{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,26]],"date-time":"2025-10-26T14:12:21Z","timestamp":1761487941953,"version":"build-2065373602"},"reference-count":34,"publisher":"Wiley","issue":"18","license":[{"start":{"date-parts":[[2007,11,12]],"date-time":"2007-11-12T00:00:00Z","timestamp":1194825600000},"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":["ChemPhysChem"],"published-print":{"date-parts":[[2007,12,21]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Two <jats:italic>p<\/jats:italic>\u2010phenylenevinylene (PV) trimers, containing 3\u2032\u2010methylbutyloxyl (in MBOPV3) and 2\u2032\u2010ethylhexyloxyl (in EHOPV3) side chains, are used as model compounds of PV\u2010based conjugated polymers (PPV) with the purpose of clarifying the origin of fast (picosecond time) components observed in the fluorescence decays of poly[2\u2010methoxy\u20105\u2010(2\u2032\u2010ethylhexyloxy)\u2010<jats:italic>p<\/jats:italic>\u2010phenylenevinylene] (MEH\u2010PPV). The fluorescence decays of MBOPV3 and EHOPV3 reveal the presence of similar fast components, which are assigned to excited\u2010state conformational relaxation of the initial population of non\u2010planar trimer conformers to lower\u2010energy, more planar conformers. The rate constant of conformational relaxation <jats:italic>k<\/jats:italic><jats:sub>CR<\/jats:sub> is dependent on solvent viscosity and temperature, according to the empirical relationship <jats:italic>k<\/jats:italic><jats:sub>CR<\/jats:sub>=<jats:italic>a\u03b7<\/jats:italic><jats:sub>o<\/jats:sub><jats:sup>\u2212\u03b1<\/jats:sup><jats:italic>\u22c5<\/jats:italic>exp(\u2212<jats:italic>\u03b1E<\/jats:italic><jats:sub>\u03b7<\/jats:sub>\/<jats:italic>RT<\/jats:italic>), where <jats:italic>a\u03b7<\/jats:italic><jats:sub>o<\/jats:sub><jats:sup>\u2212\u03b1<\/jats:sup> is the frequency factor, <jats:italic>\u03b7<\/jats:italic><jats:sub>o<\/jats:sub> is the pre\u2010exponential coefficient of viscosity, <jats:italic>E<\/jats:italic><jats:sub>\u03b7<\/jats:sub> is the activation energy of viscous flow. The empirical parameter <jats:italic>\u03b1<\/jats:italic>, relating the solvent microscopic friction involved in the conformational change to the macroscopic solvent friction (<jats:italic>\u03b1<\/jats:italic>=1), depends on the side chain. The fast component in the fluorescence decays of MEH\u2010PPV polymers (PPVs), is assigned to resonance energy transfer from short to longer polymer segments. The present results call for revising this assignment\/interpretation to account for the occurrence of conformational relaxation, concurrently with energy transfer, in PPVs.<\/jats:p>","DOI":"10.1002\/cphc.200700548","type":"journal-article","created":{"date-parts":[[2007,11,12]],"date-time":"2007-11-12T07:49:33Z","timestamp":1194853773000},"page":"2657-2664","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":61,"title":["Conformational Relaxation of <i>p<\/i>\u2010Phenylenevinylene Trimers in Solution Studied by Picosecond Time\u2010Resolved Fluorescence"],"prefix":"10.1002","volume":"8","author":[{"given":"Roberto E.","family":"Di Paolo","sequence":"first","affiliation":[]},{"given":"Jo\u00e3o","family":"Seixas de Melo","sequence":"additional","affiliation":[]},{"given":"Jo\u00e3o","family":"Pina","sequence":"additional","affiliation":[]},{"given":"Hugh D.","family":"Burrows","sequence":"additional","affiliation":[]},{"given":"Jorge","family":"Morgado","sequence":"additional","affiliation":[]},{"given":"Ant\u00f3nio L.","family":"Ma\u00e7anita","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2007,12,13]]},"reference":[{"key":"e_1_2_7_1_2","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevB.54.R8301"},{"key":"e_1_2_7_2_2","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevB.58.10218"},{"key":"e_1_2_7_3_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.chemphys.2006.09.016"},{"key":"e_1_2_7_4_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.1560939"},{"key":"e_1_2_7_5_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja0159012"},{"key":"e_1_2_7_6_2","doi-asserted-by":"publisher","DOI":"10.1021\/jp0643653"},{"key":"e_1_2_7_7_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr040084k"},{"key":"e_1_2_7_8_2","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevB.74.045210"},{"key":"e_1_2_7_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.cplett.2004.02.093"},{"key":"e_1_2_7_10_2","doi-asserted-by":"publisher","DOI":"10.1021\/ma001354d"},{"key":"e_1_2_7_11_2","doi-asserted-by":"publisher","DOI":"10.1002\/macp.1970.021310103"},{"key":"e_1_2_7_12_2","unstructured":"\u00a0"},{"key":"e_1_2_7_13_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.478288"},{"key":"e_1_2_7_14_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0009-2614(99)01356-1"},{"key":"e_1_2_7_15_2","doi-asserted-by":"publisher","DOI":"10.1038\/35016520"},{"key":"e_1_2_7_16_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1010-6030(01)00630-X"},{"key":"e_1_2_7_17_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.1469612"},{"key":"e_1_2_7_18_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.1562190"},{"key":"e_1_2_7_19_2","doi-asserted-by":"publisher","DOI":"10.1002\/cphc.200300996"},{"key":"e_1_2_7_20_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.1469612"},{"key":"e_1_2_7_21_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0379-6779(96)04484-0"},{"key":"e_1_2_7_22_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.452460"},{"key":"e_1_2_7_23_2","doi-asserted-by":"publisher","DOI":"10.1002\/cphc.200400575"},{"key":"e_1_2_7_24_2","doi-asserted-by":"publisher","DOI":"10.1021\/j100048a004"},{"key":"e_1_2_7_25_2","doi-asserted-by":"publisher","DOI":"10.1021\/jp953110e"},{"key":"e_1_2_7_26_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.443393"},{"key":"e_1_2_7_27_2","unstructured":"A. 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