Layered molecular optoelectronic assemblies

Layered functionalized electrodes are used as optoelectronic assemblies for the electronic transduction of recorded photonic signals. Functionalizatio n of a Au electrode with a photoisomerizable redox-activated monolayer enab les the amperometric transduction of the photonic information recorded by t he interface. This is exemplified with the organization of a phenoxynaphtha cene quinone monolayer (1a). Organization of a photoactivated command layer on an electrode can be used to control interfacial electron transfer and m ight be applied for the electrical transduction of recorded optical signals . This is addressed with the assembly of a nitrospiropyran photoisomerizabl e monolayer (2a) on a Au electrode which acts as a command surface for cont rolling by light interfacial electron transfer. The monolayer undergoes pho toisomerization between the neutral state (2a) and the positively charged p rotonated merocyanine state (2b). The charged interface controls the oxidat ion of dihydroxyphenylacetic acid, DHPAA (3), and of 3-hydroxytyramine, DOP A (4), and the system is used for the electrochemical transduction of optic al signals recorded by the monolayer. Functionalization of electrodes with a beta-cyclodextrin monolayer or with an eosin pi-donor layer enables the L ight-stimulated association or dissociation of the photoisomerizable N,N'-b ipyridinium azobenzene (5t) and of bis-pyridinium azobenzene (8t) to or fro m the modified surfaces. Association and dissociation of the surface-associ ated supramolecular complexes are transduced by electrochemical or piezoele ctrical signal outputs. The organization of a supramolecular system where a molecular component is translocated by light-signals between two distinct positions enables one to design 'molecular machines'. This is exemplified b y the organization of a molecular assembly consisting of a ferrocene-functi onalized beta-cyclodextrin (11) threaded onto an azobenzene-alkyl chain wir e and stoppered-with an anthracene barrier which acts as a nanoscale molecu lar machine, a Light-stimulated 'molecular train'. The ferrocene-functional ized beta-cyclodextrin is reversibly translocated between the trans-azobenz ene and the alkyl chain by cyclic light-induced isomerization of the photoa ctive monolayer. The position of the beta-cyclodextrin receptor is transduc ed by its chronoamperometric response.