Ligand Macromolecule Research Articles

Understanding the contagiousness of Covid-19 strains: A geometric approach

Protein–protein interaction occurs on surface patches with some degree of complementary geometric and chemical features. Building on this understanding, this study endeavors to characterize the spike protein of the SARS-CoV-2 virus at the morphological and geometrical levels in its Alpha, Delta, and Omicron variants. In particular, the affinity between different SARS-CoV-2 spike proteins and the ACE2 receptor present on the membrane of the human respiratory system cells is investigated. To achieve an adequate degree of geometrical accuracy, the 3D depth maps of the proteins in exam are filtered by developing an ad-hoc convolutional filter with a kernel implemented as a sphere of varying radius, simulating a ball rolling on the surface (similar to the 'rolling ball' filter). This ball ideally models a hypothetical molecule that could interface with the protein and is inspired by the geometric approach to macromolecule–ligand interactions proposed by Kuntz et al. in 1982. The aim is to mitigate the imperfections and to obtain a smoother surface that could be studied from a geometrical perspective for binding purposes. A set of geometric descriptors, borrowed from the 3D face analysis context is then mapped point-by-point onto protein depth maps. Following a feature extraction phase inspired by Histogram of Oriented Gradients and Local Binary Patterns, the final histogram features are used as input for a Support Vector Machine classifier to automatically classify the proteins according to their surface affinity, where a similarity in shape is observed between ACE2 and the spike protein of the SARS-CoV-2 Omicron variant. Finally, Root Mean Square Error analysis is used to quantify the geometrical affinity between the ACE2 receptor and the respective Receptor Binding Domains of the three SARS-CoV-2 variants, culminating in a geometrical explanation for the higher contagiousness of Omicron relative to the other variants under study.

Design, synthesis and molecular modeling of isatin-aminobenzoic acid hybrids as antibacterial and antibiofilm agents

Number of factors, including newly emerging infectious diseases and an increase in multi-drug resistant microbial pathogens with particular relevance for Gram-positive bacteria, make the treatment of infectious diseases in hospital-based healthcare a major challenge in the medical community. 4-Aminobenzoic acid (PABA), has demonstrated a variety of biological actions particularly, antimicrobial activity. In our study we coupled this vitamin-like molecule with different isatin derivatives. We investigated the antibacterial activity of the synthesized Schiff's bases. The compounds showed high selective activity against Gram-positive bacteria and showed weak or no activity against both Gram-negative bacteria and fungi. Compound 2a showed highest activity against S. aureus and B. subtilis (MIC 0.09 mmol/L). Additionally, these substances exhibit strong anti-B. Subtilis biofilm formation. We were able to shed insight on the binding mode of these new inhibitors using in silico docking of the compounds in the binding sites of a 3D structure of B. subtilis histidine kinase/Walk. The binding free energy of the compound 2a to the catalytic domain walk, of histidine kinase enzyme of B. subtilis bacteria, was calculated using molecular mechanics/generalized born surface area scoring. The key residues for macromolecule–ligand binding were postulated. The optimized 3D protein–ligand binding modes shed light on the B. subtilis HK/Walk–ligand interactions that afford a means to assess binding affinity to design new HK/Walk inhibitor as antibacterial agents.

Small molecules as cancer targeting ligands: Shifting the paradigm.

Conventional chemotherapeutics exploration is hampered due to their nonspecific distribution leading to unintended serious toxicity. Toxicity is so severe that deciding to go for chemotherapy becomes a question of concern for many terminally ill cancer patients. However, with evolving times nanotechnology assisted in reducing the haywire distribution and channelizing the movement of drug-enclosing drug delivery systems to cancer cells to a greater extent, yet toxicity issues still could not be obliterated. Thus, active targeting appeared as a refuge, where ligands actively or specifically deliver linked chemotherapeutics and carriers to cancer cells. For a very long time, large molecule weight/macromolecular ligands (peptides and big polymers) were considered the first choice for ligand-directed active cancer targeting, due to their specificity towards overexpressed native cancer receptors. However, complex characterization, instability, and the expensive nature demanded to reconnoitre better alternatives for macromolecule ligands. The concept of small molecules as ligands emerged from the idea that few chemical molecules including chemotherapeutics have a higher affinity for cancer receptors, which are overexpressed on cell membranes, and may have the ability to assist in drug cellular uptake through endocytosis. But now the question is, can they assist the conjugated macro cargos to enter the cell or not? This present review will provide a holistic overview of the small molecule ligands explored till now.

