title: Multiscale Approach to the Study of the Electronic Properties of Two Thiophene Curcuminoid Molecules.
abstract: We studied the electronic and conductance properties of two thiophene-curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), in which the only structural difference is the position of the sulfur atoms in the thiophene terminal groups. We used electrochemical techniques as well as UV/Vis absorption studies to obtain the values of the HOMO-LUMO band gap energies, showing that molecule 1 has lower values than 2. Theoretical calculations show the same trend. Self-assembled monolayers (SAMs) of these molecules were studied by using electrochemistry, showing that the interaction with gold reduces drastically the HOMO-LUMO gap in both molecules to almost the same value. Single-molecule conductance measurements show that molecule 2 has two different conductance values, whereas molecule 1 exhibits only one. Based on theoretical calculations, we conclude that the lowest conductance value, similar in both molecules, corresponds to a van der Waals interaction between the thiophene ring and the electrodes. The one order of magnitude higher conductance value for molecule 2 corresponds to a coordinate (dative covalent) interaction between the sulfur atoms and the gold electrodes.
authors.affiliation: Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago, Chile.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Etcheverry-Berríos
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Olavarría
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Mickael L
authors.initials: ML
authors.lastname: Perrin
authors.affiliation: Departament de Química Inorgànica, Universitat de Barcelona-ICMAB (Institute of MaterialsScience of Barcelona)-CSIC, Diagonal 645, 08028, Barcelona, Spain.
authors.forename: Raúl
authors.initials: R
authors.lastname: Díaz-Torres
authors.affiliation: Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago, Chile.
authors.forename: Domingo
authors.initials: D
authors.lastname: Jullian
authors.affiliation: Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo Ohiggins 3363, Estación Central, Santiago, Chile.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Ponce
authors.affiliation: Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo Ohiggins 3363, Estación Central, Santiago, Chile.
authors.forename: José H
authors.initials: JH
authors.lastname: Zagal
authors.affiliation: Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo Ohiggins 3363, Estación Central, Santiago, Chile.
authors.forename: Jorge
authors.initials: J
authors.lastname: Pavez
authors.affiliation: Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago, Chile.
authors.forename: Sergio O
authors.initials: SO
authors.lastname: Vásquez
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Herre S J
authors.initials: HS
authors.lastname: van der Zant
authors.affiliation: Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco 2008, Santiago, Chile. ddulic@ing.uchile.cl.
authors.forename: Diana
authors.initials: D
authors.lastname: Dulić
authors.affiliation: ICREA Researcher (Institució Catalana de Recerca i Estudis Avançats) at the ICMAB-CSIC, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain. nuria.aliaga@icrea.cat.
authors.forename: Núria
authors.initials: N
authors.lastname: Aliaga-Alcalde
authors.affiliation: Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago, Chile. msoler@ing.uchie.cl.
authors.forename: Monica
authors.identifier: http://orcid.org/0000-0003-2125-6809
authors.initials: M
authors.lastname: Soler
mesh_terms: D003474:Curcumin / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D015394:Molecular Structure; D036103:Nanotechnology; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D013876:Thiophenes; D006046:Gold; D003474:Curcumin
keywords: HOMO-LUMO band gap energies; curcumin; density functional calculations; differential pulse voltammetry; self-assembly