Artificial Metal-Peptide Assemblies: Bioinspired Assembly of Peptides and Metals through Space and across Length Scales

Diverse Proteomimetic Frameworks via Rational Design of π-Stacking Peptide Tectons

Peptide-based frameworks aim to integrate protein architecture into solid-state materials using simpler building blocks. Despite the growing number of peptide frameworks, there are few strategies to rationally engineer essential properties like pore size and shape. Designing peptide assemblies is generally hindered by the difficulty of predicting complex networks of weak intermolecular interactions. Peptides conjugated to polyaromatic groups are a unique case where assembly appears to be strongly driven by π-π interactions, suggesting that rationally adjusting the geometry of the π-stackers could create novel structures. Here, we report peptide elongation as a simple mechanism to predictably tune the angle between the π-stacking groups to produce a remarkable diversity of pore shapes and sizes, including some that are mesoporous. Notably, rapid jumps in pore size and shape can occur with just a single amino acid insertion. The geometry of the π-stacking residues also significantly influences framework structure, representing an additional dimension for tuning. Lastly, sequence identity can also indirectly modulate the π-π interactions. By correlating each of these factors with detailed crystallographic data, we find that, despite the complexity of peptide structure, the shape and polarity of the tectons are straightforward predictors of framework structure. These guidelines are expected to accelerate the development of advanced porous materials with protein-like capabilities.

Metal Ions Trigger the Gelation of Cysteine-Containing Peptide-Appended Coordination Cages

We report a series of coordination cages that incorporate peptide chains at their vertices, prepared through subcomponent self-assembly. Three distinct heterochiral tripeptide subcomponents were incorporated, each exhibiting an L-D-L stereoconfiguration. Through this approach, we prepared and characterized three tetrahedral metal-peptide cages that incorporate thiol and methylthio groups. The gelation of these cages was probed through the binding of additional metal ions, with the metal-peptide cages acting as junctions, owing to the presence of sulfur atoms on the peripheral peptides. Gels were obtained with cages bearing cysteine at the C-terminus. Our strategy for developing functional metal-coordinated supramolecular gels with a modular design may result in the development of materials useful for chemical separations or drug delivery.

Constructing Photocatalytic Covalent Organic Frameworks with Aliphatic Linkers

Photocatalytic covalent organic frameworks (COFs) are typically constructed with rigid aromatic linkers for crystallinity and extended π-conjugation. However, the essential hydrophobicity of the aromatic backbone can limit their performances in water-based photocatalytic reactions. Here, we for the first time report the synthesis of hydrophilic COFs with aliphatic linkers [tartaric acid dihydrazide (TAH) and butanedioic acid dihydrazide] that can function as efficient photocatalysts for H2O2 and H2 evolution. In these hydrophilic aliphatic linkers, the specific multiple hydrogen bonding networks not only enhance crystallization but also ensure an ideal compatibility of crystallinity, hydrophilicity, and light harvesting. The resulting aliphatic linker COFs adopt an unusual ABC stacking, giving rise to approximately 0.6 nm nanopores with an improved interaction with water guests. Remarkably, both aliphatic linker-based COFs show strong visible light absorption, along with a narrow optical band gap of ∼1.9 eV. The H2O2 evolution rate for TAH-COF reaches up to 6003 μmol h-1 g-1, in the absence of sacrificial agents, surpassing the performance of all previously reported COF-based photocatalysts. Theoretical calculations reveal that the TAH linker can enhance the indirect two-electron oxygen reduction reaction for H2O2 production by improving the O2 adsorption and stabilizing the *OOH intermediate. This study opens a new avenue for constructing semiconducting COFs using nonaromatic linkers.

