Supramolecular Science最新文献_第10页

Microcrystals of polydiacetylene derivatives and their linear and nonlinear optical properties 聚二乙炔衍生物的微晶体及其线性和非线性光学性质

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00021-2

Hachiro Nakanishi, Hideyuki Katagi

引用次数: 44

Molecular nanosheets of quasi-TiO2: preparation and spontaneous reassembling 准tio2分子纳米片的制备及其自发重组

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00033-9

Takayoshi Sasaki

{"title":"Molecular nanosheets of quasi-TiO2: preparation and spontaneous reassembling","authors":"Takayoshi Sasaki","doi":"10.1016/S0968-5677(98)00033-9","DOIUrl":"10.1016/S0968-5677(98)00033-9","url":null,"abstract":"<div>This paper reviews our recent progress in synthesis, optical properties and reassembling behaviour of nanosheet-crystallites of quasi-TiO2. Processing to thin anatase flakes from them is also presented. The colloidal nanosheets were synthesized by soft-chemically exfoliating a layered protonic titanate of <math><mtext>H</mtext><msub><mi></mi><mn>x</mn></msub><mtext>Ti</mtext><msub><mi></mi><mn>2-x/4</mn></msub><mtext>□</mtext><msub><mi></mi><mn><mtext>x</mtext><mtext>/4</mtext></mn></msub><mtext>O</mtext><msub><mi></mi><mn>4</mn></msub><mspace></mspace><mtext>·</mtext><mspace></mspace><mtext>H</mtext><msub><mi></mi><mn>2</mn></msub><mtext>O</mtext></math> (x∼0.7, □: vacancy). The action of bulky quarternary alkylammonium ion in large excess induced osmotic swelling involving Δd>3nm. Lowering the dose of the electrolyte promoted further interlayer expansion leading to delamination into elementary host layers. The resulting nanosheets exhibited a sharp UV-visible absorption band which is considerably blue-shifted compared to bulk TiO2. These distinct features and a well-structured photoluminescence may be interpreted as a reflection of their molecular nature. Slow drying of the colloids brought about spontaneous reassembling of the nanosheets, which was initiated by association of a limited number of the nanosheets with a very large intersheet spacing of >10nm and finally yielded a well-ordered lamellar structure. Freeze-drying of the suspension produced the lamellar phase in an open microstructure which can be converted into thin flaky particulates of anatase tens nanometers thick. The material, an assembly of the flakes, possessed a high specific surface area (40–110m2 <!-->g-1) associated with mesopores.</div>","PeriodicalId":22050,"journal":{"name":"Supramolecular Science","volume":"5 3","pages":"Pages 367-371"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0968-5677(98)00033-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76765332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 25

Photoresponsive monolayers on water and solid surfaces 水和固体表面的光响应单层膜

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00034-0

Takahiro Seki, Hidehiko Sekizawa, Keisuke Tanaka, Yoko Matsuzawa, Kunihiro Ichimura

{"title":"Photoresponsive monolayers on water and solid surfaces","authors":"Takahiro Seki, Hidehiko Sekizawa, Keisuke Tanaka, Yoko Matsuzawa, Kunihiro Ichimura","doi":"10.1016/S0968-5677(98)00034-0","DOIUrl":"10.1016/S0968-5677(98)00034-0","url":null,"abstract":"<div>Organic photochromic units and molecules can be regarded as light-driven nano molecular machines. Once such molecules are aligned at a surface, the supramolecular organization provides an efficient macroscopic mechanical response in a collective way. Amphiphilic polymers having an azobenzene (Az) side chain are the favorable materials for observation of such effects since they show marked photomechanical response with essentially full reversibility. An in situ Brewster angle microscopic observation showed marked morphological and rheological photoinduced changes in the molecular films. Moreover, we have newly found that the identical photosensitive molecular film transferred on to a solid mica surface shows large morphological changes under highly humid conditions as proven by atomic force microscopy (AFM). It is supposed that the molecular film is driven in the same mechanism both on water and water-adsorbed mica surfaces. These microscopic observations provide new insights of the photomechanical response in photochromic monolayers.</div>","PeriodicalId":22050,"journal":{"name":"Supramolecular Science","volume":"5 3","pages":"Pages 373-377"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0968-5677(98)00034-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74574177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Biomineralization of magnetic iron minerals in bacteria 磁性铁矿物在细菌中的生物矿化

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00036-4

Richard B. Frankel , Dennis A. Bazylinski , Dirk Schüler

引用次数: 55

Mesoscopic scale structures in self-organized surfactant solutions determined by small-angle neutron scattering 用小角中子散射测定自组织表面活性剂溶液中的介观尺度结构

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)80001-1

Sow-Hsin Chen, Sungmin Choi

引用次数: 7

A microporous structure of a thin film made of an ion-exchangeable layered compound 由离子交换层状化合物制成的薄膜的微孔结构

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00012-1

Ryu Abe, Junko N. Kondo, Michikazu Hara, Kazunari Domen

引用次数: 5

Nanostructure analysis of pyrolyzing conversion from organic polymer precursors to Si–C–(Ti)–O inorganic fibers 有机聚合物前驱体热解转化Si-C - (Ti) - o无机纤维的纳米结构分析

