Hierarchically Templated Synthesis of 3D-Printed Crosslinked Cyclodextrins for Lycopene Harvesting

Plants produce a wide range of bioactive phytochemicals, such as antioxidants and vitamins, which play crucial roles in aging prevention, inflammation reduction, and reducing the risk of cancer. Selectively harvesting these phytochemicals, such as lycopene, from tomatoes through the adsorption method is cost-effective and energy efficient. In this work, a templated synthesis of 3D-printed crosslinked cyclodextrin polymers featuring nanotubular structures for highly selective lycopene harvesting is reported. Polypseudorotaxanes formed by triethoxysilane-based telechelic polyethylene glycols and α-cyclodextrins (α-CDs) are designed as the template to (1) synthetically access urethane-based nanotubular structures at the molecular level, and (2) construct 3D-printed architectures with designed macroscale voids. The polypseudorotaxane hydrogels showed good rheological properties for direct ink writing, and the 3D-printed hydrogels were converted to the desired α-CD polymer network through a three-step postprinting transformation. The obtained urethane-crosslinked α-CD monoliths possess nanotubular structures and 3D-printed voids. They selectively adsorb lycopene from raw tomato juice, protecting lycopene from photo- or thermo-degradations. This work highlights the hierarchically templated synthesis approach in developing functional 3D-printing materials by connecting the bottom-up molecular assembly and synthesis with the top-down 3D architecture control and fabrication.

Visible Light-Induced Templated Metathesis of Peptide-Nucleic Acid Conjugates with a Diselenide Bridge

The use of template molecules as chemical scaffolds that significantly influence the course of the reaction has recently been intensively studied. Peptide nucleic acids (PNA) are molecules that mimic natural nucleic acids. They are a promising matrix in such reactions because they possess high affinity and specificity in their interactions. The manner of PNA interaction is predictable based on sequence complementarity. Recently, we report the visible light-induced metathesis reaction in peptides containing a diselenide bond. Herein, we present an efficient and straightforward method of the visible light-driven diselenide-based metathesis of peptide-nucleic acid conjugates. Compared to a similar photochemical transformation in peptides, a significant increase in the metathesis efficiency was obtained due to the template effect.

Starfish-Inspired Diamond-Structured Calcite Single Crystals from a Bottom-up Approach as Mechanical Metamaterials

Inspired by knobby starfish, this work demonstrates a bottom-up approach for fabricating a calcite single-crystal (CSC) with a diamond structure by exploiting the self-assembly of the block copolymer and corresponding templated synthesis. Similar to the knobby starfish, the diamond structure of the CSC gives rise to a brittle-to-ductile transition. Most interestingly, the diamond-structured CSC fabricated exhibits exceptional specific energy absorption and strength with lightweight character superior to natural materials and artificial counterparts from a top-down approach due to the nanosized effect. This approach provides the feasibility for creating mechanical metamaterials with the combined effects of the topology and nanosize on the mechanical performance.

Solvent-Free Templated Synthesis of Core-Crosslinked Star-Shaped Polymers in Supramolecular Body-Centered Cubic Phase

This study reports the exploration of a solvent-free supramolecular templated synthesis strategy toward highly core-cross-linked star-shaped polymers (CSPs). To achieve this, a kind of cross-linkable giant surfactant, based on a functionalized polyhedral oligomeric silsesquioxanes (POSS) head tethered with a diblock copolymer tail containing reactive benzocyclobutene groups, is designed and prepared. By varying the volume fraction of linear block copolymer tail, these giant surfactants can self-assemble into a body-centered cubic (BCC) structure in bulk, in which the supramolecular spheres are composed of a core of POSS cages, a middle shell of crosslinkable poly(4-vinylbenzocyclobutene) (PBCB) blocks, and a corona of inert polystyrene (PS) blocks. The solvent-free thermally induced cross-linking reaction of the benzocyclobutene groups can be finished in 5 min upon heating, resulting in well-defined polymeric spheres with over 90 linear chains surrounding the cross-linked cores. The outer PS blocks serve as the protection corona to ensure that cross-linking of giant surfactants occurs in each supramolecular spherical domain. Given the modular design and diversity of the POSS-based giant surfactants, it is believed that the strategy may enable access to a wide range of CSPs.

