Multifunctional Building Block Research Articles

Facile Synthesis of Soft Core-Shell Nanospheres for Constructing Multiresponsive Photonic Crystal Security Patterns.

Responsive photonic crystals (RPCs) presenting tunable structural colors under external stimuli are widely applied in the fields of dynamic displays, sensors, and anticounterfeiting. However, the development of multiresponsive photonic crystal (MRPC) films possessing versatile variable optical properties remains a significant challenge due to the tedious synthetic procedure of multifunctional building blocks and complex assembly processes, thereby constraining their extensive applications. In the present work, a series of soft nanospheres with a hydrophobic cores and responsive hydrophilic shells have been synthesized by a facile one-step surfactant-free emulsion polymerization method. The MRPC patterns were then prepared by depositing soft nanosphere emulsions onto the 3D-printed substrates with a topological structure followed by drying at room temperature. The shells of soft nanospheres deformed and fused with each other, resulting in the formation of transparent MRPC film patterns. The MRPC patterns exhibited brilliant structural color in a wet state but lost the color again after complete drying. Such a reversible structural color was ascribed to the change of the refractive index (RI) of the hydrophilic shell layers of nanospheres according to wetting/drying state shifting. Moreover, the on-demand designed MRPC patterns could rapidly respond to external stimuli of temperature, pH, and organic solvents in a reversible manner, and multichannel encrypted security labels were also demonstrated. We postulate that our facile and feasible approach can be applied to the systematic design and large-scale production of MRPC patterns for a variety of applications.

Multifunctional Material Building Blocks from Plant Pollen.

With its multifaceted nature, plant pollen serves not only as a key element in the reproductive cycle of seed plants but also as an influential contributor to environmental, human health, safety, and climate-related concerns. Pollen functions as a carrier of nutrients and organisms and holds a pivotal role in sustaining pollinator populations. Moreover, it is vital in ensuring the safety and quality of our food supply while presenting potential therapeutic applications. Pollen, often referred to as the diamond of the organic world due to its distinctive physical structures and properties, has been underappreciated from a material science and engineering standpoint. We propose adopting a more interdisciplinary and comprehensive approach to its study. Recent groundbreaking research has focused on the development of pollen-based building blocks that transform practically indestructible plant pollen into microgel, paper, and sponge, thereby unveiling numerous potential applications. In this review, we highlight the transformative potential of plant pollen as it is converted into a variety of building blocks, thereby unlocking myriad prospective applications through eco-friendly processing.

Catalytic Asymmetric Desymmetrization of Cyclic 1,3-Diketones Using Chiral Boro-phosphates.

Herein, we report a chiral boro-phosphate-catalyzed reductive amination for the desymmetrization of 2,2-disubstituted 1,3-cyclopentadiones with pinacolborane as the reducing agent, delivering chiral β-amino ketones with an all-carbon quaternary stereocenter in good yields (≤94%), high enantioselectivities (≤97% ee), and excellent diastereoselectivities (>20:1 dr). This reaction has a broad substrate scope and high functional group tolerance. The importance of the chiral products was also demonstrated through the preparation of multifunctional building blocks and heterocycles.

Cyanoesterthiophene Based Low‐Cost Polymer Donors for High Efficiency Organic Solar Cells

AbstractTo achieve commercial application of organic solar cells (OSCs), it is necessary to reduce material costs and improve device efficiency. This paper reports on the utilization of a multifunctional building block, namely 3‐cyanoesterthiophene, which exhibits simple structure and accessibility of synthetic for cost‐effective and high‐performance polymer donors (PDs). Meanwhile, ternary and terpolymerization strategies have been studied. Two similar PDs, PBTCl0‐TCA and PBTCl100‐TCA, are synthesized, and the devices exhibit less‐than‐satisfactory efficiency of 13.21% and 11.53% due to mismatching energy level and imperfect morphology. The two PDs with comparable structures and commendable compatibility easily form alloy‐like phase in active layer, which can effectively boost the efficiency of ternary devices to 14.17% with retained high JSC and significant improved open‐circuit voltage (VOC) and fill factor (FF). Encouraged by the ternary blending phenomenon, a polymer donor (PBTCl50‐TCA) with same ratio by random terpolymerization is designed. And over 17% efficiency binary OSCs using terpolymerization donor are demonstrated. The synergies of incorporation of the cyanoester‐group and terpolymer endow the developed PDs with deep‐lying energy levels, face‐on orientation, thermodynamic miscibility with the prevailing nonfullerene acceptor and appropriate polymer crystallinity. The findings study provide valuable insights and support for the advancement of cost‐effective and high‐performance PDs.

