{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T05:57:07Z","timestamp":1768975027727,"version":"3.49.0"},"reference-count":62,"publisher":"Wiley","issue":"42","license":[{"start":{"date-parts":[[2011,9,5]],"date-time":"2011-09-05T00:00:00Z","timestamp":1315180800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemistry A European J"],"published-print":{"date-parts":[[2011,10,10]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The production of stable phenoxyl radicals is undoubtedly a synthetic chemical challenge. Yet it is a useful way to gain information on the properties of the biological tyrosyl radicals. Recently, several persistent phenoxyl radicals have been reported, but only limited synthetic variations could be achieved. Herein, we show that the amide\u2013<jats:italic>o<\/jats:italic>\u2010substituted phenoxyl radical (i.e. with a salicylamide backbone) can be synthesised in a stable manner, thereby permitting easy synthetic modifications to be made through the amide bond. To study the effect of H\u2010bonding on the properties of the phenolate\/phenoxyl radical redox couple, simple H\u2010bonded and non\u2010H\u2010bonded <jats:italic>o<\/jats:italic>,<jats:italic>p<\/jats:italic>\u2010<jats:italic>t<\/jats:italic>Bu\u2010protected salicylamidate compounds have been prepared. Their redox properties were examined by cyclic voltammetry and showed a fully reversible one\u2010electron oxidation process to the corresponding phenoxyl radical species. Remarkably, the redox potential appears to be correlated, at least partially, with H\u2010bond strength, as relatively large differences (ca. 300\u2005mV) in the redox potential between H\u2010bonded and non\u2010H\u2010bonded phenolate salts are observed. The corresponding phenoxyl radicals produced electrochemically are persistent at room temperature for at least an hour; their UV\/Vis and EPR characterisation is consistent with that of phenoxyl radicals, which makes them excellent models of biological tyrosyl radicals. The analyses of the experimental data coupled with theoretical calculations indicate that both the deviation from planarity of the amide function and intramolecular H\u2010bonding influence the oxidation potential of the phenolate. The latter H\u2010bonding effect appears to be predominantly exerted on the phenolate and not (or only a little) on the phenoxyl radical. Thus, in these systems the H\u2010bonding energy involved in the phenoxyl radical appears to be relatively small.<\/jats:p>","DOI":"10.1002\/chem.201101509","type":"journal-article","created":{"date-parts":[[2011,9,5]],"date-time":"2011-09-05T10:12:46Z","timestamp":1315217566000},"page":"11882-11892","source":"Crossref","is-referenced-by-count":25,"title":["Persistent Hydrogen\u2010Bonded and Non\u2010Hydrogen\u2010Bonded Phenoxyl Radicals"],"prefix":"10.1002","volume":"17","author":[{"given":"Riccardo","family":"Wanke","sequence":"first","affiliation":[]},{"given":"Laurent","family":"Benisvy","sequence":"additional","affiliation":[]},{"given":"Maxim L.","family":"Kuznetsov","sequence":"additional","affiliation":[]},{"given":"M. F\u00e1tima C.","family":"Guedes\u2005da\u2005Silva","sequence":"additional","affiliation":[]},{"given":"Armando J. L.","family":"Pombeiro","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2011,9,5]]},"reference":[{"key":"e_1_2_6_1_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr9400875"},{"key":"e_1_2_6_2_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi00043a014"},{"key":"e_1_2_6_3_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi00217a037"},{"key":"e_1_2_6_4_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja002453"},{"key":"e_1_2_6_5_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja031583q"},{"key":"e_1_2_6_6_2","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200352368"},{"key":"e_1_2_6_6_3","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200352368"},{"key":"e_1_2_6_7_2","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200501132"},{"key":"e_1_2_6_7_3","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200501132"},{"key":"e_1_2_6_8_2","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200461977"},{"key":"e_1_2_6_8_3","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200461977"},{"key":"e_1_2_6_9_2","doi-asserted-by":"publisher","DOI":"10.1039\/B513221P"},{"key":"e_1_2_6_10_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja060527x"},{"key":"e_1_2_6_11_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja054167"},{"key":"e_1_2_6_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jinorgbio.2007.07.013"},{"key":"e_1_2_6_13_2","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200702486"},{"key":"e_1_2_6_13_3","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200702486"},{"key":"e_1_2_6_14_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0708967105"},{"key":"e_1_2_6_15_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr100085k"},{"key":"e_1_2_6_16_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.tet.2005.02.064"},{"key":"e_1_2_6_17_2","doi-asserted-by":"crossref","first-page":"991","DOI":"10.1002\/ange.200461842","volume":"117","author":"Kanamori D.","year":"2005","journal-title":"Angew. Chem."},{"key":"e_1_2_6_17_3","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200461842"},{"key":"e_1_2_6_18_2","doi-asserted-by":"publisher","DOI":"10.1039\/b419361j"},{"key":"e_1_2_6_19_2","unstructured":"One should note that whilst crystals of [NHOHL][NBu4]\u22c52H2O contain water molecules which establish an H\u2010bonding network (see Figure\u2005SI2 Supporting Information) the bulk organic salt does not contain water as evidenced by the NMR IR and micronalysis characterisations. In [OHNHL][NBu4]\u22c52H2O quasi\u2010planar dimers are formed through mutual intermolecular H\u2010bonding interaction between the alcohol pendant arm O(3)\u2013H(3) of one molecule and phenolate\u2013O(1) from another molecule. The latter dimers [NHOHL]2are connected through H\u2010bonding with tetramer water clusters (Figure\u2005SI2a) thereby giving rise to a hydrophilic H\u2010bonding chain sandwiched by a hydrocarbon shell generated by thetert\u2010butyl groups. The arrangement of cations and anions in these organic salts is different (Figure\u2005SI2b). In [NHOHL][NBu4]\u22c52H2O the hydrophobic NBu4cations are sandwiched between hydrophilic chains generated from theNHOHL anions and the water molecules (Figure\u2005SI2b). TheNHOHL anions in [NHOHL][NBu4] can be envisaged as trapped in nutshells of hydrophobic NBu4cations (Figure\u2005SI3)."},{"key":"e_1_2_6_20_2","volume-title":"An Introduction to Hydrogen Bonding","author":"Jeffrey G. 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