Supramolecular Templating Research Articles

Strong Quantum Confinement and Fast Photoemission Activation in CH3NH3PbI3 Perovskite Nanocrystals Grown within Periodically Mesostructured Films

In this Communication, a synthetic route is demonstrated to obtain stabilized MAPbI3 nanocrystals embedded in thin metal oxide films that display well‐defined and adjustable quantum confinement effects over a wide range of 0.34 eV. Mesostructured TiO2 and SiO2 films displaying an ordered 3D pore network are prepared by evaporation‐induced self‐assembly of a series of organic supramolecular templates in the presence of metal oxide precursors. The pores in the inorganic films obtained after thermal annealing are then used as nanoreactors to synthesize MAPbI3 crystallites with narrow size distribution and average radius comprised between 1 and 4 nm, depending on the template of choice. Both the static and dynamic photoemission properties of the ensemble display features distinctive of the regime of strong quantum confinement. Photoemission maps demonstrate that the spectral and intensity properties of the luminescence extracted from the perovskite quantum dot loaded films are homogeneous over squared centimeters areas. At variance with their bulk counterparts, constant emission intensity is reached in time scales at least four orders of magnitude shorter.

Characteristics of supramolecular imprinting template on liver meridian tropism of traditional Chinese medicine based on molecular connectivity index

The molecular connectivity index was adopted to explore the characteristics of supramolecular imprinting template of herbs distributed to liver meridian, in order to provide scientific basis for traditional Chinese medicines(TCMs) distributed to liver meridian. In this paper, with "12th five-year plan" national planning textbooks Science of Traditional Chinese Medicine and Chemistry of Traditional Chinese Medicine as the blueprint, literatures and TCMSP sub-databases in TCM pharmacology of northwest science and technology university of agriculture and forestry were retrieved to collect and summarize active constituents of TCM distributed to liver meridian, and calculate the molecular connectivity index. The average molecular connectivity index of ingredients distributed to liver meridian was 9.47, which was close to flavonoid glycosides' (9.17±2.11) and terpenes (9.30±3.62). Therefore, it is inferred that template molecule of liver meridian is similar to physicochemical property of flavonoid glycosides and terpenes, which could be best matched with imprinting template of liver meridian.

A crystalline AlPO4-5 intermediate: designed synthesis, structure, and phase transformation.

AlPO4-5 is the most extensively studied material in exploring the crystallization mechanism of aluminophosphate molecular sieves, and it can be synthesized using 4-dimethylaminopyridine (DMAP) as an organic structure-directing agent (OSDA). Achieving the AlPO4-5 intermediate in the crystalline form would be of great importance and significance for this purpose. In this study, we proposed a concept that by carefully regulating the synthesis conditions, crystalline alumimophosphate intermediates could be rationally prepared. A crystalline AlPO4-5 intermediate, (C7H11N2)2(H3O)(Al3P4O16)·(H2O)2.5 (1), was, therefore, synthesized by significantly increasing the amounts of orthophosphoric acid and DMAP. The intermediate 1 consists of alternating organic DMAP and inorganic [Al3P4O16]3- layers with abundant hydrogen bonds and can transform to the AlPO4-5 framework upon heating in air or through a steam-assisted conversion (SAC) method. To unravel the role of DMAP in the transformation, pure AlPO4-5 (2) was also synthesized by altering the synthesis conditions. The supramolecular assembly templating (SAT) effects of DMAP in 1 and 2 were verified via fluorescence spectra. Thus, the π-π stacking interactions between the DMAP molecules and the abundant hydrogen bonds between the adjacent layers are considered to be important for the phase transformation of 1. This crystalline intermediate would promote the understanding of the crystallization mechanism in the system of aluminophosphate molecular sieves.

One-dimensional supramolecular hybrids: self-assembled nanofibrous materials based on a sugar gelator and calcite developed along an unusual axis

One-dimensional (1D) supramolecular hybrid structures composed of self-assembled fibers and CaCO3 calcite crystals have been developed through an approach inspired by biomineralization. The supramolecular 1D template consisting of a low-molecular-weight gelator induces the crystal growth of calcite along an unusual axis.

