Articles publicats en revistes (Institut de Química Teòrica i Computacional (IQTCUB))

URI permanent per a aquesta col·leccióhttps://hdl.handle.net/2445/121047

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Probing the Lewis Acidity of Boronic Acids through Interactions with Arene Substituents
(Wiley-VCH, 2021-12-27) Jian, Jie; Hammink, Roel; McKenzie, Christine J.; Bickelhaupt, F. Matthias; Poater i Teixidor, Jordi; Mecinović, Jasmin
Boronic acids are Lewis acids that exist in equilibrium with boronate forms in aqueous solution. Here we experimentally and computationally investigated the Lewis acidity of 2,6-diarylphenylboronic acids; specially designed phenylboronic acids that possess two flanking aromatic rings with tunable aromatic character. Hammett analysis of 2,6-diarylphenylboronic acids reveals that their Lewis acidity remains unchanged upon the introduction of EWG/EDG at the distant para position of the flanking aromatic rings. Structural and computational studies demonstrate that polar-π interactions and solvation effects contribute to the stabilization of boronic acids and boronate forms by aromatic rings. Our physical-organic chemistry work highlights that boronic acids and boronates can be stabilized by aromatic systems, leading to an important molecular knowledge for rational design and development of boronic acid-based catalysts and inhibitors of biomedically important proteins.
Biotemplating of Metal–Organic Framework Nanocrystals for Applications in Small-Scale Robotics
(Wiley-VCH, 2021-12-07) Terzopoulou, Anastasia; Palacios-Corella, Mario; Franco, Carlos; Sevim, Semih; Dysli, Thomas; Mushtaq, Fajer; Romero-Angel, María; Martí-Gastaldo, Carlos; Gong, De; Cai, Jun; Chen, Xiang-Zhong; Pumera, Martin; deMello, Andrew J.; Nelson, Bradley J.; Pané, Salvador; Puigmartí-Luis, Josep
Biotemplating is a powerful approach for manufacturing small-scale devices. Here, the assembly of metal-organic framework (MOF) nanocrystals onto biotemplated magnetic helical structures on the cyanobacterium Spirulina platensis is reported. It is demonstrated that the authors' approach is universal and can be used to equip biotemplated structures with different functional MOF systems. The successful assembly of MOF nanocrystals on magnetically coated helical biotemplates is achieved by decorating the magnetic surface with gelatin, a naturally occurring macromolecule with synthon moieties that allows anchoring of the MOF nanocrystals via electrostatic interactions. Furthermore, as gelatin is a thermally responsive material, it can serve to free the magnetic biotemplates from the MOF nanocrystal cargoes. As such, the systems can be used as highly integrated magnetically driven microrobots with multiple functionalities. To this end, the potential of these composite helical architectures is demonstrated as MOF-based small-scale robots with applications in biomedicine and environmental remediation.
Continuous Shape Measures Study of the Coordination Spheres of Actinide Complexes. Part 1: Low Coordination Numbers
(Wiley-VCH, 2021-07-26) Álvarez, Santiago (Álvarez Reverter)
Structural analyses of a large set of molecular structures of actinide compounds allow us to establish trends for stereochemical preferences, common distortion paths, geometrical constraints imposed by different ligand topologies, and the existence of incipient bonds or of Van der Waals intramolecular interactions on purportedly vacant coordination sites. In this study the relative abundance of coordination numbers in actinide chemistry appears to be on average higher than that among the lanthanides. The detailed continuous shape measures study of normalized coordination polyhedra with coordination numbers between 1 and 6 presented here is based on more than 1,800 solid state and gas phase structural data sets.
Synthesis of 2D porous crystalline materials in simulated microgravity
(Wiley-VCH, 2021-06-04) Contreras-Pereda, Noemí; Rodríguez-San-Miguel, David; Franco, Carlos; Sevim, Semih; Vale, João Pedro; Solano, Eduardo; Fong, Wye-Khay; Giudice, Alessandra Del; Galantini, Luciano; Pfattner, Raphael; Pané, Salvador; Sotto Mayor, Tiago; Ruiz-Molina, Daniel; Puigmartí-Luis, Josep
To date, crystallization studies conducted in space laboratories, which are prohibitively costly and unsuitable to most research laboratories, have shown the valuable effects of microgravity during crystal growth and morphogenesis. Herein, an easy and highly efficient method is shown to achieve space-like experimentation conditions on Earth employing custom-made microfluidic devices to fabricate 2D porous crystalline molecular frameworks. It is confirmed that experimentation under these simulated microgravity conditions has unprecedented effects on the orientation, compactness and crack-free generation of 2D porous crystalline molecular frameworks as well as in their integration and crystal morphogenesis. It is believed that this work will provide a new 'playground' to chemists, physicists, and materials scientists that desire to process unprecedented 2D functional materials and devices.
