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The distribution of the various forms at the pH\u2010dependent thermodynamic equilibrium and the rates of several interconversion processes were measured. The most interesting feature of this multistate\/multifunctional system is related to the possibility of pH\u2010tuning the colour change caused by photoirradiation, because the\n                    <jats:italic>cis<\/jats:italic>\n                    \u2010chalcone isomer, obtained from the photoisomerization of the\n                    <jats:italic>trans<\/jats:italic>\n                    \u2010chalcone form, is spontaneously transformed into coloured species (flavylium cation and quinoidal base) at low values of pH, but reverts back to the uncoloured\n                    <jats:italic>trans<\/jats:italic>\n                    \u2010chalcone at high values of pH because of the low energy barrier between the\n                    <jats:italic>cis<\/jats:italic>\n                    and\n                    <jats:italic>trans<\/jats:italic>\n                    chalcone isomers. (\u00a9 Wiley\u2010VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)\n                  <\/jats:p>","DOI":"10.1002\/ejoc.200300508","type":"journal-article","created":{"date-parts":[[2004,1,9]],"date-time":"2004-01-09T04:00:30Z","timestamp":1073620830000},"page":"304-312","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Tuning the Photochromic Properties of a Flavylium Compound by pH"],"prefix":"10.1002","volume":"2004","author":[{"given":"Margarida\u00a0C.","family":"Moncada","sequence":"first","affiliation":[]},{"given":"Fernando","family":"Pina","sequence":"additional","affiliation":[]},{"given":"Ana","family":"Roque","sequence":"additional","affiliation":[]},{"given":"A.\u00a0Jorge","family":"Parola","sequence":"additional","affiliation":[]},{"given":"Mauro","family":"Maestri","sequence":"additional","affiliation":[]},{"given":"Vincenzo","family":"Balzani","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2004,1,9]]},"reference":[{"key":"e_1_2_5_1_2","unstructured":"D. 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