Chiroptical activity of single-handed helical silica nanotubes doped with CdS nanoparticles

Single-handed helical silica nanotubes doped with CdS nanoparticles are prepared through a supramolecular templating approach using a pair of chiral low-molecular-weight gelators (LMWGs). The handedness of the nanotubes is controlled by the self-assemblies of the LMWGs. The left- and right-handed helical nanotubes show opposite optical activities. Broad signals are observed at 250–510nm in the diffuse reflectance circular dichroism spectra. We propose that the optical activity originates from the dipole–dipole interactions of the CdS nanoparticles. The results also indicate that the silica should be chiral at the molecular level. These CdS-doped silica nanotubes have potential application as chirality sensors.

Live Templates of a Supramolecular Block Copolymer for the Synthesis of Ordered Nanostructured TiO2 Films via Guest Exchange.

In this work, we introduce a facile method based on host-guest chemistry to synthesize a range of nanostructured TiO2 materials using supramolecular templates of a dendron-jacketed block copolymer (DJBCP). The DJBCP is composed of amphiphilic dendrons (4'-(3,4,5-tridodecyloxybenzoyloxy)benzoic acid, TDB) selectively incorporated into a P4VP block of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) via hydrogen bonding. The PS-b-P4VP host acts as a structure-directing template, while the guest molecules (TDB) assist the self-assembly nanostructures and zone-axis alignment, resulting in the nanostructured template of vertically oriented cylinders formed via successive phase transformations from Im3̅m to R3̅m to P6mm upon thermal annealing in the doctor-blade-cast film. The guest molecules subsequently direct the titania precursors into the P4VP domains of the templates via supramolecular guest exchange during immersion of the film in a designated precursor solution containing a P4VP-selective solvent. The subsequent UV irradiation step leads to the formation of PS-b-P4VP/TiO2 hybrids. Finally, removal of the host template by calcination leaves behind mesoporous channels and makes sacrifices to be a carbon source for carbon-doping TiO2 materials. Various TiO2 nanoarchitectures, namely, vertical and wiggly micrometer-length channels, inverse opals, fingerprint-like channels, heterogeneous multilayers, and nanotubes, have been fabricated by highly tunable DJBCP nanostructures.

Hydrogels of Superlong Helices to Synthesize Hybrid Ag-Helical Nanomaterials.

The gelation behavior of mixtures of sodium deoxycholate (NaDC) and glutathione (GSH) in water is investigated. The system exhibits a structural transition of self-assembled hydrogels from nanofibers to nanohelix structures, and then to helical ribbons with increasing GSH concentration. Superlong helical nanofibers with left- and right-handed orientations are produced by tuning the concentration of GSH at a fixed concentration of NaDC. Random coil and β-sheet structures are significant for the formation of the helical structures, and are indicated by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectra. The mechanical strength of the "weak" hydrogels is enhanced by the introduction of appropriate suitable amount of AgNO3. Furthermore, the controlled growth of Ag nanoparticles at spatially arranged locations along the nanohelices (hybrid Ag-helical nanomaterial) is readily achieved by UV reduction of Ag (I) ions on the supramolecular helical templates.

Preparation and characterization of single-handed helical carbonaceous nanofibers using 1,4-phenylene bridged polybissilsesquioxanes

Single-handed helical carbonaceous materials attracted much attention for varieties of potential applications. Herein, single-handed helical 1, 4-phenylene bridged polybissilsesquioxane nanofibers were prepared through a supramolecular templating approach using a pair of enantiomers. After carbonization at 700 °C for 2.0 h and removal of silica using HF aqueous solution, single-handed helical carbonaceous nanofibers were obtained. The obtained samples were characterized using the field-emission scanning electron microscopy, transmission electron microscopy, N2 sorptions, X-ray diffraction, Raman spectroscopy and diffuse reflectance circular dichroism (DRCD). The Raman spectrum indicated that the carbon was amorphous. The DRCD spectra indicated that the carbonaceous nanofibers exhibited optical activity. The surface area of the left-handed helical carbonaceous nanofibers was 907 m2/g. Such material has potential applications as chirality sensor and supercapacitor electrode.