Bioinspired Nanonetwork Hydroxyapatite from Block Copolymer Templated Synthesis for Mechanical Metamaterials

Inspired by Mantis shrimp, this work aims to suggest a bottom-up approach for the fabrication of nanonetwork hydroxyapatite (HAp) thin film using self-assembled polystyrene-block-polydimethylsiloxane (PS-b-PDMS) block copolymer (BCP) with a diamond nanostructure as a template for templated sol-gel reaction. By introducing poly(vinylpyrrolidone) (PVP) into precursors of calcium nitrate tetrahydrate and triethyl phosphite, which limits the growth of forming HAp nanoparticles, well-ordered nanonetwork HAp thin film can be fabricated. Based on nanoindentation results, the well-ordered nanonetwork HAp shows high energy dissipation compared to the intrinsic HAp. Moreover, the uniaxial microcompression test for the nanonetwork HAp shows high energy absorption per volume and high compression strength, outperforming many cellular materials due to the topologic effect of the well-ordered network at the nanoscale. This work highlights the potential of exploiting BCP templated synthesis to fabricate ionic solid materials with a well-ordered nanonetwork monolith, giving rise to the brittle-to-ductile transition, and thus appealing mechanical properties with the character of mechanical metamaterials.

Preparation and characterization of templated porous carbons from sucrose by one-pot method and application as a CO2 adsorbent

The templated porous carbons were prepared from sucrose by one-pot method. In this method in which the pre-synthesis of the hard template is eliminated, the porous carbons were produced by organic-inorganic self-assembly of sucrose, tetraethyl ortosilicate (TEOS), Pluronic P123 and n-butanol in an acidic medium, and subsequent carbonization. The synthesis parameters such as sucrose amount, TEOS molar ratio and carbonization temperature were evaluated for describing their effects on the pore structures of the synthesized carbons. The prepared porous carbons were characterized by N₂ adsorption, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The carbon dioxide adsorption uptakes of the obtained porous carbons were determined at 1 bar and 273 K. The templated carbon obtained with the lowest TEOS molar ratio exhibited the highest BET surface area of 1289 m²/g and micropore volume of 0.467 cm³/g, and showed the highest CO₂ uptake of 2.28 mmol/g.

Chaotropic and Kosmotropic Anions Regulate the Outcome of Enzyme-Mediated Dynamic Combinatorial Libraries of Cyclodextrins in Two Different Ways

We demonstrate how different anions from across the Hofmeister series can influence the behavior of enzyme-mediated dynamic combinatorial libraries of cyclodextrins (CDs). Using cyclodextrin glucanotransferase to catalyze reversible transglycosylation, dynamic mixtures of interconverting cyclodextrins can be formed wherein the relative concentrations of α-CD, β-CD and γ-CD is determined by their intrinsic stabilities and any stabilizing influences of added template (guest) molecules. Here, we find that addition of high concentrations of kosmotropic anions can be used to enhance the effects of added hydrophobic templates, while chaotropic anions can themselves act as templates, causing predictable and significant changes in the cyclodextrin composition due to weak, but specific, binding interactions with α-CD.

Ni(OH)2 Templated Synthesis of Ultrathin Ni3 S2 Nanosheets as Bifunctional Electrocatalyst for Overall Water Splitting

Ultrathin nickel (Ni)-based sulfide nanosheets have been reported as excellent electrocatalysts for overall water splitting; however, the uncontrollability over thickness due to the nonlayered structure still hampers its practical application. Herein, a simple topochemical conversion strategy is employed to synthesize cobalt-doped Ni₃ S₂ (Co-Ni₃ S₂ ) ultrathin nanosheets on Ni foam. The Co-Ni₃ S₂ nanosheets are controlled synthesized by using Co-Ni(OH)₂ ultrathin nanosheets as templates with anneal and sulfurization treatment, showing exceptional electrocatalytic activity. This template-assisted method can also be applied to obtain Ni, NiO, and NiP_x nanosheets, providing a universal strategy to synthesize ultrathin nanosheets of nonlayered materials. The overall water splitting of this Co-Ni₃ S₂ ultrathin nanosheets achieves a low voltage of 1.54 V at a current density of 10 mA cm^-2 and high durability in 1 m KOH, comparable to the best performance of electrochemical water splitting ever reported. The detailed structural transformation of Ni-based sulfides in the catalytic process and its mechanism are further explored both experimentally and theoretically.

