Template Effect Research Articles

Cu-SSZ-39 zeolite nanosheets-heterogeneous catalyst for the decarboxylative cross-coupling of cinnamic acids with ethers

Zeolite with nanoscale in some dimensions always display better catalytic performance because it contains more exposed catalytic active sites. Herein, a Cu2+ exchanged SSZ-39 zeolite with nanosheet morphology was chosen as a catalyst for the preparation of 2-vinyl heterocycle ethers through decarboxylative cross-coupling of cinnamic acids with ethers. The template reaction conditions were optimized, and the possible reaction mechanism was proposed. Then, a wide range of 2-vinyl heterocycle ethers were prepared. The recycling experiment demonstrated the good sustainability of the catalyst. The potential value of the catalytic product was demonstrated through the bifunctional addition and hydrogenation reduction.

Construction of Layer-Blocked Covalent Organic Framework Heterogenous Films via Surface-Initiated Polycondensations with Strongly Enhanced Photocatalytic Properties.

Imine-linked covalent organic frameworks (COFs) usually show high crystallinity and porosity, while vinyl-linked COFs have excellent semiconducting properties and stability. Therefore, achieving the advantages of imine- and vinyl-linkages in a single COF material is highly interesting but remains challenging. Herein, we demonstrate the fabrication of a layer-blocked COF (LB-COF) heterogeneous film that is composed of imine- and vinyl-linkages through two successive surface-initiated polycondensations. In brief, the bottom layer of imine-linked COF film was constructed on an amino-functionalized substrate via Schiff-base polycondensation, in which the unreacted aldehyde edges could be utilized for initiating aldol polycondensation to prepare the second layer of vinyl-linked COF film. The resultant LB-COF film displays excellent ordering due to the crystalline templating effect from the bottom imine-linked COF layer; meanwhile, the upper vinyl-linked COF layer could strongly enhance its stability and photocatalytic properties. The LB COF also presents superior performance in photocatalytic uranium extraction (320 mg g-1), which is higher than the imine-linked (35 mg g-1) and the vinyl-linked (295 mg g-1) counterpart. This study provides a novel surface-initiated strategy to synthesize layer-blocked COF heterogeneous films that combine the advantages of each building block.

Hetero- and Homointerlocked Metal-Organic Cages.

Interlocked molecular assemblies constitute a captivating ensemble of chemical topologies, comprising two or more separate components that exhibit remarkably intricate structures. The interlocked molecular assemblies are typically identical, and heterointerlocked systems that comprise structurally distinct assemblies remain unexplored. Here, we demonstrate that metal-templated synthesis can be exploited to afford not only a homointerlocked cage but also a heterointerlocked cage. Treatment of a carboxylated 2,9-dimethyl-1,10-phenanthroline (dmp) or Cu(I) bis-dmp linker with a Ni4-p-tert-butylsulfonylcalix[4]arene cluster affords noninterlocked octahedron and quadruply interlocked double cages consisting of two identical tetragonal pyramids, respectively. In contrast, when a mixture of dmp and Cu(I) bis-dmp linkers is used, a quadruply heterointerlocked cage is produced, consisting of a tetragonal pyramid and an octahedron. With photoredox-active [Cu(dmp)2]+ in the structures, both interlocked cages exhibit remarkable performance as photocatalysts for atom transfer radical addition (ATRA) reactions of trifluoromethanesulfonyl chloride with alkenes or oxo-azidations of vinyl arenes. These interlocked structures serve the dual purpose of stabilizing photocatalytically active components against deactivation and encapsulating substrates within the cavity, resulting in yields comparable to or even surpassing those of their molecular counterparts. This work thus provides a new strategy that combines metal templating and nontemplating approaches to design new types of interlocked assemblies with intriguing architectures and properties.

Low-Temperature, Universal Synthetic Route for Mesoporous Metal Oxides by Exploiting Synergistic Effect of Thermal Activation and Plasma.

Mesoporous metal oxides exhibit excellent physicochemical properties and are widely used in various fields, including energy storage/conversion, catalysis, and sensors. Although several soft-template approaches are reported, high-temperature calcination for both metal oxide formation and template removal is necessary, which limits direct synthesis on a plastic substrate for flexible devices. Here, a universal synthetic approach that combines thermal activation and oxygen plasma to synthesize diverse mesoporous metal oxides (V2O5, V6O13, TiO2, Nb2O5, WO3, and MoO3) at low temperatures (150-200°C), which can be applicable to a flexible polymeric substrate is introduced. As a demonstration, a flexible micro-supercapacitor is fabricated by directly synthesizing mesoporous V2O5 on an indium-tin oxide-coated colorless polyimide film. The energy storage performance is well maintained under severe bending conditions.

