Inorganic Assemblies Research Articles

Aqueous Room‐Temperature Phosphorescence from Assembled Phosphors for Analytical Detection†

Comprehensive SummaryRoom‐temperature phosphorescence (RTP) has gained much attention in organic light‐emitting diodes (OLEDs), anti‐counterfeiting, encryption and bioimaging. However, efficient RTP is typically difficult due to the spin‐forbidden transition nature and susceptibility to environment quenching. In aqueous phase, such quenching is much more pronounced, leading to the collection of aqueous RTP even more challenging. Assembly systems (either organic or inorganic), provide an excellent microenvironment for accommodating of phosphors in aqueous phase, due to the excluding of typical phosphorescence quenchers (H2O and O2) and rigidification of phosphorescent molecules for inhibition of non‐radiative transitions (molecular motions). Herein, we summarized the recent progress in harvesting RTP from aqueous systems via various assembling strategies, including small molecules, supramolecular inclusion, and inorganic assembly. More specifically, the analytical explorations of these systems were discussed, from the perspective of the relationship between analytes and phosphorescence. Last, the further developments of aqueous RTP analysis were also prospected.

A functional and robust super‐hydrophobic PCC coating based on the induced assembly of modified zirconium phosphate

AbstractImproving the permeability of concrete is one of the important measures to extend the service life of concrete. In addition, for marine engineering, sewerage projects, and so on, mechanical stability and microbial induced corrosion of concrete structures cannot be ignored. We demonstrated a method to prepare high‐performance super‐hydrophobic (SHP) coating using functional zirconium phosphate (ZrP) and polydopamine (PDA) as the primary materials. The micro‐nano rough structures were constructed on the concrete surface by alternating organic–inorganic assembly guided by each other. The coatings' apparent morphology, composition, and structure were analyzed using various surface analysis techniques. Based on the construction of micro‐nano rough structures by the induced assembly of functional ZrP, the silane treatment significantly improved the water contact angle of the coating (WCA = 154° ± 3°), and the coating exhibited relatively high wear resistance, reaching 135° WCA even after 30 friction cycles. The water absorption of the specimens treated with the SHP composite coating was reduced by 79% to treated with silane. Meanwhile, the SHP composite coating showed excellent antimicrobial and anti‐ice properties, due to the role of the functional ZrP and alternating organic–inorganic assembly. It was expected that the composite coating might potentially promote and accelerate applied superhydrophobic anticorrosive coating development for marine concrete durability.

Fabrication and Characterization of NiO Nanoparticle–Porphyrin-Based Organic–Inorganic Nanohybrid Assembly: a Sustainable Redox Mediator in Dye-Sensitized Solar Cell Construction

Fabrication and Characterization of NiO Nanoparticle–Porphyrin-Based Organic–Inorganic Nanohybrid Assembly: a Sustainable Redox Mediator in Dye-Sensitized Solar Cell Construction

Nanoparticle-Mediated Assembly of Peptoid Nanosheets Functionalized with Solid-Binding Proteins: Designing Heterostructures for Hierarchy.

The fabrication of ordered architectures that intimately integrate polymer, protein, and inorganic components remains difficult. Two promising building blocks to tackle this challenge are peptoids, peptide mimics capable of self-assembly into well-defined structures, and solid-binding peptides, which offer a biological path to controlled inorganic assembly. Here, we report on the synthesis of 3.3-nm-thick thiol-reactive peptoid nanosheets from equimolar mixtures of unmodified and maleimide-derivatized versions of the Nbpe6Nce6 oligomer, optimize the location of engineered cysteine residues in silica-binding derivatives of superfolder green fluorescent protein for maleimide conjugation, and react the two components to form protein-peptoid hybrids exhibiting partial or uniform protein coverage on both of their sides. Using 10 nm silica nanoparticles, we trigger the stacking of these 2D structures into a multilayered material composed of alternating peptoid, protein, and organic layers. This simple and modular approach to hierarchical hybrid synthesis should prove useful in bioimaging and photocatalysis applications.

