title: Cation-Controlled Excimer Packing in Langmuir-Blodgett Films of Hemicyanine Amphiphilic Chromoionophores.
abstract: Supramolecular structure of ultrathin films of hemicyanine dye bearing a crown ether group (CrHCR) was tuned by lateral pressure and investigated by means of compression isotherms, UV-vis and fluorescence spectroscopies, and X-ray reflectivity. Two different types of aggregation were revealed, depending on the absence or the presence of metal cations in the water subphase. While CrHCR forms at high surface pressures head-to-tail stacking aggregates on pure water, changing the subphase to a metal-cation-containing one leads to the appearance of well-defined excimers with head-to-head orientation. The structure of monolayers transferred onto solid supports by the Langmuir-Blodgett (LB) technique was examined by use of X-ray reflectivity measurements and molecular modeling. A model of cation-induced excimer formation in hemicyanine Langmuir monolayers is proposed. Finally, fluorescence emission properties of LB films of CrHCR can be managed by appropriate changes in the subphase composition, this last one determining the type of chromophore aggregation.
authors.affiliation: Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Moscow, Russia.
authors.forename: S L
authors.initials: SL
authors.lastname: Selektor
authors.affiliation: National Research Centre Kurchatov Institute, Moscow, Russia.|Moscow Institute of Physics and Technology, Moscow, Russia.
authors.forename: M A
authors.initials: MA
authors.lastname: Shcherbina
authors.affiliation: National Research Centre Kurchatov Institute, Moscow, Russia.|Enikolopov Institute of Synthetic Polymer Materials RAS, Moscow, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Bakirov
authors.affiliation: Univ. Bordeaux, LOMA, UMR 5798, F-33400 Talance, France; CNRS, LOMA, UMR 5798, F-33400 Talence, France.
authors.forename: P
authors.initials: P
authors.lastname: Batat
authors.affiliation: Univ. Bordeaux, LOMA, UMR 5798, F-33400 Talance, France; CNRS, LOMA, UMR 5798, F-33400 Talence, France.
authors.forename: C
authors.initials: C
authors.lastname: Grauby-Heywang
authors.affiliation: Institute of Physics, University of Siegen , 57072 Siegen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Grigorian
authors.affiliation: Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Moscow, Russia.
authors.forename: V V
authors.initials: VV
authors.lastname: Arslanov
authors.affiliation: National Research Centre Kurchatov Institute, Moscow, Russia.|Moscow Institute of Physics and Technology, Moscow, Russia.
authors.forename: S N
authors.initials: SN
authors.lastname: Chvalun
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D002412:Cations; D043844:Crown Ethers / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007476:Ionophores / Q000737:chemistry*; D008027:Light; D008958:Models, Molecular; D055668:Photochemical Processes; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D002232:Carbocyanines; D002412:Cations; D043844:Crown Ethers; D005456:Fluorescent Dyes; D007476:Ionophores; D013501:Surface-Active Agents; C000601156:tetramethylene hemicyanine