{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,26]],"date-time":"2025-10-26T20:51:39Z","timestamp":1761511899540},"reference-count":21,"publisher":"Wiley","issue":"13-14","license":[{"start":{"date-parts":[[2003,12,22]],"date-time":"2003-12-22T00:00:00Z","timestamp":1072051200000},"content-version":"vor","delay-in-days":3066,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Angew. Chem. Int. Ed. Engl."],"published-print":{"date-parts":[[1995,7,31]]},"abstract":"<jats:p><jats:bold>Despite the absence of water channels<\/jats:bold>, H\/D and H<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/tex2gif-stack-1.gif\" xlink:title=\"urn:x-wiley:05700833:media:ANIE199514521:tex2gif-stack-1\" \/>O\/H<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/tex2gif-stack-2.gif\" xlink:title=\"urn:x-wiley:05700833:media:ANIE199514521:tex2gif-stack-2\" \/>O exchange experiments show that water molecules diffuse rapidly through the crystal lattice of \u03b2\u2010cyclodextrin \u00b7 12H<jats:sub>2<\/jats:sub>O (CD). Exchange takes place in minutes and follows first\u2010order kinetics. This is explained by the structural fluctuations of the \u03b2\u2010CD molecules, which became apparent in crystallographic studies and in computer simulations.<\/jats:p>","DOI":"10.1002\/anie.199514521","type":"journal-article","created":{"date-parts":[[2004,1,16]],"date-time":"2004-01-16T14:13:06Z","timestamp":1074262386000},"page":"1452-1453","source":"Crossref","is-referenced-by-count":35,"title":["Rapid Water Diffusion in a Cage\u2010Type Crystal Lattice: \u03b2\u2010Cyclodextrin Dodecahydrate"],"prefix":"10.1002","volume":"34","author":[{"given":"Thomas","family":"Steiner","sequence":"first","affiliation":[]},{"given":"Aida M. Moreira","family":"da Silva","sequence":"additional","affiliation":[]},{"given":"Jos\u00e9 J. C.","family":"Teixeira\u2010Dias","sequence":"additional","affiliation":[]},{"given":"J\u00f6rn","family":"M\u00fcller","sequence":"additional","affiliation":[]},{"given":"Wolfram","family":"Saenger","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2003,12,22]]},"reference":[{"key":"e_1_2_1_1_2","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-642-85135-3"},{"key":"e_1_2_1_2_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00336a039"},{"key":"e_1_2_1_3_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00091a014"},{"key":"e_1_2_1_4_2","doi-asserted-by":"publisher","DOI":"10.1007\/BF00577069"},{"key":"e_1_2_1_4_3","doi-asserted-by":"publisher","DOI":"10.1007\/BF00261901"},{"key":"e_1_2_1_5_2","doi-asserted-by":"publisher","DOI":"10.1080\/00268979100100881"},{"key":"e_1_2_1_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/0022-2836(89)90157-5"},{"key":"e_1_2_1_6_3","doi-asserted-by":"publisher","DOI":"10.1021\/ja00031a001"},{"key":"e_1_2_1_7_2","unstructured":"\u03b2\u2010CD is a macrocyclic oligosaccharide consisting of seven \u03b1(1\u20134) linkedD\u2010glucopyranose units. From aqueous solution it crystallizes as a dodecahydrate \u03b2\u2010CD \u00b7 12H2O space group monoclinicP21. X\u2010ray [3] and neutron [2] crystal structures show thatalltwelve H2O are disordered to some degree. About seven H2O are distributed over eleven partially occupied sites in the \u03b2\u2010CD cavity; the other five H2O molecules are distributed over eight sites in interstices. The \u03b2\u2010CD molecules are packed in a herringbone arrangement so that the H2O molecules in neighboring crystal asymmetric units are sterically isolated from each other [3]. The \u03b2\u2010CD molecule carries 21 O\uf8ffH groups of which only five have an ordered H position. The other 16 exhibit dynamic orientational disorder (\u201cflip\u2010flop\u201d disorder [2]). Of these 16 disordered O\uf8ffH groups four are hydrogen\u2010bonded only to other O\uf8ffH groups and are consequently not directly accessible to water molecules."