Using CIVT-SELEX to Select Aptamers as Genetic Parts to Regulate Gene Circuits in a Cell-Free System.

The complexity of genetic circuits has not seen a significant increase over the last decades, even with the rapid development of synthetic biology tools. One of the bottlenecks is the limited number of orthogonal transcription factor-operator pairs. Researchers have tried to use aptamer-ligand pairs as genetic parts to regulate transcription. However, most aptamers selected using traditional methods cannot be directly applied in gene circuits for transcriptional regulation. To that end, we report a new method called CIVT-SELEX to select DNA aptamers that can not only bind to macromolecule ligands but also undergo significant conformational changes, thus affecting transcription. The single-stranded DNA library with affinity to our example ligand human thrombin protein is first selected and enriched. Then, these ssDNAs are inserted into a genetic circuit and tested in the in vitro transcription screening to obtain the ones with significant inhibitory effects on downstream gene transcription when thrombins are present. These aptamer-thrombin pairs can inhibit the transcription of downstream genes, demonstrating the feasibility and robustness of their use as genetic parts in both linear DNAs and plasmids. We believe that this method can be applied to select aptamers of any target ligands and vastly expand the genetic part library for transcriptional regulation.

Analysis of protein structures containing HEPES and MES molecules

X‐ray crystallography is the main experimental method behind ligand–macromolecule complexes found in the Protein Data Bank (PDB). Applying bioinformatics methods to such structural data can fuel drug discovery, albeit under the condition that the information is correct. Regrettably, a small number of structures in the PDB are of suboptimal quality due to incorrectly identified and modeled ligands in protein–ligand complexes. In this paper, we combine a theoretical‐graph approach, nuclear density estimates, bioinformatics methods, and prior chemical knowledge to analyze two non‐physiological ligands, HEPES and MES, that are frequent components of crystallization and purifications buffers. Our analysis includes quantum mechanics calculations and Cambridge Structure Database (CSD) queries to define the ideal conformation of these ligands, geometry analysis of PDB deposits regarding several quality factors, and a search for homologous structures to identify other small molecules that could bind in place of the parasitic ligand. Our results highlight the need for careful refinement of macromolecule–ligand complexes and better validation tools that integrate results from all relevant resources.

Evidence for new enantiospecific interaction force in chiral biomolecules

Evidence for new enantiospecific interaction force in chiral biomolecules

Next generation 3D pharmacophore modeling

Abstract3D pharmacophore models are three‐dimensional ensembles of chemically defined interactions of a ligand in its bioactive conformation. They represent an elegant way to decipher chemically encoded ligand information and have therefore become a valuable tool in drug design. In this review, we provide an overview on the basic concept of this method and summarize key studies for applying 3D pharmacophore models in virtual screening and mechanistic studies for protein functionality. Moreover, we discuss recent developments in the field. The combination of 3D pharmacophore models with molecular dynamics simulations could be a quantum leap forward since these approaches consider macromolecule–ligand interactions as dynamic and therefore show a physiologically relevant interaction pattern. Other trends include the efficient usage of 3D pharmacophore information in machine learning and artificial intelligence applications or freely accessible web servers for 3D pharmacophore modeling. The recent developments show that 3D pharmacophore modeling is a vibrant field with various applications in drug discovery and beyond.This article is categorized under: Computer and Information Science > Chemoinformatics Computer and Information Science > Computer Algorithms and Programming Molecular and Statistical Mechanics > Molecular Interactions

Macromolecules with Different Charges, Lengths, and Coordination Groups for the Coprecipitation Synthesis of Magnetic Iron Oxide Nanoparticles as T1 MRI Contrast Agents.