Supramolecular Nucleic Acid-Based Organosilica Nanoparticles Responsive to Physical and Biological Inputs.

Organosilica nanoparticles that contain responsive organic building blocks as constitutive components of the silica network offer promising opportunities for the development of innovative drug formulations, biomolecule delivery, and diagnostic tools. However, the synthetic challenges required to introduce dynamic and multifunctional building blocks have hindered the realization of biomimicking nanoparticles. In this study, capitalizing on our previous research on responsive nucleic acid-based organosilica nanoparticles, we combine the supramolecular programmability of nucleic acid (NA) interactions with sol-gel chemistry. This approach allows us to create dynamic supramolecular bridging units of nucleic acids in a silica-based scaffold. Two peptide nucleic acid-based monoalkoxysilane derivatives, which self-assemble into a supramolecular bis-alkoxysilane through direct base pairing, were chosen as the noncovalent units inserted into the silica network. In addition, a bridging functional NA aptamer leads to the specific recognition of ATP molecules. In a one-step bottom-up approach, the resulting supramolecular building blocks can be used to prepare responsive organosilica nanoparticles. The supramolecular Watson-Crick-Franklin interactions of the organosilica nanoparticles result in a programmable response to external physical (i.e., temperature) and biological (i.e., DNA and ATP) inputs and thus pave the way for the rational design of multifunctional silica materials with application from drug delivery to theranostics.

The flexibility of CuI chains and the functionality of pyrazine-2-thiocarboxamide keys to obtaining new Cu(I)-I coordination polymers with potential use as photocatalysts for organic dye degradation

This research focuses on two interesting aspects in the synthesis of new coordination polymers (CPs) taking advantage of the lability of coordination bonds. The first is the use of multifunctional and flexible building blocks, such as pyrazine-2-thiocarboxamide (Pyrtca) and CuI, and the second is the modification of the synthetic conditions to expand the amount of different crystalline phases. This means that starting from the same building blocks, we can increase the number of compounds obtained and diversify their final properties, as well as their possible applications. Furthermore, Cu(I)-halogen coordination polymers have been extensively studied for a long time due to their interesting optoelectronic properties. However, despite being usually semiconductors, research related to their possible behavior as photocatalysts is almost non-existent. In this work, we present five compounds, four coordination compounds with formulas [CuI(Pyrtca)]n (CP1), [Cu3I3(Pyrtca)7] (2) [Cu2I2(Pyrtca)]n(CP4 and CP4′) and a transformation of the starting ligand to a cationic imidazole derivative (compound 3) where copper iodine serves as a catalyst. All the compounds have been characterized by different techniques including single-crystal X-ray diffraction. The antibacterial behavior of CP1 against E. Coli DH5, E. Coli BL21, and C. glabrata (CECT 1448), as well as their optoelectronic properties, are also discussed in the work. The value of the band gap obtained (1.91 eV) for the two-dimensional coordination polymer of formula [Cu2I2(Pyrtca)]n(CP4) allows us to study its behavior as a photocatalyst in the degradation of persistent dyes in water with interesting results, achieving a total degradation of Methylene Blue and Rhodamine B in 40 min under UV–visible light.

Water-Based Dynamic Depsipeptide Chemistry: Building Block Recycling and Oligomer Distribution Control Using Hydration-Dehydration Cycles.

