Co-reporter:Xue Liu, Hao Xu, Lin Zhang, Lu Han, Jingang Jiang, Peter Oleynikov, Li Chen, and Peng Wu
ACS Catalysis December 2, 2016 Volume 6(Issue 12) pp:8420-8420
Publication Date(Web):November 11, 2016
DOI:10.1021/acscatal.6b02032
The crystalline structure of UTL zeolite experienced an unusual orientated collapse and reconstruction within an extremely narrow time window during the structural stabilization process by nitric acid treatment at elevated temperature. Taking full advantage of this unique structural change, extra-large-pore Sn-UTL zeolites were postsynthesized via the reaction between the SnCl4 molecules and the silanols in the hydroxyl nests, which occurred concomitantly with the removal of Ge and/or Si species from the dense layer. The original UTL topology was restored thereafter, leading to a Sn-incorporated analogue. The usage of the most seriously collapsed intermediate structure, which was captured by timing during the precisely controlled acid treatment, was vital for achieving Sn-UTL zeolites with a larger amount of isolated Sn species effectively incorporated. With tetrahedrally coordinated Sn ions in the highly stabilized UTL topology consisting of intersecting 12- and 14-membered ring (MR) pore channels, Sn-UTL showed promising catalytic performance in the Meerwein–Pondorf–Verley reaction as well as in the Baeyer–Villiger oxidation reactions of ketones using H2O2 or even bulky tert-butyl hydroperoxide (TBHP) as an oxidant.Keywords: extra-large pore; germanosilicate; selective oxidation; stannosilicate; structural rearrangement;
Co-reporter:Yuanyuan Cao;Yingying Duan;Shunai Che
Chemical Communications 2017 vol. 53(Issue 41) pp:5641-5644
Publication Date(Web):2017/05/18
DOI:10.1039/C7CC02382K
Screw-like hierarchical chiral fibres were constructed by co-templating two building tectons, DNA and porphyrin, under the bridging effect of cationic organosilane. The chirality transfer from the DNA molecule to meso-tetra(4-sulfonatophenyl)porphyrin assemblies in turn affected the subsequent arrangement of DNA assemblies, thus indicating a multi-dimensional hierarchical chiral amplification process from the molecular scale to the macroscopic scale.
Co-reporter:Zhixing Lin;Dr. Shaohua Liu;Wenting Mao;Hao Tian;Nan Wang;Ninghe Zhang;Dr. Feng Tian; Lu Han; Xinliang Feng; Yiyong Mai
Angewandte Chemie 2017 Volume 129(Issue 25) pp:7241-7246
Publication Date(Web):2017/06/12
DOI:10.1002/ange.201702591
AbstractWe herein report the tunable self-assembly of simple block copolymers, namely polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers, into porous cubosomes with inverse or mesophases of controlled unit cell parameters as well as hexasomes with an inverse hexagonal (p6mm) structure, which have been rarely observed in polymer self-assembly. A new morphological phase diagram was constructed for the solution self-assembly of PS-b-PEO based on the volume fraction of the PS block against the initial copolymer concentration. The formation mechanisms of the cubosomes and hexasomes have also been revealed. This study not only affords a simple system for the controllable preparation and fundamental studies of ordered bicontinuous structures, but also opens up a new avenue towards porous architectures with highly ordered pores.
Co-reporter:Zhixing Lin;Dr. Shaohua Liu;Wenting Mao;Hao Tian;Nan Wang;Ninghe Zhang;Dr. Feng Tian; Lu Han; Xinliang Feng; Yiyong Mai
Angewandte Chemie International Edition 2017 Volume 56(Issue 25) pp:7135-7140
Publication Date(Web):2017/06/12
DOI:10.1002/anie.201702591
AbstractWe herein report the tunable self-assembly of simple block copolymers, namely polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers, into porous cubosomes with inverse or mesophases of controlled unit cell parameters as well as hexasomes with an inverse hexagonal (p6mm) structure, which have been rarely observed in polymer self-assembly. A new morphological phase diagram was constructed for the solution self-assembly of PS-b-PEO based on the volume fraction of the PS block against the initial copolymer concentration. The formation mechanisms of the cubosomes and hexasomes have also been revealed. This study not only affords a simple system for the controllable preparation and fundamental studies of ordered bicontinuous structures, but also opens up a new avenue towards porous architectures with highly ordered pores.