Template Assisted Formation of 32 and 34π Octaphyrins Embedded with Dithienopyrrole Cores: A New Scaffold to Unravel Proton Coupled Redox Switching and (Anti)Aromaticity.

Herein, we report two distinct octaphyrins obtained by the condensation of new dithieno[3,2-b:2',3'-d]pyrrole based tetrapyrrane under two different acidic conditions. Fourfold meso-substituted octaphyrin was the major product when the reaction was performed in the presence of an aryl aldehyde using trifluoroacetic acid. Whereas, the sixfold meso-substituted octaphyrin was obtained when the precursor was condensed with pentafluorobenzaldehyde using para-toluenesulfonic acid. Such a template effect of aryl aldehydes in oxidative coupling reactions is realized for the first time in literature. Experimental and theoretical studies suggested that the oxidized form of fourfold meso-substituted octaphyrin is 32π antiaromatic and undergoes proton-coupled electron transfer (PCET) to the protonated form of 34π aromatic congener upon treatment with protic acids. Furthermore, small organic molecules such as alcohols and amines were also found to promote chemical reduction. Single crystal X-ray structure revealed that the aromatic counterpart is highly planar and stabilized by several intermolecular H-bonding and F-F interactions, leading to a large 3D supramolecular arrangement and exhibited colorimetric sensing for fluoride and hydroxide anions. On the other hand, sixfold meso-substituted octaphyrin did not show (anti)aromatic features, PCET or anion sensing, but its intriguing absorption features associated with protonation could make it an ideal candidate for pH-dependent bioimaging.

Confined Lewis Pairs: Investigation of the X- →Si20 Interaction in Halogen-Encapsulating Silafulleranes.

A joint theoretical and experimental study on 32 endohedral silafullerane derivatives [X@Si20 Y20 ]- (X=F-I; Y=F-I, H, Me, Et) and -[Cl@Si20 H12 Y8 ]- (Y=F-I) is presented. First, we evaluated the structure-determining template effect of Cl- in a systematic series of concave silapolyquinane model systems. Second, we investigated the X- →Si20 interaction energy ( ) as a function of X- and Y and found the largest values for electron-withdrawing exohedral substituents Y. Given that X- ions can be considered as Lewis bases and empty Si20 Y20 clusters as Lewis acids, we classify our inseparable host-guest complexes [X@Si20 Y20 ]- as "confined Lewis pairs". Third, 35 Cl NMR spectroscopy proved to be highly diagnostic for an experimental assessment of the Cl- →Si20 interaction as the paramagnetic shielding and, in turn, (35 Cl) of the endohedral Cl- ion correlate inversely with . Finally, we disclose the synthesis of [PPN][Cl@Si20 Y20 ] (Y=Me, Et, Br) and provide a thorough characterization of these new silafulleranes.

Confined Lewis Pairs: Investigation of the X−→Si20 Interaction in Halogen‐Encapsulating Silafulleranes

AbstractA joint theoretical and experimental study on 32 endohedral silafullerane derivatives [X@Si20Y20]− (X=F‐I; Y=F‐I, H, Me, Et) and ‐[Cl@Si20H12Y8]− (Y=F‐I) is presented. First, we evaluated the structure‐determining template effect of Cl− in a systematic series of concave silapolyquinane model systems. Second, we investigated the X−→Si20 interaction energy ( ) as a function of X− and Y and found the largest values for electron‐withdrawing exohedral substituents Y. Given that X− ions can be considered as Lewis bases and empty Si20Y20 clusters as Lewis acids, we classify our inseparable host–guest complexes [X@Si20Y20]− as “confined Lewis pairs”. Third, 35Cl NMR spectroscopy proved to be highly diagnostic for an experimental assessment of the Cl−→Si20 interaction as the paramagnetic shielding and, in turn, (35Cl) of the endohedral Cl− ion correlate inversely with . Finally, we disclose the synthesis of [PPN][Cl@Si20Y20] (Y=Me, Et, Br) and provide a thorough characterization of these new silafulleranes.