The high kinetic barrier to amide bond formation has historically placed narrow constraints on its utility in reversible chemistry applications. Slow kinetics has limited the use of amides for the generation of diverse combinatorial libraries and selection of target molecules. Current strategies for peptide-based dynamic chemistries require the use of nonpolar co-solvents or catalysts or the incorporation of functional groups that facilitate dynamic chemistry between peptides. In light of these limitations, we explored the use of depsipeptides: biorelevant copolymers of amino and hydroxy acids that would circumvent the challenges associated with dynamic peptide chemistry. Here, we describe a model system of N-(α-hydroxyacyl)-amino acid building blocks that reversibly polymerize to form depsipeptides when subjected to two-step evaporation–rehydration cycling under moderate conditions. The hydroxyl groups of these units allow for dynamic ester chemistry between short peptide segments through unmodified carboxyl termini. Selective recycling of building blocks is achieved by exploiting the differential hydrolytic lifetimes of depsipeptide amide and ester bonds, which we show are controllable by adjusting the solution pH, temperature, and time as well as the building blocks’ side chains. We demonstrate that the polymerization and breakdown of the depsipeptides are facilitated by cyclic morpholinedione intermediates, and further show how structural properties dictate half-lives and product oligomer distributions using multifunctional building blocks. These results establish a cyclic mode of ester-based reversible depsipeptide formation that temporally separates the polymerization and depolymerization steps for the building blocks and may have implications for prebiotic polymer chemical evolution.

Polyhydroxylated Nanosized Graphite as Multifunctional Building Block for Polyurethanes.

Polyurethane nanocomposites were prepared with a nanosized high surface area graphite (HSAG) functionalized on its edges with hydroxyl groups as a building block. Edge functionalization of HSAG was obtained through reaction with KOH. The addition of OH groups was demonstrated by means of infrared (FTIR) and thermogravimetric analysis (TGA), and the Boehm titration allowed estimation of a level of about 5.0 mmolOH/gHSAG. Results from wide-angle X-ray diffraction (WAXD) and Raman spectroscopy suggested that functionalization of the graphene layers occurred on the edges. The evaluation of the Hansen solubility parameters of G-OH revealed a substantial increase of δP and δH parameters with respect to HSAG. In line with these findings, homogeneous and stable dispersions of G-OH in a polyol were obtained. PU were prepared by mixing a dispersion of G-OH in cis-1,4-butenediol with hexamethylene diisocyanate. A model reaction between catechol, 1,4-butanediol, and hexamethylene diisocyanate demonstrated the reactivity of hydroxylated aromatic rings with isocyanate groups. PU-based G-OH, characterized with WAXD and differential scanning calorimetry (DSC), revealed lower Tg, higher Tc, Tm, and crystallinity than PU without G-OH. These results could be due to the higher flexibility of the polymer chains, likely a consequence of the dilution of the urethane bonds by the carbon substrate. Hence, G-OH allowed the preparation of PU with a larger temperature range between Tg and Tm, with potential positive impact on material applications. The model reaction between butylisocyanate and 1-butanol revealed that HSAG and G-OH promote efficient formation of the urethane bond, even in the absence of a catalyst. The effect of high surface area carbon on the nucleophilic oxygen attack to the isocyanate group can be hypothesized. The results here reported lead us to comment that a reactive nanosized sp2 carbon allotrope, such as G-OH, can be used as a multifunctional building block of PU. Indeed, G-OH is a comonomer of PU, a promoter of the polymerization reaction, and can definitely act as reinforcing filler by tuning its amount in the final nanocomposite leading to highly versatile materials. The larger temperature range between Tg and Tm, together with the presence of G-OH acting as a reinforcing agent, could allow the production of piezoresistive sensing, shape-memory PU with good mechanical features.

Transition metal halide nanowires: A family of one-dimensional multifunctional building blocks

Low-dimensional materials with definite geometrical and electronic structures have long been pursued to fulfill the requirement of technological devices toward miniaturization, multifunctionality, and precise manufacturing. Inspired by the emerging transition metal halide monolayers with intriguing magnetic behavior, here we systematically explore stable one-dimensional (1D) structures of transition metal halides. By first-principles calculations, a total of 208 TMX2 and TMX3 (TM is 3d, 4d, 5d transition metal elements; X = F, Cl, Br, I) nanowires have been predicted, showing diverse electronic and magnetic properties, such as ferromagnetic semiconductors, half metals, and antiferromagnets. They possess many application-desired characters, including a wide range of bandgaps, small carrier effective masses, outstanding capability for solar energy harvesting, and strong ferromagnetic or antiferromagnetic order. This large family of TMXn nanowires provides a great platform for exploring exotic 1D physics as well as for designing high-performance devices.