Luminescent N-heterocycles based molecular backbone interleaved within LDH host structure and dispersed into polymer

A pyrazino-1,3a,6a-triazapentalene dye-based molecule was intercalated by direct co-precipitation method into the galleries of negatively charged layered double hydroxide (LDH) to form a new luminescent LDH filler. The materials of cation composition Zn/Al = 2 lead to well-defined organic inorganic assemblies. The structure of the hybrid materials was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR) and UV–visible spectra. Optical properties of the materials, at both solid state and slurry state, were also recorded and absolute photoluminescent quantum yields (PLQY) were determined showing that the nanohybrid LDH slurry exhibited higher luminescence properties under UV excitation than the corresponding LDH powder. LDH fillers were used to prepare composite films by dispersion in both hydrophobic or hydrophilic polymer matrix such as poly (dimethyl siloxane) (PDMS) and poly(ethylene oxide) (PEO), respectively. Composite films were characterized by Small Angle X-ray Scattering (SAXS) and PLQY were recorded in order to compare the behaviour of the nanohybrid LDH filler in both polymer matrices. It was found that the aggregation of particles is still observed by SAXS.

Mesoscopic Reaction–Diffusion Fronts Control Biomorph Growth

Biomorphs are inorganic assemblies of crystalline nanorods that form noncrystalline microshapes such as helices, funnels, and leaf-shaped sheets. This nanoscale-to-microscale self-organization occurs from simple reactants in aqueous solution and suggests new engineering methods as well as insights into biomineralization; to date, however, the underlying mechanisms are not understood. Here we describe a reaction–diffusion model for sheet growth that reproduces the experimentally observed biomorph shapes. The sheet edges are logarithmic spirals caused by the propagation failure of the crystallization front. The resulting defect motion is dynamically related to nonlinear wave dynamics in subexcitable media such as the photoinhibited Belousov–Zhabotinsky reaction. An expanded model includes a nematic-like director field that sets the average nanorod orientation irreversibly during crystallization. The growth front of worm-like biomorph helices also obeys logarithmic spirals, suggesting future applications of ...

Synthesis of Quantum Dot-ZnS Nanosheet Inorganic Assembly with Low Thermal Fluorescent Quenching for LED Application.

In this report, to tackle the thermal fluorescent quenching issue of II-VI semiconductor quantum dots (QDs), which hinders their on-chip packaging application to light-emitting diodes (LEDs), a QD-ZnS nanosheet inorganic assembly monolith (QD-ZnS NIAM) is developed through chemisorption of QDs on the surface of two-dimensional (2D) ZnS nanosheets and subsequent assembly of the nanosheets into a compact inorganic monolith. The QD-ZnS NIAM could reduce the thermal fluorescent quenching of QDs effectively, possibly due to fewer thermally induced permanent trap states and decreased Förster resonance energy transfer (FRET) among QDs when compared with those in a reference QD composite thin film. We have demonstrated that the QD-ZnS NIAM enables QDs to be directly packaged on-chip in LEDs with over 90% of their initial luminance being retained at above 85 °C, showing advantage in LED application in comparison with conventional QD composite film.

Back Cover: A Modular Approach to Inorganic Phosphazane Macrocycles (Angew. Chem. Int. Ed. 31/2017)

The union of organic and macrocyclic chemistry: The formation of large inorganic macrocycles containing phosphazane units linked by sulfur or selenium becomes straightforward with the method described by D. S. Wright et al. in their Communication on page 9087 ff.This allows the introduction of a range of organic substituents, facilitating the tuning of the steric and electronic host environment, and marks a significant step towards the development of synthetic tools in macromolecular inorganic assembly that mirror those in organic synthesis.

Inorganic assembly catalysts for artificial photosynthesis: general discussion.

Inorganic assembly catalysts for artificial photosynthesis: general discussion.

Artificial photosynthesis: closing remarks.

