Articles publicats en revistes (Química Inorgànica i Orgànica)

URI permanent per a aquesta col·leccióhttps://hdl.handle.net/2445/9245

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Conformational sampling of seven-membered rings using extended puckering collective variables in metadynamics
(American Institute of Physics (AIP), 2025-09-24) Sagiroglugil, Mert; Nin Hill, Alba; Rovira i Virgili, Carme
Seven-membered rings, though scarce in biosynthetic pathways, are increasingly recognized as conformationally rich scaffolds for engineered enzymes and drug leads. Accurately capturing their flexibility requires the use of enhanced-sampling methods. Here we present a set of collective variables (CVs) for metadynamics simulations that extend the Cremer–Pople puckering coordinates to seven-membered rings, and we validate them on cycloheptane and other molecules of increasing complexity (buxenine-G, two azepane derivatives, and ε-caprolactone). The new CVs can be used directly in PLUMED—a popular open-source library for enhanced-sampling and free-energy methods—so they can be used directly in metadynamics workflows. They allow the investigation of conformational transitions, the identification of metastable states, and the mapping of free-energy landscapes of any seven-membered-ring molecule. This provides a quantitative framework for probing the conformational behavior of flexible seven-membered scaffolds and will aid in the rational design of conformationally locked substrates for enzyme engineering and related applications.
Spin coherence and electron spin distribution of a Silver(II) S = ½ molecular system
(American Chemical Society, 2025-06-11) Serra, Judit; Salvadori, Enrico; Liao, Yu-Kai; Gallen Ortiz, Albert; Escuer Fité, Albert; Chiesa, Mario; Mayans Ayats, Júlia
The spin–lattice relaxation time, spin coherence, and spin distribution have been studied through ac susceptometry, pulse EPR, and ultralow-frequency Raman spectroscopy on a silver(II)-derived molecular system with spin 1/2. The combination of magnetometry and spectroscopy techniques demonstrates the occurrence of slow spin magnetic relaxation induced by a spin–phonon interaction. The magnetic behavior and the spin coherence of this AgII-derived system open the door to a new cation into the scarce family of S = 1/2 slow magnetic relaxing systems for further applications in quantum technologies.
π-π Stacking Determines the Selectivity of Unnatural DNA Base Pairs Even without Polymerase
(American Chemical Society, 2026-01-01) Noori, Zahra; Bermejo, Andreu; Bofill i Villà, Josep M.; Poater i Teixidor, Jordi
Expanding the genetic alphabet requires a mechanistic understanding of how synthetic bases are faithfully replicated alongside natural DNA. We present a quantum chemical study reproducing the experimentally observed single-nucleotide incorporation selectivity of Hirao’s unnatural base pairs (UBPs) by the 3′–5′ exonuclease-deficient Klenow fragment of Escherichia coli DNA polymerase I. Our analysis focuses on the highly selective DsPx pair, benchmarking its behavior against canonical Watson–Crick pairs and other UBPs. Strikingly, the observed selectivity emerges without explicitly modeling the polymerase, relying solely on computed stacking energies within the DNA helix. Molecular orbital and energy-decomposition analyses show that both electrostatic and dispersion interactions strengthen DsPx’s affinity more, capturing experimental fidelity trends and explaining its superior performance relative to related systems. We further evaluate other selective UBPs, including QPa, DsPa, and DsPn. Together, these results provide a quantitative framework for UBP incorporation selectivity and highlight the crucial role of noncovalent interactions in stabilizing synthetic bases within DNA. By bridging computation and experiment, this work advances design principles for synthetic genetic systems and contributes to unraveling the molecular origins of DNA replication fidelity.