Universal Antifouling and Photothermal Antibacterial Surfaces Based on Multifunctional Metal-Phenolic Networks for Prevention of Biofilm Formation.

Biofilms formed from the pathogenic bacteria that attach to the surfaces of biomedical devices and implantable materials result in various persistent and chronic bacterial infections, posing serious threats to human health. Compared to the elimination of matured biofilms, prevention of the formation of biofilms is expected to be a more effective way for the treatment of biofilm-associated infections. Herein, we develop a facile method for endowing diverse substrates with long-term antibiofilm property by deposition of a hybrid film composed of tannic acid/Cu ion (TA/Cu) complex and poly(ethylene glycol) (PEG). In this system, the TA/Cu complex acts as a multifunctional building block with three different roles: (i) as a versatile "glue" with universal adherent property for substrate modification, (ii) as a photothermal biocidal agent for bacterial elimination under irradiation of near-infrared (NIR) laser, and (iii) as a potent linker for immobilization of PEG with inherent antifouling property to inhibit adhesion and accumulation of bacteria. The resulted hybrid film shows negligible cytotoxicity and good histocompatibility and could prevent biofilm formation for at least 15 days in vitro and suppress bacterial infection in vivo, showing great potential for practical applications to solve the biofilm-associated problems of biomedical materials and devices.

Light-Responsive Dynamic Protein Hydrogels Based on LOVTRAP.

Protein-based hydrogels can mimic many aspects of native extracellular matrices (ECMs) and are promising biomedical materials that find various applications in cell proliferation, drug/cell delivery, and tissue engineering. To be adapted for different tasks, it is important that the mechanical and/or biochemical properties of protein-based hydrogels can be regulated by external stimuli. Light as a regulation stimulus is of advantage because it can be easily applied in demanded spatiotemporal manners. The noncovalent binding between the light-oxygen-voltage-sensing domain 2 (LOV2) and its binding partner ZDark1 (zdk1), named as LOVTRAP, is a light-responsive interaction. The binding affinity of LOVTRAP is much higher in dark than that under blue light irradiation. Taking advantage of these light-responsive interactions, herein we endeavored to use LOVTRAP as a crosslinking mechanism to engineer light-responsive protein hydrogels. Using LOV2-containing and zdk1-containing multifunctional protein building blocks, we successfully engineered a light-responsive protein hydrogel whose viscoelastic properties can change in response to light: in the dark, the hydrogel showed higher storage modulus; under blue light irradiation, the storage modulus decreased. Due to the noncovalent nature of the LOVTRAP, the engineered LOVTRAP protein hydrogels displayed shear-thinning and self-healing properties and served as an excellent injectable protein hydrogel. We anticipated that this new class of light-responsive protein hydrogels will broaden the scope of dynamic protein hydrogels and help develop other light-responsive protein hydrogels for biomedical applications.

Desymmetrization of 1,3-Diones by Catalytic Enantioselective Condensation with Hydrazine.

We present herein an unprecedented desymmetrization of meso 1,3-diones by enantioselective intermolecular condensation. Under the catalysis by a chiral phosphoric acid, a range of readily available 1,3-diones undergo reaction with hydrazines to produce cyclic and acyclic keto-hydrazones bearing an all-carbon quaternary center in high efficiency and enantioselectivity. These compounds are also highly versatile for the preparation of multifunctional building blocks and heterocycles in excellent stereoselectivity.

Unconventional inorganic precursors determine the growth of metal-organic frameworks

Abstract Crystalline metal-organic frameworks (MOFs) are an emerging type of the hybrid materials with multifunctional inorganic and organic building blocks, which have been applied in a wide range of energy-related and environment-related applications. In this context, a remaining challenge in the systematical syntheses of hierarchically porous MOFs composites is existing to alter supermolecular structure, chemical composition, and versatile functionality. It is generally accepted that the regulation of MOF preparation is of great significance, which is related to the solubility of those starting inorganic components. We learn that there are several possible drawbacks induced by conventional soluble metal precursors in homogeneous reaction conditions, so the increasing research interest in the facile synthesis of MOFs and their derivatives from insoluble metal templates and/or precursors has been ignited in the past decade. In this review, we aim to provide an overview of the facile preparation and usage of MOF materials by using the unconventional inorganic precursors in heterogeneous synthetic conditions, including template types, preparation methods, extension strategies, advantages, limitations and related applications.