Co-reporter:Wenting Mao;Xin Cao;Qingqing Sheng; Dr. Lu Han; Dr. Shunai Che
Angewandte Chemie International Edition 2017 Volume 56(Issue 36) pp:10610-10610
Publication Date(Web):2017/08/28
DOI:10.1002/anie.201783661
NetworksA silica scaffold with a shifted “plumber's nightmare” network is reported by L. Han and co-workers in their Communication on page 10670 ff.
Co-reporter:Dr. Liguo Ma;Dr. Yuanyuan Cao;Dr. Yingying Duan;Dr. Lu Han; Shunai Che
Angewandte Chemie International Edition 2017 Volume 56(Issue 30) pp:8657-8662
Publication Date(Web):2017/07/17
DOI:10.1002/anie.201701994
AbstractPhysical fabrication of chiral metallic films usually results in singular or large-sized chirality, restricting the optical asymmetric responses to long electromagnetic wavelengths. The chiral molecule-induced formation of silver films prepared chemically on a copper substrate through a redox reaction is presented. Three levels of chirality were identified: primary twisted nanoflakes with atomic crystal lattices, secondary helical stacking of these nanoflakes to form nanoplates, and tertiary micrometer-sized circinates consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption- and scattering-based optical activities at UV/Vis wavelengths based on their hierarchical chirality. The Ag films showed chiral selectivity for amino acids in catalytic electrochemical reactions, which originated from their primary atomic crystal lattices.
Co-reporter:Wenting Mao;Xin Cao;Qingqing Sheng; Dr. Lu Han; Dr. Shunai Che
Angewandte Chemie International Edition 2017 Volume 56(Issue 36) pp:10670-10675
Publication Date(Web):2017/08/28
DOI:10.1002/anie.201704639
AbstractBicontinuous structures with hyperbolic surfaces have been found in a variety of natural and synthetic systems. Herein, we present the synthesis and structural study of the shifted double-primitive networks, which is known as the rare “plumber's nightmare”, and its interconversion into diamond networks. The scaffold was prepared by self-assembly of an amphiphilic triblock terpolymer and silica precursors. Electron crystallography indicates that the structure consists of two sets of hollow primitive networks shifted along 0.75b and 0.25c axes (2pcu(38 63), space group Cmcm). The “side-by-side” epitaxial relationship of the primitive and diamond networks with unit cell ratio of about 1.30 has been directly observed with the intermediate surface related to the rPD family. These results bring new insights to previous theoretical studies.
Co-reporter:Dr. Liguo Ma;Dr. Yuanyuan Cao;Dr. Yingying Duan;Dr. Lu Han; Shunai Che
Angewandte Chemie 2017 Volume 129(Issue 30) pp:8783-8788
Publication Date(Web):2017/07/17
DOI:10.1002/ange.201701994
AbstractPhysical fabrication of chiral metallic films usually results in singular or large-sized chirality, restricting the optical asymmetric responses to long electromagnetic wavelengths. The chiral molecule-induced formation of silver films prepared chemically on a copper substrate through a redox reaction is presented. Three levels of chirality were identified: primary twisted nanoflakes with atomic crystal lattices, secondary helical stacking of these nanoflakes to form nanoplates, and tertiary micrometer-sized circinates consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption- and scattering-based optical activities at UV/Vis wavelengths based on their hierarchical chirality. The Ag films showed chiral selectivity for amino acids in catalytic electrochemical reactions, which originated from their primary atomic crystal lattices.
Co-reporter:Xin Cao, Dongpo Xu, Yuan Yao, Lu Han, Osamu Terasaki, and Shunai Che
Chemistry of Materials 2016 Volume 28(Issue 11) pp:3691
Publication Date(Web):May 9, 2016
DOI:10.1021/acs.chemmater.6b00308
Triply periodic constant mean curvature surface structures have been discovered in a variety of biological and self-assembly systems. Among them, the single gyroid is of significant interest, because of its unique geometry, inherent chirality, and corresponding spectacular optical properties. Despite theoretical and experimental efforts on this structure, so far, limited progress has been made regarding the formation of the single-network structures and the structural relationships with the thermodynamically stable double networks. Herein, we report the electron microscopic observation and analysis on the interconversion between the single gyroid and double diamond structure in an amphiphilic ABC triblock terpolymer templated macroporous silica synthesis system with a solvent mixture of tetrahydrofuran and water. The two structures were interconnected by a “side-by-side” epitaxial relationship with rescaling of the unit cell. The single-network structure was formed via a new type of alternating gyroid under the restricted epitaxial intergrowth, in which the hydrophilic block with the silica source and the solvent tetrahydrofuran formed the two chemically distinct, interpenetrating gyroid networks of opposite chirality in a matrix of the hydrophobic block.
