Symmetry-induced quantum interference effects in metalloporphyrin wires

Abstract

We calculate the electronic and transport properties of a series of metalloporphyrin molecules sandwiched between gold electrodes using a combination of density functional theory and scattering theory. The impact of strong correlations at the central metallic atom is gauged by comparing our results obtained using conventional DFT and DFT + U approaches. The zero- and finite-bias transport properties may or may not show spin-filtering behavior, depending on the nature of the d state closest to the Fermi energy. The type of d state depends on the metallic atom and gives rise to interference effects that produce different Fano features. The inclusion of the U term opens a gap between the d states and changes the conductance and spin-filtering behavior qualitatively in some of the molecules. We explain the origin of the quantum interference effects found as due to the symmetry-dependent coupling between the d states and other molecular orbitals and propose the use of these systems as nanoscale chemical sensors. We also demonstrate that an adequate treatment of strong correlations is really necessary to correctly describe the transport properties of metalloporphyrins and similar molecular magnets.

Impact of Fano and Breit-Wigner resonances in the thermoelectric properties of nanoscale junctions

“…With such a model we have analyzed in detail the impact of Fano resonances on the charge transport properties of these systems. 47 We have found that these molecules contribute with three broad resonances to the transmission coefficients of the junctions, which correspond to HOMO-1 (a σ molecular orbital), the HOMO, and the LUMO (which has π character). In addition, the 3d atom contributes with a spin-polarized strongly localized state, which hybridizes with HOMO-1 or the LUMO, depending on the element, and gives rise to a Fano resonance.…”

“…The metallic elements which produce states close to the Fermi level are Fe and Cu atoms. 47 We therefore focus in this study on only Fe and Cu metalloporphyrins dithiolate.…”

Tuning the electrical conductance of metalloporphyrin supramolecular wires

“…Following early work, which established their chemical and biological properties6789, porphyrins have become a focus of interest both for experimental and theoretical investigations of molecular electronics101112 and for the design of complexes using supramolecular chemistry, leading to a diverse array of structures available for nano-scale building blocks13. This unique combination of properties is exploited in nature, where for example metalloporphyrins acts as charge carriers in naturally occurring processes such as photosynthesis14151617 and in the respiratory chain1819.…”

Surface Morphology of Fe(III)-Porphyrin Thin Layers as Characterized by Atomic Force Microscopy

“…As such, individual molecules can be considered as single nanometer devices [10][11][12]. There have been several fascinating studies of coupling between the porphyrin molecules and the thin layers of substrates [13][14][15][16][17]. Magnetic characteristics and the effect of external magnetic fields on molecules metalloporphyrin have been studied [18][19][20].Charge carrier mobility under the influence of a magnetic field in Hall effect configuration on porphyrin-based materials has also been observed [21][22][23][24][25][26][27].For the detection of neurotransmitters, graphite electrodes coated by electropolymerized porphyrins have been studied since1997 [6].…”