Reconfigurable laminates enable multifunctional robotic building blocks

Folding and assembling of two-dimensional laminated materials have greatly facilitated robot fabrication by creating robots with lightweight body frames, articulated joints, and embedded actuators and sensors. The combinations of rigid laminates bridged by thin-film flexures, often called rigid-flex linkages, have been extensively used in micro- and macro-scale robots to achieve complex joint motions with simplified kinematic and dynamic properties. Much like traditional robots these rigid-flex laminate robots are designed with a fixed body-plan, and thus may face challenges when environments require mechanical reconfiguration such as stiffening joints for load support or changing appendage morphologies for navigating confined spaces. Recent advances in adaptive materials and smart actuators have highlighted the features that robots with morphable geometries and tunable mechanical properties can provide, such as self-folding joints and variable stiffness and damping mechanisms. However, incorporation of these reconfigurable elements into laminate robots has been limited. In this paper, we present a new method for creating quasi two-dimensional structures for robotics, called reconfigurable laminates, that use geometric reconfiguration of laminate layers to alter passive mechanical properties and actuate joints. Unlike traditional rigid-flex linkages with single-layered flexures, here we create laminate joints with dual-layered soft hinges and rigid channels allowing a multitude of reconfiguration opportunities including: sliding-layer laminates for passive stiffness control, snapping-hinge locks for reconfigurable joints, and buckle-bend joints for bending actuation. Through experimental characterization we demonstrate the capabilities of these multifunctional robotic building blocks.

Multiple hydrogen-bonded cross-linked photo-responsive liquid crystal elastomers with photo-responsive fluorescence

Luminescent liquid crystal elastomers (LCEs) have wide application prospect in fluorescent soft actuators and dynamic display devices. α-Cyanostilbene shows a rigid rod structure, aggregation-induced emission enhancement (AIEE) characteristic and photo-induced trans-cis isomerization, which can be used as multifunctional building block to prepare stimulus responsive luminescent LCEs. In this paper, a series of physically cross-linked luminescent LCEs showing photo-induced deformation behavior and photo-responsive fluorescence are obtained (named as LCE-M(x)-L(y), x and y denote the feed mole fraction of M6PVPC10 and ME6UPy respectively, x + y = 1, y = 0.04, 0.06, 0.08, 0.10, 0.12). The photo-induced deformation, luminescent property, and the intrinsic relationship between the luminescent behavior and the photo-induced bending behavior of LCEs were studied in particular. Under the irradiation of 365 nm ultraviolet light, the prepared uniaxially oriented LCEs bent toward the direction of light. The deformation rate, the maximum bending angle of polymers are sensitive to crosslinking agent content, and increase with increasing crosslinking agent content. All the prepared LCEs also behave AIEE characteristic and can emit strong fluorescence in solid state. Meanwhile, LCE-M(x)-L(y) presents stimuli-sensitive fluorescence, and the emission intensity decreases with increasing of 365 nm UV light irradiation time. The emission intensity variation with 365 nm UV irradiation is proved to be related to the photo-induced deformation, which can be used to monitor the deformation of LCEs.

Acrylic boronate: a multifunctional C3 building block for catalytic synthesis of rare organoborons and chemoselective heterobifunctional ligations.

A novel C3 acylboron building block; acrylic boronate was successfully prepared and its versatility for catalytic synthesis of several previously inaccessible organoborons is described. Cross-metathesis and Pd-catalyzed coupling of acrylic boronate enabled two complementary routes to highly functionalized α,β-unsaturated acylborons and two new types of conjugated borylated products: α,β,γ,δ-unsaturated and bis-α,β unsaturated acylborons. The synthetic application of α,β-unsaturated acylborons was demonstrated for the first time, thereby providing a general and highly regioselective route to medicinally important 3-boryl pyrazoles. Acrylic boronate also provided a unique bis-electrophilic platform for rapid and chemoselective labeling of cysteines with acylboron tags which are potentially useful for site-selective functionalization and orthogonal ligation of proteins.