New modelling approach for nitrogen transfer and water passage in gas-permeable membranes for wastewater treatment
(Elsevier B.V., 2026-04-25) Serra Toro, Andreu; Romero-Vidal, T.; Pelizzaro, V.; Da Silva, C.; Valentino, Francesco; Astals Garcia, Sergi; Dosta Parras, Joan; Mas i Pujadas, Francesc
Gas-permeable membranes (GPM) have emerged as a promising technology for recovering total ammoniacal nitrogen (TAN) from wastewater. However, simultaneous transport of ammonia and water across hydrophobic membranes dilute the trapping solution and reduces its value. Additionally, water transport hinders nitrogen transfer analysis, which is used to assess membrane performance. Existing modelling approaches often rely on osmotic pressure estimates or assume constant volumes, which limits their applicability when treating real wastewaters. This study presents a new modelling approach to describe the coupled transport of ammonia and water across GPM using only experimentally measurable variables such as TAN concentration and solution volume. A key feature of this model is its capacity to capture dilution effects caused by water flux and accurately estimate TAN diffusion without requiring chemical speciation data. Laboratory experiments with synthetic and waste-derived effluents, including anaerobic digestion supernatant, acidogenic fermentation liquid, and industrial wastewater accurately reproduced TAN concentration over time. For synthetic wastewater, the mean ammonia permeability was 1.26·10-6 m/s, while waste effluents showed broader values from 0.58·10-6 to 1.83·10-6 m/s due to matrix component interactions. This narrow distribution confirms the robustness of the model, as permeability is a membrane-intrinsic parameter. Water transport significantly increased trapping solution volume, up to 149% in synthetic media and 292% in high-strength effluents, increasing with the osmotic pressure gradient between solutions. The proposed model provides a practical tool to obtain membrane-intrinsic ammonia permeability and to model TAN recovery in GPM treating real effluents, helping to bridge the gap between theoretical transport models and experimental applications.
Cosmic-ray acceleration and escape from supernova remnant W44 as probed by Fermi-LAT and MAGIC
(EDP Sciences, 2025-01-23) Abe, S.; Abhir, J.; Abhishek, A.; Acciari, V. A.; Aguasca Cabot, Arnau; Agudo, I.; Aniello, T.; Ansoldi, S.; Antonelli, L. A.; Arbet-Engels, Axel; Arcaro, C.; Asano, K.; Babić, A.; Baquero, A.; Barres de Almeida, U.; Barrio, J. A.; Batković, I.; Bautista, A.; Baxter, J.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Bernete, J.; Berti, A.; Besenrieder, J.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G.; Bošnjak, Ž.; Bronzini, E.; Burelli, I.; Busetto, G.; Campoy-Ordaz, A.; Carosi, A.; Carosi, R.; Carretero-Castrillo, Mar; Castro-Tirado, A.J.; Cerasole, D.; Ceribella, G.; Chai, Yandong; Chilingarian, A.; Cifuentes, A.; Colombo, E.; Contreras, J.L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Menezes, R.; Del Popolo, A.; Delfino, M.; Delgado, Jordi; Delgado Mendez, C.; Di Pierro, F.; Dominis Prester, D.; Donini, A.; Dorner, D.; Doro, M.; Elsaesser, D.; Emery, G.; Escudero, J.; Fariña, L.; Fattorini, A.; Foffano, L.; Font, L.; Fröse, S.; Fukazawa, Y.; García López, R.J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giesbrecht Paiva, J.G.; Giglietto, N.; Gliwny, P.; Godinović, N.; Gozzini, Sara Rebecca; Gradetzke, T.; Grau, R.; Green, J.G.; Günther, P.; Hadasch, D.; Hahn, A.; Hassan, T.; Heckmann, L.; Herrera, J.; Hrupec, D.; Hütten, M.; Imazawa, R.; Ishio, K.; Jiménez