Considerable efforts have been focused on the exploitation of macromolecule ligands for synthesis of magnetic Fe3O4 nanoparticles as T1 magnetic resonance imaging (MRI) contrast agents, but studies that concern macromolecule ligands with different charges and coordination groups are still limited. Herein, we used poly(acrylic acid) (PAA), poly(allylamine hydrochloride) (PAH), and polyvinyl alcohol (PVA), which possess negative, positive and neutral charges with carboxylic acid, amino and hydroxyl groups respectively, as templates and stabilizers to fabricate Fe3O4 nanoparticles through coprecipitation reaction. The obtained Fe3O4-PAA, Fe3O4-PAH, and Fe3O4-PVA nanoparticles showed T1 contrast performance with r1 relaxivities of 23.4, 60.3, and 30.6 mM s−1 at 0.5 T (25 °C), and a r2/r1 ratio of 2.62, 3.82, and 7.26, respectively. The cell viability assay revealed that Fe3O4-PAA and Fe3O4-PVA exhibited good biocompatibility, while Fe3O4-PAH displayed high cytotoxicity. In vivo T1-weighted (1 T) mice showed that both Fe3O4-PAA and Fe3O4-PVA were able to display remarkably brighten the contrast enhancement for the mice tumor and kidney sites, but Fe3O4-PAA had better contrast performance. This work highlights that the macromolecule ligands play an important role in the biocompatibility and T1 contrast performance of magnetic Fe3O4 nanoparticles.

T₁-Weight Magnetic Resonance Imaging Performances of Iron Oxide Nanoparticles Modified with a Natural Protein Macromolecule and an Artificial Macromolecule.

To optimize the iron oxide nanoparticles as T1-weight contrast for in vivo magnetic resonance imaging (MRI), numbers of macromolecule ligands have been explored with considerable effort. However, reports refer to the comparison of the T1-weight contrast performances of iron oxide nanoparticles modified with natural and artificial macromolecule ligands are still limited. In this work, we used a typical natural protein macromolecule (bovine serum albumin, BSA) and an artificial macromolecule (poly(acrylic acid)-poly(methacrylic acid), PMAA-PTTM) as surface ligands to fabricate Fe3O4-BSA and Fe3O4-PMAA-PTTM nanoparticles with similar size and magnetization by the coprecipitation method and compared their MRI performances. In vitro and in vivo experiments revealed that Fe3O4-BSA with lower cytotoxicity exhibited higher r2/r1 ratio in solution and darkening contrast enhancement for liver and kidney sites of mice under T1-weight imaging, while Fe3O4-PMAA-PTTM displayed much lower r2/r1 ratio in solution and brighter contrast enhancement for liver and kidney sites. These remarkably different MRI behaviors demonstrated that the surface ligands play an important role for optimizing the MRI performance of Fe3O4 nanoparticles. We expect these results may facilitate the design of macromolecule ligands for developing an iron oxide–based T1-weight contrast agent.

Determination of the endothelin-1 recognition sites of endothelin receptor type A by the directed-degeneration method

G-protein coupled receptors (GPCRs) play indispensable physiological roles in cell proliferation, differentiation, and migration; therefore, identifying the mechanisms by which ligands bind to GPCRs is crucial for developing GPCR-targeting pharmaceutics and for understanding critical biological functions. Although some structural information is available regarding the interactions between GPCRs and their small molecule ligands, knowledge of how GPCRs interact with their corresponding macromolecule ligands, such as peptides and proteins, remains elusive. In this study, we have developed a novel strategy to investigate the precise ligand recognition mechanisms involved in the interaction of endothelin receptor type A (ETA) with its ligand, endothelin-1 (ET-1); we call this method “directed degeneration” method. Through flow cytometric screening of a randomized ETA library, statistical analysis of the identified sequences, and biochemical studies, the ligand interaction map was successfully obtained.

Effect of substituent groups with two types on benzene ring on photoluminescence property of complexes of benzoic acid—Functionalized polystyrene with Eu(III) Ion

Abstract Two benzoic acid derivatives, methoxybenzoic acid (MOBA) and formylbenzoic acid (FBA), on whose benzene ring, an electron-donating substituent group (methoxy group) and an electron-withdrawing substituent group (formyl group) exist, respectively, were bonded onto the side chains of polystyrene (PS) through polymer reactions, obtaining two benzoic acid derivative-functionalized PSs, PS-MOBA and PS-FBA. The two macromolecule ligands were made to coordinate to Eu 3+ ion, preparing two binary polymer-rare earth complexes, PS-(MOBA) 3 -Eu(III) and PS-(FBA) 3 -Eu(III) as well as two ternary complexes with phenanthroline (Phen) as the second small-molecule ligand. The luminescence property of theses complexes was mainly examined, and the effect of the two types of substituent groups on the benzene ring of the bonded benzoic acid on the photo physical behavior of these complexes was investigated in depth. The experimental results show that both the two types of substituent groups on the benzene ring of the bonded benzoic acid can effectively strengthen their fluorescence emission intensities, but the mechanisms are different. For MOBA series complexes, through p-π conjugation effect between methoxy group and the π orbit of the bonded ligand MOBA, the triplet state level of the bonded ligand MOBA can be remarkably decline, so the energy level matching degree between the triplet state level of the bonded ligand MOBA and the resonant energy level of Eu(III) ion is greatly enhanced, resulting in a drastically enhancing of the luminescence intensities of the MOBA series complexes. For FBA series complexes, through n–π* transition between the formyl group and π* orbit of the bonded ligand FBA and the accompanying intraligand charge transfer, the triplet state energy of the bonded ligand FBA can also be reduced, and the energy level matching degree can also be improved, leading to an obvious enhancement of luminescence intensities of the complexes.