Tailored Cis-Trans Isomeric Metal-Covalent Organic Frameworks for Coordination Configuration-Dependent Electrochemiluminescence

Precise manipulation of the coordination configuration within substances can modulate the band structure and catalytic properties of the target material. Metal-covalent organic frameworks (MCOFs), a crystal material amalgamating the benefits of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), can integrate a predetermined coordination environment into the frameworks for amplifying the catalytic effect. In this study, we delicately synthesize isomeric MCOFs using bis(glycinato)copper as the aminoligand via kinetically and thermodynamically favorable pathways to yield cis-MCOF and trans-MCOF products, respectively, thereby introducing a cis-trans isomeric coordination field into the framework. Moreover, the twisted skeleton derived from the flexibility of amino acid and β-ketoenamine linkages endows trans-MCOF with surprising water dispersibility. Compared to cis-MCOF, the trans isomerism displays a significant enhancement in cathodic electrochemiluminescence via the catalysis of Cu nodes toward K2S2O8. The density of states analysis shows that the d-band center of trans-MCOF is closer to the Fermi level, leading to more stable adsorption binding to promote the catalysis. This study is the first report on constructing predesign coordination configuration MCOFs via an easy-handling method, which gives the guidelines for the design of amino acid-based MCOF materials.

Precise Regulation the Multiemission Based on Soft Double Salt for Information Encryption

Manipulation of multiemissive luminophores is meaningful for exploring luminescent materials. Herein, we report a soft double salt assembly strategy that could result in well-organized nanostructures and different luminescence based on multiple weak intermolecular interactions thanks to the existence of electrostatic attraction between the anionic and cationic platinum(II) complexes. The cationic complexes B1 and B2 can coassemble with anionic complex A, respectively, and the emission switches from monomeric and excimeric emission to the triplet metal-metal-to-ligand charge transfer (3MMLCT) along with morphology changes from 0-dimensional (0-D) nanospheres to 3-dimensional (3-D) nanostructures. It is demonstrated that an isodesmic growth mechanism is adopted during the spontaneous self-assembly process, and the relative negative ΔG values make the anionic and cationic complex molecules prefer to form aggregates based on π-π stacking, Pt···Pt interactions, and electrostatic interactions. The coassembly strategy between anionic and cationic complexes endows them with multicolor luminescent and apparent color as optical materials for advanced information encryption.

Computation-Driven Rational Design of Self-Assembled Short Peptides for Catalytic Hydrogen Production

Self-assembling peptides represent a captivating area of study in nanotechnology and biomaterials. This interest is largely driven by their unique properties and the vast application potential across various fields such as catalytic functions. However, design complexities, including high-dimensional sequence space and structural diversity, pose significant challenges in the study of such systems. In this work, we explored the possibility of self-assembled peptides to catalyze the hydrolysis of hydrosilane for hydrogen production using ab initio calculations and carried out wet-lab experiments to confirm the feasibility of these catalytic reactions under ambient conditions. Further, we delved into the nuanced interplay between sequence, structural conformation, and catalytic activity by combining modeling with experimental techniques such as transmission electron microscopy and nuclear magnetic resonance and proposed a dual mode of the microstructure of the catalytic center. Our results reveal that although research in this area is still at an early stage, the development of self-assembled peptide catalysts for hydrogen production has the potential to provide a more sustainable and efficient alternative to conventional hydrogen production methods. In addition, this work also demonstrates that a computation-driven rational design supplemented by experimental validation is an effective protocol for conducting research on functional self-assembled peptides.

Therapeutic Peptides, Proteins and their Nanostructures for Drug Delivery and Precision Medicine

Peptide and protein nanostructures with tunable structural features, multifunctionality, biocompatibility and biomolecular recognition capacity enable development of efficient targeted drug delivery tools for precision medicine applications. In this review article, we present various techniques employed for the synthesis and self-assembly of peptides and proteins into nanostructures. We discuss design strategies utilized to enhance their stability, drug-loading capacity, and controlled release properties, in addition to the mechanisms by which peptide nanostructures interact with target cells, including receptor-mediated endocytosis and cell-penetrating capabilities. We also explore the potential of peptide and protein nanostructures for precision medicine, focusing on applications in personalized therapies and disease-specific targeting for diagnostics and therapeutics in diseases such as cancer.