Deep Eutectic Solvents as Media for the Prebiotic DNA-Templated Synthesis of Peptides

Translation of genetic information into peptide products is one of the fundamental processes of biology. How this occurred prebiotically, in the absence of enzyme catalysts, is an intriguing question. Nucleic acid-templated synthesis (NATS) promotes reactions by bringing building blocks tethered to complementary DNA strands into close proximity and has been shown to enable peptide synthesis without enzymes—it could therefore serve as a model for prebiotic translation of information stored in nucleic acid sequences into functional peptides. The decomposition of highly reactive DNA adapters has so far limited the effectiveness of NATS, but these studies have been performed exclusively in aqueous solution. Deep eutectic solvents (DESs) have been proposed as a feasible solvent for prebiotic replication of nucleic acids, and here are studied as media for prebiotic translation using NATS as a model. DESs are shown to enhance the stability of DNA-conjugated activated esters, the precursors of peptides. However, this enhanced stability was coupled with decreased amine reactivity that hampered the formation of peptide bonds in DESs. These properties are exploited to demonstrate the storage of DNA-conjugated activated esters in a DES followed by transfer into aqueous buffer to activate the NATS of peptides “on demand.” These findings, together with the reported functions of DESs in prebiotic processes, shed light on how DESs could have facilitated the non-enzymatic translation of genetic information into functional peptides on the early Earth.

Patchy Templated Synthesis of Macroporous Colloidal Hollow Spheres and Their Application as Catalytic Microreactors

Porous colloidal hollow spheres have been applied to diversified fields over the past few decades. However, developing simple and efficient methods to prepare such porous hollow spheres with macro pores remains a challenge. To address this problem, we present a patchy templated synthesis route, which can be used to prepare such colloidal hollow spheres that have macro pores through the shells. This was achieved by using patchy poly(styrene-co-sodium styrenesulfonate) spheres as the template and poly(allylamine hydrochloride) as binding molecules. SiO₂ can site-selectively only grow on one kind of patch, resulting in the formation of porous hollow spheres. The pore sizes can be tuned from ∼50 to 400 nm. The resulting porous hollow spheres have a Janus character so that Au nanoparticles can only be attached to the interior surfaces in situ, which can be used as catalytic microreactors and show the catalytic performance of pore size dependence.

Templated chemistry for bioorganic synthesis and chemical biology

In light of the 2018 Max Bergmann Medal, this review discusses advancements on chemical biology-driven templated chemistry developed in the author's laboratories. The focused review introduces the template categories applied to orient functional units such as functional groups, chromophores, biomolecules, or ligands in space. Unimolecular templates applied in protein synthesis facilitate fragment coupling of unprotected peptides. Templating via bimolecular assemblies provides control over proximity relationships between functional units of two molecules. As an instructive example, the coiled coil peptide-templated labelling of receptor proteins on live cells will be shown. Termolecular assemblies provide the opportunity to put the proximity of functional units on two (bio)molecules under the control of a third party molecule. This allows the design of conditional bimolecular reactions. A notable example is DNA/RNA-triggered peptide synthesis. The last section shows how termolecular and multimolecular assemblies can be used to better characterize and understand multivalent protein-ligand interactions.

Hierarchically Structured CeO2 Catalyst Particles From Nanocellulose/Alginate Templates for Upgrading of Fast Pyrolysis Vapors

Hierarchically structured porous materials often exhibit advantageous functionality for many applications including catalysts, adsorbents, and filtration systems. In this study, we report a facile approach to achieve hierarchically structured, porous cerium oxide (CeO₂) catalyst particles using a templating method based on nanocellulose, a class of renewable, plant-derived nanomaterials. We demonstrate the catalyst performance benefits provided by this templating method in the context of Catalytic Fast Pyrolysis (CFP) which is a promising conversion technology to produce renewable fuel and chemical products from biomass and other types of organic waste. We show that variations in the porous structures imparted by this templating method may be achieved by modifying the content of cellulose nanofibrils, cellulose nanocrystals, and alginate in the templating suspensions. Nitrogen physisorption reveals that nearly 10-fold increases in surface area can be achieved using this method with respect to commercially available cerium oxide powder. Multiscale electron microscopy further verifies that bio-derived templating can alter the morphology of the catalyst nanostructure and tune the distribution of meso- and macro-porosity within the catalyst particles while maintaining CeO₂ crystal structure. CFP experiments demonstrate that the templated catalysts display substantially higher activity on a gravimetric basis than their non-templated counterpart, and that variations in the catalyst architecture can impact the distribution of upgraded pyrolysis products. Finally, we demonstrate that the templating method described here may be extended to other materials derived from metal chlorides to achieve 3-dimensional networks of hierarchical porosity.