Martínez, I.; Jormanainen, J.; Kayanoki, T.; Kerszberg, D.; Kluge, G.W.; Kobayashi, Y.; Kouch, P.M.; Kubo, H.; Kushida, J.; Láinez, M.; Lamastra, A.; Leone, F.; Lindfors, E.; Linhoff, L.; Lombardi, S.; Longo, F.; López-Coto, R.; López-Moya, M.; López-Oramas, A.; Loporchio, S.; Lorini, A.; Lyard, E.; Machado de Oliveira Fraga, B.; Majumdar, P.; Makariev, M.; Maneva, G.; Mang, N.; Manganaro, M.; Mangano, S.; Mannheim, K.; Mariotti, M.; Martínez, Manel; Martínez-Chicharro, M.; Mas-Aguilar, A.; Mazin, D.; Menchiari, S.; Mender, S.; Miceli, D.; Miener, T.; Miranda, J.M.; Mirzoyan, R.; Molero González, M.; Molina, Edgar; Mondal, H.A.; Moralejo, A.; Morcuende, D.; Nakamori, T.; Nanci, C.; Nava, L.; Neustroev, V.; Nickel, L.; Nievas Rosillo, M.; Nigro, C.; Nikolić, L.; Nishijima, K.; Njoh Ekoume, T.; Noda, K.; Nozaki, S.; Ohtani, Y.; Okumura, A.; Otero-Santos, J.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, Riccardo; Paredes i Poy, Josep Maria; Peresano, M.; Persic, M.; Pihet, Marine; Pirola, G.; Podobnik, F.; Prada Moroni, P.G.; Prandini, E.; Principe, G.; Priyadarshi, C.; Rhode, W.; Ribó Gomis, Marc; Rico, J.; Righi, C.; Sahakyan, N.; Saito, T.; Satalecka, K.; Saturni, F.G.; Schleicher, B.; Schmidt, K.; Schmuckermaier, F.; Schubert, J.L.; Schweizer, T.; Sciaccaluga, A.; Silvestri, G.; Sitarek, J.; Sliusar, V.; Sobczynska, D.; Spolon, A.; Stamerra, A.; Strišković, J.; Strom, D.; Strzys, M.; Suda, Y.; Suutarinen, S.; Tajima, H.; Takahashi, M.; Takeishi, R.; Temnikov, P.; Terauchi, K.; Terzić, T.; Teshima, M.; Truzzi, S.; Tutone, A.; Ubach, S.; van Scherpenberg, J.; Vazquez Acosta, M.; Ventura, Salvador; Viale, I.; Vigorito, C.F.; Vitale, V.; Vovk, I.; Walter, Rudolf; Will, M.; Wunderlich, Carolin; Yamamoto, T.; Di Tria, R.; Di Venere, L.; Giordano, F.; Bissaldi, E.; Green, D.; Morlino, G.
Context. The supernova remnant (SNR) W44 and its surroundings are a prime target for studying the acceleration of cosmic rays (CRs). Several previous studies established an extended gamma-ray emission that is set apart from the radio shell of W44. This emission is thought to originate from escaped high-energy CRs that interact with a surrounding dense molecular cloud complex. Aims. We present a detailed analysis of Fermi-LAT data with an emphasis on the spatial and spectral properties of W44 and its surroundings. We also report the results of the observations performed with the MAGIC telescopes of the northwestern region of W44. Finally, we present an interpretation model to explain the gamma-ray emission of the SNR and its surroundings. Methods. We first performed a detailed spatial analysis of 12 years of Fermi-LAT data at energies above 1 GeV, in order to exploit the better angular resolution, while we set a threshold of 100 MeV for the spectral analysis. We performed a likelihood analysis of 174 hours of MAGIC data above 130 GeV using the spatial information obtained with Fermi-LAT. Results. The combined spectra of Fermi-LAT and MAGIC, extending from 100 MeV to several TeV, were used to derive constraints on the escape of CRs. Using a time-dependent model to describe the particle acceleration and escape from the SNR, we show that the maximum energy of the accelerated particles has to be ≃40 GeV. However, our gamma-ray data suggest that a small number of lower-energy particles also needs to escape. We propose a novel model, the broken-shock scenario, to account for this effect and explain the gamma-ray emission.
Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) Studies of Porphyrin Adsorption on Graphene: Insights on the Effect of Substituents and Central Metal on Adsorption Energies
(Wiley, 2024-12-05) Gara, Rayene; Morales García, Ángel; Arfaoui, Youssef; Illas i Riera, Francesc
Combining metalloporphyrins (MPr) and graphene constitutes key composites in the development of photovoltaic devices. Here, we focus on the analysis of the properties of metalloporphyrins/graphene systems by means of the density functional theory (DFT) and its time-dependent (TDDFT) version, focusing on the ground and singlet excited states. Our benchmark analysis concludes that ωB97XD density functional combined with 6-31G(d)/Def2-TZVP basis set is a better-suited method for simulating accurate MPr adsorption on graphene. It is shown that a reduced atomic model where the external organic shell of the structure is removed provides the same resulting optoelectronic properties of the original model, constituting an important speed-up of the calculations when studying porphyrins-derived molecules. We observe that ZnPr provides the highest light harvesting efficiency (LHE) value. In addition, we find out that the adsorption energy increases monotonically with the size of the graphene flake and the highest stability involves the use of graphene comprising above 500 atoms. Besides, CdPr and HgPr keep their properties as photosensitizers when they are bonded to graphene and show promising values in terms of LHE emerging as suitable solar energy harvesters.
Design of donor–acceptor type benzotrithiophene-based covalent organic frameworks for visible-light-driven overall water splitting
(Elsevier Ltd., 2025-12-23) Wang, Chao; Ontiveros Cruz, Diego; Sousa Romero, Carmen
Benefitting from the abundant accessible catalytic sites and well-defined porous architectures enhancing mass transport, two-dimensional (2D) covalent organic frameworks (COFs) are emerging as promising photocatalysts for overall water splitting (OWS). However, the performance of many known COFs for this application remains unsatisfactory, primarily due to stringent requirements for precise band alignment, the limitation posed by overpotentials in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and mutual interference between the two half-reactions. Herein, we propose eight donor–acceptor (D–A) type 2D benzotrithiophene-based COFs (BTT-COFs), constructed from experimentally feasible building blocks via Schiffbase condensation reaction. By incorporating D–A pairs into the frameworks, these BTT-COFs exhibit enhanced intermolecular charge transfer characteristics as anticipated, thereby promoting efficient carrier separation during OWS. Concurrently, the D–A combinations enable precise modulation of the electronic structure, affording band gaps ranging from 2.35 to 2.89 eV with band-edge arrangements appropriately aligned for photocatalytic OWS under neutral conditions (pH = 7). Among them, the BTT-COF1 (incorporating benzotrithiophene and 1,3,5-triaminobenzene), BTT-COF2 (featuring benzotrithiophene and 2,4,6-triamino-1,3-diazine), and BTT-COF3 (consisting of benzotrithiophene and 2,4,6-triamino-1,3,5-triazine) are found to be capable of spontaneously driving OWS under their intrinsic photoinduced bias potentials. The remaining BTTCOFs require external bias to facilitate the reaction. Crucially, the theoretical solar-to-hydrogen (STH) conversion efficiencies of these materials range from 1.8 % to 10.0 %, highlighting their potential as efficient photocatalysts for OWS.
Long-Distance Charge Transport between Cytochrome c and Complex III is Mediated by Protons and Reactive Oxygen Species
(Wiley-VCH, 2025-09-12) Lagunas, Anna; Gomila, Alexandre M. J.; Nin Hill, Alba; Guerra-Castellano, Alejandra; Pérez-Mejías, Gonzalo; Samitier i Martí, Josep; Rovira i Virgili, Carme; Rosa, Miguel A. de la; Díaz Moreno, Irene; Gorostiza Langa, Pablo Ignacio
Electron transfer (ET) between redox proteins is an essential process in the respiratory and photosynthetic transport chains. While intra-protein ET is well characterized, the experimental methods to investigate inter-protein ET are limited by the presence of the solvent and by the transient nature of the protein– protein interaction and ET event, which are averaged in protein ensembles. Wiring precisely oriented redox protein partners to the nanoscale electrodes of an electrochemical scanning tunneling microscope allows recording the time- and distance-dependence of the current flowing between them. These methods have revealed that the current flowing between individual protein pairs extends beyond tunneling distances and that it is electrochemically gated. However, the corresponding mechanism and the identity of the charge carriers in aqueous solution remain to be elucidated. To determine the species involved in long-distance charge transport between the redox partner proteins Cc and Cc1 of the respiratory chain, recordings are performed as a function of pH, in heavy water solutions, and in degassed solutions. It is observed that the spatial span and electrochemical gating of long-distance currents are reduced at high pH, in heavy water, and at low oxygen concentration, showing that the currents are assisted by superoxide anions and by protons.
