Functional Building Blocks Research Articles

Solvent‐Influenced Fragmentations in Free‐Standing Three‐Dimensional Covalent Organic Framework Membranes for Hydrophobicity Switching

AbstractThe ordered open organic frameworks membranes are attractive candidates for flow‐assisted molecular separations. The physicochemical properties of such membranes mostly depend on their selectively chosen functional building blocks. In this work, we have introduced a novel concept of functional switchability of three‐dimensional covalent organic framework (3D‐COF) membranes through a simple solvent‐influenced fragmentation method. This room‐temperature interfacial synthesis provides free‐standing 3D‐COF membranes with distinct physicochemical properties from the same building monomers. Notably, the change of solvent from chloroform to ethyl acetate switches the membrane property from hydrophilic (water contact angle 60°) to hydrophobic (water contact angle 142°) nature. The hydrophobic 3D‐COF membrane selectively passes oil molecules from an oil–water emulsion with a gravitational flux of 1536 L m−2 h−1.

Solvent-Influenced Fragmentations in Free-Standing Three-Dimensional Covalent Organic Framework Membranes for Hydrophobicity Switching.

The ordered open organic frameworks membranes are attractive candidates for flow‐assisted molecular separations. The physicochemical properties of such membranes mostly depend on their selectively chosen functional building blocks. In this work, we have introduced a novel concept of functional switchability of three‐dimensional covalent organic framework (3D‐COF) membranes through a simple solvent‐influenced fragmentation method. This room‐temperature interfacial synthesis provides free‐standing 3D‐COF membranes with distinct physicochemical properties from the same building monomers. Notably, the change of solvent from chloroform to ethyl acetate switches the membrane property from hydrophilic (water contact angle 60°) to hydrophobic (water contact angle 142°) nature. The hydrophobic 3D‐COF membrane selectively passes oil molecules from an oil–water emulsion with a gravitational flux of 1536 L m−2 h−1.

One‐pot Synthesis of 3‐Aryliden‐2,3‐dihydro‐4‐quinolones from o‐Anilinopropargyl Alcohols via Aldol Condensation of In Situ Generated 2,3‐Dihydroquinolin‐4‐ones and Aryl Aldehydes

AbstractA one‐pot conversion of o‐anilinopropargyl alcohols to 3‐aryliden‐2,3‐dihydro‐4‐quinolone derivatives with 20 mol% TfOH as the catalyst has been devised. The method may proceed through a sequential Meyer‐Schuster rearrangement of o‐anilinopropargyls/intramolecular conjugated addition/aldol condensation of in situ generated 2,3‐dihydroquinolin‐4‐ones and aldehydes. Finally, the subsequent additions succeeded between 3‐benzyliden‐2,3‐dihydro‐4‐quinolones and hydrazines to give fused multicycles. The reaction is metal‐ and ligand‐free, proceeds under mild conditions, gives high yields, and has a broad substrate scope, making it a valuable method for the construction of 3‐aryliden‐2,3‐dihydro‐4‐quinolone functionalized building blocks.

Synthesis of block copolymers containing 3-chloro-2-hydroxypropyl methacrylate by NMP – a versatile platform for functionalization

This study highlights the potential of 3-chloro-2-hydroxypropyl methacrylate (ClHPMA) as a functional building block in nanostructured block copolymer architectures.

Na2SrB16O26: a new borate with independent interpenetrating B-O networks and deep-ultraviolet cutoff edge.

A new borate, Na2SrB16O26, was synthesized by the high-temperature solution method. It exhibits complicated interpenetrating 3D B-O frameworks composed of the functional building block (FBB) [B8O16]. The UV-vis-NIR diffuse reflectance spectroscopy shows that it has a deep-ultraviolet (DUV) cutoff edge (<200 nm). The relationship between the structures and optical properties was uncovered by theoretical calculations. By the first-principles calculation, the birefringence is estimated to be 0.07 at 1064 nm. The response electron distribution anisotropy (REDA) analysis indicates that the [BO3] units contribute mainly to the generation of the moderate birefringence.

Constructing two-dimensional heterojunction through decorating covalent organic framework with MoS2 for enhanced photoelectrochemical water oxidation

Photoelectrochemical (PEC) water splitting is regarded as one of the most effective route to address energy crisis and environmental issues. Two-dimensional covalent organic frameworks (2D COFs) have made some advances in PEC water splitting owing to their functionalized building blocks, remarkable structural stability, and unique conjugated structures, etc. Unfortunately, the PEC performance of COFs is severely hindered because of the poor surface charge transfer, surface recombination at the photoanode/electrolyte junction, and sluggish oxygen evolution reaction (OER) kinetics. Herein, we report an efficient 2D heterojunction through decorating a 2D COF with MoS2 for enhanced PEC water oxidation. The photocurrent density and incident photon conversion efficiency (IPCE) of the resultant photoanode are effectively improved by constructing 2D COF-based heterojunction. Such a strategy of constructing 2D heterojunction can not only efficiently accelerate the charge separation and transfer but also promote the separation of photogenerated electron-hole pairs for oxygen evolution. This work provides rational suggestions for developing COF-based photocatalysts to address the energy crisis and various environmental issues.