Preparation of single-handed helical and C-shaped 3-aminophenol-formaldehyde resin nanotubes and single-handed helical carbonaceous nanotubes

Single-handed helical and C-shaped 3-aminophenol-formaldehyde resin nanotubes were prepared via a supramolecular templating approach. The chiral templates and 3-aminophenol were initially organized into helical nanoribbons, followed by the adsorption of formaldehyde onto the surfaces of the helical nanoribbons. Subsequent to polymerization and further thermosetting of the resin oligomers, 3-aminophenol-formaldehyde resin nanotubes were obtained after removing the templates. When low amounts of 3-aminophenol were added, straight C-shaped 3-aminophenol-formaldehyde resin nanotubes were obtained. Increasing the amount of added 3-aminophenol led to the formation of single-handed helical nanotubes instead. When the single-handed helical resin nanotubes were carbonized at 900 °C under Ar, single-handed helical carbonaceous nanotubes were obtained. Raman spectrum indicates that this carbon is predominantly amorphous. Circular dichroism spectra illustrate that both the helical resin nanotubes and the carbonaceous nanotubes exhibit optical activity. This work indicates that the added amount and the edge-adsorption mode of the precursors on the templates determine the final morphology and chirality of the products.

A Stable Extra-Large-Pore Zeolite with Intersecting 14- and 10-Membered-Ring Channels.

The development of inorganic frameworks with extra-large pores (larger than 12-membered rings) has attracted considerable attention because of their potential applications in catalysis, the separation of large molecules, and so forth. We herein report the synthesis of the new extra-large-pore zeolite NUD-2 by using the supramolecular self-assembly of simple aromatic organic cations as structure-directing agents (SDAs). NUD-2 is a high-silicon-content germanosilicate with interconnecting 14×10-membered-ring channels. The SDAs in NUD-2 can be removed by calcination in air at 550 °C to yield permanent pores with a BET surface area of 500 m(2) g(-1) . Both germanium and organic cations in NUD-2 can also be removed by treatment with acid at lower temperature, thus not only affording recycling of germanium and SDAs, but also providing a highly stable siliceous zeolite. In addition, aluminum ions can be incorporated into the framework of NUD-2. The NUD-2 structure is yet another extra-large-pore zeolite synthesized by using the supramolecular self-assembling templating approach, thus demonstrating that this approach is a general and applicable strategy for synthesis of new large- and extra-large-pore zeolites.

Fabrication of chiral mesoporous carbonaceous nanofibers and their electrochemical energy storage

Chiral carbon-based nanomaterials possess many superior properties originated both from their nano-sized structure and their chirality. We presented a facile way to synthesize chiral mesoporous carbonaceous nanofibers (chiral MCNFs) through a supramolecular templating method, using a pair of chiral low-molecular-weight gelators as the templates, resorcinol, formaldehyde and tetraethyl orthosilicate as the precursors, respectively. Besides, the chiral MCNFs exhibited optical activity; the electrochemical measurements implied that they also showed good capacitance and lithium-ion storage performances.

Supramolecular Templating Approach for the Solvent-Free Synthesis of Open-Framework Metal Oxalates.

A series of open-framework metal oxalates (metal = Zn, Co, Mn, Bi, In) were prepared under solvent-free conditions by a supramolecular templating approach. These compounds have cationic, anionic, and neutral frameworks with pore apertures ranging from small 8-membered rings (8 MRs) to extra-large 16 and 20 MRs. The zinc oxalate exhibits a proton conductivity of 2.6 × 10(-3) S cm(-1) at 60 °C under 98% relative humidity.

