{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T16:35:50Z","timestamp":1790267750366,"version":"4.1.0"},"reference-count":71,"publisher":"Wiley","issue":"66","license":[{"start":{"date-parts":[[2019,11,4]],"date-time":"2019-11-04T00:00:00Z","timestamp":1572825600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["chemistry-europe.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Chemistry A European J"],"published-print":{"date-parts":[[2019,11,27]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>This work aimed to render phenomenologically autonomous the otherwise stepwise operation of a catenane\u2010based molecular switch, which is chemically triggered by the decarboxylation of 2\u2010cyano\u20102\u2010phenylpropanoic acid (<jats:bold>2<\/jats:bold>). Given that any amount of <jats:bold>2<\/jats:bold> in stoichiometric excess with respect to the catenane is consumed in a side reaction, the authors resorted to the corresponding anhydride <jats:bold>5<\/jats:bold>, the slow hydrolysis of which, due to adventitious water in dichloromethane, continuously produces in situ the actual fuel <jats:bold>2<\/jats:bold>. As a consequence, the machine does not require a reloading after each cycle, but switches back and forth as long as fuel is present.<\/jats:p>","DOI":"10.1002\/chem.201904048","type":"journal-article","created":{"date-parts":[[2019,10,1]],"date-time":"2019-10-01T05:53:35Z","timestamp":1569909215000},"page":"15205-15211","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":32,"title":["The Hydrolysis of the Anhydride of 2\u2010Cyano\u20102\u2010phenylpropanoic Acid Triggers the Repeated Back and Forth Motions of an Acid\u2013Base Operated Molecular Switch"],"prefix":"10.1002","volume":"25","author":[{"given":"Chiara","family":"Biagini","sequence":"first","affiliation":[{"name":"Dipartimento di Chimica Universit\u00e0 di Roma \u201cLa Sapienza\u201d and Istituto, CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione  P.le A. Moro 5 00185 Roma Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giorgio","family":"Capocasa","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica Universit\u00e0 di Roma \u201cLa Sapienza\u201d and Istituto, CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione  P.le A. Moro 5 00185 Roma Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valerio","family":"Cataldi","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica Universit\u00e0 di Roma \u201cLa Sapienza\u201d and Istituto, CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione  P.le A. Moro 5 00185 Roma Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniele","family":"Del Giudice","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica Universit\u00e0 di Roma \u201cLa Sapienza\u201d and Istituto, CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione  P.le A. Moro 5 00185 Roma Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luigi","family":"Mandolini","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica Universit\u00e0 di Roma \u201cLa Sapienza\u201d and Istituto, CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione  P.le A. Moro 5 00185 Roma Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6742-0988","authenticated-orcid":false,"given":"Stefano","family":"Di Stefano","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica Universit\u00e0 di Roma \u201cLa Sapienza\u201d and Istituto, CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione  P.le A. Moro 5 00185 Roma Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2019,11,4]]},"reference":[{"key":"e_1_2_7_1_1","unstructured":"\u00a0"},{"key":"e_1_2_7_2_2","doi-asserted-by":"publisher","DOI":"10.1039\/C5CS00874C"},{"key":"e_1_2_7_3_2","doi-asserted-by":"publisher","DOI":"10.1039\/C7CS00245A"},{"key":"e_1_2_7_4_2","doi-asserted-by":"publisher","DOI":"10.1002\/open.201700181"},{"key":"e_1_2_7_5_1","unstructured":"\u00a0"},{"key":"e_1_2_7_6_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201702992"},{"key":"e_1_2_7_6_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201702992"},{"key":"e_1_2_7_7_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201703216"},{"key":"e_1_2_7_7_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201703216"},{"key":"e_1_2_7_8_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.chemrev.5b00146"},{"key":"e_1_2_7_9_1","unstructured":"\u00a0"},{"key":"e_1_2_7_10_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1057886"},{"key":"e_1_2_7_11_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja015919c"},{"key":"e_1_2_7_12_2","doi-asserted-by":"publisher","DOI":"10.1002\/chem.200400243"},{"key":"e_1_2_7_13_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0509011103"},{"key":"e_1_2_7_14_1","unstructured":"\u00a0"},{"key":"e_1_2_7_15_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201602594"},{"key":"e_1_2_7_15_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201602594"},{"key":"e_1_2_7_16_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.aao1377"},{"key":"e_1_2_7_17_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.7b03996"},{"key":"e_1_2_7_18_1","unstructured":"\u00a0"},{"key":"e_1_2_7_19_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature18013"},{"key":"e_1_2_7_20_2","doi-asserted-by":"publisher","DOI":"10.1039\/C8SC05469J"},{"key":"e_1_2_7_21_1","doi-asserted-by":"publisher","DOI":"10.1002\/poc.591"},{"key":"e_1_2_7_22_1","doi-asserted-by":"publisher","DOI":"10.1021\/ol303495n"},{"key":"e_1_2_7_23_1","unstructured":"\u00a0"},{"key":"e_1_2_7_24_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200453779"},{"key":"e_1_2_7_24_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200453779"},{"key":"e_1_2_7_25_2","first-page":"118102","volume":"90","author":"Turberfield