Liquid Crystal Templates Combined with Photolithography Enable Synthesis of Chiral Twisted Polymeric Microparticles

Liquid crystals (LC), when combined with photolithography, enable synthesis of microparticles with 2D and 3D shapes and internal complexities. Films of nematic LCs are prepared using mixtures of reactive (RM257) and non-reactive mesogens with controlled alignment of LCs at the confining surfaces, photo-polymerized the RM257 using a photomask, and then extracted the unreacted mesogens to yield the polymeric microparticles. The extraction results in a controlled anisotropic shrinkage amount dependent on the RM257 content and the direction dependent on LC alignment. Control over the aspect ratio, size, and thickness of the microparticles are obtained with a coefficient of variance less than 2%. In addition, non-parallel LC anchoring at the two surfaces results in a controllable right- or left-handed twisting of microparticles. These methods may find substantial use in applications including drug delivery, emulsions, separations, and sensors, besides their potential in revealing new fundamental concepts in self-assembly and colloidal interactions.

Importing Tin Nanoparticles into Biomass-Derived Silicon Oxycarbides with High-Rate Cycling Capability Based on Supercritical Fluid Technology

Silicon oxycarbides (SiOC) are regarded as potential anode materials for lithium-ion batteries, although inferior cycling stability and rate performance greatly limit their practical applications. Herein, amorphous SiOC is synthesized from Chlorella by means of a biotemplate method based on supercritical fluid technology. On this basis, tin particles with sizes of several nanometers are introduced into the SiOC matrix through the biosorption feature of Chlorella. As lithium-ion battery anodes, SiOC and Sn@SiOC can deliver reversible capacities of 440 and 502 mAh g^-1 after 300 cycles at 100 mA g^-1 with great cycling stability. Furthermore, as-synthesized Sn@SiOC presents an excellent high-rate cycling capability, which exhibits a reversible capacity of 209 mAh g^-1 after 800 cycles at 5000 mA g^-1 ; this is 1.6 times higher than that of SiOC. Such a novel approach has significance for the preparation of high-performance SiOC-based anodes.

Template-Assisted Synthesis of Luminescent Carbon Nanofibers from Beverage-Related Precursors by Microwave Heating

Luminescent carbon nanomaterials are important materials for sensing, imaging, and display technologies. This work describes the use of microwave heating for the template-assisted preparation of luminescent carbon nanofibers (CNFs) from the reaction of a range of beverage-related precursors with the nitrogen-rich polyethyleneimine. Highly luminescent robust carbon fibers that were 10 to 30 m in length and had a diameter of 200 nm were obtained under moderate conditions of temperature (250-260 °C) and a short reaction time (6 min). The high aspect ratio fibers showed wavelength-dependent emission that can be readily imaged using epifluorescence. The development of these multi-emissive one-dimensional (1D) carbon nanomaterials offers potential for a range of applications.

Templating and Catalyzing [2+2] Photocycloaddition in Solution Using a Dynamic G-Quadruplex

We describe a templating/covalent capture strategy that enables photochemical formation of 8 cyclobutanes in one noncovalent assembly. This process was characterized by experiment and quantum mechanical/molecular mechanics (ONIOM) calculations. Thus, KI and 16 units of 5'-cinnamate guanosine form a G-quadruplex where C=C π bonds in neighboring G₄ -quartets are separated by 3.3 Å, enabling [2+2] photocycloaddition in solution. This reaction is high-yielding (>90 %), regio- and diastereoselective. Since all components are in dynamic equilibrium this photocycloaddition is catalytic in K⁺ .