Capture of mechanically interlocked molecules by rhodium-mediated terminal alkyne dimerisation.

The transition metal-mediated dimerisation of terminal alkynes is an attractive and atom-economic method for preparing conjugated 1,3-enynes. Using a phosphine-based macrocyclic pincer ligand, we demonstrate how this transformation can be extended to the synthesis of novel, hydrocarbon-based interlocked molecules: a rotaxane by 'active' metal template synthesis and a catenane by sequential 'active' and 'passive' metal template procedures.

Direct growth of ferroelectric orthorhombic ZrO2 on Ru by atomic layer deposition at 300 °C.

Fluorite-structured binary oxide ferroelectrics exhibit robust ferroelectricity at a thickness below 10 nm, making them highly scalable and applicable for high-end semiconductor devices. Despite this promising prospect, achieving highly reliable ferroelectrics still demands a significant thermal budget to form a ferroelectric phase, being a hurdle for their use in high-end complementary metal oxide semiconductor (CMOS) processing. Here, we report a robust ferroelectric behavior of an 8 nm-thick ZrO2 film deposited via plasma-enhanced atomic layer deposition at 300 °C on a (002)-oriented Ru without any post-annealing process, demonstrating high compatibility with CMOS processing. We propose that a plausible mechanism for this is the local domain matching epitaxy based on the high-resolution transmission electron microscopy and piezoelectric force microscopy results, where the templating effect between [101]-oriented grains of orthorhombic ZrO2 and [010]-oriented grains of Ru enables the direct growth of ferroelectric ZrO2. The 2Pr value is 20 μC cm-2, and it can be further improved by post-annealing at 400 °C to 23 μC cm-2 without showing the wake-up behavior. Ferroelectric switching shows stable endurance for up to 109 cycles, showcasing its high potential in CMOS-compatible applications and nanoelectronics with a low thermal budget.

Revealing the effect of templates on atomic scale ordering and the hydrophilic properties of aluminophosphates

The atomic-scale ordering induced by templates leads to significant differences in the hydrophilic properties of AFI zeotypes.

Synthesis, structure and spectroelectrochemistry of hybrid metal(iv)phthalocyaninato-capped 3d-metal pyrazoloximates as prospective precursors of stimuli-induced (responsive) single-molecule magnets, logic gates and qubits

Hybrid binuclear complexes and their ZrIVMIIIMIIMIIZrIV-pentanuclear analogs were prepared using the template reactions of 3-acetylpyrazoloxime with metal(iv) phthalocyaninate on the metal ion as a matrix.

Selective halide ion binding templation effect for a quadruple-stranded-helicate enabling the activation of C–Br bonds

Here, we report the study on mechanism of anion-induced templation effect, in which nucleophilic anions serving as ligand competitors to destroy partial coordination bonds in a library of metallo-macrocycles and form quadruple-stranded helicates.

Growth mechanism of Al2O3 on surface of ZrO2 inclusions: experimental and first principles investigation

Zr has been widely used in high-quality steel due to its strong deoxidizing capacity and ability of improve performance of steel. ZrO2–Al2O3 inclusions with core-shell structure were observed in this study. The structure, electronic properties, and energy changes of ZrO2 and ZrO2–Al2O3 systems were studied based on first principles calculation. It indicates that ZrO2 can be used as the heterogeneous nucleation core of Al2O3. Al atoms were preferentially adsorbed on the bridge site of ZrO2 (001) and then form the ZrO2–Al2O3 interface. The template effect of ZrO2 was nine adsorption atomic layers, among which layers 1–5 was a coherent epitaxial layer, layers 5–9 was the transition layer, and the atomic ratio was 3:2. The growth mechanism of Al2O3 on ZrO2 surface was discussed. The results help understand the formation of inclusion at atomic scale and find ways to control the characteristics of inclusion in steel with Zr treatment.

Controlling the structural and adsorption features of polyoxovanadate-based metal–organic clusters by adjustable template effect

An adjustable template effect was employed to activate the evolution of polyoxovanadate-based metal–organic clusters, resulting in unprecedented structural archetypes as well as customized dye and iodine adsorption features.

Three in One: Three Different Molybdates Trapped in a Thiacalix[4]arene Protected Ag72 Nanocluster for Structural Transformation and Photothermal Conversion.