Synthesis of Functional Building Blocks for Type III-B Rotaxane Dendrimer.

Second-generation type III-B rotaxane dendrons, equipped with succinimide and acetylene functional groups, were synthesized successfully and characterized by NMR spectroscopy and mass spectrometry. A cell viability study of a dendron with a normal cell line of L929 fibroblast cells revealed no obvious cytotoxicity at a range of 5 to 100 μM. The nontoxic properties of the sophisticated rotaxane dendron building blocks provided a choice of bio-compatible macromolecular machines that could be potentially developed into polymeric materials.

Synthesis and Functionality Study of Photoswitchable Hydrazone Oligodeoxynucleotides.

This article provides a detailed procedure for the chemical synthesis and characterization of photoswitchable hydrazone phosphoramidite and its incorporation into oligodeoxynucleotides. The synthesis starts with commercially available deoxyuridine, followed by conversion of the 4-oxo into a 4-chloro moiety via Appel reaction to install the key hydrazone group in the absence of base. The hydrazone phosphoramidite building block is compatible with the conventional amidite chemistry protocols for solid-phase synthesis of oligodeoxynucleotides. Our method expands the current nucleotide pool by adding a novel, functional DNA building block that is suitable for a broad spectrum of applications, including the regulation of DNA-enzyme interactions and DNA synthesis by irradiation with cell-friendly blue light. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparation of photoswitchable hydrazone phosphoramidite Basic Protocol 2: Synthesis and purification of oligodeoxynucleotides containing the hydrazone photoswitch Basic Protocol 3: Primer extension assay for functionality studies of hydrazone cytidine.

High‐Performance Ultrathin Molecular Rectifying Diodes Based on Organic/Inorganic Interface Engineering

AbstractThe bottom‐up engineering of organic/inorganic hybrids is a crucial step toward advanced nanomaterial technologies. Understanding the energy level alignment at hybrid interfaces provides a valuable comprehension of the systems′ electronic properties – which are decisive for well‐designed device applications. Here, active interfaces of ultrathin (≈10 nm) molecular rectifying diodes that are capable of achieving a 4‐order‐magnitude rectification ratio along with 10 MHz cutoff frequency, both in a single nanodevice, are engineered. Atomic force microscopy and Kelvin‐Probe analysis are employed to investigate the surface potential of the hybrid devices′ organic/inorganic interfaces, which comprise a metal (M) electrode in contact with a few‐nanometer‐thick copper phthalocyanine (CuPc) film. Thereby a nanometer‐resolved quantification of the CuPc film work functions as well as the M/CuPc diode's space‐charge densities are delivered. By recognizing that the molecular rectifying diode is a functional building block for nanoscale electronics, the findings address crucial advances to the design of high‐performance molecular rectifiers based on organic/inorganic interface engineering.

Modular Evolution of the Drosophila Metabolome.

Comparative phylogenetic studies offer a powerful approach to study the evolution of complex traits. Although much effort has been devoted to the evolution of the genome and to organismal phenotypes, until now relatively little work has been done on the evolution of the metabolome, despite the fact that it is composed of the basic structural and functional building blocks of all organisms. Here we explore variation in metabolite levels across 50 My of evolution in the genus Drosophila, employing a common garden design to measure the metabolome within and among 11 species of Drosophila. We find that both sex and age have dramatic and evolutionarily conserved effects on the metabolome. We also find substantial evidence that many metabolite pairs covary after phylogenetic correction, and that such metabolome coevolution is modular. Some of these modules are enriched for specific biochemical pathways and show different evolutionary trajectories, with some showing signs of stabilizing selection. Both observations suggest that functional relationships may ultimately cause such modularity. These coevolutionary patterns also differ between sexes and are affected by age. We explore the relevance of modular evolution to fitness by associating modules with lifespan variation measured in the same common garden. We find several modules associated with lifespan, particularly in the metabolome of older flies. Oxaloacetate levels in older females appear to coevolve with lifespan, and a lifespan-associated module in older females suggests that metabolic associations could underlie 50 My of lifespan evolution.