Liquid Crystal-Templated Synthesis of Mesoporous Membranes with Predetermined Pore Alignment

We demonstrate that polymeric films templated from liquid crystals (LCs) provide basic design principles for the synthesis of mesoporous films with predetermined pore alignment. Specifically, we used LC mixtures of reactive [4-(3-acryloyoxypropyloxy) benzoic acid 2-methyl-1,4-phenylene ester (RM257)] and nonreactive [4-cyano-4'-pentylbiphenyl (5CB)] mesogens confined in film geometries. The LC alignment was maintained by functionalization of the surfaces contacting the films during polymerization. Through photopolymerization followed by extraction of the unreacted mesogens, films of area in the order of 10 cm² were obtained. We found that, when restricted to an area either through a mechanical or a configurational constraint, open and accessible pores were incorporated into the films. The average direction of the pores could be determined by the LC director during polymerization, and the average diameter of the pores can be tuned in the range of 10-40 nm by varying the reactive monomer concentration. The polymeric films synthesized here can potentially be used for the ultrafiltration purposes. We demonstrated successful separations of proteins and nanoparticles from aqueous media using the polymeric films. The films exhibited 2 orders of magnitude higher flux when the pores were aligned parallel to the permeate direction compared to the perpendicular direction. Overall, the outcomes of this study provide basic tools for the synthesis of porous polymeric films with predetermined pore directions that can potentially be suitable for separations, drug delivery, catalysts, and so forth.

Low-Weight 3D Al2 O3 Network as an Artificial Layer to Stabilize Lithium Deposition

Lithium metal has been regarded as an ideal anode for high-energy-density batteries. However, safety and efficiency concerns still linger due to dendrite formation, reactions between the liquid electrolyte and lithium, high resistance with lithium metal, and the weight of interface layer. A new nanometer-thick, hollow, Al₂ O₃ fiber network with an elastic and porous 3D structure has been prepared through an atomic-layer deposition process by using cotton sacrificial templates. Through a comparison study of the lithium deposition behavior by employing artificial layers with different structures, the low-weight 3D layer with lithiophilic properties overcomes the issues resulting from the 2D rigid Al₂ O₃ layer and provides a low overpotential and dendrite-free growth of lithium metal. Moreover, stable lithium deposition enables Li-Li symmetric cells with a 3D artificial layer to be stably cycled 300 times in carbonate-based electrolyte, with superior rate capability, and with a LiNi_1/3 Co_1/3 Mn_1/3 O₂ cathode.

Template-Directed Synthesis of an Inverted Spiro Architecture

The regular bicyclic spiro motif is highly abundant given its synthetic accessibility while the diastereomer-virtually obtained through inversion at the central atom-is almost unknown. We have developed methodology to access the elusive inverted spiro architecture by employing a covalent template-directed approach. Comparison with the regular spiro bicycle analog unequivocally established the diastereomeric relationship, providing insight into the fascinating stereochemical and structural properties.

Ultralight, Flexible, and Semi-Transparent Metal Oxide Papers for Photoelectrochemical Water Splitting

Thanks to their versatile functionality, metal oxides (MOs) constitute one of the key family materials in a variety of current demands for sensor, catalysis, energy storage and conversion, optical electronics, and piezoelectric mechanics. Much effort has focused on engineering specific nanostructure and macroscopic morphology of MOs that aims to enhance their performances, but the design and controlled synthesis of ultrafine nanostructured MOs in a cost-effective and facile way remains a challenge. In this work, we have exploited the advantages of intrinsic structures of graphene oxide (GO) papers, serving as a sacrificial template, to design and synthesize two-dimensional (2D) layered and free-standing MO papers with ultrafine nanostructures. Physicochemical characterizations showed that these MO materials are nanostructured, porous, flexible, and ultralight. The as-synthesized materials were tested for their potential application in photoelectrochemical (PEC) energy conversion. In terms of PEC water splitting, copper oxide papers were used as an example and exhibited excellent performances with an extremely high photocurrent-to-weight ratio of 3 A cm^-2 g^-1. We have also shown that the synthesis method is generally valid for many earth-abundant transition metals including copper, nickel, iron, cobalt, and manganese.

