Jose M Mercero

Universidad del País Vasco / Euskal Herriko Unibertsitatea | UPV/EHU · Advanced Polymers and Materials: Physics, Chemistry and Technology

The catalytic, enantio- and diastereoselective addition of hydantoin surrogates II to "rigidified" vinylidene bis(sulfone) reagents is developed, thus overcoming the inability of commonly employed β-substituted vinylic sulfones to react. Adducts are transformed in enantioenriched 5,5-disubstituted hydantoins through hydrolysis and reductive desulfo...

Clusters are “ensembles of like objects or individuals,” according to the dictionary. In chemistry, it refers to aggregations of atoms or molecules that appear close together and are chemically interrelated. Clusters are made of a number of atoms or molecules, not too small and not too big, loosely referred to as “intermediate” between the molecula...

In this work, we have computed and implemented one‐body integrals concerning Gaussian confinement potentials over Gaussian basis functions. Then, we have set an equivalence between Gaussian and Hooke atoms and we have observed that, according to singlet and triplet state energies, both systems are equivalent for large confinement depth for a series...

In this work, we present a systematic procedure to build phase diagrams for chemically relevant properties by the use of a semi-supervised machine learning technique called uncertainty sampling. Concretely, we focus on ground state spin multiplicity and chemical bonding properties. As a first step, we have obtained single-eutectic-point-containing...

The high catalytic activity of Pt is accompanied by a high affinity for CO, making it extremely susceptible to poisoning. Such CO poisoning limits the use of proton exchange membrane fuel cells. In this work, using state-of-the-art global minima search techniques and exhaustive electronic structure characterization, the dopant concentration is pinp...

In thiswork,we have computed and implemented one-body integrals concerning gaussian confinement potentials over gaussian basis functions. Then, we have set an equivalence between gaussian and Hooke atoms and we have observed that, according to singlet and triplet state energies, both systems are equivalent for large confinement depth for a series o...

Using Fourier-transform ion cyclotron resonance mass spectrometry, it was experimentally determined that Sc + in the highly diluted gas phase reacts with SO 2 to form ScO + and SO. By 18 O labeling, ScO + was shown to play the role of a catalyst when further reacting with SO 2 in a Mars-van Krevelen-like oxygen exchange process. High-level quantum...

The reliability of the recently proposed natural orbital functional supplemented with second-order Møller–Plesset calculations (NOF-MP2) has been assessed for the mechanistic studies of elementary reactions of transition metal compounds by investigating the dehydrogenation of water by the scandium cation. Both high- and low-spin state potential ene...

The vulnerability towards CO poisoning is a major drawback affecting the efficiency and long‐term performance of platinum catalysts in fuel cells. In the present work, by a combination of density functional theory calculations and mass spectrometry experiments, we test and explain the promotional effect of Ge on Pt catalysts with higher resistance...

The reliability of the recently proposed natural orbital functional supplemented with second-order M{\o}ller-Plesset calculations, (NOF-MP2), has been assessed for the mechanistic studies of elementary reactions of transition metal compounds by investigating the dehydrogenation of water by the scandium cation. Both high- and low-spin state potentia...

Bifunctional amine/squaramide catalyst promoted direct aldol addition of an hydantoin surrogate to pyridine 2‐carbaldehyde N‐oxides to afford aldol adducts bearing two vicinal tertiary/quaternary carbons in high diastereo‐ and enantioselectivity (dr up to >20:1; ee up to 98%) is reported. Acid hydrolysis of adducts followed by reduction of the N‐ox...

Correction for ‘The stability of biradicaloid versus closed-shell [E(μ-XR)] 2 (E = P, As; X = N, P, As) rings. Does aromaticity play a role?’ by Rafael Grande-Aztatzi et al. , Phys. Chem. Chem. Phys. , 2016, 18 , 11879–11884.

Correction for ‘The aromaticity of dicupra[10]annulenes’ by Rafael Grande-Aztatzi et al., Phys. Chem. Chem. Phys., 2017, 19, 9669–9675.