Structure and luminescent property of complexes of aryl carboxylic acid-functionalized polystyrene with Eu(III) and Tb(III) ions

Via polymer reactions, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polystyrene (PS), respectively, and two aryl carboxylic acid-functionalized polystyrenes, PSNA and PSBA, were obtained. Using PSNA and PSBA as macromolecule ligands and Eu3+ and Tb3+ ions as central ions, various luminescent binary polymer-rare earth complexes were prepared. At the same time, with 1,10-phenanthroline (Phen) and 4,4′-bipyridine (Bipy) as small-molecule co-ligands, various ternary polymer-rare earth complexes were also prepared. On the basis of characterizing PSNA, PSBA and complexes, the relationship between structure and luminescent property for these prepared complexes were mainly investigated. The study results show that the macromolecule ligands PSNA and PSBA, or the bonded NA and BA ligands, can strongly sensitize the fluorescence emissions of Eu3+ ion or Tb3+ ion, but the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions, namely it is strongly dependent on the matching degree of energy levels. The fluorescence emission of the binary complex PS-(NA)3-Eu(III) is stronger than that PS-(BA)3-Eu(III), indicating ligand NA has stronger sensitization action for Eu3+ ion than ligand BA; the binary complex PS-(BA)3-Tb(III) emit strong characteristic fluorescence of Tb3+ ion, displaying that ligand BA can strongly sensitize Tb3+ ion, whereas the binary complex PS-(NA)3-Tb(III) nearly does not emit the characteristic fluorescence of Tb3+ ion, showing that ligand NA does not sensitize Tb3+ ion. The fluorescence intensity of the ternary complexes is much stronger than that of the binary complexes in the same series.

Thermodynamics and solvent linkage of macromolecule–ligand interactions

Binding involves two steps, desolvation and association. While water is ubiquitous and occurs at high concentration, it is typically ignored. In vitro experiments typically use infinite dilution conditions, while in vivo, the concentration of water is decreased due to the presence of high concentrations of molecules in the cellular milieu. This review discusses isothermal titration calorimetry approaches that address the role of water in binding. For example, use of D2O allows the contribution of solvent reorganization to the enthalpy component to be assessed. Further, the addition of osmolytes will decrease the water activity of a solution and allow effects on Ka to be determined. In most cases, binding becomes tighter in the presence of osmolytes as the desolvation penalty associated with binding is minimized. In other cases, the osmolytes prefer to interact with the ligand or protein, and if their removal is more difficult than shedding water, then binding can be weakened. These complicating layers can be discerned by different slopes in ln(Ka) vs osmolality plots and by differential scanning calorimetry in the presence of the osmolyte.

Self-healing metallo-supramolecular polymers from a ligand macromolecule synthesized via copper-catalyzed azide–alkyne cycloaddition and thiol–ene double “click” reactions

In this study, we develop a series of new materials that can simultaneously and reversibly self-heal without external stimuli based on metallo-supramolecular interactions. Multiple tridentate 2,6-bis(1,2,3-trizaol-4-yl)pyridine (BTP) ligand units synthesized via a copper-catalyzed azide–alkyne cycloaddition (CuAAC) “click” reaction are incorporated into the polymer backbone of a ligand macromolecule through a thiol–ene “click” reaction. 3D transient supramolecular networks are formed from the ligand macromolecule upon coordination with transition and/or lanthanide metal ions. As compared to the ligand macromolecule, the resultant supramolecular films exhibit improved mechanical properties, such as Young's modulus, strength and toughness, which can be readily tuned by the stoichiometric ratio of Zn2+ to Eu3+ to Tb3+. The supramolecular films exhibit characteristics of weakly crosslinked networks where the storage modulus G′ and loss modulus G′′ scaled with normalized frequency ωaT by the same slope of 0.5. Both the supramolecular bulk films and gels are found to exhibit fast and effective self-healing properties by virtue of the kinetically labile nature of the metal–ligand interactions.