Synthesis and Biological Activities of Some Metal Complexes of Peptides: A Review

Peptides, both natural and synthetic, are well suited for a wide range of purposes and offer versatile applications in different fields such as biocatalysts, injectable hydrogels, tumor treatment, and drug delivery. The research of the better part of the cited papers was conducted using various database platforms such as MetalPDB. The rising prominence of therapeutic peptides encompasses anticancer, antiviral, antimicrobial, and anti-neurodegenerative properties. The metals Na, K, Mg, Ca, Fe, Mn, Co, Cu, Zn, and Mo are ten of the twenty elements that are considered essential for life. Crucial for understanding the biological role of metals is the exploration of metal-bound proteins and peptides. Aside from essential metals, there are other non-essential metals that also interact biologically, exhibiting either therapeutic or toxic effects. Irregularities in metal binding contribute to diseases like Alzheimer's, neurodegenerative disorders, Wilson's, and Menkes disease. Certain metal complexes have potential applications as radiopharmaceuticals. The examination of these complexes was achieved by preforming UV-Vis, IR, EPR, NMR spectroscopy, and X-ray analysis. This summary, although unable to cover all of the studies in the field, offers a review of the ongoing experimentation and is a basis for new ideas, as well as strategies to explore and gain knowledge from the extensive realm of peptide-chelated metals and biotechnologies.

Pore Restructuring of Peptide Frameworks by Mutations at Distal Packing Residues

Porous framework materials are highly useful for catalysis, adsorption, and separations. Though they are usually made from inorganic and organic building blocks, recently, folded peptides have been utilized for constructing frameworks, opening up an enormous structure-space for exploration. These peptides assemble in a metal-free fashion using π-stacking, H-bonding, dispersion forces, and the hydrophobic effect. Manipulation of pore-defining H-bonding residues is known to generate new topologies, but the impact of mutations in the hydrophobic packing region facing away from the pores is less obvious. To explore their effects, we synthesized variants of peptide frameworks with mutations in the hydrophobic packing positions and found by single-crystal X-ray crystallography (SC-XRD) that they induce significant changes to the framework pore structure. These structural changes are driven by a need to maximize van der Waals interactions of the nonpolar groups, which are achieved by various mechanisms including helix twisting, chain flipping, chain offsetting, and desymmetrization. Even subtle changes to the van der Waals interface, such as the introduction of a methyl group or isomeric replacement, result in significant pore restructuring. This study shows that the dispersion interactions upholding a peptide material are a rich area for structural engineering.

Metal-driven folding and assembly of a minimal β-sheet into a 3D-porous honeycomb framework

In contrast to short helical peptides, constrained peptides, and foldamers, the design and fabrication of crystalline 3D frameworks from the β-sheet peptides are rare because of their high self-aggregation propensity to form 1D architectures. Herein, we demonstrate the formation of a 3D porous honeycomb framework through the silver coordination of a minimal β-sheet forming a peptide having terminal metal coordinated 4- and 3-pyridyl ligands.

Hydrolytic nanozymes: Preparation, properties, and applications

Hydrolytic nanozymes, as promising alternatives to hydrolytic enzymes, can efficiently catalyze the hydrolysis reactions and overcome the operating window limitations of natural enzymes. Moreover, they exhibit several merits such as relatively low cost, easier recovery and reuse, improved operating stability, and adjustable catalytic properties. Consequently, they have found relevance in practical applications such as organic synthesis, chemical weapon degradation, and biosensing. In this review, we highlight recent works addressing the broad topic of the development of hydrolytic nanozymes. We review the preparation, properties, and applications of six types of hydrolytic nanozymes, including AuNP-based nanozymes, polymeric nanozymes, surfactant assemblies, peptide assemblies, metal and metal oxide nanoparticles, and MOFs. Last, we discuss the remaining challenges and future directions. This review will stimulate the development and application of hydrolytic nanozymes.