Mechanism of Bacterial Arginine N-Glycosylation: A Chemically Challenging Post-Translational Modification
(American Chemical Society, 2026-02-06) Piniello, Beatriz; García-García, Abel; Pietrucci, Fabio; Hurtado Guerrero, Ramón; Rovira i Virgili, Carme
Arginine N-glycosylation is a post-translational modification that bacterial pathogens use to subvert host immunity, yet the catalytic activation of the intrinsically weak guanidinium nucleophile has remained unresolved. Based on structural data, a direct inverting SN2 mechanism had been suggested, but alternative, more stepwise routes and the identity of the catalytic base could not be firmly established. Here, we delineate the molecular mechanism by which the nonlocus of enterocyte effacement (non-LEE)-encoded effector protein B1 (NleB1), a promising virulence factor of enteropathogens, transfers N-acetylglucosamine (GlcNAc) to arginine residues of host substrates. Using structural modeling, extensive molecular dynamics, and state-of-the-art QM/MM free-energy simulations combined with kinetic experiments, we elucidate the catalytic mechanism of NleB1. The reaction proceeds through a single-step, dissociative SN2-type mechanism, with no stable intermediate. Proton transfer to the catalytic base occurs immediately after the transition state, and is preceded by distortion (loss of planarity) of the acceptor guanidinium that primes nucleophilic attack. The simulations unambiguously identify Glu253, rather than Asp186, as the general base, and reveal that Glu253 plays multiple roles: it disrupts the planar guanidinium conformation of the acceptor arginine to enhance nucleophilicity, orients Arg117, accepts its proton, and subsequently promotes product relaxation via guanidinium replanarization, while Asp186 acts structurally to stabilize the donor substrate. Together, these residues enable a chemically demanding transformation that challenges chemical expectations for guanidinium reactivity. This study provides a comprehensive mechanistic study of arginine N-glycosylation, resolving its long-standing mechanistic conundrum and establishing catalytic rules likely conserved among Arg-specific glycosyltransferases.
Novel octapeptide containing the RGD sequence as a potential anti-SARS-CoV-2 agent: design, synthesis, and theoretical studies
(Springer Verlag, 2025-11-20) Lemos, Reiner; Ortiz, Orlando; Almagro, Luis; Makowski, Kamil; Rodríguez, Hortensia; Albericio Palomera, Fernando; Suarez, Margarita
The design of peptide-based inhibitors targeting cell receptors represents a promising strategy in the development of antiviral agents. In this study, a novel octapeptide containing the RGD sequence was rationally designed to explore its potential interaction with integrins. The peptide was functionalized with a malonic moiety to enhance its binding capabilities and potential bioactivity. Conformational and physicochemical properties were evaluated using DFT-PBEh-3ccalculations. Molecular docking studies revealed favorable interactions with the integrin α5β1, including coordination with the Mg²⁺ ion at the active site. The peptide was successfully synthesized via Fmoc-based solid-phase peptide synthesis (SPPS) and fully characterized by NMR, IR, MS, and RP-HPLC.
Study of carbon-supported copper catalysts from orange peels − Preparation, characterization, and application in α-pinene oxidation
(Elsevier B.V., 2025-05-01) Kaminska, Adrianna; Sreńscek-Nazzal, Joanna; Serafin, Jarosław; Kałamagad, Agnieszka; Kiełbasa, Karolina; Wróblewska, Agnieszka
The use of orange peel as a precursor for activated carbon (AC) is a promising way to valorize this waste due to its ease of acquisition and the high elemental carbon content of this raw material. In this study, two different methods for the synthesis of carbon catalysts based on AC from biomass were presented. In these methods, H3PO4 was used as the chemical activator, while Cu (NO3)2 acted as the metal precursor for the active phase of the catalyst. Copper was introduced into the carbon material at different stages of preparation (before and after carbonization). The catalysts were characterized using FTIR, XRD, SEM, EDX and XPS. The textural properties were investigated using N2 sorption at −196 °C. These materials were successfully used in the oxidation of α-pinene and the conversion of this cheap terpene into compounds of great industrial importance (α-pinene oxide, verbenone and verbenol). The results showed that the material prepared by impregnating the already prepared carbon support (AC_5%Cu_impregnation) was more active. For this catalyst, the conversion of α-pinene was 53 mol%, while this value for AC_5%Cu_oven sample was 43 mol%. The selectivity of the α-pinene oxide was 48 mol% for AC_5%Cu_impregnation sample and 39 mol% for AC_5%Cu_oven catalyst. The selectivities of the other products eg. verbenone and verbenol were not significantly different for both catalysts. Considering catalytic activity, it was found that a better method of prepared catalysts for use in the α-pinene oxidation was impregnation of carbonaceous support with a copper salt solution after the carbonization process.