Structure and photoluminescence property of complexes of aromatic carboxylic acid-functionalized polysulfone with Eu(Ⅲ) and Tb(Ⅲ)

With chloromethylated polysulfone as starting substance, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polysulfone (PSF) via polymer reactions, obtaining two kinds of aromatic carboxyl acid-functionalized polysulfone, PSFNA and PSFBA. Subsequently, the luminescent binary and ternary polymer-rare earth complexes of Eu(Ⅲ) and Tb(Ⅲ) were prepared through coordination reactions, respectively, with PSFNA and PSFBA as macromolecule ligands and with 1,10-phenanthroline (Phen) and 4,4′-bipyridine (Bipy) as small-molecule co-ligands. This work focuses on investigating the relationship between structure and photoluminescence property of these complexes. The experimental results indicate that the macromolecule ligands PSFNA and PSFBA can strongly sensitize the fluorescence emissions of Eu3+ ion or Tb3+ ion, and the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions. The fluorescence emission of the binary complex PSF–(NA)3–Eu(Ⅲ) is stronger than that PSF–(BA)3–Eu(Ⅲ), suggesting the bonded ligand NA has stronger sensitization action for Eu3+ ion than ligand BA; The binary complex PSF–(BA)3–Tb(Ⅲ) emit very strong characteristic fluorescence of Tb3+ ion, displaying that ligand BA can strongly sensitize Tb3+ ion, whereas PSF–(NA)3–Tb(Ⅲ) does not emit the characteristic fluorescence of Tb3+ ion, showing that the bonded ligand NA does not sensitize Tb3+ ion. The fluorescence intensity of the ternary complexes is stronger than that of the binary complexes in the same series. The solid films of these complexes also emit the strong characteristic fluorescence of Eu3+ ion or Tb3+ ion.

Synthesis and characterization of Fe(II),Co(II),Ni(II),Cu(II) and Zn(II) complexes with Hexaaza macromolecule Ligands Derived from Semicarbazide

Synthesis and characterization of Fe(II),Co(II),Ni(II),Cu(II) and Zn(II) complexes with Hexaaza macromolecule Ligands Derived from Semicarbazide

Using metal-ligand interactions to access biomimetic supramolecular polymers with adaptive and superb mechanical properties.

The development of polymer materials that exhibit excellent mechanical properties and can respond to environmental stimuli is of great scientific and commercial interest. In this work, we report a series of biomimetic supramolecular polymers using a ligand macromolecule carrying multiple tridentate ligand 2,6-bis(1,2,3-triazol-4-yl)pyridine (BTP) units synthesized via CuAAC in the polymer backbone together with transition and/or lanthanide metal salts. The metal-ligand complexes phase separate from soft linker segments, acting as physical crosslinking points in the materials. The metallo-supramolecular films exhibit superb mechanical properties, i.e., high tensile strength (up to 18 MPa), large strain at break (>1000%) and exceptionally high toughness (up to 70 MPa), which are much higher than those of the ligand macromolecule and are tunable by adjusting the stoichiometric ratio of Zn2+ to Eu3+ and the stoichiometry of metal ion to ligand. The metal-ligand hard phase domains are demonstrated to be thermally stable but mechanically labile, similar to the behaviors of covalent mechanophores. The thermal stability and mechanical responsiveness are also dependent on the compositions of metal ions. The disruption of the hard phase domains and the dissociation of metal-ligand complexes under stretching are similar to the unfolding of modular domains in modular biomacromolecules and are responsible for the superb mechanical properties. In addition, the biomimetic metallo-supramolecular materials display promising responsive properties to UV irradiation and chemicals. These well designed, created and characterized robust structures will inspire further accurate tailoring of biomimetic responsive materials at the molecular level and/or nanoscale.

