{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T11:27:54Z","timestamp":1789558074116,"version":"build-2803163510"},"reference-count":45,"publisher":"American Chemical Society (ACS)","issue":"3","license":[{"start":{"date-parts":[[2017,6,19]],"date-time":"2017-06-19T00:00:00Z","timestamp":1497830400000},"content-version":"vor","delay-in-days":172,"URL":"https:\/\/pubs.acs.org\/page\/policy\/authorchoice_termsofuse.html"}],"funder":[{"DOI":"10.13039\/100000057","name":"U.S. Department of Health and Human Services","doi-asserted-by":"publisher","award":["U54GM087519-06"],"award-info":[{"award-number":["U54GM087519-06"]}],"id":[{"id":"10.13039\/100000057","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000070","name":"U.S. Department of Health and Human Services","doi-asserted-by":"publisher","award":["R01EB019950-02"],"award-info":[{"award-number":["R01EB019950-02"]}],"id":[{"id":"10.13039\/100000070","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000165","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CHE-1346572"],"award-info":[{"award-number":["CHE-1346572"]}],"id":[{"id":"10.13039\/100000165","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000165","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CHE-1362454"],"award-info":[{"award-number":["CHE-1362454"]}],"id":[{"id":"10.13039\/100000165","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100006151","name":"U.S. Department of Energy","doi-asserted-by":"publisher","award":["DE-AC02-06CH11357"],"award-info":[{"award-number":["DE-AC02-06CH11357"]}],"id":[{"id":"10.13039\/100006151","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2017,2,3]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>We report the design, synthesis, and electron spin relaxation properties of hydrophilic tetracarboxylate ester pyrroline nitroxides 1 and 2, which serve as models in the search for new spin labels for DEER distance measurement at room temperature. The nitroxides are designed to have the methyl groups further away from the N\u2013O spin site to decrease the inequivalent couplings of the unpaired electron to the methyl protons that shorten Tm at T &amp;gt; 70 K in currently used labels. The key step in the synthesis of 1 and 2 is the reaction of the dianion of pyrrole-1,2,5-tricarboxylic acid tert-butyl ester dimethyl ester with electrophiles such as methyl chloroformate and methyl bromoacetate. Structures of 1 and 2 are confirmed by X-ray crystallography. Studies of electron spin relaxation rates in rigid trehalose\/sucrose matrices reveal approximately temperature independent values of 1\/Tm for 1 and 2 up to about 160 K and modest temperature dependence up to 295 K, demonstrating that increasing the distance between the nitroxide moiety and methyl groups is effective in lengthening Tm at T &amp;gt; 70 K.<\/jats:p>","DOI":"10.1021\/acs.joc.6b02737","type":"journal-article","created":{"date-parts":[[2016,12,29]],"date-time":"2016-12-29T11:24:19Z","timestamp":1483010659000},"page":"1538-1544","source":"Crossref","is-referenced-by-count":24,"title":["Synthesis and Electron\nSpin Relaxation of Tetracarboxylate\nPyrroline Nitroxides"],"prefix":"10.1021","volume":"82","author":[{"given":"Shengdian","family":"Huang","sequence":"first","affiliation":[{"name":"University of Nebraska , , , ,","place":["Lincoln, Nebraska, United States, 68588-0304"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph T.","family":"Paletta","sequence":"additional","affiliation":[{"name":"University of Nebraska , , , ,","place":["Lincoln, Nebraska, United States, 68588-0304"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hanan","family":"Elajaili","sequence":"additional","affiliation":[{"name":"University of Denver , , , ,","place":["Denver, Colorado, United States, 80208-2436"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kirby","family":"Huber","sequence":"additional","affiliation":[{"name":"University of Denver , , , ,","place":["Denver, Colorado, United States, 80208-2436"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maren","family":"Pink","sequence":"additional","affiliation":[{"name":"Indiana University , , , ,","place":["Bloomington, Indiana, United States, 47405-7102"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Suchada","family":"Rajca","sequence":"additional","affiliation":[{"name":"University of Nebraska , , , ,","place":["Lincoln, Nebraska, United States, 68588-0304"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gareth R.","family":"Eaton","sequence":"additional","affiliation":[{"name":"University of Denver , , , ,","place":["Denver, Colorado, United States, 80208-2436"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandra S.","family":"Eaton","sequence":"additional","affiliation":[{"name":"University of Denver , , , ,","place":["Denver, Colorado, United States, 80208-2436"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8856-1536","authenticated-orcid":true,"given":"Andrzej","family":"Rajca","sequence":"additional","affiliation":[{"name":"University of Nebraska , , , ,","place":["Lincoln, Nebraska, United States, 68588-0304"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2016,12,29]]},"reference":[{"key":"2026090218425291700_cit1","doi-asserted-by":"publisher","first-page":"5034","DOI":"10.1002\/anie.201002547","volume":"50","author":"Tebben","year":"2011","journal-title":"Angew. 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