Tailored Fabrication of Transferable and Hollow Weblike Titanium Dioxide Structures

The preparation of weblike titanium dioxide thin films by atomic layer deposition on cellulose biotemplates is reported. The method produces a TiO₂ web, which is flexible and transferable from the deposition substrate to that of the end application. Removal of the cellulose template by calcination converts the amorphous titania to crystalline anatase and gives the structure a hollow morphology. The TiO₂ webs are thoroughly characterized using electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy to give new insight into manufacturing of porous titanium dioxide structures by means of template-based methods. Functionality and integrity of the TiO₂ hollow weblike thin films were successfully confirmed by applying them as electrodes in dye-sensitized solar cells.

Shape-Persistent Graphite Replica of Metal Wires

A facile one-step procedure for a template-assisted fabrication of hollow carbon tubes is reported, using organic halides as the carbon source. The shape-persistent tubes are obtained with arbitrary shapes as hollow replicas of the metal template. They feature a high quality of graphite, and a high conductivity of 1.31 ± 0.05 · 10⁶ S·m^-1 .

Synthesis of Five-Porphyrin Nanorings by Using Ferrocene and Corannulene Templates

The smallest and most strained member of a family of π-conjugated cyclic porphyrin oligomers was synthesized by using pentapyridyl templates based on ferrocene and corannulene. Both templates are effective for directing the synthesis of the butadiyne-linked cyclic pentamer, despite the fact that the radii of their N5 donor sets are too small by 0.5 Å and 0.9 Å, respectively (from DFT calculations). The five-porphyrin nanoring exhibits a structured absorption spectrum and its fluorescence extends to 1200 nm, reflecting strong π conjugation and Herzberg-Teller vibronic coupling.

Ice-Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement

Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates.

Chemically Locked Bicelles with High Thermal and Kinetic Stability

In situ polymerization of a bicellar mixture composed of a phospholipid and polymerizable surfactants afforded unprecedented stable bicelles. The polymerized composite showed an aligned phase over a wide thermal range (25 to >90 °C) with excellent (2)H quadrupole splitting of the solvent signal, thus implying versatility as an alignment medium for NMR studies. Crosslinking of the surfactants also brought favorable effects on the kinetic stability and alignment morphology of the bicelles. This system could thus offer a new class of scaffolds for biomembrane models.

Caterpillar track complexes in template-directed synthesis and correlated molecular motion

Small alterations to the structure of a star-shaped template totally change its mode of operation. The hexapyridyl template directs the conversion of a porphyrin dimer to the cyclic hexamer, but deleting one pyridine site changes the product to the cyclic decamer, while deleting two binding sites changes the product to the cyclic octamer. This surprising switch in selectivity is explained by the formation of 2:1 caterpillar track complexes, in which two template wheels bind inside the nanoring. Caterpillar track complexes can also be prepared by binding the hexapyridyl template inside the 8- and 10-porphyrin nanorings. NMR exchange spectroscopy (EXSY) experiments show that these complexes exhibit correlated motion, in which the conrotatory rotation of the two template wheels is coupled to rotation of the nanoring track. In the case of the 10-porphyrin system, the correlated motion can be locked by binding palladium(II) dichloride between the two templates.

Mesoporous carbon-vanadium oxide films by resol-assisted, triblock copolymer-templated cooperative self-assembly

Unlike other crystalline metal oxides amenable to templating by the combined assemblies of soft and hard chemistries (CASH) method, vanadium oxide nanostructures templated by poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) triblock copolymers are not preserved upon high temperature calcination in argon. Triconstituent cooperative assembly of a phenolic resin oligomer (resol) and an OBO triblock in a VOCl3 precursor solution enhances the carbon yield and can prevent breakout crystallization of the vanadia during calcination. However, the calcination environment significantly influences the observed mesoporous morphology in these composite thin films. Use of an argon atmosphere in this processing protocol leads to nearly complete loss of carbon-vanadium oxide thin film mesostructure, due to carbothermal reduction of vanadium oxide. This reduction mechanism also explains why the CASH method is not more generally successful for the fabrication of ordered mesoporous vanadia. Carbonization under a nitrogen atmosphere at temperatures up to 800 °C instead enables formation of a block copolymer-templated mesoporous structure, which apparently stems from the formation of a minor fraction of a stabilizing vanadium oxynitride. Thus, judicious selection of the inert gas for template removal is critical for the synthesis of well-defined, mesoporous vanadia-carbon composite films. This resol-assisted assembly method may generally apply to the fabrication of other mesoporous materials, wherein inorganic framework crystallization is problematic due to kinetically competitive carbothermal reduction processes.