An extensive theoretical investigation of the electronic structure of a tested fair model dicupra[10]annulene compound, based on the analysis of atom-pair delocalization indices, Bader's molecular graph, the inspection of the canonical molecular orbitals, the z components of their Nuclear Independent Chemical Shifts, NICS(0)zz, and the normalized G...

The non-monotonic behavior of the electron repulsion energy and the interelectronic distance, as a function of the internuclear separation, in the $^{3}\Pi_{u}$ excited state of the hydrogen molecule has been assessed by explicitly calculation and analysis of the electron-pair density distribution functions from high level ab initio Full Configurat...

The structural and optical properties of both the naked and passivated bimetallic Al5Au5nanoclusters have been analyzed based on data obtained from ab initiodensity functional theory and quantum molecular dynamics simulations. It has been found that the Al5Au5nanocluster possesses a hollow shaped minimum energy structure with segregated Al and Au l...

High-level multiconfigurational self-consistent field calculations, supplemented with multiconfigurational quasi-degenerate perturbation theory ab initio calculations with the aug-cc-pVTZ basis set, demonstrate that the [E(μ-XH)]2 (E = P, As; X = N, P, As) compounds possess one planar and one butterfly-like isomer. The calculations predict that for...

Aromaticity Study The lowest lying singlet, triplet, and quintet spin states of D3h Al{{{\minus \hfill \atop 3\hfill}}} have strong multireference character, which impedes the straightforward application of the Hückel-Baird-like electron counting rules based on the inspection of the molecular orbitals. However, electron delocalization can be assess...

The usefulness of aromaticity/antiaromaticity concepts to foresee structural stability patterns and salient features of the electronic structure of small inorganic and all-metal rings has been put forward. A critical revision of the advances made in the theoretical methods to assess the aromaticity/antiaromaticity of these compounds has also been m...

Multiconfigurational high-level electronic structure calculations show that the ring-like cluster anion has three close low-lying electronic states of different spin, all of them having strong multiconfigurational character. The aromaticity of the cluster has, therefore, been studied by means of total electron delocalization and normalized multicen...

The potential energy surfaces of a series of clusters with formula CBe5Linn-4 (n=1-5) are systematically explored. Our computations show that the lithium cations preserve the CBe54- pentagon, such that the global minimum structure for these series of clusters has a planar pentacoordinate carbon (ppC). The systems are primarily connected by a networ...

The increased availability of aluminium in biological environments, due to human intervention in the last century, raises concerns on the effects that this so far "excluded from biology" metal might have on living organisms. Consequently, the bioinorganic chemistry of aluminium has emerged as a very active field of research. This review will focus...

The potential energy surface and fluxionality of C6Li6 is discussed by G. Moreno et al. in their Full Paper on page 12668 ff., providing a new structure of C6Li6, which can be described as three C22− fragments, strongly aggregated through lithium bridges. At high temperatures fluxionality is perceived instead of dissociation. At 600 and 900 K, Born...

The potential energy surface of C6Li6 was re-examined and a new non-symmetric global minimum was found. The new structure can be described as three C22- fragments strongly aggregated through lithium bridges. At high temperatures, fluxionality is perceived instead of dissociation. At 600 and 900a K, the BOMD simulations show that the lithium mobilit...

Peptides can assemble to supramolecular structures, of which fibers are of special biochemical and medical relevance. We employed Raman and infrared spectroscopy to elucidate the chemical integrity of fibers built from peptides and peptide derivates that contain the aromatic side groups fluorenyl and phenyl. Because the observed spectra compare ver...

Peptides can assemble to supramolecular structures, of which fibers are of special biochemical and medical relevance. We employed Raman and infrared spectroscopy to elucidate the chemical integrity of fibers built from peptides and peptide derivates that contain the aromatic side groups fluorenyl and phenyl. Because the observed spectra compare ver...