A novel view of modelling interactions between synthetic and biological polymers via docking

Multipoint interactions between synthetic and natural polymers provide a promising platform for many topical applications, including therapeutic blockage of virus-specific targets. Docking may become a useful tool for modelling of such interactions. However, the rigid docking cannot be correctly applied to synthetic polymers with flexible chains. The application of flexible docking to these polymers as whole macromolecule ligands is also limited by too many possible conformations. We propose to solve this problem via stepwise flexible docking. Step 1 is docking of separate polymer components: (1) backbone units (BU), multi-repeated along the chain, and (2) side groups (SG) consisting of functionally active elements (SG(F)) and bridges (SG(B)) linking SG(F) with BU. At this step, probable binding sites locations and binding energies for the components are scored. Step 2 is docking of component-integrating models: [BU](m), SG = SG(F)-SG(B), BU-SG, BU-BU(SG)-BU, BU(SG)-[BU](m)-BU(SG), and [BU(var)(SG(var))](m). Every modelling level yields new information, including how the linkage of various components influences on the ligand-target contacts positioning, orientation, and binding energy in step-by-step approximation to polymeric ligand motifs. Step 3 extrapolates the docking results to real-scale macromolecules. This approach has been demonstrated by studying the interactions between hetero-SG modified anionic polymers and the N-heptad repeat region tri-helix core of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp41, the key mediator of HIV-1 fusion during virus entry. The docking results are compared to real polymeric compounds, acting as HIV-1 entry inhibitors in vitro. This study clarifies the optimal macromolecular design for the viral fusion inhibition and drug resistance prevention.

Studies on preparation, structure and fluorescence emission of polymer-rare earth complexes composed of aryl carboxylic acid-functionalized polystyrene and Tb(Ⅲ) ion

4-(Chloromethyl) benzoic acid (CMBA) was first bonded onto the side chains of polystyrene (PS) via a polymer reaction, Friedel–Crafts alkylation reaction, and aryl carboxylic acid-functionalized polystyrene (PSBA) was generated. The functionalized polystyrene was used to prepare rare earth metal complexes. By using PSBA as macromolecule ligand, the binary polymer-rare earth complexes, PS-(BA)n-Tb(Ⅲ), were prepared, and at the same time, ternary polymer-rare earth complexes, PS-(BA)n-Tb(Ⅲ)-(Phen)m, i.e. the mixed complexes in which both polymer-based aryl carboxylic acid and 1,10-phenanthroline as ligands were also prepared. The complexes were fully characterized using FTIR and proton NMR spectroscopy. Both ultraviolet absorption and fluorescence emission spectra for the complexes were recorded. The relationship between complex structure and the intensity of fluorescence emission was established. The experimental results show that the fluorescence emission from the central metal ion in the complex is strongly sensitized by the aryl carboxylic acid ligands chemically attached to the side chains of PSBA, and an apparent “Antenna Effect” is produced for these complexes. In the dilute solution of PSBA, the formed complex belongs to intramolecular complex. For the binary intramolecular complex, the apparent saturated coordination number of Tb3+ ion is 10, and here the binary complex has the structure of PS-(BA)5-Tb(Ⅲ) and it has the strongest fluorescence emission among all of the binary complexes. When small-molecule Phen is added into the binary complex solution, the ternary complex PS-(BA)n-Tb(Ⅲ)-(Phen)m will be formed. As compared with the conventional ternary complexes PS-(BA)1-Tb(Ⅲ)-Phen2 and PS-(BA)1-Tb(Ⅲ)-(Phen)3 (the molar ratio of the central ion and the two ligands is conventional), the ternary complex with the structure of PS-(BA)5-Tb(Ⅲ)-(Phen)1 has the strongest fluorescence emission because of the complete coordination of the ligands to Tb3+ ion and the removal of the substituted water molecules around Tb3+ ion.

Multi-responsive self-healing metallo-supramolecular gels based on “click” ligand

Metallo-supramolecular gels were prepared using a ligand macromolecule containing the tridentate 2,6-bis(1,2,3-trizol-4-yl)pyridine (BTP) ligand unit synthesized via CuAAC “click” chemistry in the main chain, together with transition metal ions and/or lanthanide ions. The gelation and gel properties, e.g. swelling, emission, rheological properties, thermo- and chemo-responsive properties, can be tuned by the careful selection of metal ions and their combinations, solvents, concentration, etc. Most interestingly, the gels exhibited repeatable autonomic healing ability. Moreover, the repeatable self-healing ability of the gels found practical application in the repairing of metal coatings.