title: Langmuir and Langmuir-Blodgett films containing a porphyrin-ruthenium complex.
abstract: The fabrication of supramolecular structures from the tetraruthenated porphyrin-containing phosphines, {TPyP[RuCl3(dppb)]4}, RuTPyP, is demonstrated with Langmuir and Langmuir-Blodgett films. The surface pressure-molecular area isotherms (pi-A) point to an edge-on arrangement for the RuTPyP molecules in the condensed state. Weak aggregation in the Langmuir films was indicated by non-zero surface potentials at large areas per molecule and a slight red shift in the ultraviolet-visible absorption spectrum in comparison to the spectrum in solution. Further aggregation occurs in the Z-type Langmuir-Blodgett films, which was confirmed with ultraviolet-visible spectroscopy of the deposited films. Fourier transform infrared and Raman spectroscopic data for powder and Langmuir-Blodgett films indicate that the RuTPyP molecules are chemically stable in Langmuir-Blodgett films regardless of the contact with water during film fabrication. The nanostructured nature of the Langmuir-Blodgett films was manifested in cyclic voltammetry due to the high sensitivity of the metallic centers in RuTPyP. Electrodes modified with Langmuir-Blodgett films exhibit an anodic peak at 100 mV and a cathodic peak at 7 mV, which is assigned to RuIII/RuII redox processes. Furthermore, Langmuir-Blodgett films from RuTPyP showed electrocatalytic activity for oxidation of benzyl alcohol, illustrated by a large shift of 100 mV in the anodic peak at 400 mV, while electropolymerized and cast films of the same compound displayed smaller and no activities, respectively.
authors.affiliation: Departamento de Química, Universidade Estadual de Ponta Grossa, Ponta Grossa/PR, Brazil.
authors.forename: Karen
authors.initials: K
authors.lastname: Wohnrath
authors.forename: Luis R
authors.initials: LR
authors.lastname: Dinelli
authors.forename: Sarita V
authors.initials: SV
authors.lastname: Mello
authors.forename: Carlos J L
authors.initials: CJ
authors.lastname: Constantino
authors.forename: Roger M
authors.initials: RM
authors.lastname: Leblanc
authors.forename: Alzir A
authors.initials: AA
authors.lastname: Batista
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
mesh_terms: D040761:Biomimetic Materials / Q000032:analysis / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D003460:Crystallization / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D008422:Materials Testing; D008567:Membranes, Artificial; D049329:Nanostructures / Q000032:analysis / Q000737:chemistry*; D011166:Porphyrins / Q000032:analysis / Q000737:chemistry*; D012428:Ruthenium / Q000032:analysis / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; D011166:Porphyrins; D012428:Ruthenium