Multiple twinning on a silica mesoporous crystal

この論文は国立情報学研究所の電子図書館事業により電子化されました。研究会報告シリカメソ多孔結晶は,アモルファスシリカを骨格にメソスケールの空隙(2-50nm)が周期配列した結晶である.シリカメソ多孔結晶は,シリカの前駆体と水における界面活性剤の共同的な自己組織化を利用して合成され,界面活性剤は焼成によって取り除かれる.従ってその空隙は水-界面活性剤-シリカ系での界面活性剤ミセルの構造を反映すると考えられる.本研究で我々は十面体や二十面体のような結晶学的点群とは相容れない粒子外形を示すシリカメソ多孔結晶の構造解析を行った.まず電子線結晶学に基づいた高分解能電子顕微鏡像の解析から,その結晶構造は球状ミセルの立方最密充填であることを示す.また特徴的な上記結晶外形はメソスケールにおける多重双晶の結果であることを報告する

Single Diamond Structured Titania Scaffold

Single diamond (SD) network, discovered in beetles and weevils skeletons, is the holy grail in photonic materials with widest complete bandgap to date. Such structure influences the propagation of electromagnetic waves in defined frequency and is significant in photonic crystals, light-harvesting applications, optical waveguides, laser resonators, etc. However, efforts until now have not allowed a start-to-finish understanding on the production process of the unbalanced single network scaffold in natural organisms and the thermodynamical instability of SD makes it extremely difficult to be obtained by self-assembly compared to the energetically favored bicontinuous double diamond and other easily formed lattices, thus the artificial fabrication of such photonic structure in practical synthesis has last-long as a formidable challenge. Herein, we report the unprecedented bottom-up fabrication of SD titania scaffold through a one-pot co-folding scenario employing a simple diblock copolymer poly(ethylene oxide)-block-polystyrene (PEO45-b-PS241) as template and titanium diisopropoxide bis(acetylacetonate) as inorganic precursor in a mixed solvent, in which the inorganic species selectively organized in one of the skeleton enclosed by diamond minimal surface of the polymer matrix in a simultaneous assembling process. Electron crystallography investigations exhibited the tetrahedral-connected SD frameworks with space group Fd-3m in polycrystalline anatase form. Photonic bandgap calculation shows that the structure reveals a complete bandgap of 11.54 % with the dielectric contrast of titania (6.25). This work provides a straightforward solution to the complex synthesis puzzle and offers a new reference for biological relevant materials, next-generation optical devices, etc

Enantiomeric Discrimination by Surface- Enhanced Raman Scattering- Chiral Anisotropy of Chiral Nanostructured Gold Films

A surface- enhanced Raman scattering- chiral anisotropy (SERS- ChA) effect is reported that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films (CNAFs) equipped in the normal Raman scattering Spectrometer. The CNAFs provided remarkably higher enhancement factors of Raman scattering (EFs) for particular enantiomers, and the SERS intensity was proportional to the enantiomeric excesses (ee) values. Except for molecules with mesomeric species, all of the tested enantiomers exhibited high SERS- ChA asymmetry factors (g), ranging between 1.34 and 1.99 regardless of polarities, sizes, chromophores, concentrations and ee. The effect might be attributed to selective resonance coupling between the induced electric and magnetic dipoles associated with enantiomers and chiral plasmonic modes of CNAFs.Absolution by SERS: A surface- enhanced Raman scattering chiral anisotropy effect is presented that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films. It is applied in the normal Raman scattering system to identify the absolute configuration and composition of enantiomers, overcoming disadvantages of polarimeter systems and chromatography.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156417/3/anie202006486-sup-0001-misc_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156417/2/anie202006486_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156417/1/anie202006486.pd

Enantiomeric Discrimination by Surface- Enhanced Raman Scattering- Chiral Anisotropy of Chiral Nanostructured Gold Films

A surface- enhanced Raman scattering- chiral anisotropy (SERS- ChA) effect is reported that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films (CNAFs) equipped in the normal Raman scattering Spectrometer. The CNAFs provided remarkably higher enhancement factors of Raman scattering (EFs) for particular enantiomers, and the SERS intensity was proportional to the enantiomeric excesses (ee) values. Except for molecules with mesomeric species, all of the tested enantiomers exhibited high SERS- ChA asymmetry factors (g), ranging between 1.34 and 1.99 regardless of polarities, sizes, chromophores, concentrations and ee. The effect might be attributed to selective resonance coupling between the induced electric and magnetic dipoles associated with enantiomers and chiral plasmonic modes of CNAFs.Absolution by SERS: A surface- enhanced Raman scattering chiral anisotropy effect is presented that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films. It is applied in the normal Raman scattering system to identify the absolute configuration and composition of enantiomers, overcoming disadvantages of polarimeter systems and chromatography.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156470/3/ange202006486_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156470/2/ange202006486.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156470/1/ange202006486-sup-0001-misc_information.pd

Amino/quaternary ammonium groups bifunctionalized large pore mesoporous silica for pH-responsive large drug delivery{

Mesoporous nanoparticles functionalized with amino groups on the pore surface and quaternary ammonium groups on the particle surface with particle sizes of 500-800 nm in length and 300-500 nm in diameter and a pore size of 7.2-7.4 nm, have been obtained through a post-synthesis and cocondensation method. Bleomycin (BLM) has been chosen as a model anti-cancer drug with a large molecular size, and the iron essential for organisms has been utilized for constructing NH 2 -Fe-BLM coordination bond architecture in the pore surface. The BLM was released under mildly acidic pH conditions by cleavage of the Fe-BLM coordination bond triggered by pH reduction. Cell assays show that mesoporous nanoparticles have good dispersity and good cell penetrating properties due to the positively charged quaternary ammonium groups on the outer surface of the nanoparticles. These organic functionalized large pore mesoporous materials can be utilized as carriers in the pHresponsive delivery of an anti-cancer drug with a large molecular size, opening up new opportunities for their further application in controlled release of biomacromolecules

Optically Active Chiral DNA–Silica Hybrid Free-Standing Films

Chiral DNA–silica hybrid free-standing films (CDSFs) with antipodal handedness were fabricated via the self-assembly of DNA and a silica source in the presence of a costructure-directing agent. The scattering-based optical activity (OA) of these films across the entire visible spectrum coming from the chiral DNA supermolecular structure can easily be tuned to various narrow-band OAs by changing the absorption bands of the backgrounds or by introducing colorful chromophore molecules into the films. These films provide an extremely facile strategy for achieving OA of targeted wavelengths, which may facilitate the design of optical instruments