Anion Tuned Structural Modulation and Nonlinear Optical Effects of Metal-Ion Directed 310 -Helix Networks

Metals play an important role in the structure and functions of various proteins. The combination of metal ions and peptides have been emerging as an attractive field to create advanced structures and biomaterials. Here, we are reporting the anion-influenced, silver ion coordinated diverse networks of designed short tripeptide 310 -helices with terminal pyridyl groups. The short peptides adopted classical right-handed, left-handed and 310 EL -helical conformations in the presence of different silver salts. The peptides have displayed conformational flexibility to accommodate different sizes and interactions of anions to yield a variety of metal-coordinated networks. The complexes of metal ions and peptides have shown different porous networks, right- and left-handed helical polymers, transformation of helix into superhelix and 2 : 2 metal-peptide macrocycles. Further, the metal-peptide crystals with inherent dipoles of helical peptides gave striking second harmonic generation response. The optical energy upconversion from NIR to red and green light is demonstrated. Overall, we have shown the utilization of short 310 -helices for the construction of diverse metal-coordinated helical networks and notable non-linear optical effects.

Tailoring Enantiomeric Chiral Channels in Metal-Peptide Networks: A Novel Foldamer-Based Approach for Host-Guest Interactions

Designing chiral channels in organic frameworks presents an ongoing challenge due to the intricate control of size, shape, and functionality required. A novel approach is presented, which crafts enantiomeric chiral channels in metal-peptide networks (MPNs) by integrating short foldamer ligands with CuI clusters. The MPN structure serves as a 3D blueprint for host-guest chemistry, fostering modular substitution to refine chiral channel properties at the atomic scale. Incorporating hydrogen bond networks augments guest molecule interactions with the channel surface. This approach expedites enantiomer discrimination in racemic mixtures and incites adaptable guest molecules to take on specific axially chiral conformations. Distinct from traditional metal-organic frameworks (MOFs) and conventional reticular architectures, this foldamer-based methodology provides a predictable and customizable host-guest interaction system within a 3D topology. This innovation sets the stage for multifunctional materials that merge host-guest interaction systems with metal-complex properties, opening up potential applications in catalysis, sensing, and drug delivery.

Biasing the Formation of Solution-Unstable Intermediates in Coordination Self-Assembly by Mechanochemistry

Due to the reversible nature of coordination bonds and solvation effect, coordination self-assembly pathways are often difficult to elucidate experimentally in solution, as intermediates and products are in constant equilibration. The present study shows that some of these transient and high-energy self-assembly intermediates can be accessed by means of ball-milling approaches. Among them, highly aqueous-unstable Pd3 L11 and Pd6 L14 open-cage intermediates of the framed Fujita Pd6 L14 cage and Pd2 L22 , Pd3 L21 and Pd4 L22 intermediates of Mukherjee Pd6 L24 capsule are successfully trapped in solid-state, where Pd=tmedaPd2+ , L1=2,4,6-tris(4-pyridyl)-1,3,5-triazine and L2=1,3,5-tris(1-imidazolyl)benzene). Their structures are assigned by a combination of solution-based characterization tools such as standard NMR spectroscopy, DOSY NMR, ESI-MS and X-ray diffraction. Collectively, these results highlight the opportunity of using mechanochemistry to access unique chemical space with vastly different reactivity compared to conventional solution-based supramolecular self-assembly reactions.

Noncovalent Peptide Assembly Enables Crystalline, Permutable, and Reactive Thiol Frameworks

Though thiols are exceptionally versatile, their high reactivity has also hindered the synthesis and characterization of well-defined thiol-containing porous materials. Leveraging the mild conditions of the noncovalent peptide assembly, we readily synthesized and characterized a number of frameworks with thiols displayed at many unique positions and in several permutations. Importantly, nearly all assemblies were structurally determined using single-crystal X-ray diffraction to reveal their rich sequence-structure landscape and the cooperative noncovalent interactions underlying their assembly. These observations and supporting molecular dynamics calculations enabled rational engineering by the positive and negative design of noncovalent interactions. Furthermore, the thiol-containing frameworks undergo diverse single-crystal-to-single-crystal reactions, including toxic metal ion coordination (e.g., Cd2+, Pb2+, and Hg2+), selective uptake of Hg2+ ions, and redox transformations. Notably, we find a framework that supports thiol-nitrosothiol interconversion, which is applicable for biocompatible nitric oxide delivery. The modularity, ease of synthesis, functionality, and well-defined nature of these peptide-based thiol frameworks are expected to accelerate the design of complex materials with reactive active sites.