Complex magnetic dynamics in an akaganéite-based iron deficiency drug

Magnetic dynamics of iron oxyhydroxide akaganéite nanoparticles, functional building blocks of the newest generation iron deficiency drug Ferinject, has been studied. While magnetism of the involved nanoparticles relies in general on bulk properties of akaganéite, the low temperature magnetic dynamics of Ferinject differs a lot from large number of other iron-oxides-based intravenous drugs in pharmaceutical practice. Clear separation of the high-temperature (Curie) and the low-temperature (spin-freezing) regimes has been identified. Instead of standard single superparamagnetic blocking temperature we show that the spin freezing relies on the two dominant and superimposed relaxations, characterizing the temperature ranges 50–100 K and 4.2–10 K, respectively. Complex magnetic dynamics is interpreted to rely on presence of the two assemblies of nanoparticles differing significantly in their average sizes. Bimodal distribution of particle sizes has been confirmed using atomic force microscopy. The knowledge of the drug’s physicochemical characteristics has been thus significantly improved.

Bu4NHSO4‐Catalyzed Direct N‐Allylation of Pyrazole and its Derivatives with Allylic Alcohols in Water: A Metal‐Free, Recyclable and Sustainable System

AbstractAllylic amines are valuable and functional building blocks. Direct N‐allylation of pyrazole and its derivatives as an atom economic strategy to provide allylic amines has been achieved only using commercial Bu4NHSO4 as the metal‐free catalyst and water as the solvent without any additives. 11–93% isolated yields were obtained for the N‐allylation of pyrazole and its derivatives with allylic alcohols. Bu4NHSO4 could be reused for six times by simple extraction nearly without loss of catalytic activity and was also suitable for a gram‐scale production. The reaction of allylic ether and pyrazole did not occur to give the desired product indicated that allylic ether was not the active intermediate in the pathway. Density functional theory (DFT) calculations reveal that there are hydrogen bonding effects among substrates, solvent and catalyst, especially the one formed between allylic alcohol and H2O. Control experiments in different protic solvents further demonstrate the intermolecular hydrogen bonding of allylic alcohol and water.magnified image

Modular ketal-linked prodrugs and biomaterials enabled by organocatalytic transisopropenylation of alcohols

Isopropenyl ethers are critical intermediates for accessing medicinally valuable ketal-based prodrugs and biomaterials, but traditional approaches for the synthesis of isopropenyl ethers suffer from poor functional group compatibility and harsh reaction conditions. Here, we develop an organocatalytic transisopropenylation approach to solve these challenges, enabling the synthesis of isopropenyl ethers from various hydroxyl-group-containing small-molecule drugs, polymers, and functional building blocks. The method provides a straightforward and versatile synthesis of isopropenyl ethers, features excellent tolerance of diverse functional groups, applies to a wide range of substrates, and allows scalable synthesis. The development of this organocatalytic transisopropenylation approach enables access to modular preparation of various acid-sensitive ketal-linked prodrugs and functionalized ketalated biomaterials. We expect our syntheses and transformations of isopropenyl ethers will find utility in several diverse fields, including medicinal chemistry, drug delivery, and biomaterials.

Recent Advances in the Fabrication and Environmental Science Applications of Cellulose Nanofibril-Based Functional Materials.

Cellulose is one of the important biomass materials in nature and has shown wide applications in various fields from materials science, biomedicine, tissue engineering, wearable devices, energy, and environmental science, as well as many others. Due to their one-dimensional nanostructure, high specific surface area, excellent biodegradability, low cost, and high sustainability, cellulose nanofibrils/nanofibers (CNFs) have been widely used for environmental science applications in the last years. In this review, we summarize the advance in the design, synthesis, and water purification applications of CNF-based functional nanomaterials. To achieve this aim, we firstly introduce the synthesis and functionalization of CNFs, which are further extended for the formation of CNF hybrid materials by combining with other functional nanoscale building blocks, such as polymers, biomolecules, nanoparticles, carbon nanotubes, and two-dimensional (2D) materials. Then, the fabrication methods of CNF-based 2D membranes/films, three-dimensional (3D) hydrogels, and 3D aerogels are presented. Regarding the environmental science applications, CNF-based nanomaterials for the removal of metal ions, anions, organic dyes, oils, and bio-contents are demonstrated and discussed in detail. Finally, the challenges and outlooks in this promising research field are discussed. It is expected that this topical review will guide and inspire the design and fabrication of CNF-based novel nanomaterials with high sustainability for practical applications.

A Perspective on Muscle Synergies and Different Theories Related to Their Adaptation

The human motor system is a complex neuro-musculo sensory system that needs further investigations of neuro-muscular commands and sensory-motor coupling to decode movement execution. Some researchers suggest that the central nervous system (CNS) activates a small set of modules termed muscle synergies to simplify motor control. Further, these modules form functional building blocks of movement as they can explain the neurophysiological characteristics of movements. We can identify and extract these muscle synergies from electromyographic signals (EMG) recorded in the laboratory by using linear decomposition algorithms, such as principal component analysis (PCA) and non-Negative Matrix Factorization Algorithm (NNMF). For the past three decades, the hypothesis of muscle synergies has received considerable attention as we attempt to understand and apply the concept of muscle synergies in clinical settings and rehabilitation. In this article, we first explore the concept of muscle synergies. We then present different strategies of adaptation in these synergies that the CNS employs to accomplish a movement goal.