L-Dopa in small peptides: an amazing functionality to form supramolecular materials.

l-Dopa (3,4-dihydroxyphenylalanine) is a chiral amino acid generated via biosynthesis from l-tyrosine in plants and some animals. The presence of multiple interacting sites makes l-Dopa a multifunctional building block for the preparation of supramolecular materials. The possibility to form hydrogen bonds and the presence of the aromatic ring allow l-Dopa molecules to interact through a series of non-covalent interactions. The additional presence of the catechol moiety really makes this compound unique: not only does it have implications in the self-assembly process of Dopa itself and with other substrates, but also it highly increases the number of applications of the final material, since it works as an antioxidant, radical trapper, metal chelator, reducing agent and adhesive. l-Dopa and catechol containing derivatives have been extensively introduced inside both synthetic and natural polymers to obtain amazing functional materials. In this review we report the preparation of small peptides containing l-Dopa, focusing on the supramolecular materials that can be obtained with them, ranging from fibrils to fibres, gels, films and coatings, all having the different applications mentioned above and many others.

Photoredox-mediated hydroalkylation and hydroarylation of functionalized olefins for DNA-encoded library synthesis.

DNA-encoded library (DEL) technology features a time- and cost-effective interrogation format for the discovery of therapeutic candidates in the pharmaceutical industry. To develop DEL platforms, the implementation of water-compatible transformations that facilitate the incorporation of multifunctional building blocks (BBs) with high C(sp3) carbon counts is integral for success. In this report, a decarboxylative-based hydroalkylation of DNA-conjugated trifluoromethyl-substituted alkenes enabled by single-electron transfer (SET) and subsequent hydrogen atom termination through electron donor–acceptor (EDA) complex activation is detailed. In a further photoredox-catalyzed hydroarylation protocol, the coupling of functionalized, electronically unbiased olefins is achieved under air and within minutes of blue light irradiation through the intermediacy of reactive (hetero)aryl radical species with full retention of the DNA tag integrity. Notably, these processes operate under mild reaction conditions, furnishing complex structural scaffolds with a high density of pendant functional groups.

A nonlinear magnonic nano-ring resonator

The field of magnonics, which aims at using spin waves as carriers in data-processing devices, has attracted increasing interest in recent years. We present and study micromagnetically a nonlinear nanoscale magnonic ring resonator device for enabling implementations of magnonic logic gates and neuromorphic magnonic circuits. In the linear regime, this device efficiently suppresses spin-wave transmission using the phenomenon of critical resonant coupling, thus exhibiting the behavior of a notch filter. By increasing the spin-wave input power, the resonance frequency is shifted, leading to transmission curves, depending on the frequency, reminiscent of the activation functions of neurons, or showing the characteristics of a power limiter. An analytical theory is developed to describe the transmission curve of magnonic ring resonators in the linear and nonlinear regimes, and is validated by a comprehensive micromagnetic study. The proposed magnonic ring resonator provides a multi-functional nonlinear building block for unconventional magnonic circuits.

A modular biomimetic strategy for the synthesis of macrolide P-glycoprotein inhibitors via Rh-catalyzed C-H activation

One of the key challenges to overcome multidrug resistance (MDR) in cancer is the development of more effective and general strategies to discover bioactive scaffolds. Inspired by natural products, we describe a strategy to achieve this goal by modular biomimetic synthesis of scaffolds of (Z)-allylic-supported macrolides. Herein, an Rh(III)-catalyzed native carboxylic acid-directed and solvent-free C−H activation allylation with high stereoselectivity and chemoselectivity is achieved. The generated poly-substituted allylic alcohol as a multifunctional and biomimetic building block is crucial for the synthesis of (Z)-allylic-supported macrolides. Moreover, the unique allylic-supported macrolides significantly potentiate the sensitivity of tumor cells to cytotoxic agents such as vinorelbine and doxetaxel by reversing p170-glycoprotein-mediated MDR. Our findings will inspire the evolution of synthetic chemistry and open avenues for expedient and diversified synthesis of bioactive macrocyclic molecules.