Cobalt-stabilized propargylic oxocarbenium ions enable direct and asymmetric nickel(II) catalyzed aldol-like reactions
(American Chemical Society, 2026-07-03) Tarrach, Xènia; O’Neill, Leah; Costa i Arnau, Anna M.; Romea, Pedro; Urpí Tubella, Fèlix; Sánchez Castillo, Laura; Berhane, Esrom; Fernández Vilana, Marc; Danczura, Emilia; Puigjaner Vallet, Ma. Cristina
We describe a direct and asymmetric aldol-like reaction between a wide range of N-acyl-1,3-oxazolidine-2-thiones and cobalt-protected propargylic acetals catalyzed by a chiral nickel(II) complex leading to syn β-alkoxy derivatives. This overcomes longstanding limitations associated with acetals from aliphatic aldehydes, selectively providing syn aldol adducts in excellent yields as single stereoisomers (dr >97:3, er up to >99:1). Furthermore, the cobalt fragment enables downstream intramolecular Pauson-Khand cyclizations, granting rapid access to densely functionalized bicyclic architectures.
Unlocking room temperature phosphorescence in dibenzothiophene-based systems via the Scholl reaction
(Elsevier B.V., 2025-07) Fabregat, Clara; Bujaldón Carbó, Roger; Garcia Amorós, Jaume; Volyniuk, Dmytro; Ghasemi, Melika; Grazulevicius, Juozas V.; Velasco Castrillo, Dolores
A family of butterfly-shaped diphenanthro[9,10-b:9′,10′-d]thiophene derivatives has been straightforwardly synthesized from tetrabromothiophene via consecutive Suzuki-Miyaura and Scholl reactions, targeting potential charge-transporting and light-emitting organic materials. Indeed, time of flight measurements displayed hole mobility values up to 4.7 × 10−5 cm2 V−1 s−1 under an applied electric field of 6 × 105 V cm−1. Spectroscopic studies showed promising photoluminescence, with quantum yields up to 27.5 % and adjustable emissions ranging from deep blue to sky blue in solution and in solid films, respectively. Moreover, the synthesized compounds revealed room-temperature phosphorescence when introduced as dopants in Zeonex films, a highly sought-after characteristic in metal- and halogen-free organic materials. This phenomenon delineates a spectral transition from deep blue to warm-white emission as the environment shifts from air-equilibrated to vacuum conditions, which entails different applications such as lighting or oxygen-sensing devices. Phosphorescence, which was further corroborated in dilute solutions of THF at 77 K, does not occur on the non-cyclized synthetic precursors, demonstrating the key role of the Scholl reaction to unlock it. These findings make evidence of the potential of this core for advancing optoelectronic device functionalities.
Supramolecular sensing with luminescent gold(I) and platinum (II) organometallics
(Elsevier B.V., 2026-03-01) Lázaro Palacios, Ariadna; Pinto Martínez, Andrea; Rodríguez Raurell, Laura
Luminescent chemosensors based on supramolecular principles provide sensitive, non-invasive detection of diverse analytes. Among non-covalent interactions, metallophilic forces, weak attractions between closed-shell metal centers, have proven effective in tuning photophysical properties. This review highlights recent advances in gold (I) and platinum(II) chemosensors, where Au(I)···Au(I) and Pt(II)···Pt(II) contacts govern sensing. Analyte binding modulates metal–metal proximity, switching luminescence via unique emissive states such as MMLCT. These interactions also drive aggregation-induced emission (AIE), vapochromism, and excimer-like emission. Applications include detecting heavy metals, anions, VOCs, PAHs, and biorelevant molecules. Overall, leveraging metallophilic interactions offers a versatile strategy for designing advanced luminescent sensors.
Exploring the toxicity of mononuclear piano-stool Ru(II) anticancer agents: A comprehensive literature review
(Elsevier B.V., 2025-11-15) Sojka, Martin; Gámez Enamorado, Patrick
Piano-stool Ru(II) complexes have emerged as a promising class of anticancer agents characterized by structural modularity and diverse cytotoxic activities. The present review consolidates over three decades of research, analyzing IC50 data for 1,449 mononuclear Ru(II) compounds across 151 cancer and healthy cell lines. The whole dataset reveals structure-activity relationships (SAR), emphasizing the role of multidentate ligands – particularly NN-, NO-, and OO-types – and ηn-rings in modulating the biological activity. Compounds with cyclopentadienyl groups often exhibit remarkable effectiveness, achieving sub-micromolar IC50 values and demonstrating efficacy against drug-resistant cancer lines. The bibliographic analysis highlights the versatility of certain ligand combinations, particularly triphenylphosphane with mono- and bidentate ligands, including bipyridine or thioacetamide motifs, which drive exceptional cytotoxic properties. Despite the extensive data set, some gaps remain as some cancer types are underrepresented, and the mechanism(s) of action of the Ru(II)-based cytotoxic agents is(are) not yet fully understood. Future possible research directions within this remarkable family of mononuclear half-sandwich Ru(II) complexes are given.