Incorporation of Chiral Frustrated Lewis Pair into Metal-Organic Framework with Tailored Microenvironment for Heterogeneous Enantio- and Chemoselective Hydrogenation

The development of efficient heterogeneous catalysts with multiselectivity (e.g., enantio- and chemoselectivity) has long been sought after but with limited progress being made so far. To achieve enantio- and chemoselectivity in a heterogeneous system, as inspired by enzymes, we illustrate herein an approach of creating an enzyme-mimic region (EMR) within the nanospace of a metal-organic framework (MOF) as exemplified in the context of incorporating a chiral frustrated Lewis pair (CFLP) into a MOF with a tailored pore environment. Due to the high density of the EMR featuring the active site of CFLP and auxiliary sites of the hydroxyl group/open metal site within the vicinity of CFLP, the resultant EMR@MOF demonstrated excellent catalysis performance in heterogeneous hydrogenation of α,β-unsaturated imines to afford chiral β-unsaturated amines with high yields and high enantio- and chemoselectivity. The role of the hydroxyl group/open metal site in regulating chemoselectivity was proved by the observation of a catalyst-substrate interaction experimentally, which was also rationalized by computational results. This work not only contributes a MOF as a new platform for multiselective catalysis but also opens a promising avenue to develop heterogeneous catalysts with multiselectivity for challenging yet important transformations.

Peptide-derived coordination frameworks for biomimetic and selective separation

Peptide-derived metal-organic frameworks (PMOFs) have emerged as a class of biomimetic materials with attractive performances in analytical and bioanalytical chemistry. The incorporation of biomolecule peptides gives the frameworks conformational flexibility, guest adaptability, built-in chirality, and molecular recognition ability, which greatly accelerate the applications of PMOFs in enantiomeric separation, affinity separation, and the enrichment of bioactive species from complicated samples. This review focuses on the recent advances in the engineering and applications of PMOFs in selective separation. The unique biomimetic size-, enantio-, and affinity-selective performances for separation are discussed along with the chemical structures and functions of MOFs and peptides. Updates of the applications of PMOFs in adaptive separation of small molecules, chiral separation of drug molecules, and affinity isolation of bioactive species are summarized. Finally, the promising future and remaining challenges of PMOFs for selective separation of complex biosamples are discussed.

Exploring Helical Peptides and Foldamers for the Design of Metal Helix Frameworks: Current Trends and Future Perspectives

Flexible and biocompatible metal peptide frameworks (MPFs) derived from short and ultra-short peptides have been explored for the storage of greenhouse gases, molecular recognition, and chiral transformations. In addition to short flexible peptides, peptides with specifically folded conformations have recently been utilized to fabricate a variety of metal helix frameworks (MHFs). The secondary structures of the peptides govern the structure-assembly relationship and thereby control the formation of three-dimensional (3D)-MHFs. Particularly, the hierarchical structural organization of peptide-based MHFs has not yet been discussed in detail. Here, we describe the recent progress of metal-driven folded peptide assembly to construct 3D porous structures for use in future energy storage, chiral recognition, and biomedical applications, which could be envisioned as an alternative to the conventional metal-organic frameworks (MOFs).

Recent applications and chiral separation developments based on stationary phases in open tubular capillary electrochromatography (2019–2022)

Capillary electrochromatography (CEC) plays a significant role in chiral separation via the double separation principle, partition coefficient difference between the two phases, and electroosmotic flow-driven separation. Given the distinct properties of the inner wall stationary phase (SP), the separation ability of each SP differs from one another. Particularly, it provides large room for promising applications of open tubular capillary electrochromatography (OT-CEC). We divided the OT-CEC SPs developed over the past four years into six types: ionic liquids, nanoparticle materials, microporous materials, biomaterials, non-nanopolymers, and others, to mainly introduce their characteristics in chiral drug separation. There also added a few classic SPs that occurred within ten years as supplements to enrich the features of each SP. Additionally, we discuss their applications in metabolomics, food, cosmetics, environment, and biology as analytes in addition to chiral drugs. OT-CEC plays an increasingly significant role in chiral separation and may promote the development of capillary electrophoresis (CE) combined with other instruments in recent years, such as CE with mass spectrometry (CE/MS) and CE with ultraviolet light detector (CE/UV).