},{"key":"e_1_2_1_8_2","doi-asserted-by":"publisher","DOI":"10.1248\/cpb.34.2178"},{"key":"e_1_2_1_9_2","unstructured":"For a \u03b2\u2010CD \u00b7 12 H2O crystal of 0.4 \u00d7 0.3 \u00d7 0.2 mm3 dehydration was observed to follow e\u2212ktwithk= 0.33 min\u22121 and was completed after \u224815 min [3]. This can serve to estimate an isotropic diffusion constant (which is only a very rough estimate because crystals are anisotropic): in isotropic diffusion the mean square distance of random walks in a time periodtis <r2> = 6Dt. Assuming that in the above experiment most water molecules must have walked distances \u22480.1 mm withint< 10 min a diffusion constantD\u2248 3 \u00d7 10\u22128cm2s\u22121is required (Din pure water: 2.2 \u00d7 10\u22125cm2s\u22121[19])."},{"key":"e_1_2_1_10_2","unstructured":"Samples for Raman spectroscopy: (a) commercially available \u03b2\u2010CD (Wacker\u2010Chemie M\u00fcnchen) hydrated by contact with the atmosphere. b) Ground crystals of \u03b2\u2010CD \u00b7 12 H2O grown from solutions in H2O."},{"key":"e_1_2_1_11_2","unstructured":"Jobin\u2010Yvon T64000 Raman spectrometer (with software for determining band intensities). Coherent\u2010Innova 300\u201305 Ar+laser \u03bb = 514.5 nm 100 mW at the sample position standard errors of measured wavenumbers \u22481 cm\u22121. Samples sealed in capillary tubes with 0.8 mm inner diameter."},{"key":"e_1_2_1_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/0924-2031(90)80041-2"},{"key":"e_1_2_1_13_2","unstructured":"In Figure 2 thevOHband fort= 0 min exposure corresponds to \u224845 H(O) atoms per \u2248\u2010CD (21 C \uf8ff OH 12 H2O). As estimated from the integrated intensities thevOHband at 120 min represents 9.0 \u00b1 1.0 H(O) atoms per \u03b2\u2010CD ( = 80% exchange) and the flat spectrum (around 3400 cm\u22121) for 930 min is compatible with less than 1.0 H(O) atom per \u03b2\u2010CD."},{"key":"e_1_2_1_14_2","unstructured":"H218O from Isotec Inc. Miamisburg (Ohio) labeled as 97 atom %."},{"key":"e_1_2_1_15_2","unstructured":"Varian MAT311A mass spectrometer modified by AMD Intectra Kratos DS90 data system EI (70 eV) ion accelerating voltage 5 kV direct inlet probe sample heating rate \u22485\u00b0 min\u22121. Sample transfer into the spectrometer requires 1\u20132 minutes in which slight back\u2010exchange with atmospheric H216O cannot be avoided. Background intensity from contamination with atmospheric water in the sample crucible and in the spectrometer also cannot be completely avoided."},{"key":"e_1_2_1_16_2","unstructured":"The sample with longest exposure to H218O eight days still contained 10% H216O (i.e. only 90% H218O). For the water reservoir producing the vapor a content of \u22488% H216O was measured. As the16O\/18O ratios in the water reservoir and in the sample were barely different the exchange in the sample is actually better than 90%."},{"key":"e_1_2_1_17_2","unstructured":"This means that a given water molecule on the average performs many diffusion jumps between two H\u2010(or D)\u2010transfer processes. The distance walked between two such processes is therefore large compared to the jump distance. However this distance need not be \u201cmacroscopic\u201d: it is assumed that during its journey from the surface to the interior of the crystal a water molecule experiences many H\u2010(or D)\u2010transfer processes."},{"key":"e_1_2_1_18_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00818a042"},{"key":"e_1_2_1_19_2","volume-title":"The Structure and Properties of Water","author":"Eisenberg D.","year":"1969"}],"container-title":["Angewandte Chemie International Edition in English"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fanie.199514521","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/anie.199514521","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,8,30]],"date-time":"2023-08-30T07:38:12Z","timestamp":1693381092000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/anie.199514521"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1995,7,31]]},"references-count":21,"journal-issue":{"issue":"13-14","published-print":{"date-parts":[[1995,7,31]]}},"alternative-id":["10.1002\/anie.199514521"],"URL":"https:\/\/doi.org\/10.1002\/anie.199514521","archive":["Portico"],"relation":{},"ISSN":["0570-0833"],"issn-type":[{"value":"0570-0833","type":"print"}],"subject":[],"published":{"date-parts":[[1995,7,31]]}}}