Person: Díaz Blanco, Cristina
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First Name
Cristina
Last Name
Díaz Blanco
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
Identifiers
4 results
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Now showing 1 - 4 of 4
Item Engineering the HOMO–LUMO gap of indeno[1,2b]fluorene(Journal of Materials Chemistry C, 2022) Casares, Raquel; Martínez-Pinel, Álvaro; Rodríguez-González, Sandra; Márquez, Irene ; Lezama, Luis; González, Maria Teresa; Leary, Edmund; Blanco, Víctor; Fallaque, Joel ; Díaz Blanco, Cristina; Martín, Fernando; Cuerva, Juan ; Millán, AlbaA direct, efficient and versatile strategy for the modulation of optoelectronic and magnetic properties of indeno[1,2-b]fluorene has been developed. 4-Substituted-2,6-dimethylphenyl acetylene groups placed in the apical carbon of the five-membered rings lead to redshifted absorption maxima (lmax rangin from 600–700 nm) and considerable narrowing of the HOMO–LUMO energy gap (down to 1.5 eV). Experimental and theoretical data show an increase in the diradical character (y) and a decrease of the singlet-triplet energy gap. Moreover, we have investigated the single-molecule conductance of the antiaromatic indeno[1,2-b]fluorene for the first time by including thiomethyl (-SMe) anchor groups on the phenylacetylene moiety. Conductance values one order of magnitude higher than those of a reference linear 3-ring para-phenylene ethylene have been found, despite the longer length of the S-to-S molecular junction. First principles transport calculations support this high conductance value.Item Self-energy corrected DFT-NEGF for conductance in molecular junctions: an accurate and efficient implementation for TRANSIESTA package applied to Au electrodes(Journal of physics: Condensed Matter, 2022) Fallaque, Joel ; Rodríguez-González, Sandra; Martín, Fernando; Díaz Blanco, CristinaIn view of the development and the importance that the studies of conductance through molecular junctions is acquiring, robust, reliable and easy-to-use theoretical tools are the most required. Here, we present an efficient implementation of the self-energy correction to density functional theory non-equilibrium Green functions method for TRANSIESTA package. We have assessed the validity of our implementation using as benchmark systems a family of acene complexes with increasing number of aromatic rings and several anchoring groups. Our theoretical results show an excellent agreement with experimentally available measurements assuring the robustness and accuracy of our implementation.Item A simple model to engineer single-molecule conductance of acenes by chemical disubstitution(Nanoscale, 2022) Fallaque, Joel ; Rodríguez-González, Sandra; Díaz Blanco, Cristina; Martín, FernandoUnderstanding and controlling electrical conductivity at the single-molecule level is of fundamental importance for the development of new molecular electronic devices. This ideally requires considering the many different options offered by the molecular structure, the nature of the electrodes, and all possible molecule-electrode anchoring configurations, which is experimentally tedious and theoretically very expensive. Here we present a systematic theoretical study of the conductance of di-amino, di-methylthio and di-(4-methylthio)phenyl acenes, from benzene to pentacene, and for all possible distributions of two identical linkers symmetrically placed on opposite sides of the same ring. We show that, for all investigated compounds, the relative variation of the conductance is well explained by the variations of the HOMO energies as predicted by a simple extended-Hückel approach, i.e., without the need for further input from more elaborate calculations. The model predicts quite nicely that diamino acenes are better conductors than their corresponding dimethylthio analogues, and both much better than the di-(4-methylthio)phenyl counterparts, irrespective of the linkers’ relative positions. It also predicts, for a given pair of linkers, the variations in the conductance resulting from changing the acene size and/or the relative position of the linkers. These variations can be as large as an order of magnitude, and therefore can be used to engineer molecular conductance. Finally, we show that a similar approach should be useful to predict trends in the relative conductance of a large variety of disubstituted acene isomers, including various linkers.Item Tailoring single-molecule conductance with structured graphene electrodes(Applied Surface Science, 2024) Fallaque, Joel ; Rodríguez-González, Sandra; Díaz Blanco, Cristina; Martín, FernandoModulation of electric currents through single-molecule junctions is usually achieved by synthesis of molecules with desired functionalities, in conjunction with suitable molecule–electrode contacts through specific anchoring groups. An alternative to this approach, barely explored so far, is to use structured electrodes, where conductivity could eventually be controlled by changing the specific anchoring site within the very same electrode. Here, we theoretically investigate how to exploit the pronounced anisotropy of corrugated graphene deposited on Ru(0001) (Gr/Ru) to tailor single-molecule conductivity in 4-aminophenyl and 4-aminobenzonitrile. We show that currents induced in the upper and lower anchoring positions in the Gr/Ru moiré are substantially different, irrespective of the chosen molecule. The magnitude of these currents can differ by as much as an order of magnitude at specific bias voltages. We also show that both molecules display rectifying properties, which can differ by up to a factor of five in different anchoring sites. Interestingly, the observed modulations strongly depend on the chemical binding nature between the molecule and the electrode, (strong) covalent bond for 4-aminophenyl and (weak) physisorption for 4-aminobenzonitrile. All this suggests that Gr/Ru can be an ideal electrode to modulate single-molecule electric conductivity under experimental conditions that are available in many laboratories.