Rational design of organic diradicals with robust high-spin ground state based on antiaromatic linkers
(Royal Society of Chemistry, 2024-11-21) Santiago, Raul; Carvajal Barba, M. Àngels; Poater i Teixidor, Jordi; Moreira, Ibério de Pinho Ribeiro; Bromley, Stefan Thomas; Deumal i Solé, Mercè; Ribas Ariño, Jordi
Fully-organic molecules with high-spin ground states are promising building blocks for new lightweight flexible magnetic materials for emerging technological applications (e.g. spintronics). In this study, we explore the potential of diradicals made of two diphenylmethyl-based open-shell cores covalently linked via different types of pentalene and diazapentalene-based antiaromatic couplers (including dibenzopentalenes and acene-inserted derivatives). Accurate electronic structure calculations have been employed to target non-bonding and non-disjoint frontier molecular orbitals that favor high-spin configurations, leading to the identification of diradicals displaying robust triplet ground states. These candidates exhibit singlet-triplet energy gaps that are up to ten times the thermal energy at room temperature. These substantial gaps emerge from strong interactions between the p-systems of the open-shell centers and the antiaromatic coupler. These interactions not only result in high spin states but are also found to lead to an enhanced stability of the diradicals by drastically dampening their inherent antiaromatic character as compared to the bare couplers, and promoting a high degree of spin density delocalization. These findings highlight the potential of pentalene-based diradicals as building blocks for developing new advanced fully organic magnetic materials.
Gas-Phase Production of Hydroxylated Silicon Oxide Cluster Cations: Structure, Infrared Spectroscopy, and Astronomical Relevance
(American Chemical Society, 2024-06-20) Donato, Andreu A. de; Ghejan, Bianca-Andreea; Bakker, Joost M; Bernhardt, Thorsten M.; Bromley, Stefan Thomas; Lang, Sandra M.
The interaction of free cationic silicon oxide clusters, SixOy+ (x = 2–5, y ≥ x), with dilute water vapor, was investigated in a flow tube reactor. Product mass distributions indicate cluster size-dependent dissociative water adsorption. To probe the structure and vibrational spectra of the resulting SixOyH2+ (x = 2–4) clusters, we employed infrared multiple photon dissociation spectroscopy and density functional theory calculations. The planar rhombic cluster core of the disilicon oxides (x = 2) appears to be retained upon dissociative adsorption of one H2O unit, whereas a significant structural transformation of the tri- and tetra-silicon oxides (x = 3 and 4) is induced, resulting in an increased coordination of the Si atoms and more 3D cluster structures. In an astronomical context, we discuss the potential relevance of SixOyHz+ clusters as seeds for dust nucleation and catalysts for carbon-based chemistry in diffuse or translucent interstellar clouds, where all the necessary conditions for producing these species are found. In the produced clusters, the frequency of the isolated silanol Si–OH stretching vibrational mode is considerably blue-shifted compared to that in hydroxylated bulk silica and small inorganic compounds. This mode has a characteristic frequency range between 1200 cm–1 (8.3 μm) and 1090 cm–1 (9.2 μm) and is associated with the anomalously small Si–OH bond lengths in these ionised species. In infrared observations such high frequency Si–O stretching modes are usually associated with a pure bulk silica component of silicate cosmic dust. The presence of SixOyH2+ clusters in low silica astrophysical environments could thus potentially be detected via their signature Si−O band using the James Webb space telescope.
Stable 1,3,2-Benzodithiazolyl Radicals: Modification ofReactivity, Crystal Packing, and Solid State MagneticProperties by Fluorination
(Wiley-VCH Verlag, 2026-02-26) Buravlev, Alexander A.; Makarov, Alexander Yu.; Ribas Ariño, Jordi; Carvajal Barba, M. Àngels; Deumal i Solé, Mercè; Balmohammadi, Yaser; Grabowsky, Simon; Shundrina, Inna K.; Zakharov, Boris A.; Irtegova, Irina G.; Uvarov, Mikhail N.; Bogomyakov, Artem S; Bagryanskaya, Irina Yu.; Shundrin, Leonid A.; Zibarev, Andrey V.