A series of clusters with the general formula CBe(5)E(-) (E = Al, Ga, In, Tl) are theoretically shown to have a planar pentacoordinate carbon atom. The structures show a simple and rigid topological framework-a planar EBe(4) ring surrounding a C center, with one of the ring Be-Be bonds capped in-plane by a fifth Be atom. The system is stabilized by...

The Piris Natural Orbital Functional, in its 5th version (PNOF5), has been used to obtain the localized bonding picture of methane that agrees well with the Pauling proposition of hybrid orbitals, and to predict the two-peak structure of its vertical valence ionization energy spectrum. The ionization energies have been calculated using the extended...

The structures and bonding of the CE42−clusters (E = Al, Ga, In, Tl) have been theoretically studied via B3LYP/def2-TZVP computations. Total energies were recalculated at the CCSD(T)/def2-TZVPP//B3LYP/def2-TZVP level in order to corroborate the energy differences. Our computations show that all the CE42−and CE4Li−clusters (E = Al, Ga, In,Tl) have a...

Metal sandwich complexes made of metallic Al(3)R(3) aromatic three-membered rings have been characterized, and their structural and electronic properties have been studied using density functional theory. The perfluorinated cyclotrialane ring has been identified as a very stable ligand for sandwichlike complexation, as it bears both large sigma and...

Endohedral first-row transition-metal-doped TM@Zn(i)S(i) nanoclusters, in which TM stands for the first-row transition-metals from Sc to Zn, and i=12, 16, have been characterized. In these structures the dopant metals are trapped inside spheroidal hollow semiconducting nanoclusters. It is observed that some of the transition metals are trapped in t...

Intermetalloid clusters: A theoretical study describes a new endohedral stannaspherene Mn@Sn12 (left in figure) and its dimer. The Mn doping produces a neutral cluster with a very high spin. Three isomers are characterised for the dimer in which the antiferromagnetic coupling between the two manganese centres is favoured.

Among the most frequent protein binding sites served by Mg(II), we identify those which have higher affinity towards Al(III). We also estimate the free energies of metal exchange for all these binding sites taking into account solvent effects explicitly. The obtained results show that thermodynamically favored Mg(II)/Al(III) exchange reactions take...

Several toxic effects arise from Al's presence in living systems, one of them being the alteration of the natural role of enzymes and non-enzyme proteins. Al(III) is capable of entering protein active sites that in normal conditions should be occupied by other metals. Even if Mg(II) is an ubiquitous metal in biological systems, the interference of...

In recent years, BN fullerenes have been synthesized experimentally. As their carbon counterparts, these BN fullerenes could be assembled in molecular solids, but this possibility has been studied little in the literature. In this work, we focus on the smallest synthesized BN fullerene, B12N12, which is built by squares and hexagons. First, the int...

Four approximate Density Functional Theory methods, the standard hybrid B3LYP functional, the hybrid mPW1PW91 functional designed to account for van der Waals forces, the one-parameter meta hybrid TPSSh functional, the general-purpose meta hybrid MPWB1K functional and one Molecular Orbital Theory method, the standard Moller−Plesset perturbation the...

The coordination properties of three natural aromatic amino acids (AAAs)sphenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp)sto AlIII are studied in this work, devoting special attention to the role of the aromatic side chain. A comparison with aluminum(III)-alanine complexes is also presented. The polarizability arising from the ring has bee...

In recent years, BN fullerenes have been synthesized experimentally. As their carbon counterparts, these BN fullerenes could be assembled in molecular solids, but this possibility has been studied little in the literature. In this work, we focus on the smallest synthesized BN fullerene, B 12 N 12 , which is built by squares and hexagons. First, the...

Four approximate Density Functional Theory methods, the standard hybrid B3LYP functional, the hybrid mPW1PW91 functional designed to account for van der Waals forces, the one-parameter meta hybrid TPSSh functional, the general-purpose meta hybrid MPWB1K functional and one Molecular Orbital Theory method, the standard Moller-Plesset perturbation the...