This paper derives from my closing remarks lecture at the 198th Faraday Discussion meeting on Artificial Photosynthesis, Kyoto, Japan, February 28-March 2. The meeting had sessions on biological approaches and fundamental processes, molecular catalysts, inorganic assembly catalysts, and integration of systems for demonstrating realistic devices. The field has had much progress since the previous Faraday Discussion on Artificial Photosynthesis in Edinburgh, UK, in 2011. This paper is a personal account of recent discussions and developments in the field, as reflected in and discussed during the meeting. First it discusses the general directions of artificial photosynthesis and some considerations for a future solar fuels technology. Then it comments on some scientific directions in the area of the meeting.

Discrete Silver(I)-Palladium(II)-Oxo Nanoclusters, {Ag4 Pd13 } and {Ag5 Pd15 }, and the Role of Metal-Metal Bonding Induced by Cation Confinement.

We introduce the class of discrete silver(I)-palladium(II)-oxo nanoclusters with the preparation of {Ag4 Pd13 } and {Ag5 Pd15 }. Both polyanions represent the first examples of noble metal-capped polyoxo-noble-metalates in a fully inorganic assembly, featuring an unprecedented host-guest mode containing hetero- and homometallic Ag-Pd and Ag-Ag bonding interactions. Comprehensive theoretical calculations suggest that the Ag-Pd metallic bonds originate partially from surface confinement of AgI guest ions onto the anionic polyoxopalladate host that is induced by strong electrostatic forces. This work opens the field of fully inorganic silver-palladium-oxo nanoclusters, which can be considered as discrete mixed noble metal precursors for the formation of monodisperse core-shell nanoparticles, with high relevance for catalysis.

Synthesis and characterization of a pure inorganic 3D network based on the [Sr2P9HMo12O71]20–cluster and strontium(II) linkers

Novel supramolecular networks based on an anionic polymolybdophosphate cluster Sr10(H2O)12[Sr2P9HMo12O71] is hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, thermogravimetric analysis, infrared, ultraviolet spectroscopy, and cyclic voltammetry in an aqueous solution. It crystallizes in the orthorhombic space group Pnmm (No. 59) with a = 12.699(1) A, b = 14.914(1) A, c = 23.851(2) A and Z = 2. The compound is made up of unusual shaped-cage [Sr2P9HMo12O71]20−. The strontium cations are divided in two kinds. The first occupy vacant sites in the [P9Mo12O68]n– polyoxoanions unit and the second [Sr(H2O)6]2+, [Sr(H2O)4]2+, and [Sr(H2O)2]2+ serve to bridge together the adjacent polymolybdophosphate clusters to yield unprecedented three-dimensional pure inorganic assemblies of the shaped-cage polymolybdophosphate clusters.

Host–Guest and Electrostatic Interactions in Supramolecular Nanoparticle Clusters

The influence of the charge, structure, and host–guest interactions of different soft polymeric components on their assembly with negatively charged inorganic gold and up‐converting nanoparticles (NPs) functionalized with cyclodextrins (CD‐AuNPs and CD‐UCNPs) was studied. The inter‐/intramolecular interplay was evaluated by changing the morphology and the charge of the polymeric component. Use of a linear, anionic guest‐functionalized polymer resulted in the formation of thin coating layers around the CD‐AuNPs and CD‐UCNPs without further NP aggregation. When the branched cationic polymer poly(ethylene imine) (PEI) was used instead, small clusters were obtained before the electrostatic neutralization point, whereas large NP aggregates were obtained above the neutralization point. When branched cationic guest‐functionalized dendrimers were used, clusters were obtained at a 1:1 host/guest stoichiometry. In this case, self‐assembly occurred when still far away from the neutrality point, indicating that this cluster formation is driven by supramolecular host–guest interactions. The luminescence of the CD‐UCNPs with the linear polymer was quenched due to C–H vibrational modes of the guest polymer, whereas in the case of electrostatic cluster formation by PEI the luminescence of CD‐UCNPs was enhanced after the neutralization point, due to the formation of densely packed NP assemblies. These findings should be useful for the design of hybrid polymeric–inorganic assemblies for sensing and biomedical applications.