Crystalline Metal-Peptide Networks: Structures, Applications, and Future Outlook

Metal-peptide networks (MPNs), which are assembled from short peptides and metal ions, are considered one of the most fascinating metal-organic coordinated architectures because of their unique and complicated structures. Although MPNs have considerable potential for development into versatile materials, they have not been developed for practical applications because of several underlying limitations, such as designability, stability, and modifiability. In this review, we summarise several important milestones in the development of crystalline MPNs and thoroughly analyse their structural features, such as peptide sequence designs, coordination geometries, cross-linking types, and network topologies. In addition, potential applications such as gas adsorption, guest encapsulation, and chiral recognition are introduced. We believe that this review is a useful survey that can provide insights into the development of new MPNs with more sophisticated structures and novel functions.

Stereoselective Construction of Chiral Linear [3]Catenanes and [2]Catenanes

We have successfully constructed a chiral linear [3]catenane stereoselectively by coordination-driven self-assembly using a ditopic monodentate ligand containing l-valine residues with a binuclear half-sandwich organometallic rhodium(III) unit. Furthermore, by increasing the steric hindrance of the amino acid residues in the ligand, a chiral [2]catenane was obtained, which can be regarded as the factor catenane of the chiral linear [3]catenane from a topological viewpoint. Notably, the resulting molecular catenanes all exhibit complex coconformational mechanical helical chirality and planar chirality ascribed to the point chirality of the ligands. Linear [3]catenanes and [2]catenanes with the opposite chirality can be obtained by using ligands containing the corresponding d-amino acid residues, which have been confirmed by single-crystal X-ray diffraction, NMR, mass spectrometry, and circular dichroism spectroscopy.

Studying Peptide-Metal Ion Complex Structures by Solution-State NMR

Metal chelation can provide structural stability and form reactive centers in metalloproteins. Approximately one third of known protein structures are metalloproteins, and metal binding, or the lack thereof, is often implicated in disease, making it necessary to be able to study these systems in detail. Peptide-metal complexes are both present in nature and can provide a means to focus on the binding region of a protein and control experimental variables to a high degree. Structural studies of peptide complexes with metal ions by nuclear magnetic resonance (NMR) were surveyed for all the essential metal complexes and many non-essential metal complexes. The various methods used to study each metal ion are presented together with examples of recent research. Many of these metal systems have been individually reviewed and this current overview of NMR studies of metallopeptide complexes aims to provide a basis for inspiration from structural studies and methodology applied in the field.

Exploration of Structured Symmetric Cyclic Peptides as Ligands for Metal-Organic Frameworks

Despite remarkable advances in the assembly of highly structured coordination polymers and metal-organic frameworks, the rational design of such materials using more conformationally flexible organic ligands such as peptides remains challenging. In an effort to make the design of such materials fully programmable, we first developed a computational design method for generating metal-mediated 3D frameworks using rigid and symmetric peptide macrocycles with metal-coordinating sidechains. We solved the structures of six crystalline networks involving conformationally constrained 6 to 12 residue cyclic peptides with C2, C3, and S2 internal symmetry and three different types of metals (Zn2+, Co2+, or Cu2+) by single-crystal X-ray diffraction, which reveals how the peptide sequences, backbone symmetries, and metal coordination preferences drive the assembly of the resulting structures. In contrast to smaller ligands, these peptides associate through peptide-peptide interactions without full coordination of the metals, contrary to one of the assumptions underlying our computational design method. The cyclic peptides are the largest peptidic ligands reported to form crystalline coordination polymers with transition metals to date, and while more work is required to develop methods for fully programming their crystal structures, the combination of high chemical diversity with synthetic accessibility makes them attractive building blocks for engineering a broader set of new crystalline materials for use in applications such as sensing, asymmetric catalysis, and chiral separation.