Single-handed helical SiC fiber preparation using 1,4-phenylene-bridged polybissilsesquioxane

Single-handed helical mesoporous 1,4-phenylene-bridged polybissilsesquioxane fibers were synthesized using a previously reported supramolecular templating approach by increasing the concentration of NaOH. They exhibit optical activity and the size of the mesopores is approximately 2.5nm. Single-handed helical SiC fibers, which consisted of β-SiC nanoparticles, were prepared by carbothermal reduction of the 1,4-phenylene-bridged polybissilsesquioxane fibers. The handedness of the SiC fibers was the same as that of the mesoporous 1,4-phenylene-bridged polybissilsesquioxane fibers. The left- and right-handed helical SiC fibers showed opposite optical activities. Signals were identified in the diffuse reflectance circular dichroism spectra. Since the β-SiC phase belongs to the non-chiral F¯43m space group, we suggest that the optical activity originates from chiral defects on the SiC nanoparticle surfaces.

(Invited) DNA As Supramolecular Template for the Assembly of Porphyrin Arrays

DNA has become very attractive as scaffold for functional molecules on the nanometre scale.1 The sequence specific insertion of modified nucleotides using automated DNA synthesis allows for the creation of new designer molecules with a wide range of potential applications. We have established a general synthetic route to porphyrin-nucleosides and their subsequent site specific incorporation into oligonucleotides to create multiporphyrin arrays. Up to eleven consecutive porphyrins could be incorporated into DNA giving access to a multiporphyrin array of approximately 10 nm in length, which corresponds to the highest amount of DNA modification with a large hydrophobic metal complex.2 The spectroscopic data and structure calculations indicate the formation of a stable helical array in the single strand porphyrin-DNA. The π-stack of the porphyrins leads to strong electronic interaction between the chromophores. A zipper array with induced stability and energy transfer properties has recently been realised, providing access to the first reversible photonic wire based on a DNA scaffold.3 We will present our latest results in terms of structure analysis of porphyrin modified DNA, which includes the stepwise built up of a porphyrin-DNA system and its detailed analysis using CD spectroscop and thermal analysis with absorption and fluorescence spectroscopy. In addition, a novel LNA derived porphyrin building block will be discussed which shows large differences in excitonic coupling depending on the DNA sequence.4 Several applications of porphyrin-DNA will also be described, including highly sensitive genosensors5 and DNA origami nanopores.6

Chinese medicine preparation supramolecular imprinting templates based on in vitro release characteristics of BYHW sustained-release tablet

The study focused on the in vitro release of Buyanghuanwu (BYHW) elementary osmotic pump sustained release tablets. Its band similarity was calculated by the total quantum statistical moment. Meanwhile, in vitro release characteristics were analyzed to discuss the existence of supramolecular imprinting templates. The results show that the same imprint templates may exist in different structures of traditional Chinese medicine(TCM)'s multi-components. The BYHW sustained release tablets prepared by elementary osmotic pump can meet the objectives of "overall control, synchronous release". However, the supramolecular imprinting templates in TCM compound prescriptions should be further explored, the overall and synchronous release of different components was controlled through imprinting templates, so as to seek the more suitable sustained release preparation technology for multiple components of TCM, and make it in line with the characteristics of TCM.

Charged Inorganic Nanowire‐Directed Mineralization of Amorphous Calcium Carbonate

AbstractCharged inorganic nanowires (e.g., tellurium nanowires, TeNWs), analogous to supramolecular templates, have been used to direct the mineralization of uniform amorphous calcium carbonate (ACC) shells on their surfaces. The role of surface charges of TeNWs, mixed solvent ratio, and the diameter of the TeNWs is discussed, and the formation mechanism of ACC‐coated tellurium nanowires (ACC@TeNWs) is elucidated. This charged‐nanowire‐directed mineralization process represents a new approach that could be extended for the synthesis of other amorphous inorganic nanostructures in the future.

Supramolecular PEGylated Dendritic Systems as pH/Redox Dual-Responsive Theranostic Nanoplatforms for Platinum Drug Delivery and NIR Imaging.

