Examinando por Autor "Mendizabal, Fernando"

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    Closed-shell d10-d10 mechanochromic [AuPh(CNPh)]n complex: quantum chemistry electronic and optical properties
    (Royal Society of Chemistry, 2024-02) Mendizabal, Fernando; Ceron, María Luisa; Lara, Dina; Miranda-Rojas, Sebastián
    The electronic structure, spectroscopic properties, and solid state chemistry of monomer and dimers of [AuPh(CNPh)] complex were studied at post-Hartree-Fock (MP2, SCS-MP2, and CC2) and density functional theory levels. The absorption spectra of these complexes were calculated using single excitation time-dependent (TD) methods at DFT, CC2, and SCS-CC2 levels. The influences of the bulk are accounted for at the PBE-D3 level, incorporating dispersion effects. The calculated values agree with the experimental range, where absorption and emission energies reproduce experimental trends with large Stokes shifts. The aurophilic interaction is identified as a key factor influencing the spectroscopic and structural properties of these complexes. The intermetallic interactions were found as the main factor responsible for MMCT electronic transitions in the models studied. © 2024 The Royal Society of Chemistry.
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    Electronic and optical properties of [Au(CH3CSS)]4cluster. A quantum chemistry study
    (Royal Society of Chemistry, 2020-09) Mendizabal, Fernando; Miranda-Rojas, Sebastián
    The uses of the sulfur-gold bond in the design of new molecular clusters have gained increasing attention in recent years. Their size and shape are diverse providing a wide variety of optical and electronic properties. Here we present a computational study of the absorption and emission properties of a small [Au(dithioacetate)]4 cluster as a model for these systems. The electronic structure of the Au4S8 core of this cluster permits rationalization of the source of the optical properties and how these are connected with that specific structural scaffold. Due to the complex nature of the aurophilic intramolecular interactions taking place in this system, several methods were used, such as the MP2, SCS-MP2, PBE-D3, and TPSS-D3 levels; both in gas and solvent phases. The absorption spectra of the cluster were calculated by the single excitation time-dependent-DFT (TD-DFT) method, CC2, SCS-CC2, and ADC(2) levels. The ab initio correlated calculations and previously reported experimental data have been used to assess the performance of our calculations. Moreover, the emission T1-So transition was calculated, where the SCS-CC2 level showed an excellent agreement with the experimental results. The core Au4S8 was identified as mainly responsible for the absorption and emission transitions according to the theoretical model. This journal is © The Royal Society of Chemistry.
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    Exploration of the interaction strength at the interface of anionic chalcogen anchors and gold (111)‐based nanomaterials
    (MDPI AG, 2020-06-20) Miranda-Rojas, Sebastián; Mendizabal, Fernando
    Nowadays, the use of sulfur‐based ligands to modify gold‐based materials has become a common trend. Here, we present a theoretical exploration of the modulation of the chalcogenides‐gold interaction strength, using sulfur, selenium, and tellurium as anchor atoms. To characterize the chalcogenide‐gold interaction, we designed a nanocluster of 42 gold atoms (Au42) to model a gold surface (111) and a series of 60 functionalized phenyl‐chalcogenolate ligands to determine the ability of electron‐donor and ‐withdrawing groups to modulate the interaction. The analysis of the interaction was performed by using energy decomposition analysis (EDA), non‐covalent interactions index (NCI), and natural population analysis (NPA) to describe the charge transfer processes and to determine data correlation analyses. The results revealed that the magnitudes of the interaction energies increase following the order S < Se < Te, where this interaction strength can be augmented by electron‐donor groups, under the donor‐acceptor character the chalcogen–gold interaction. We also found that the functionalization in meta position leads to better control of the interaction strength than the ortho substitution due to the steric and inductive effects involved when functionalized in this position.