A. J.","year":"2003","journal-title":"J. Phys. Chem. Lett."},{"key":"e_1_2_7_26_2","doi-asserted-by":"publisher","DOI":"10.1021\/nl049784v"},{"key":"e_1_2_7_27_1","unstructured":"\u00a0"},{"key":"e_1_2_7_28_2","doi-asserted-by":"publisher","DOI":"10.1021\/nl049527q"},{"key":"e_1_2_7_29_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200460522"},{"key":"e_1_2_7_29_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200460522"},{"key":"e_1_2_7_30_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200501262"},{"key":"e_1_2_7_30_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200501262"},{"key":"e_1_2_7_31_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.200500703"},{"key":"e_1_2_7_31_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.200500703"},{"key":"e_1_2_7_32_1","unstructured":"Chemical fuels have been also used to drive chiral information see:"},{"key":"e_1_2_7_33_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja302711z"},{"key":"e_1_2_7_34_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.9b00941"},{"key":"e_1_2_7_35_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201403480"},{"key":"e_1_2_7_35_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201403480"},{"key":"e_1_2_7_36_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.copbio.2016.10.014"},{"key":"e_1_2_7_37_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201905250"},{"key":"e_1_2_7_37_3","first-page":"9881","volume":"131","year":"2019","journal-title":"Angew. Chem."},{"key":"e_1_2_7_38_1","unstructured":"\u00a0"},{"key":"e_1_2_7_39_2","doi-asserted-by":"publisher","DOI":"10.1039\/C7SC04123C"},{"key":"e_1_2_7_40_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.joc.9b01164"},{"key":"e_1_2_7_41_1","unstructured":"Throughout the manuscript the term \u201cfuel\u201d is used as a synonymous of \u201cstimulus\u201d although machine2is definitely a switch and not a motor (see Ref.\u2005[3]). However we feel that \u201cfuel\u201d and \u201cstimulus\u201d are appropriately interchangeable considering that the fuel system is the main object of the present article and acids undergoing decarboxylation at convenient rates have been demonstrated to be able to trigger the motions of both molecular switches (see Ref.\u2005[5a] [5c] [12a] and [12b]) and motors (see Ref.\u2005[5b])."},{"key":"e_1_2_7_42_1","doi-asserted-by":"publisher","DOI":"10.1002\/chem.201800474"},{"key":"e_1_2_7_43_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0022-2275(20)39603-6"},{"key":"e_1_2_7_44_1","doi-asserted-by":"publisher","DOI":"10.1055\/s-2007-990812"},{"key":"e_1_2_7_45_1","doi-asserted-by":"publisher","DOI":"10.1080\/713744563"},{"key":"e_1_2_7_46_1","unstructured":"Estimate of water content was based on a comparison between the intensity of the more or less sharp singlet of free water at 1.55\u2005ppm and the intensity of the signals of other species of known concentration. In the case of reaction mixtures the comparison was based on the first spectrum recorded after addition of anhydride\u20055."},{"key":"e_1_2_7_47_1","unstructured":"Consumption of 2.0\u2005mmanhydride\u20055in the presence of 2.0\u2005mmcatenane1(t1\/2=8\u2005h) turned out to be faster than the background reaction (t1\/2=29\u2005h compare Figure\u2005S1 in the Supporting Information with Figure\u20051). A similar result was obtained in the presence of 4.0\u2005mmneocuproine (t1\/2=3\u2005h) suggesting that the phenanthroline moiety acts as a general base or nucleophilic catalyst."},{"key":"e_1_2_7_48_1","unstructured":"The1H\u2005NMR spectrum ofB\u201cdiffers markedly from that ofB\u2032(see Ref.\u2005[12]) in which there is no trace of the upfield shifted signals of the phenanthroline hydrogens of1H+. WhereasB\u2032is an ion pair in strict sense in that the two partners are held together only by electrostatic attraction an important additional contribution to the driving force for association of the partners inB\u201dwas suggested (see Ref.\u2005[5a]) to come from an electron-donor\u2013acceptor (EDA) interaction between the electron-rich benzyl carbanion and the electron-poor phenanthroline core of1H+. As a consequence the protons of one phenanthroline unit are exposed to the shielding effect of the ring current of the aromatic counterion."