Polyoxometalates (POMs) represent crucial intermediates in the formation of insoluble metal oxides from soluble metal ions, however, the rapid hydrolysis-condensation kinetics of MoVI or WVI makes the direct characterization of coexisted molecular species in a given medium extremely difficult. Silver nanoclusters have shown versatile capacity to encapsulate diverse POMs, which provides an alternative scene to appreciate landscape of POMs in atomic precision. Here, we report a thiacalix[4]arene protected silver nanocluster (Ag72b) that simultaneously encapsulates three kinds of molybdates (MoO4 2- , Mo6 O22 8- and Mo7 O25 8- ) in situ transformed from classic Lindqvist Mo6 O19 2- , providing more deep understanding on the structural diversity and condensation growth route of POMs in solution. Ag72b is the first silver nanocluster trapping so many kinds of molybdates, which in turn exert collective template effect to aggregate silver atoms into a nanocluster. The post-reaction of Ag72b with AgOAc or PhCOOAg produces a discrete Ag24 nanocluster (Ag24a) or an Ag28 nanocluster based 1D chain structure (Ag28a), respectively. Moreover, the post-synthesized Ag28a can be utilized as potential ignition material for further application. This work not only provides an important model for unlocking dynamic features of POMs at atom-precise level but also pioneers a promising approach to synthesize silver nanoclusters from known to unknown.

Three in One: Three Different Molybdates Trapped in a Thiacalix[4]arene Protected Ag72 Nanocluster for Structural Transformation and Photothermal Conversion

AbstractPolyoxometalates (POMs) represent crucial intermediates in the formation of insoluble metal oxides from soluble metal ions, however, the rapid hydrolysis‐condensation kinetics of MoVI or WVI makes the direct characterization of coexisted molecular species in a given medium extremely difficult. Silver nanoclusters have shown versatile capacity to encapsulate diverse POMs, which provides an alternative scene to appreciate landscape of POMs in atomic precision. Here, we report a thiacalix[4]arene protected silver nanocluster (Ag72b) that simultaneously encapsulates three kinds of molybdates (MoO42−, Mo6O228− and Mo7O258−) in situ transformed from classic Lindqvist Mo6O192−, providing more deep understanding on the structural diversity and condensation growth route of POMs in solution. Ag72b is the first silver nanocluster trapping so many kinds of molybdates, which in turn exert collective template effect to aggregate silver atoms into a nanocluster. The post‐reaction of Ag72b with AgOAc or PhCOOAg produces a discrete Ag24 nanocluster (Ag24a) or an Ag28 nanocluster based 1D chain structure (Ag28a), respectively. Moreover, the post‐synthesized Ag28a can be utilized as potential ignition material for further application. This work not only provides an important model for unlocking dynamic features of POMs at atom‐precise level but also pioneers a promising approach to synthesize silver nanoclusters from known to unknown.

Tuning the Cerium-Based Metal-Organic Framework Formation by Template Effect and Precursor Selection.

The novel metal-organic framework [(CH3)2NH2]2[Ce2(bdc)4(DMF)2]·2H2O (Ce-MOF, H2bdc-terephthalic acid, DMF-N,N-dimethylformamide) was synthesized by a simple solvothermal method. Ce-MOF has 3D connectivity of bcu type with a dinuclear fragment connected with eight neighbors, while three types of guest species are residing in its pores: water, DMF, and dimethylammonium cations. Dimethylamine was demonstrated to have a decisive templating effect on the formation of Ce-MOF, as its deliberate addition to the solvothermal reaction allows the reproducible synthesis of the new framework. Otherwise, the previously reported MOF Ce5(bdc)7.5(DMF)4 (Ce5) or its composite with nano-CeO2 (CeO2@Ce5) was obtained. Various Ce carboxylate precursors and synthetic conditions were explored to evidence the major stability of Ce-MOF and Ce5 within the Ce carboxylate-H2bdc-DMF system. The choice of precursor impacts the surface area of Ce-MOF and thus its reactivity in an oxidative atmosphere. The in situ PXRD and TG-DTA-MS study of Ce-MOF in a nonoxidative atmosphere demonstrates that it eliminates H2O and DMF along with (CH3)2NH guest species in two distinct stages at 70 and 250 °C, respectively, yielding [Ce2(bdc)3(H2bdc)]. The H2bdc molecule is removed at 350 °C with the formation of novel modification of Ce2(bdc)3, which is stable at least up to 450 °C. According to the total X-ray scattering study with pair distribution function analysis, the most pronounced local structure transformation occurs upon departure of DMF and (CH3)2NH guest species, which is in line with the in situ PXRD experiment. In an oxidative atmosphere, Ce-MOF undergoes combustion to CeO2 at a temperature as low as 390 °C. MOF-derived CeO2 from Ce-MOF, Ce5, and CeO2@Ce5 exhibits catalytic activity in the CO oxidation reaction.

