior and reveal the programmable negative feedback response of the hydrogel, including the adaptation of its elastic modulus and its potential as a glucose sensor.

A smart material built upon the photo-thermochromic effect and its use for managing indoor temperature

We demonstrate a material by dispersing a thermochromic mixture of leuco dye, developer, and solvent as microspheres in a polymer matrix to improve the efficiency of building energy management. The smart, photo-thermochromic film can automatically switch between a colored and colorless state in response to climate temperature and light to realize photothermal heating and cooling.

Adjustable color response during plasmon resonance by monochromatic light irradiation

A combination of plasmonic nanoparticles with a semiconductor is a feasible approach to realize multiple color exhibitions. The phenomenon is based on plasmon-driven charge separation between electrons and metal ions, but suitable only for light excitation with different wavelengths. Here, we introduce a color-adjustable method under monochromatic light irradiation. A smart strategy is proposed to construct sandwich structures of a hydrogel coating layer, thermally deposited Ag nanoparticles, and mesoporous TiO₂ matrices. The contacting mode of TiO₂ and nano-Ag at the Schottky interface is strongly dependent on the pore morphology of the oxide. Surface and interface plasmon resonances result in sample color switching from cyan to green and from brown to purple, respectively. The color response ability is further controlled by hydrogel coating, besides the exciting light wavelength. This Letter paves a bright way for colorful displays and information encryption.

Synergistic covalent-and-supramolecular polymers connected by [2]pseudorotaxane moieties

Synergistic covalent-and-supramolecular polymers, in which covalent polymers and supramolecular polymers connect with each other through [2]pseudorotaxane moieties, are designed and synthesized. The unique topological structure effectively enhances the synergistic effect between these two polymers, thereby generating a novel class of mechanically adaptive materials.

Pillar[5]arene-Derived endo-Functionalized Molecular Tube for Mimicking Protein-Ligand Interactions

Artificial tubular molecular pockets bearing polar functionalities on their inner surface are useful model systems for understanding the mechanisms of protein-ligand interactions in living systems. We herein report a pillar[5]arene-derived molecular tube, [P4-(OH)BPO], whose endo conformational isomer endo-[P4-(OH)BPO] possesses an inwardly pointing hydrogen-bond (H-bond) donor (OH) in its deep cavity and a strong H-bond acceptor (C═O) on its predominantly hydrophobic inner surface, rendering it a perfect protein binding pocket mimetic. A fragment-based drug design model was established using endo-[P4-(OH)BPO] and a library of various shape-complementary fragment ligands (1-38). On the basis of the binding affinity data for "fragment-pocket" complexes G⊂endo-[P4-(OH)BPO] (G = 1-38), two rationally designed "lead molecules" (39 and 40) were identified as being able to enhance binding affinity significantly by forming H-bonds with both the donor and acceptor of endo-[P4-(OH)BPO]. The described work opens new avenues for developing pillar[n]arene-derived protein binding pocket-mimetic systems for studies of protein-ligand interactions and mechanisms of enzymatic reactions.

Highly Branched Pillar[5]arene-Derived Porous Aromatic Frameworks (PAFs) for Removal of Organic Pollutants from Water

The adsorption process is widely used for the treatment of wastewater containing organic pollutants. We fabricated highly branched pillar[5]arene-based porous aromatic frameworks (PAFs), PAF-P5, for the adsorption and removal of organic pollutants (short-chain alkyl derivatives 1-3 and pesticide molecules 4-6) from water with high removal efficiency (RE). However, PAF-P5 was incapable of adsorbing aromatic organic dyes 7-9. Adsorption kinetic studies indicated that the adsorption is mainly driven by strong host-guest interactions between 1-3 and the pillar[5]arene units in PAF-P5, while 4-6 only weakly interacted with the pillar[5]arene units in PAF-P5. Moreover, chemically breaking down the pillar[5]arene rings in PAF-P5 caused changes in the pore size, the microenvironment inside of the pores, and the frame morphology, and the resultant frameworks, PAF-DeP5, exhibited poor adsorption toward 1-6 but adsorbed 7-9 possibly through physical adsorption as implied by fitting the experimental data into the adsorption kinetic models.