Co-reporter:Yuanyuan Cao;Dr. Kunche Kao;Dr. Chungyuan Mou;Dr. Lu Han;Dr. Shunai Che
Angewandte Chemie International Edition 2016 Volume 55( Issue 6) pp:2037-2041
Publication Date(Web):
DOI:10.1002/anie.201509068
Abstract
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.
Co-reporter:Yuanyuan Cao;Dr. Kunche Kao;Dr. Chungyuan Mou;Dr. Lu Han;Dr. Shunai Che
Angewandte Chemie 2016 Volume 128( Issue 6) pp:2077-2081
Publication Date(Web):
DOI:10.1002/ange.201509068
Abstract
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.
Co-reporter:Le Xu, Xinyi Ji, Jin-Gang Jiang, Lu Han, Shunai Che, and Peng Wu
Chemistry of Materials 2015 Volume 27(Issue 23) pp:7852
Publication Date(Web):November 10, 2015
DOI:10.1021/acs.chemmater.5b03658
Zeolites with intergrown structures are particularly interesting because they often exhibit unique performance in heterogeneous catalysis. This raises the bar of the structural characterizations and remains an enormous challenge to understand the synthesis conditions and the formation mechanisms of such intergrown materials. Herein, a novel intergrown zeolite (ECNU-5) was successfully synthesized via a rapid dissolution–recrystallization (RDR) route, which reorganized the conventional MWW layer stacking into two new different polymorphs, ECNU-5A and ECNU-5B. Structure elucidation indicates both polymorphs are reconstructed from the same MWW layer but are different in relative shift between adjacent layers. ECNU-5 is the first structure-determined zeolite with interrupted structure that MWW layers shift in the horizontal direction, in which the two polymorphs are never predicted before and are additional members of the MWW family. The unique geometry mismatch between the organic structure-directing agent (OSDA) and inorganic silicate framework is ascribed to causing the zeolite layer shift. Moreover, the implementation of silylation technique readily expanded the interlayer pore of as-made ECNU-5, producing the interlayer-expanded zeolite (IEZ-ECNU-5), which maintained the original stacking sequence of MWW sheets.
Co-reporter:Yuan Yao, Ji Feng, Lu Han and Shunai Che
RSC Advances 2015 vol. 5(Issue 124) pp:102256-102260
Publication Date(Web):23 Nov 2015
DOI:10.1039/C5RA19123H
The self-assembly of nanoparticles to hierarchal structures receives increasing concern nowadays. In this paper, we report hierarchal silica clusters composed of multi-lamellar silica vesicles (MSVCs) through self-assembly and mineralization. Herein, an amphiphilic comb-like polymer with a siloxane skeleton and Pluronic P123 were introduced as the co-template, and tetraethoxysilane (TEOS) was the silica source. The flexible templates and gradually solidified silica shell provided the vesicles with proper hardness to adapt to the shape change during the aggregation and fusion, and the morphology of the MSVCs was fixed by silica finally. The obtained MSVCs were 400–700 nm in dimension, and composed of several multi-lamellar silica vesicles with ca. 105–130 nm in size, respectively. The effect of template ratio, pH value and temperature were discussed to illustrate the proper conditions for preparing hierarchal MSVCs, and the formation of MSVCs was discussed based on time-dependent observations.
