photochromism of new unsymmetrical isomeric diarylethenes bearing a methoxyl group

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1、ResearchArticleReceived:31August2008,Revised:11January2009,Accepted:30January2009,PublishedonlineinWileyInterScience:23March2009(www.interscience.wiley.com)DOI10.1002/poc.1545Photochromismofnewunsymmetricalisomericdiarylethenesbearingamethoxylgroupa*,WeijunLiuaaShouzh

2、iPuandWenjuanMiaoThreenewunsymmetricalisomericdiaryletheneshavingamethoxylsubstituentatortho-,meta-,andpara-positionoftheterminalbenzenering,namely1-(2,5-dimethyl-3-thienyl)-2-[2-methyl-5-(2-methoxylphenyl)-3-thienyl]perfluorocyclopentene(1o),1-(2,5-dimethyl-3-thienyl)

3、-2-[2-methyl-5-(3-methoxylphenyl)-3-thienyl]perfluorocyclopentene(2o),and1-(2,5-dimethyl-3-thienyl)-2-[2-methyl-5-(4-methoxylphenyl)-3-thienyl]perfluorocyclopentene(3o),havebeensynthesized.Thesubstituentpositioneffectofmethoxylgroupontheirproperties,includingphotochromi

4、smandfluorescencebothinhexanesolutionandinPMMAfilm,andtheirelectrochemicalproperties,wereinvestigatedindetail.ThesediarylethenesshowedgoodphotochromismbothinsolutionandinPMMAfilm.Forthesamephotochromicdiarylethenebackbone,theelectron-donatingmethoxylsubstituentcaneffecti

5、velydepressthecyclizationquantumyieldsandincreasethecycloreversionquantumyieldscomparedtothoseofdiarylethenesbearingchlorineatomsreportedpreviously.Diarylethenes1o–3oshowedclearfluorescentswitchesbyphotoirradiationbothinhexaneandinPMMAfilm.Inaddition,cyclicvoltammetryte

6、stsshowedthattheelectron-donatingmethoxylgroupatdifferentpositionontheterminalbenzeneringhadasignificanteffectontheelectrochemicalpropertiesoftheseisomericdiarylethenes.Copyrightß2009JohnWiley&Sons,Ltd.Keywords:photochromism;diarylethene;methoxylsubstituentpositioneffe

7、ct;propertyIntroductionpheneringswouldincreasethecycloreversionquantum[19]yields.Morimitsuetal.andTakamiandIriereportedthatPhotochromismisdefinedasaphotoinducedreversiblebulkyalkoxysubstituentsat2-and20-positionofthiopheneringsphotocolorationinasinglechemicalspeciesbet

8、weentwoformswouldextraordinarilydecreasethecycloreversionquantumyieldhavingdifferentabsorptionspectra,whichisbroughtaboutbya