{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T16:00:12Z","timestamp":1787500812264,"version":"build-2736575974"},"reference-count":27,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2011,11,29]],"date-time":"2011-11-29T00:00:00Z","timestamp":1322524800000},"content-version":"vor","delay-in-days":28,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Contrast Media & Molecular"],"published-print":{"date-parts":[[2011,11]]},"abstract":"\n The amide proton exchange rates in various lanthanide(III) DOTA\u2013tetraamide complexes were investigated by CEST as a function of variable chemical structures and charges on the amide substituents. Comparisons were made between YbDOTA\u2013(gly)\n 4<\/jats:sub>\n \u2212<\/jats:sup>\n (Yb\u20101), YbDOTA\u2013(NHCH\n 2<\/jats:sub>\n PO\n 3<\/jats:sub>\n )\n 4<\/jats:sub>\n 5\u2212<\/jats:sup>\n (Yb\u20102) and YbDOTA\u2013(NHCH\n 2<\/jats:sub>\n PO\n 3<\/jats:sub>\n Et\n 2<\/jats:sub>\n )\n 4<\/jats:sub>\n 3+<\/jats:sup>\n (Yb\u20103). The general shapes of the CEST vs pH profiles were similar for the three complexes but they showed maximum CEST intensities at different pH values, pH 8.3, 8.8 and 6.9 for Yb\u20101, Yb\u20102 and Yb\u20103, respectively. This indicates that a more negatively charged substituent on the amide helps stabilize the partial positive charge on the amide nitrogen and consequently more base is required to catalyze proton exchange. The chemical shifts of the \u2013NH protons in Yb\u20101 and Yb\u20102 were similar (\u221217\u2009ppm) while the \u2013NH proton in Yb\u20103 was at \u221213\u2009ppm. This shows that the crystal field produced by the amide oxygen donor atoms in Yb\u20103 is substantially weaker than that in the other two complexes. In an effort to expand the useful range of pH values that might be measured using these complexes as CEST agents, the shapes of the CEST vs pH curves were also determined for two thulium(III) complexes with much larger hyperfine shifted \u2013NH proton resonances. The ratio of CEST from \u2013NH exchange in Tm\u20101 compared with CEST from \u2013NH exchange in Tm\u20103 was found to be linear over an extended pH range, from 6.3 to 7.4. This demonstrates a potential advantage of using mixtures of lanthanide(III) DOTA\u2013tetraamides for mapping tissue pH by use of ratiometric CEST imaging. Copyright \u00a9 2011 John Wiley & Sons, Ltd.\n <\/jats:p>","DOI":"10.1002\/cmmi.445","type":"journal-article","created":{"date-parts":[[2011,12,5]],"date-time":"2011-12-05T23:35:54Z","timestamp":1323128154000},"page":"459-464","source":"Crossref","is-referenced-by-count":18,"title":["The\n pH<\/scp>\n sensitivity of \u2013NH exchange in\n LnDOTA<\/scp>\n \u2013tetraamide complexes varies with amide substituent"],"prefix":"10.1002","volume":"6","author":[{"given":"Ana Christina L.","family":"Opina","sequence":"first","affiliation":[{"name":"Department of Chemistry University of Texas at Dallas 800 W. Campbell Road Richardson TX 75083\u20100688 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yunkou","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Texas at Dallas 800 W. Campbell Road Richardson TX 75083\u20100688 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Piyu","family":"Zhao","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Texas at Dallas 800 W. Campbell Road Richardson TX 75083\u20100688 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Garry","family":"Kiefer","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Texas at Dallas 800 W. Campbell Road Richardson TX 75083\u20100688 USA"},{"name":"Macrocyclics 1309 Record Crossing Dallas TX 75235 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. Dean","family":"Sherry","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Texas at Dallas 800 W. Campbell Road Richardson TX 75083\u20100688 USA"},{"name":"Advanced Imaging Research Center UT Southwestern Medical Center 5323 Harry Hines Blvd Dallas TX 75390\u20108568 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2011,11,29]]},"reference":[{"key":"e_1_2_6_2_1","doi-asserted-by":"publisher","DOI":"10.1063\/1.1734121"},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910100113"},{"key":"e_1_2_6_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.pnmrs.2006.01.001"},{"key":"e_1_2_6_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1521-3773(19981016)37:19<2673::AID-ANIE2673>3.0.CO;2-#"},{"key":"e_1_2_6_6_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja005820q"},{"key":"e_1_2_6_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/1521-3773(20021115)41:22<4334::AID-ANIE4334>3.0.CO;2-1"},{"key":"e_1_2_6_8_1","doi-asserted-by":"publisher","DOI":"10.1021\/ar020228m"},{"key":"e_1_2_6_9_1","doi-asserted-by":"publisher","DOI":"10.1039\/b509907m"},{"key":"e_1_2_6_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/1522-2594(200011)44:5<799::AID-MRM18>3.0.CO;2-S"},{"key":"e_1_2_6_11_1","doi-asserted-by":"publisher","DOI":"10.1006\/jmre.1998.1440"},{"key":"e_1_2_6_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.10106"},{"key":"e_1_2_6_13_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.rli.0000116607.26372.d0"},{"key":"e_1_2_6_14_1","doi-asserted-by":"publisher","DOI":"10.1021\/ic0702926"},{"key":"e_1_2_6_15_1","doi-asserted-by":"publisher","DOI":"10.1039\/b211939k"},{"key":"e_1_2_6_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/ejic.200700178"},{"key":"e_1_2_6_17_1","doi-asserted-by":"publisher","DOI":"10.1002\/hlca.200590042"},{"key":"e_1_2_6_18_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910350106"},{"key":"e_1_2_6_19_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.bi.41.070172.004351"},{"key":"e_1_2_6_20_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja00962a007"},{"key":"e_1_2_6_21_1","doi-asserted-by":"publisher","DOI":"10.1158\/0008-5472.CAN-05-4193"},{"key":"e_1_2_6_22_1","doi-asserted-by":"publisher","DOI":"10.1002\/nbm.683"},{"key":"e_1_2_6_23_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910170203"},{"key":"e_1_2_6_24_1","doi-asserted-by":"publisher","DOI":"10.1021\/mp900040u"},{"key":"e_1_2_6_25_1","doi-asserted-by":"publisher","DOI":"10.1002\/cmmi.149"},{"key":"e_1_2_6_26_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja106018n"},{"key":"e_1_2_6_27_1","doi-asserted-by":"publisher","DOI":"10.1002\/chem.200800402"},{"key":"e_1_2_6_28_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.20408"}],"container-title":["Contrast Media & Molecular Imaging"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fcmmi.445","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/cmmi.445","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,9,23]],"date-time":"2023-09-23T10:06:47Z","timestamp":1695463607000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/cmmi.445"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011,11]]},"references-count":27,"journal-issue":{"issue":"6","published-print":{"date-parts":[[2011,11]]}},"alternative-id":["10.1002\/cmmi.445"],"URL":"https:\/\/doi.org\/10.1002\/cmmi.445","archive":["Portico"],"relation":{},"ISSN":["1555-4309","1555-4317"],"issn-type":[{"value":"1555-4309","type":"print"},{"value":"1555-4317","type":"electronic"}],"subject":[],"published":{"date-parts":[[2011,11]]}}}