Applications of Material-Binding Peptides: A Review

Material-binding peptides (MBPs) are functionalized adhesive materials consisting of a few to several dozen amino acids. This affinity between MBPs and materials is regulated by multiple interactions, including hydrogen bonding, electrostatic, hydrophobic interactions, and π-π stacking. They show selective binding and high affinity to a diverse range of inorganic and organic materials, such as silicon-based materials, metals, metal compounds, carbon materials, and polymers. They are used to improve the biocompatibility of materials, increase the efficiency of material synthesis, and guide the controlled synthesis of nanomaterials. In addition, these can be used for precise targeting of proteins by conjugating to target biomolecules. In this review, we summarize the main designs and applications of MBPs in recent years. The discussions focus on more efficient and functional peptides, including evolution and overall design of MBPs. We have also highlighted the recent applications of MBPs, such as functionalization of material surfaces, synthesis of nanomaterials, drug delivery, cancer therapy, and plastic degradation. Besides, we also discussed the development trend of MBPs. This interpretation will accelerate future investigations to bottleneck the drawbacks of available MBPs, promoting their commercial applications.

Supramolecular Hybrids from Cyanometallate Complexes and Diblock Copolypeptide Amphiphiles in Water

The self-assembly of discrete cyanometallates has attracted significant interest due to the potential of these materials to undergo soft metallophilic interactions as well as their optical properties. Diblock copolypeptide amphiphiles have also been investigated concerning their capacity for self-assembly into morphologies such as nanostructures. The present work combined these two concepts by examining supramolecular hybrids comprising cyanometallates with diblock copolypeptide amphiphiles in aqueous solutions. Discrete cyanometallates such as [Au(CN)2]-, [Ag(CN)2]-, and [Pt(CN)4]2- dispersed at the molecular level in water cannot interact with each other at low concentrations. However, the results of this work demonstrate that the addition of diblock copolypeptide amphiphiles such as poly-(L-lysine)-block-(L-cysteine) (Lysm-b-Cysn) to solutions of these complexes induces the supramolecular assembly of the discrete cyanometallates, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Electron microscopy images confirmed the formation of nanostructures of several hundred nanometers in size that grew to form advanced nanoarchitectures, including those resembling the original nanostructures. This concept of combining diblock copolypeptide amphiphiles with discrete cyanometallates allows the design of flexible and functional supramolecular hybrid systems in water.

Assembly of π-Stacking Helical Peptides into a Porous and Multivariable Proteomimetic Framework

The evolution of proteins from simpler, self-assembled peptides provides a powerful blueprint for the design of complex synthetic materials. Previously, peptide-metal frameworks using short sequences (≤3 residues) have shown great promise as proteomimetic materials that exhibit sophisticated capabilities. However, their development has been hindered due to few variable residues and restricted choice of side-chains that are compatible with metal ions. Herein, we developed a noncovalent strategy featuring π-stacking bipyridyl residues to assemble much longer peptides into crystalline frameworks that tolerate even previously incompatible acidic and basic functionalities and allow an unprecedented level of pore variations. Single-crystal X-ray structures are provided for all variants to guide and validate rational design. These materials exhibit hallmark proteomimetic behaviors such as guest-selective induced fit and assembly of multimetallic units. Significantly, we demonstrate facile optimization of the framework design to substantially increase affinity toward a complex organic molecule.

A biomimetic metal–organic framework with cuboid inner cavities for enantioselective separation

A biomimetic metal–organic framework with cuboid inner cavities and multiple recognition sites was constructed from a phenylalanine-derived ligand. It can enantioselectively separate various racemic alcohols, diols and epoxides with ee up to 99.5%.

Exploring the similarity of single-layer covalent organic frameworks using electronic structure calculations

Exploiting a similarity metric to classify COFs according to the degree of π-electron conjugation of their bridges.