(Invited) Hierarchical Inorganic Assemblies for the Photocatalytic Reduction of CO2 By H2o

The multi-electron processes of CO2 reduction and H2O oxidation, which constitute the essential reactions of sunlight to fuel conversion (artificial photosynthesis) require efficient coupling of light absorber and catalyst. Using all-inorganic heterobinuclear units such as ZrOCo anchored on high surface area silica, we have developed photodeposition methods for the directional assembly of nanometer sized catalyst clusters for H2O oxidation or CO2 reduction with proper coupling to the binuclear light absorber. Copper oxide nanoclusters were assembled adjacent to the Zr acceptor sites of the heterobinuclear unit, and light driven reduction of CO2 upon excitation of the ZrOCo unit demonstrated. Illumination of the ZrOCo chromophore coupled to a metal oxide nanocatalyst for H2O oxidation affords closing of the photocatalytic cycle in the absence of sacrificial agents. Time resolved FT-IR spectroscopy provided detailed mechanistic insight into the multi-electron reactions of H2O oxidation and CO2 reduction on the metal oxide catalyst surfaces under reaction conditions, with surface intermediates and their kinetics uncovered for the first time. To achieve CO2 photoreduction by H2O under product separation on the nanoscale, Co3O4-SiO2 core-shell nanotubes were developed in which the inner surface acts as efficient water oxidation catalyst while the nanoscale silica layer with embedded molecular wires serves as a proton conducting, gas impermeable separation membrane with tight control of electron transport. Completing the photocatalytic cycle on the nanoscale seeks to minimize side reactions and efficiency degrading transport processes. Characterization of the assembly by transient spectroscopy and photoelectrochemical measurements will be discussed. References Zhang, M.; de Respinis, M.; Frei, H. Nature Chem. 2014, 6, 362. Kim, W.; Yuan, G.; McClure, B. A.; Frei, H. J. Am. Chem. Soc. 2014, 136, 11034. McCure, B. A.; Frei, H. J. Phys. Chem. C 2014, 118, 11601. Kim. W.; Frei, H. ACS Catal. 2015, 5, 5627. Yuan, G.; Agiral, A.; Pellet, N.; Kim, W.; Frei, H. Faraday Discuss. 2014, 176. 233. Edri, E.; Frei, H. J. Phys. Chem. C 2015, 119, 000.

Oriented Chiral DNA-Silica Film Guided by a Natural Mica Substrate.

The formation of highly ordered chiral organic/inorganic films with high density and long-range orientation is important in constructing chiral devices, such as broadband polarization devices, liquid-crystal displays, or negative-reflection materials. A feasible strategy is presented to fabricate three-dimensional mesostructured chiral DNA-silica assemblies into large-scale oriented arrangements. The highly ordered film was aligned by a mica crystal substrate with the bridging effect of suitable divalent metal ions, followed by the growth of the DNA-silica composite by bottom-up assembly with a "quartet templating" method. This simple and effective route would perform well in the alignment and arrangement of highly charged biomolecules, such as polypeptides, proteins, viruses, and their inorganic assemblies, and furthermore could allow the fabrication of chiral optical materials with long-range ordering.

Oriented Chiral DNA–Silica Film Guided by a Natural Mica Substrate

AbstractThe formation of highly ordered chiral organic/inorganic films with high density and long‐range orientation is important in constructing chiral devices, such as broadband polarization devices, liquid‐crystal displays, or negative‐reflection materials. A feasible strategy is presented to fabricate three‐dimensional mesostructured chiral DNA–silica assemblies into large‐scale oriented arrangements. The highly ordered film was aligned by a mica crystal substrate with the bridging effect of suitable divalent metal ions, followed by the growth of the DNA–silica composite by bottom‐up assembly with a “quartet templating” method. This simple and effective route would perform well in the alignment and arrangement of highly charged biomolecules, such as polypeptides, proteins, viruses, and their inorganic assemblies, and furthermore could allow the fabrication of chiral optical materials with long‐range ordering.