Impact of fluorination on crystal and molecular structure, heteroatom reactivity, and solid-state magnetic properties of thermally-stable π-radicals is studied experimentally and computationally with 1,3,2-benzodithiazolyl 1· and its 4,7-difluoro, 4,5,6,7-tetra-fluoro, and 4,7-difluoro-5,6-(hexafluoropropane-1,3-diyl) derivatives 2-4, respectively. Radicals 2 -4 are isolated by vacuum thermolysis of their unusual covalent 2:1 adducts with 7,7,8,8-tetracyanoquinodimethane. The impact of fluorination on reactivity is evidenced by transformation of 2-4 and 2 +-4 + into corresponding 2H-1-oxo-1,3,2-benzodithiazoles under the influence of air’s or solvents’ moisture; back transformation into the cations under the action of protic acids; and formation of a paramagnetic molecular complex between 3 and naphthalene, whereas 1 and octafluoronaphthalene do not exhibit complexation. The crystal structures of 3 and 4 reveal a novel packing motif featuring radical pairs linked by four-center interactions that stack into offset π-columns, forming a unique zip-π-stack synthon that incorporates head-over-tail π-pairs of radicals. Despite the formation of π-pairs, polycrystalline 3 and 4 display a nonzero effective magnetic moment that rises with temperature above 200 K, although the values remain significantly lower than those of the high-temperature polymorphs of magnetically-bistable 1 and 2·. This behavior can be rationalized by different magnetic topologies and values of spin exchange between the radicals.
Engineered SnO 2/BiOI fibers via electrospinning for robust visible-light/peroxymonosulfate -driven multipollutant mineralization
(Elsevier B.V., 2026-03-01) Huidobro, Laura; Allés, Miquel; Abid, Mahmoud; Bechelany, Mikhael; Sousa Romero, Carmen; Gómez, Elvira; Serrà i Ramos, Albert
Engineered photocatalysts capable of operating under visible light and realistic water matrices are needed to address emerging pharmaceutical contaminants. Here, we fabricate SnO2/BiOI fibrous heterostructures by electrospinning SnO2 nanofibers decorated with solvothermally synthesized BiOI followed by calcination. The electrospun fibers provide a mechanically robust, high-surface-area scaffold, while BiOI incorporation enhances visible-light absorption and creates SnO2/BiOI heterointerfaces. Textural, optical, and spectroscopic analyses reveal progressive surface decoration, increased surface area, and defect-rich Bi environments as BiOI loading increases. Using tetracycline (TC) as a model contaminant at neutral pH, SnO2/BiOI composites markedly outperform pristine SnO2 under visible light and/or peroxymonosulfate (PMS), with an optimal BiOI content (SBO2) under single-stimulus conditions and near-complete TC mineralization for the highest loading (SBO3) in the PMS + visible-light system. Radical scavenging indicates that SO4•− and •OH are the dominant reactive species, with O2•−, h+ and e− playing secondary roles. A multipollutant mixture (TC, sulfamethoxazole, levofloxacin, lansoprazole) is mineralized by >80% in both Milli-Q and tap water, and SBO3 retains high activity over nine cycles with Bi and I leaching below 0.05% after 48 h. Density functional theory calculations, combined with XPS, support an S-scheme SnO2/BiOI heterojunction, enabling spatial separation of strongly reducing electrons in BiOI and oxidizing holes in SnO2. Although high PMS loadings can partially mask intrinsic catalyst differences, these results outline a practical design platform for heterogeneous (slurry), visible-responsive, PMS-assisted photocatalysts for pharmaceutical-laden effluents.
Formation of a covalent adduct in retaining β-Kdo glycosyl-transferase WbbB via substrate-mediated proton relay
(Wiley-VCH, 2024-07-22) Sagiroglugil, Mert; Liao, Qinghua; Planas, Antoni; Rovira i Virgili, Carme
The GT99 domain of the membrane-anchored WbbB glycosyltransferase (WbbBGT99) catalyzes the transfer of 3-deoxy-D-manno-oct-2-acid (β-Kdo) to an O-antigen saccharide acceptor with retention of stereochemistry. It has been proposed that the enzyme follows an unprecedented double-displacement mechanism involving the formation of covalent adduct between the Kdo sugar and an active site residue (Asp232) that is properly oriented for nucleophilic attack. Here we use QM/MM metadynamics simulations on recently reported crystal structures to provide theoretical evidence for the formation of such adduct and unveil the atomic details of the chemical reaction. Our results support the interpretation made on the basis of X-ray and mass spectrometry analyses. Moreover, we show that the formation of the β-Kdo-Asp232 adduct is assisted by the sugar Kdo-carboxylate group, which mediates the transfer of a proton from Asp232 towards the phosphate leaving group, alleviating electrostatic repulsion between the two negatively charged carboxylate groups. The computed mechanism also explains whyvHis265, previously proposed to act as a general acid, does not impairvcatalysis. This mechanism can be extended to other related enzymes, expanding the repertoire of GT mechanisms in Nature.