Co-reporter:Yanhang Ma, Lu Han, Keiichi Miyasaka, Peter Oleynikov, Shunai Che, and Osamu Terasaki
Chemistry of Materials 2013 Volume 25(Issue 10) pp:2184
Publication Date(Web):April 27, 2013
DOI:10.1021/cm401294j
Close-packed spheres can be stacked into two crystalline structures: cubic close-packed (ccp) and hexagonal close-packed (hcp). Both of these structures were found in silica mesoporous crystals (SMCs). Herein, pure hcp mesostructure with P63/mmc symmetry of silica mesoporous crystals (SMCs) has been obtained in the synthetic system of cationic gemini surfactant as template and the N-[(3-trimethoxysilyl)propyl]ethylenediamine triacetix acid trisodium salt (EDTA-silyl) as the costructure directing agent (CSDA), which gives rise to the three-dimensional (3D) hexagonal structure and hexagonal plate morphology. The formation of the pure hcp structure was controlled by organic/inorganic interface curvature induced by charge matching between carboxylate groups of the CSDA and quaternary ammonium head groups of surfactant. Electrostatic potential distribution 3D map was reconstructed using Fourier analysis of HRTEM images based on electron crystallography, which showed characteristic features of the shape and connectivity of mesopores in the hcp structure. Small windows for connecting cages can be found only between layers, which determine the symmetry and local curvature of structures. As a result, the point group symmetry of mesopores becomes 6̅m2, instead of the m3̅m symmetry observed for perfect spheres in the ccp. The mechanism of stabilization and favorable growth of the pure hcp structure in mesoscale has been proposed based on synthesis strategy and symmetry support. This work provides people a better understanding of the priority of two sphere close-packed forms by comparing hcp and ccp structures.Keywords: costructure directing agent; electron microscopy; hexagonal close-packing; silica mesoporous crystals; surfactant;
Co-reporter:Yuanyuan Cao, Junjie Xie, Ben Liu, Lu Han and Shunai Che
Chemical Communications 2013 vol. 49(Issue 11) pp:1097-1099
Publication Date(Web):03 Jan 2013
DOI:10.1039/C2CC37470F
Multi-helical DNA–silica fibers were synthesised by the self-assembly of DNA molecules with cationic organosilanes and silica sources. By electron microscopy images and circular dichroism spectra, three-level helical structures in the silica fibers have been revealed, i.e. the DNA double-helix, the secondary left-handed DNA packing and the tertiary right-handed twisting.
Co-reporter:Lu Han, Chenyu Jin, Ben Liu, and Shunai Che
Chemistry of Materials 2012 Volume 24(Issue 3) pp:504
Publication Date(Web):January 11, 2012
DOI:10.1021/cm202874w
DNA–silica complex (DSC) mesocrystals have been synthesized by the self-assembly of DNA as template, N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAPS) as costructure directing agent (CSDA), and tetraethyl orthosilicate (TEOS) as the silica source. A full-scale synthesis-field diagram of DSCs has been constructed, and fibrous products, two-dimensional (2D)-hexagonal p6mm, and 2D-square p4mm platelets have been obtained by varying the synthetic conditions. The rare 2D-square structure possessed an inconsistent hexagonal morphology and appeared as the dominant mesostructure. The combination of X-ray diffraction patterns, scanning electron microscopy images, and high-resolution transmission electron microscopy images provided visible evidence for the mesostructural constructions of the 2D-square symmetry that transformed from the 2D-hexagonal symmetry. The driving force for this transformation seems to be the polymerization of the silica species during synthesis, which caused a decrease in the negative charge density from the silicate network. This led to close interactions of the opposing charges along the DNA–DNA interface upon quaternary ammonium phosphate electrostatic “zippers” to facilitate the formation of the 2D-square lattice.Keywords: biomineralization; DNA; electron microscopy; liquid crystal; self-assembly;
Co-reporter:Yuanyuan Cao, Yingying Duan, Lu Han and Shunai Che
Chemical Communications 2017 - vol. 53(Issue 41) pp:NaN5644-5644
Publication Date(Web):2017/04/27
DOI:10.1039/C7CC02382K
Screw-like hierarchical chiral fibres were constructed by co-templating two building tectons, DNA and porphyrin, under the bridging effect of cationic organosilane. The chirality transfer from the DNA molecule to meso-tetra(4-sulfonatophenyl)porphyrin assemblies in turn affected the subsequent arrangement of DNA assemblies, thus indicating a multi-dimensional hierarchical chiral amplification process from the molecular scale to the macroscopic scale.
Co-reporter:Yuanyuan Cao, Junjie Xie, Ben Liu, Lu Han and Shunai Che
Chemical Communications 2013 - vol. 49(Issue 11) pp:NaN1099-1099
Publication Date(Web):2013/01/03
DOI:10.1039/C2CC37470F
Multi-helical DNA–silica fibers were synthesised by the self-assembly of DNA molecules with cationic organosilanes and silica sources. By electron microscopy images and circular dichroism spectra, three-level helical structures in the silica fibers have been revealed, i.e. the DNA double-helix, the secondary left-handed DNA packing and the tertiary right-handed twisting.
![7,11,18,21-Tetraoxatrispiro[5.2.2.5.2.2]heneicosane](http://img.cochemist.com/ccimg/200/183-10-8.png)
![7,11,18,21-Tetraoxatrispiro[5.2.2.5.2.2]heneicosane](http://img.cochemist.com/ccimg/200/183-10-8_b.png)