The first-excited 1Σg+ state of the hydrogen molecule has a potential energy curve with two minima, labeled as E and F, respectively. In the transition from the E minimum to the F minimum, the mean interelectronic distance decreases as the nuclear distance increases, which is in contrast to the behavior of the ground state. Previously the F minimum...

We present an ab initio study of the acid hydrolysis of a highly twisted amide and a planar amide analogue. The aim of these studies is to investigate the effect that the twist of the amide bond has on the reaction barriers and mechanism of acid hydrolysis. Concerted and stepwise mechanisms were investigated using density functional theory and pola...

The excitation energies of small ZnS nanoclusters characterized in previous studies have been calculated using TDDFT. The relativistic pseudopotentials of Stevens et al have been used, including Zn 4s2 electrons and S 3s2 and 3p4 electrons as valence electrons. Results obtained with these pseudopotentials are compared to those obtained considerin...

In this paper we make use of a carefully chosen counterion model, B(CF2Cl)3, for a molecularly well-defined metallocenic catalyst counterion, B(C6F5)3, to perform a comparison of Cp2M(CH3)2-type metallocene activities toward ethylene polymerization, for M = Ti, Zr, and Hf. Monomer complexation and chain-insertion barriers are calculated and discuss...

We report on novel sandwichlike structures [Al(4)MAl(4)](q-) (q=0-2 and M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W) based on the recently synthesized all-metal aromatic Al(4)(2-) square ring. The sandwichlike structures have two aromatic tetraaluminum square rings which trap a transition-metal cation from either the first, second, or third row. The stab...

Density functional theory and a polarizable continuum model are used to (i) understand the affinity modulating mechanisms of the interaction between the metal-ion-dependent adhesion site (MIDAS) of a selected integrin, lymphocyte function-associated antigen-1 (LFA-1) and a ligand mimetic acetate molecule and to (ii) propose a new, promising family...

Al(III) toxicity in living organisms is based on competition with other metal cations. Mg(II) is one of the most affected cations, since the size similarity dominates over the charge identity. The slow ligand exchange rates for Al(III) render the ion useless as a metal ion at the active sites of enzymes and provide a mechanism by which Al(III) inhi...

A systematic study of cation-pi interactions between alkali metal ions and the cyclopentadienyl ring of ferrocene is presented. The alkali metal (Li+, Na+, K+, Rb+, Cs+) salts of the ditopic mono(pyrazol-1-yl)borate ligand [1,1'-fc(BMe2pz)2]2- crystallize from dimethoxyethane as multiple-decker sandwich complexes with the M+ ions bound to the pi fa...

The methods of the quantum electronic structure theory are reviewed and their implementation for the gas phase chemistry emphasized. Ab initio molecular orbital theory, density functional theory, quantum Monte Carlo theory and the methods to calculate the rate of complex chemical reactions in the gas phase are considered. Relativistic effects, othe...

The water-promoted hydrolysis of a highly twisted amide is studied using density functional theory in conjunction with a continuum dielectric method to introduce bulk solvent effects. The aim of these studies is to reveal how the twisting of the C-N bond affects the neutral hydrolysis of amides. To do so, both concerted and stepwise mechanisms are...

The reaction of the iron oxide cation with the hydrogen molecule is studied in this work using the diffusion quantum Monte Carlo (DMC) method. Previous attempts achieved a qualitative agreement between theory and experiments, but not a satisfactory quantitative explana-tion which concurs with the experimental facts. The DMC method provides a consis...

Several structures of small CdiXi clusters, i ≤ 16, have been characterized. Ringlike structures have been found to be the lowest lying structures for i ≤ 5 clusters and three-dimensional spheroid structures for larger ones, i = 6−16. This trend has been ascribed to the stability of obtuse X−Cd−X angles in the first case and to the stability gained...