Importance of Specific Interactions between Support, Metal Oxide Nanostructures and Noble Metal or Organometallic Sites in Efficient Electrocatalytic and Bioelectrocatalytic Reduction of Oxygen

Systems utilizing carbon nanostructures (e.g. nanotubes) and noble metal nanoparticles can form advanced electrocatalytic materials with well-defined composition, structure and thickness. We explore here the ability of inorganic structures to stabilize and derivatize metal (Au, Pt, Pd) and carbon nanostructures. Among inorganic systems, polyoxometallates of tungsten are attractive since they can not only adsorb irreversibly on solid surfaces but also exhibit reversible stepwise multi-electron transfer reactions. The concept of the layer-by-layer formation of hybrid inorganic assemblies composed of anionic polyoxometallate-protected carbon nanotubes (or metal nanoparticles) and ultra-thin nanostructures of positively charged metal oxide (vanadia, titania, zirconia) nanostructures (alone or in combination with tungsten oxide) will be described and discussed here. The resulting novel composite materials are characterized by fast dynamics of charge propagation. When it comes to the electrocatalytic reduction of oxygen, polyoxometallates can also be applied to stabilize and link Pt, Pd and various alloyed Pt-based catalytic nanoparticles.To produce bioelectrocatalytic materials for oxygen reduction, we explore unique properties of biofilms, i.e. polymeric aggregates of microorganisms, in which cells adhere to each other on the electrode surfaces. Such systems are characterized by extracellular electron transfers involving c-type cytochromes (heme-containing proteins). Biofilms grown on inert carbon electrode substrates tend to exhibit electrocatalytic properties towards oxygen and hydrogen peroxide reductions in neutral media. The processes have been found to be further enhanced by introduction of multi-walled carbon nanotubes (MCNTs) that are modified with ultra-thin layers of organic (e.g. 4-(pyrrole-l-yl) benzoic acid. We expect here attractive electrostatic interactions between carboxyl-group containing anionic adsorbates and positively charged domains of the biofilm with c-type cytochrome enzymatic sites. Coexistence of the above components leads to synergistic effect that is evident from positive shift of the oxygen reduction voltammetric potentials and significant increase of voltammetric currents. Most likely, the reduction of oxygen has been initiated at the molecular (e.g. intentionally added metalloporphyrin redox centers), whereas the undesirable hydrogen peroxide intermediate are further decomposed at the cytochrome sites. Acknowledgement We appreciate collaboration with Krzysztof Miecznikowski, Adam Lewera, Beata Dembinska, Jakub Sek, and Anna Dobrzeniecka from Faculty of Chemistry, University of Warsaw.

Isopolymolybdate-induced organic–inorganic hybrid assemblies with copper ions and bichelate-bridging ligands

Heptamolybdate is used as a “molecular adaptor” to modulate the metal–organic coordination building units in the hydrothermal environment, with new polyoxometalate-induced hybrid assemblies isolated demonstrating good photocatalytic activity.

ChemInform Abstract: Polymeric Hydrogels and Nanoparticles: A Merging and Emerging Field

AbstractReview: 152 refs.

The effect of the adaptor protein Isd11 on the quaternary structure of the eukaryotic cysteine desulphurase Nfs1

Small inorganic assemblies of alternating ferrous/ferric iron and sulphide ions, so-called iron–sulphur (Fe–S) clusters, are possibly nature’s most ancient prosthetic groups. One of the early actors in Fe–S cluster biosynthesis is a protein complex composed of a cysteine desulphurase, Nfs1, and its functional binding partner, Isd11. Although the essential function of Nfs1·Isd11 in the liberation of elemental sulphur from free cysteine is well established, little is known about its structure. Here, we provide evidence that shows Isd11 has a profound effect on the oligomeric state of Nfs1.