Tailored design of hierarchically porous metal/N-codoped carbon from soft-templated bimetallic ZIFs for the high-efficiency adsorption of tetracycline hydrochloride

Zeolitic imidazolate framework-8 (ZIF-8) is attracting considerable attention as a superior precursor to fabricate efficient carbon-based absorbents for many contaminants. However, most carbon materials still suffer from low-efficiency mass transfer and few active sites. Herein, transition metal/nitrogen-codoped hierarchically porous carbons (MNHCs) were controllably constructed by pyrolysis of soft-templated bimetallic ZIFs to enhance tetracycline hydrochloride (TCH) adsorption. Benefitting from its large specific surface area (920.73 m2 g−1), excellent hierarchical pore structure, high N content and abundant Lewis acid sites, the optimum MNHC (HC1000-Fe2Zn98) obtained at 1000 ℃ and the Fe/(Fe + Zn) molar ratio of 2 % improved the adsorption affinity for TCH and reduced the TCH diffusion resistance compared with other MNHCs, resulting in excellent adsorption of TCH. The synergistic effect of Fe and soft templates (sodium dodecyl benzene sulfonate, SDBS) added to the precursor significantly improved pore structure and enriched adsorption active sites of the derived carbon. The adsorption kinetics and isotherm data fitted well with pseudo-second-order kinetics and the Sips model (qm = 245.6 mg g−1), respectively. Adsorption experiments and characterization analyses suggested various adsorption interactions between TCH and MNHCs via pore fillings, coordination, H-bonding and π-π interactions. This study offers a facile strategy for fabricating hierarchically porous carbon for removing organic contaminants from water.

Synthesis of temperature-sensitive ion-imprinted polymer based on chitosan for selective separation of La3+ from aqueous solution: Effect of different salt anions in the template

Temperature-sensitive chitosan-based ion-imprinted polymer (TCIIP) is a promising adsorption material due to its ability to recycle only by rinsing with cold deionized water. However, little attention has been paid to the role of salt anions in the template. Herein, lanthanum ion-imprinted polymers ([La3+-anions]-CS-IIPs) were synthesized using different lanthanum salts containing anions (NO3-, Cl- and CH3COO-) as template, CS and NIPIM as functional monomer, BIS as crosslinker, APS as initiator. The adsorption performance of La3+ in aqueous solution on the [La3+-anions]-CS-IIPs have been studied. SEM, BET, XPS and FTIR were performed to characterize the synthesized materials. The results showed that the disparities in adsorption capacity and selectivity of the three [La3+-anions]-CS-IIPs could be attributed to the template effect and various affinities for rare earth ions, arising from salt anions with different geometric shapes, ionic radii and rare earth ion complexing capacities. The adsorption capacity of these [La3+-anions]-CS-IIPs is [La3+-NO3-]-CS-IIPs > [La3+-CH3COO-]-CS-IIPs > [La3+-Cl-]-CS-IIPs. Three kinetic and isothermal adsorption models in each were used to investigate the adsorption mechanism of La3+ on [La3+-anion]-CS-IIPs. The adsorption capability of three [La3+-anions]-CS-IIPs retained above 92% in the 4 times adsorption-desorption process. Meanwhile, three [La3+-anions]-CS-IIPs clearly have higher adsorption affinities for La3+ than Ce3+, Nd3+, Y3+. The adsorption selectivity of [La3+-anions]-CS-IIPs is [La3+-CH3COO-]-CS-IIP > [La3+-Cl-]-CS-IIP > [La3+-NO3-]-CS-IIP. The findings of this work provide an idea for regulating the selective adsorption behavior of rare earth ion imprinted polymers by utilizing the anions effect.

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.