Aluminum (III) cation interactions with relevant bioligands have been studied in a protein-model environment (in the gas and aqueous phases) using density functional theory methods. The protein model consists of the metal cation bound to a chosen bioligand and water molecules interacting with the cation to complete its first coordination shell. The...

We report a new sandwich-like structure (Al4TiAl42-) based on the recently synthesized all-metal aromatic Al42- squares. This structure has two aromatic squares (-2 charged each) trapping a titanium +2 cation. These all-metal aromatic squares have been detected by various metallic counterions, with a global charge of -1. Thus, we have also characte...

Several structures of small Cd i X i clusters, i e 16, have been characterized. Ringlike structures have been found to be the lowest lying structures for i e 5 clusters and three-dimensional spheroid structures for larger ones, i) 6-16. This trend has been ascribed to the stability of obtuse X-Cd-X angles in the first case and to the stability gain...

A sequential ligand addition to the aluminum (III) cation has been studied using the B3LYP functional and a combined all-electron/pseudopotentials basis set. The aluminum complexes are compared with analogous magnesium (II) complexes. Different thermodynamical data, such as incremental binding energies, enthalpies, entropies and free energies, are...

In this work, the ground states of CdiOi clusters (i = 1−9, 12, 15) are studied. Ringlike structures have been found to be the global minima for clusters as large as i = 7, and three-dimensional structures (clustertubes and spheroids) are observed to be the global minima for larger ones (i = 8, 9, 12, 15). This trend has been ascribed to the stabil...

Time-dependent density-functional theory (TDDFT) is used to study the excitation energies of the global minima of small Zn(i)O(i) clusters, i = 1-15. The relativistic compact effective core potentials and shared-exponent basis set of Stevens, Krauss, Basch, and Jasien (SKBJ), systematically enlarged with extra functions, were used throughout this w...

The equilibrium bond lengths, harmonic vibrational frequencies, ionization energies and dissociation energies of the iron dimer and its cation were determined by hybrid density functional theory calculations supplemented by single point calculations using coupled cluster theory. Calculations predict correctly the state as the ground state of Fe2. T...

We present an ab initio study of the pKa of a series of twisted amides in aqueous solution. The shift of the pKa with respect to the known value for trimethylamine (TMA) is used in the evaluation. Calculations were made with density functional theory using the B3PW91 functional. Aqueous solvent effect is introduced by use of the polarizable continu...

In this work, the ground states of Cd i O i clusters (i) 1-9, 12, 15) are studied. Ringlike structures have been found to be the global minima for clusters as large as i) 7, and three-dimensional structures (clustertubes and spheroids) are observed to be the global minima for larger ones (i) 8, 9, 12, 15). This trend has been ascribed to the stabil...

The land-mark paper of Heitler and London[1] on the ground state of H2 opened the way to a theoretical understanding of the chemical bond and marks the birth of quantum chemistry. Interestingly, their trial wave function for the ground st ate of H2 includes only covalent configurations, i.e., by excluding explicitly ionic configurations. Namely, be...

The relative stability of various charge states of a number of selected elements has been studied as a function of increasing screening due to a weakly bound plasma represented by the statically screened Coulomb potential of the Yukawa-type. Elements with positive electron affinity in a vacuum are predicted to undergo a sequential electron detachme...

The structure, energetics, vibrations, and barrier to internal rotation around the N···H−O hydrogen bond of the binary pyridine−formic acid complex are calculated using one properly selected hybrid density functional theory procedure. The calculations demonstrate that the most stable isomer of the complex has a strong N···H−O hydrogen-bonding inter...

Aluminum (III) and magnesium (II) interactions with the aromatic containing aminoacid side chains are studied using the B3LYP density functional. Bader and the NBO analyses have been performed on the optimized structures in order to shed light on the effect of the metal on the aromatic rings. We began by studying the interactions between the metal...