Understanding the Chemical Bond in Semiconductor/MXene Composites: TiO2 Clusters Anchored on the Ti2C MXene Surface
(Wiley-VCH, 2024-02-22) García-Romeral, Néstor; Keyhanian, Masoomeh; Morales García, Ángel; Viñes Solana, Francesc; Illas i Riera, Francesc
First-principles calculations on titania clusters (TiO2)n (n=5 and 10) supported on the pristine Ti2C (0001) surface were carried out to understand the properties of semiconductor/MXene composites with implications in (photo)-catalysis. The reported results reveal a high exothermic interaction accompanied by a substantial charge transfer with a concomitant, notorious, deformation of the titania nanoclusters. The analysis of the density of states analysis of the composite systems evidences a metallic character with titania related states crossing the Fermi level. The picture of the chemical bonds is completed by the analysis of X-Ray Photoelectron Spectra (XPS) features, evidencing clear shifts of the C(1s) and O(1s) related peaks relative to the isolated systems that have a quite complex origin. This detailed analysis provides insights to experimentalists interested in the design and synthesis of these systems with possible applications in catalys
Chemical bonding and electronic properties along Group 13 metal oxides
(Springer Verlag, 2024-05-07) Kapse, Samadhan; Voccia, Maria; Viñes Solana, Francesc; Illas i Riera, Francesc
The present work provides a systematic theoretical analysis of the nature of the chemical bond in Al 2 O 3, Ga 2 O 3 ,and In2O3 group 13 cubic crystal structure metal oxides. The influence of the functional in the resulting band gap is assessed. The topological analysis of the electron density provides unambiguous information about the degree of ionicity along the group which is linearly correlated with the band gap values and with the cost of forming a single oxygen vacancy. Overall, this study offers a comprehensive insight into the electronic structure of metal oxides and their interrelations. This will help researchers to harness information effectively, boosting the development of novel metal oxide catalysts or innovative methodologies for their preparation.
Engineered π⋯π interactions favour supramolecular dimers $\mathrm{X@[FeL_{3}]_{2}(X = Cl, Br, I)}$: solid state and solution structure
(Royal Society of Chemistry, 2024-05-28) Risa, Arnau; Barrios Moreno, Leoní Alejandra; Diego, Rosa; Roubeau, Olivier; Aleshin, Dmitry Y.; Nelyubina, Yulia; Novikov, Valentin; Teat, Simon J.; Ribas Ariño, Jordi; Aromí Bedmar, Guillem
Ditopic bis-pyrazolylpyridine ligands usually react with divalent metal ions ($\mathrm{M^{2+}}$) to produce dinuclear triple- stranded helicates $\mathrm{[M_{2}L_{3}]^{4+}}$ or, via $\mathrm{\pi\cdots\pi}$ interactions, dimers of monoatomic complexes $\mathrm{([ML_{3}]_{2})^{4+}}$. The introduction of an additional benzene ring at each end of ligand L increases the number of aromatic contacts within the supramolecular aggregate by 40%, driving the self-recognition process in an irreversible manner. Consequently, the mixing of new bis-pyrazolylquinoline L2 with $\mathrm{FeX_{2}}$ salts leads to crystallization of the tripartite high-spin assemblies $\mathrm{(X@[Fe(L2)_{3}]_{2})^{3+}(X = Cl, Br or I)}$. The aggregates exhibit exceptional stability, as confirmed by a combination of paramagnetic $\mathrm{^{1}H}$ NMR techniques, demonstrating their persistence in solution. Our investigations further reveal that the guests$\mathrm{Br^{-}}$ and $\mathrm{I^{-}}$ are retained inside the associate in solution but $\mathrm{Cl^{-}}$ is immediately released, resulting in the formation of the empty supramolecular dimer $\mathrm{([Fe(L2)_{3}]_{2})^{4+}}$
Family of Quasi-Isotropic $Mn^{II}$ and ${Mn_2}^{II}$ Complexes Exhibiting Slow Relaxation of the Magnetization
(American Chemical Society, 2024-10-16) Pilichos, Evangelos; Font Bardia, Ma. Mercedes; Aullón López, Gabriel; Mayans Ayats, Júlia; Escuer Fité, Albert