Recently, self-assembling small dendrimers into supramolecular dendritic systems offers an alternative strategy to develop multifunctional nanoplatforms for biomedical applications. We herein report a dual-responsive supramolecular PEGylated dendritic system for efficient platinum-based drug delivery and near-infrared (NIR) tracking. With a refined molecular/supramolecular engineering, supramolecular dendritic systems were stabilized by bioreducible disulfide bonds and endowed with NIR fluorescence probes, and PEGylated platinum derivatives coordinated onto the abundant peripheral groups of supramolecular dendritic templates to generate pH/redox dual-responsive theranostic supramolecular PEGylated dendritic systems (TSPDSs). TSPDSs markedly improved the pharmacokinetics and biodistribution of platinum-based drugs, owing to their stable nanostructures and PEGylated shells during the blood circulation. Tumor intracellular environment (low pH value and high glutathione concentration) could trigger the rapid disintegration of TSPDSs due to acid-labile coordination bonds and redox-cleavable disulfide linkages, and then platinum-based drugs were delivered into the nuclei to exert antitumor activity. In vivo antitumor treatments indicated TSPDSs not only provided high antitumor efficiency which was comparable to clinical cisplatin, but also reduced renal toxicity of platinum-based drugs. Moreover, NIR fluorescence of TSPDSs successfully visualized in vitro and in vivo fate of nanoplatforms and disclosed the intracellular platinum delivery and pharmacokinetics. These results confirm tailor-made supramolecular dendritic system with sophisticated nanostructure and excellent performance is a promising candidate as smart theranostic nanoplatforms.

Ammonium-crown ether supramolecular cation-templated assembly of an unprecedented heterobicluster-metal coordination polymer with enhanced NLO properties.

An ammonium-crown ether host-guest supramolecular cation-templated synthetic methodology has been developed to construct a structurally unprecedented heterobicluster-metal coordination polymer (HCM-CP 1) based on tetranuclear clusters [WS4Cu3](+) with different connection environments, pentanuclear clusters [WS4Cu4](2+), and Cu(+) building metal ions. HCM-CP 1 exhibits enhanced NLO properties, which may be ascribed to the incorporation of diverse building cluster components.

Transcription of G-quartet supramolecular aggregates into hierarchical mesoporous silica nanotubes.

The use of 5-guanosine monophosphate (GMP) with Sr(2+) ions to form G-quadruplex bundles as supramolecular templates for the preparation of hierarchical mesoporous silica nanotube materials is reported here, and some mesopores with a diameter of 4-22 nm were obtained. Furthermore, some mesopore channels which run perpendicularly to the center axis of the tube and penetrate right through the outer wall of the nanotubes were achieved by removing the templates. Besides, porous hollow silica spheres were obtained by changing some of the reaction conditions during the process of preparation. Their structures are stable even after high temperature calcination. A formation mechanism was proposed and discussed, and their structures were characterized using a number of means including X-ray diffraction, IR spectra, N2 adsorption-desorption isotherms, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Formation of CdS in Supramolecular Dendrimer–Dye Assemblies: Electrostatic and Electrostatic-Coordination Templating

A novel concept for the formation of organic–inorganic hybrid nanostructures based on a tunable supramolecular templating mechanism involving several types of noncovalent interactions is presented. Different organic–inorganic hybrid structures with narrow size distributions composed of a cationic dendrimer, an oppositely charged divalent diazo dye, and CdS can be created: First, larger supramolecular structures consisting of several 100 to 1000 dendrimers is built based on ionic and π–π interaction. Second, with this self-assembled template, the hybrid nanostructure forms based on electrostatics and coordination interaction. The influence on shape and internal structure of the supramolecular hybrid architectures was investigated. A size control of the assemblies is possible in a range of 60–420 nm. The prospect to direct self-assembly and templating through the controlled combination of different noncovalent interactions potentially allows to create tailor-made systems for various applications.