},{"key":"e_1_2_7_49_1","unstructured":"Slow solvent evaporation from the cell became appreciable after a few hours. This prevented reliable measurements to be carried out at prolonged reaction times. The slow evaporation of the volatile dichloromethane solvent clearly shows that the small Teflon stopper of our 1.0\u2005mm spectrophotometric cell is not a perfect seal. Considering that we found no appreciable water absorption by a dichloromethane sample in a NMR tube after 24\u2005h and the timescale of the spectrophotometric experiment (Figure\u20052) compares well with the timescale of the1H\u2005NMR experiment carried out at the same initial concentrations (Figure\u20051) we argue that the amount of atmospheric water possibly taken in by the reaction mixture in the UV\/Vis cell does not affect the reaction rate to a significant extent."},{"key":"e_1_2_7_50_1","unstructured":"\u00a0"},{"key":"e_1_2_7_51_2","volume-title":"Fundamentals of Carbanion Chemistry","author":"Cram D. J.","year":"1965"},{"key":"e_1_2_7_52_2","volume-title":"Physical Organic Chemistry","author":"Hammett L. P.","year":"1970"},{"key":"e_1_2_7_53_2","volume-title":"The Ionization of Carbon Acids","author":"Jones J. R.","year":"1973"},{"key":"e_1_2_7_54_2","volume-title":"The Mechanisms of Fast Reactions in Solution","author":"Caldin E. F.","year":"2001"},{"key":"e_1_2_7_55_1","unstructured":"As a classical example the rate constant of the reaction between H3O+and (CH3CHNO2)\u2212is as low as 16\u2009m\u22121\u2009s\u22121 whereas the corresponding reaction of borate anion a species with very similar basicity is diffusion-controlled (see Ref.\u2005[22b] p.\u2005324)."},{"key":"e_1_2_7_56_1","unstructured":"An additional run was carried out in the presence of 2.0\u2005mm1and 12.0\u2005mm5. After a first phase in which the behavior of the system was superimposable to that of the experiment carried out with 8\u2005mm5 a number of intense1H\u2005NMR signals appeared in the spectrum related to unidentified species probably due to the insurgence of undesired side reactions."},{"key":"e_1_2_7_57_1","unstructured":"In the case of [5]o=2.0\u2005mm [B\u201c]max=0.5\u00d7[1]o=1.0\u2005mm v1=4.8\u00d710\u22127\u2009m\u2009s\u22121; in the case of [5]o=4.0\u2005mm [B\u201d]max=0.7\u00d7[1]o=1.4\u2005mm v1=6.7\u00d710\u22127\u2009m\u2009s\u22121; eventually in the case of [5]o=8.0\u2005mm [B\u201c]max=0.9\u00d7[1]o=1.8\u2005mm v1=8.6\u00d710\u22127\u2009m\u2009s\u22121."},{"key":"e_1_2_7_58_1","unstructured":"The solubility of water in dichloromethane is about 0.13\u2009m(0.17\u2009% w\/w; see IUPAC-NIST Solubility Database NIST Standard Reference Database\u2005106) which means that the amount of water in this experiment roughly exceeds that in the previous experiments by an order of magnitude."},{"key":"e_1_2_7_59_1","unstructured":"It can be speculated that if catenane1was exposed to the action of a substoichiometric amount of any stable acid then the same motions triggered by acid1would also occur due to spontaneous proton exchange between catenane molecules. As a matter of fact the latter exchange reaction if any is not under the control of the experimenter: in principle it would go on for an infinite time while due to the presence of anhydride5 the back and forth motions of switch1are triggered and continue as long as the former is present. Furthermore the proton exchange between catenane1molecules which is slow on1H\u2005NMR time scale (see Figure\u2005S7 Supporting Information) when trifluoroacetic acid is used as substoichiometric protonating agent is expected to be much slower when the counterion is the carbanion inB\u201cthat strongly interacts with the phenanthroline core of1H+(see Ref.\u2005[20])."},{"key":"e_1_2_7_60_1","unstructured":"\u00a0"},{"key":"e_1_2_7_61_2","doi-asserted-by":"publisher","DOI":"10.1039\/C4OB01009D"},{"key":"e_1_2_7_62_2","doi-asserted-by":"publisher","DOI":"10.1021\/ma502392v"}],"container-title":["Chemistry \u2013 A European Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/chem.201904048","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/chem.201904048","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/chem.201904048","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T13:27:36Z","timestamp":1760275656000},"score":1,"resource":{"primary":{"URL":"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/10.1002\/chem.201904048"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,11,4]]},"references-count":71,"journal-issue":{"issue":"66","published-print":{"date-parts":[[2019,11,27]]}},"alternative-id":["10.1002\/chem.201904048"],"URL":"https:\/\/doi.org\/10.1002\/chem.201904048","archive":["Portico"],"relation":{},"ISSN":["0947-6539","1521-3765"],"issn-type":[{"value":"0947-6539","type":"print"},{"value":"1521-3765","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,11,4]]},"assertion":[{"value":"2019-09-03","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2019-11-04","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}