The improvements in the characterization of II–VI-compound-based solar cells and the recent experimental characterization of small clusters and nanoparticles make the study of small II–VI clusters very interesting. In this work, the ground states of small ZniXi clusters are studied, X=Se,Te, i=1–9. Ringlike structures have been found to be the glob...

In this paper, we have extended our studies concerning aluminum (III) and amino acid chain interactions. We focus on the sulfur containing amino acid chains of cysteine (Cys) and methionine (Met) and analyze the interactions with the toxic aluminum (III) and the nontoxic magnesium (II) cations. We start with the simplest model representing the amin...

The stable isomers of the ferrocene--lithium cation gas-phase ion complex have been studied with the hybrid density functional theory. The method of calculation chosen has been tested checking its performance for the more studied protonated ferrocene species. Our calculations demonstrate that the procedure used is reliable. We have found two isomer...

Electron pair densities and their moments associated with a set of multiconfigurational wavefunctions that systematically include nondynamic electron correlation have been constructed for the beryllium isoelectronic sequence. The obtained two-electron quantities are compared to the Hartree-Fock and nearly exact configuration interaction results. It...

Aluminum(III) and magnesium(II) interactions with the asparagine and glutamine amino acid chains are studied by the density functional approach. Bader analysis and natural bonding orbital analysis were also performed to analyze the bonding interactions. We began by studying the interactions between the cations and the formamide, and we added two me...

Multiple biological processes are regulated by kinases and phosphatases. This study aims to provide nonenzymatic models for phosphorylation and dephosphorylation of serine, threonine, and tyrosine phosphate using ab initio guantum mechanical calculations. We reduce the problem to methyl phosphate hydrolysis to model serine/threonine, and the hydrol...

The radial and electron-pair density functions of two bound excited states of the helium anion have been calculated at the full configuration-interaction level with an extended basis set. It is shown that the form of the radial density in the (1s2s2p)4P and (2p3)4S states of He- is readily interpreted in terms of orbital contributions, even at the...

The atomic electron-electron counterbalance density d(0) represents the probability density of finding any two electrons exactly at mirror positions with respect to the nucleus. We have computed these densities from accurate configuration interaction and Hartree-Fock-like wave functions for the isoelectronic series of He and first-row atoms. Our ca...

We have performed an ab initio study of aluminum(III) cation with the aspartic and glutamic amino acid residues, i.e., the carboxylate group. Density functional theory methodology was used, and the covalent and noncovalent interactions were analyzed using natural bond orbital theory. First we have investigated the smallest functional moiety of thes...

The stability of the bound excited states of both the hydrogen and helium anions in an environment represented by the statically screened Coulomb potential have been studied. Energies have been calculated at the full configuration interaction level of theory, as a function of the screening parameter. Our calculations demonstrate that the bound exci...

The molecular and electronic structures of the isomers of both neutral and negative (TiXH6)0/-, X = B, Al, Ga, systems have been studied. For each of the neutral systems, a Cs isomer of signature (2, 3, 1) (where (a, b, c) signifies a is the number of terminal Ti−H bonds, b is the number of hydrogen bridging bonds, and c is the number of terminal X...

The molecular and electronic structures of TiXH6+ compounds have been studied. All stable structures found have strong two-electron three-center Ti−H−X bonds, which determine their geometrical characteristics. One important structural feature, found for all the isomers studied, is the absence of Ti−X bonding interactions, so that the molecular stru...

Alternant X2Y2 (X = N, P, As, and Sb and, Y = O, S, Se, and Te) cyclic planar and butterfly like isomers have been studied at the complete-active-space self-consistent-field (CASSCF) molecular orbital and second-order configuration-interaction (SOCI) levels of theory with optimized basis sets including f-functions. The salient geometrical features,...

The first-excited $^1 \Sigma_g^+$ state of the hydrogen molecule has a potential energy curve with two minima, labeled as E and F, respectively. In the transition from the E minimum to the F minimum, the mean interelectronic distance decreases as the nuclear distance increases, which is in contrast to the behavior of the ground state. Previously th...