Optically Active Functionalized Building Blocks for Peptidyl Olefin Peptidomimetics

AbstractPeptidyl olefins can function as bio‐active peptide isosteres or as intermediates in the synthesis of other peptidomimetics. We previously developed a stereoselective chemo‐enzymatic approach to optically active C‐terminal building blocks for the synthesis of peptidyl olefins. These building units include a sulfone functionality, to enable a Julia‐Kocienski reaction with N‐terminal aldehydes. Here, we extend this synthetic methodology to building blocks that are functionalized at their side chains with oxygen, nitrogen or halogen. The method features key enzymatic hydrolysis of prochiral diesters to the corresponding hydroxy esters, a step that introduces the optical activity. The ordering of the subsequent chemical reactions, either protection‐methanolysis‐functionalization or functionalization‐methanolysis‐protection, determines the absolute stereochemistry of the final building blocks.

Diarylfluorene‐Based Organic Semiconductor Materials toward Optoelectronic Applications

AbstractModular production is a convenient strategy that not only realizes the mass production of conjugated materials, but also precisely regulates their photoelectrical property for optoelectronic applications. Diarylfluorene is a functional building block in constructing organic semiconductors arising from its special electronic, spacial, and conformational structure. Because of easy chemical modification, tunable electronic structure, and high photoluminescence quantum yield, diarylfluorene‐based conjugated materials have undergone remarkable development in variety of low‐cost optoelectronic devices. Herein, the authors present an overview mainly to describe the recent research progresses of diarylfluorene‐based molecules, including 9,9′‐diarylfluorene, heteroatom‐containing spirocyclic diarylfluorene, and 4‐position substituted 9,9′‐diarylfluorene. The synthetic routes, molecular structures as well as their diverse applications toward optoelectronic devices are introduced and summarized systematically. Finally, the future challenges and development are also discussed in this vital research field.

Förster Resonance Energy Transfer in Linear DNA Multifluorophore Photonic Wires: Comparing Dual versus Split Rail Building Block Designs

AbstractDNA scaffolds provide a means to precisely organize chromophores into large biomimetic exciton networks and direct energy transport for nanoscale sensing and light‐harvesting applications. Here, a functional building block of minimal complexity that maximizes the Förster resonance energy transfer (FRET) efficiency is sought. Using a model system consisting of three FRET steps in a 4‐dye cascade: Cy3→Cy3.5→Cy5→Cy5.5, we evaluate how this building block employs multiple interacting versus redundant FRET pathways. Variants of a dual rail design, where one or two copies of each dye are aligned in rigid linear parallel rows, are compared to a split rail format, where varying degrees of spacing are introduced between the rows. The FRET processes are assessed via steady‐state, time‐resolved, and single‐molecule spectroscopy. Experiments and simulation reveal the dual rail design as more efficient than the split rail and suggest the design principle that efficient FRET networks must balance the increase in FRET rate from multiple interacting pathways with undesirable fluorescence quenching between dyes in close proximity. Hybrid fluorophore combinations are identified as a strategy to mitigate this quenching, leading to optimized dual rails capable of 50% end‐to‐end efficiency. These insights can help guide the design of functional photonic wires based on DNA scaffolds.

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

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

Building a Personal Brand as a CEO: A Case Study of Vivy Yusof, the Cofounder of FashionValet and the dUCk Group

Social media is a new platform for CEOs to build their image and create a strong personal brand to represent themselves and their company. This research examines an outstanding Malaysian fashion icon and social media–savvy businesswoman with over a million followers on Instagram, Vivy Yusof, the youngest Malaysian e-commerce mogul and an example of a successful CEO who has used personal branding to build an empire in the fashion industry. The objectives of this research are to identify the type of messages Vivy Yusof communicates to her audience through her personal Instagram posts and to identify the ways Vivy Yusof’s audience engages with her posts on Instagram. Her Instagram post content is classified using the Honeycomb framework that comprises seven functional building blocks, namely, presence, relationships, reputation, groups, identity, conversations, and sharing. In this study, the content of Vivy Yusof’s Instagram posts is categorized by how she focuses on the various functional building blocks in her posts and the implications these blocks have on how her audience interacts with the posts. Her social media presence confirms the importance of CEO personal branding because of her role and influence on the masses evidenced by the willingness of her followers to interact (through likes and comments) and engage with her posts on any subject matter, relating either to her business or personal life. The study contributes to a growing body of literature on personal branding strategies by shedding light on the association between content strategies and engagement with social media content.