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00010-8

Kenji Suzuki, Tomoaki Kamiyama

{"title":"Nanostructure analysis of pyrolyzing conversion from organic polymer precursors to Si–C–(Ti)–O inorganic fibers","authors":"Kenji Suzuki, Tomoaki Kamiyama","doi":"10.1016/S0968-5677(98)00010-8","DOIUrl":"10.1016/S0968-5677(98)00010-8","url":null,"abstract":"<div>The Si–C–(Ti)–O inorganic fibers prepared by pyrolyzing poly(titano) carbosilane organic polymer precursors are well known to keep a very high tensile strength of about 250kgmm-2 at high temperatures above 1000°C in air for several hours. The structural evolution during the organic-to-inorganic conversion was measured by small angle X-ray scattering (SAXS) using a point-collimated Cu Kα X-ray beam and a two-dimensional imaging plate detector. The SAXS profile for the fibers generally comprises two components; an anisotropic scattering observed in the lower q region (<0.07Å-1) and an isotropic one in the higher q region (>0.1Å-1), where <math><mtext>q=4π</mtext><mspace></mspace><mtext>sin</mtext><mspace></mspace><mtext>θ/λ</mtext></math> is the scattering vector. The isotropic SAXS profiles, which sensitively depend on the pyrolyzing temperature, are contributed from the β-SiC nanoparticles embedded in the amorphous matrix of the fibers. The very high mechanical strength of the Si–C–(Ti)–O inorganic fibers originates from the formation of a carbon-rich shell-like interface boundary surrounding the β-SiC nanoparticles which is sharply separated from the amorphous matrix.</div>","PeriodicalId":22050,"journal":{"name":"Supramolecular Science","volume":"5 3","pages":"Pages 223-226"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0968-5677(98)00010-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89158262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Micro- and mesoscopic structure of poly(vinyl alcohol) gels determined by neutron and light scattering 用中子和光散射法测定聚乙烯醇凝胶的微观和介观结构

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00009-1

T. Kanaya, H. Takeshita, Y. Nishikoji, M. Ohkura, K. Nishida, K. Kaji

{"title":"Micro- and mesoscopic structure of poly(vinyl alcohol) gels determined by neutron and light scattering","authors":"T. Kanaya, H. Takeshita, Y. Nishikoji, M. Ohkura, K. Nishida, K. Kaji","doi":"10.1016/S0968-5677(98)00009-1","DOIUrl":"10.1016/S0968-5677(98)00009-1","url":null,"abstract":"<div>We studied the structure of poly(vinyl alcohol) (PVA) gels formed in mixtures of dimethyl sulfoxide (DMSO) and water using several scattering techniques such as wide-angle neutron scattering (WANS), small-angle neutron scattering (SANS), ultra-small-angle neutron scattering (U-SANS) and light scattering (LS) to cover a very wide Q range from 10-4 to 10Å-1. The WANS measurements have revealed that the cross-linking points of the gels are crystallites, and the size and its distribution have been evaluated by the SANS measurements. The SANS results have also shown that the structure observed in the low Q range below 10-2 <!-->Å-1 is dominated by a liquid–liquid-phase separation. The early stage of the phase separation has been studied in detail using the time-resolved LS technique, while the late stage has been investigated by the U-SANS technique because the LS measurements cannot access the opaque samples. On the basis of the results, we present a quantitative sketch of the structure of the PVA gel.</div>","PeriodicalId":22050,"journal":{"name":"Supramolecular Science","volume":"5 3","pages":"Pages 215-221"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0968-5677(98)00009-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86737165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 29

Precise recognition of nucleotides and their derivatives through hydrogen bonding in water by poly(vinyldiaminotriazine) 聚乙烯二氨基三嗪在水中通过氢键精确识别核苷酸及其衍生物

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00040-6

Hiroyuki Asanuma, Takeshi Ban, Sumie Gotoh, Takayuki Hishiya, Makoto Komiyama

引用次数: 26

Sol–gel derived organic–inorganic composites recognizing molecular asymmetry 识别分子不对称的溶胶-凝胶衍生有机-无机复合材料

Supramolecular Science Pub Date : 1998-07-01 DOI: 10.1016/S0968-5677(98)00045-5

Fujio Mizukami , Yoshikatsu Akiyama , Hiroyuki Izutsu

{"title":"Sol–gel derived organic–inorganic composites recognizing molecular asymmetry","authors":"Fujio Mizukami , Yoshikatsu Akiyama , Hiroyuki Izutsu","doi":"10.1016/S0968-5677(98)00045-5","DOIUrl":"10.1016/S0968-5677(98)00045-5","url":null,"abstract":"<div>A new type of optically active organic-inorganic composite was prepared by a sol–gel method in which tetraethoxysilane (TEOS) is hydrolyzed in the presence of an optically active organic compound (d-lactose, d-glucose, d-sorbitol, d-fructose, l-tartaric acid, l-malic acid, or l-mandelic acid). Optical resolution of tris(pentane-2,4-dionato)metal complexes was performed by using the new sol–gel derived composites, composites prepared by conventional techniques (kneading with l-lactose, l-fructose or l-tartaric acid, and impregnation with an l-lactose, l-fructose or l-tartaric acid solution) and the optically active organic compounds themselves. The sol–gel derived composites showed much higher optical resolution abilities than the composites prepared by conventional techniques. In addition, the optically active organic compounds could not resolve the racemate into the enantiomers under similar conditions. X-ray diffraction and NMR results disclosed that an optically active organic compound in the sol–gel derived composite is highly dispersed, most likely, because it bonds to silicon atoms. Thus, it was deduced that optically active molecules dispersed at a molecular level recognize the chirality of the metal chelate compound. The high-resolution ability of the sol–gel derived composites arises from the combined effect of the silica support (adsorbing power) and the highly dispersed molecules (chiral recognition power).</div>","PeriodicalId":22050,"journal":{"name":"Supramolecular Science","volume":"5 3","pages":"Pages 433-437"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0968-5677(98)00045-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79754134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5