Scalable high-fidelity growth of semiconductor nanorod arrays with controlled geometry for photovoltaic devices using block copolymers

Controlled density semiconducting oxide arrays are highly desirable for matching nanometer length scales specific to emerging applications. This work demonstrates a facile one-step method for templating hydrothermal growth which provides arrays with high-fidelity tuning of nanorod spacing and diameter. This solution-based method leverages the selective swelling of block copolymer micelle templates, which can be rationally designed by tuning molecular weight and volume fraction.

Templated Synthesis of Magnetic Nanoparticles through the Self-Assembly of Polymers and Surfactants

The synthesis of superparamagnetic nanoparticles (NPs) for various technological applications continues to be an interesting research topic. The successful application of superparamagnetic NPs to each specific area typically depends on the achievement of high magnetization for the nanocrystals obtained, which is determined by their average size and size distribution. The size dispersity of magnetic NPs (MNPs) is markedly improved when, during the synthesis, the nucleation and growth steps of the reaction are well-separated. Tuning the nucleation process with the assistance of a hosting medium that encapsulates the precursors (such as self-assembled micelles), dispersing them in discrete compartments, improves control over particle formation. These inorganic-organic hybrids inherit properties from both the organic and the inorganic materials, while the organic component can also bring a specific functionality to the particles or prevent their aggregation in water. The general concept of interest in this review is that the shape and size of the synthesized MNPs can be controlled to some extent by the geometry and the size of the organic templates used, which thus can be considered as molds at the nanometer scale, for both porous continuous matrices and suspensions.

Cyclodextrin-templated porphyrin nanorings

α- and β-Cyclodextrins have been used as scaffolds for the synthesis of six- and seven-legged templates by functionalizing every primary CH₂OH with a 4-pyridyl moiety. Although these templates are flexible, they are very effective for directing the synthesis of macrocyclic porphyrin oligomers consisting of six or seven porphyrin units. The transfer of chirality from the cyclodextrin templates to their nanoring hosts is evident from NMR and circular dichroism spectroscopy. Surprisingly, the mean effective molarity for binding the flexible α-cyclodextrin-based template within the six-porphyrin nanoring (74 m) is almost as high as for the previously studied rigid hexadentate template (180 m). The discovery that flexible templates are effective in this system, and the availability of a template with a prime number of binding sites, open up many possibilities for the template-directed synthesis of larger macrocycles.

SnO₂ tube-in-tube nanostructures: Cu@C nanocable templated synthesis and their mutual interferences between heavy metal ions revealed by stripping voltammetry

SnO2 tube-in-tube nanostructures are synthesized using Cu@C nanocables as effective sacrificial templates. It is revealed by stripping voltammetry that SnO2 tube-in-tube nanostructures show excellent performances in the determination of heavy metal ions, which might be related to the extraordinary adsorbing capacities of the hollow structure to metal ions, i.e., metal ions could diffuse into the interior of tubular structure.

Fabrication of anisotropic metal nanostructures using innovations in template-assisted lithography

Advances in the burgeoning field of plasmonics are increasingly dependent on the ability to fabricate metal nanostructures with precisely defined shapes and orientations, on a scale suitable for technological developments. Recent innovations in top-down lithography have created new windows of opportunity to produce anisotropic metal nanostructures en masse, with near-term applications in photonics, biosensing, and other nanotechnology-enabled pursuits. We focus specifically on C-shaped nanostructures (nanocrescents and split-ring resonators), which can be fabricated by using novel variants of shadow-mask lithography, substrate etching, or microcontact printing.

Designing, fabricating, and imaging Raman hot spots

We have developed a probe of the electromagnetic mechanism of surface-enhanced Raman scattering via Au nanodisk arrays generated by using on-wire lithography. In this approach, disk thickness and interparticle gap are precisely controlled from 5 nm to many micrometers. Confocal Raman microscopy demonstrates that disk thickness and gap play a crucial role in determining surface-enhanced Raman scattering intensities. Theoretical calculations also demonstrate that these results are consistent with the electromagnetic mechanism, including the surprising result that the largest enhancement does not occur for the smallest gaps.