Slow relaxation of magnetization has been studied for a family of mononuclear MnII complexes and one ferromagnetic dinuclear system, all of them presenting very weak anisotropy. Complexes with formula $[\{NiL1Mn-(H_{2}O)_{2}(MeOH)\}\{NiL1\}_{2}](ClO_{4})_{2}$ (1), [Mn{NiL1}2](ClO4)2 (2), $[Mn\{NiL2\}_{2}](ClO_{4})_{2}(RR-L2^{2-}, 3RR, SS-L2^{2-}, 3SS)$, $[Mn\{NiL3\}_{2}](ClO_{4})_{2}(RR-L3^{2-}, 4RR, SS-L3^{2-}, 4SS)$ and $(\mu_{1,1}-N_{3})_{2}[Ni_{2}Mn_{2}(L1)_{2}(N_{3})_{2}]$ (5) are derived from compart- mental Schiff bases, in which the NiII environment is square planar and thus diamagnetic. All of the systems have been structurally and magnetically characterized. Zero field splitting (D) values for the MnII cations have been obtained from EPR spectroscopy and NEVPT2 calculations. The slow relaxation of the magnetization for 1−5 has been studied by means of ac magnetometry and rationalized on the basis of their low, but not zero, anisotropy, providing the first example of a polynuclear MnII complex, with S = 5 ground state, exhibiting slow relaxation.
No Switching Cooperativity between Coordinated Azo Ligands on Complexes Having $M^{II}(phosphane-k^2P)\}^{2+}\ ( M = Pd, Pt)$ Scaffolds
(American Chemical Society, 2024-08-21) Raïch Panisello, Ot; Jover Modrego, Jesús; Puigjaner Vallet, Ma. Cristina; Ferrer García, Montserrat; Martínez López, Manuel, 1957-
A series of square-planar palladium and platinum compounds with cis-blocking phosphanes and terminal azobenzene ligands ${[M(dppp)-(azo)_{2}] (OTf)_{2} (azo = CN(C_{6}H_{4})-N = N-(C_{6}H_{4})CN (iso-cyano), CN(C_{6}H_{4})-N = N-(C_{6}H_{5}) (iso-Ph)) and [{M_{2}(tpbz)}(azo)_{4}](OTf)_{4}(azo = CN(C_{6}H_{4})-N = N-(C_{6}H_{5})}$ have been synthesized and fully characterised. Similarly to the uncoordinated ligands, the new coordination compounds have shown to be photochemically active with respect to their trans-to-cis isomerization process. Their cis-to-trans back spontaneous reaction have been studied as a function of solvent, temperature and pressure and the corresponding activation parameters determined in order to investigate the mechanism of these transformations. The results obtained are indicative of the operation of a rotational mechanism with no cooperativity between the azo ligands attached to the same metal. DFT calculations have been carried out in order to estimate the relative energies of the different photoisomers for the theoretical interpretation of the experimental data.
Unlocking the predictive power of quantum-inspired representations for intermolecular properties in machine learning
(Royal Society of Chemistry (RSC), 2024-01-17) Santiago, Raul; Vela Llausí, Sergi; Deumal i Solé, Mercè; Ribas Ariño, Jordi
The quest for accurate and efficient Machine Learning (ML) models to predict complex molecular properties has driven the development of new quantum-inspired representations (QIR). This study introduces MODA (Molecular Orbital Decomposition and Aggregation), a novel QIR-class descriptor with enhanced predictive capabilities. By incorporating wave-function information, MODA is able to capture electronic structure intricacies, providing deeper chemical insight and improving performance in unsupervised and supervised learning tasks. Specially designed to be separable, the multi-moiety regularization technique unlocks the predictive power of MODA for both intra- and intermolecular properties, making it the first QIR-class descriptor capable of such distinction. We demonstrate that MODA shows the best performance for intermolecular magnetic exchange coupling (JAB) predictions among the descriptors tested herein. By offering a versatile solution to address both intra- and intermolecular properties, MODA showcases the potential of quantum-inspired descriptors to improve the predictive capabilities of ML- based methods in computational chemistry and materials discovery.

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