Revealing the spin structure, exchange constants and local anisotropy in nanoparticles with polarised neutron powder diffraction: Mn3O4 as case study
(Elsevier, 2026-10-01) Kibalin, Iurii; Gukasov, Arsen; Golosovsky, Igor; Roca, A. G.; López-Ortega, Alberto; Estrader i Bofarull, Marta; Hansen, Thomas C.; Puente Orench, Ines; Lelièvre-Berna, Eddy; Nogués, Josep
The functional magnetic properties of nanostructured materials can be distinctly different from their bulk counterparts. Understanding these properties is crucial for basic material science and for applications using nanostructured magnetic materials. However, determining intrinsic magnetic structures, exchange constants and local magnetic anisotropy in nanoparticles poses considerable challenges. Here, polarised neutron powder diffraction (PNPD) data, analysed in the frame of the Local Susceptibility and Model Hamiltonian approaches, is used to gain information on the contribution of the different magnetic sublattices on the magnetisation process in Mn3O4 nanoparticles in unprecedented detail. The magnetic order is found to be a Yafet-Kittel-type canted structure with inter- and intra-sublattice antiferromagnetic couplings, similar to bulk. PNPD corroborates that the c-axis is the hard-axis and the individual contributions of each magnetic site to the easy-plane magnetic anisotropy are determined. Remarkably, the analysis of the PNPD data provides the foremost determination of the microscopic magnetic parameters in nanoparticles, namely, intra- and inter- sub-lattice exchange constants and the local anisotropy parameter. The obtained values are consistent with bulk Mn3O4 experimental and theoretical results. These results open the path for the use of PNPD to gain unique magnetic information in nanostructured materials, particularly in complex, novel, or poorly understood systems.
Targeted KRASG12V Degradation in vivo Elicits Lung Adenocarcinoma Regression with Subsequent Relapse from Dysregulated Proteolysis
(American Association for Cancer Research, 2026-08-14) Martín Cardona, Albert; García-Pérez, Inés M.; San José, Sonia; Rojo, Pep; Riego Mejías, Carlos; Teodosio, Cristina; Barbosa, Bárbara M. G.; Sánchez Zarzalejo, Carolina; Folch i Casanovas, Ignasi; Odena Caballol, Antonia; Jarió Ruana, Sònia; Hijazo Pechero, Sara; Rodríguez-López, Silvia; Entrialgo-Cadierno, Rodrigo; Nokin, Marie-Julie; Muñoz Félix, José Manuel; Loa-Mesón, Diana; Guruceaga, Elisabeth; Stephan-Otto Attolini, Camille; Ambrogio, Chiara; Villanueva Garatachea, Alberto; Vicent, Silvestre; Riera Mestre, Antoni; Santamaria, David; Mayor-Ruiz, Cristina
Recent drug discovery breakthroughs led to the approval of KRASG12C inhibitors in lung adenocarcinoma (LUAD). Unfortunately, clinical responses are often hampered by the rapid resistance onset. Proteolysis-targeting chimeras (PROTACs) have emerged as promising alternatives to traditional inhibition. However, there is limited mechanistic understanding of KRAS degradation in vivo. Here, we developed a preclinical LUAD mouse model and demonstrated that targeted oncogenic KRAS degradation induces rapid tumor regression primarily due to cancer cell-autonomous mechanisms. Yet, transcriptional, histological, and immunophenotypic analyses revealed a substantial remodeling of the tumor microenvironment. Notably, disease relapse observed during prolonged PROTAC treatment stemmed mostly from proteolysis machinery dysregulation, indicating resistance mechanisms distinct from those reported upon KRAS inhibition. Collectively, these findings highlight the therapeutic potential of KRAS degradation in LUAD, providing insights into both cell-intrinsic and -extrinsic mechanisms that accompany antitumor responses and support the ongoing clinical exploration of this approach.
Transition metaldoped TiO₂ and CeO₂ photocatalysts modified with Ti₃C₂ MXene for PMS-driven advanced oxidation of pharmaceutical pollutants
(Elsevier B.V., 2025-09-26) Serafin, Jarosław; Bujaldón Carbó, Roger; Sreńscek-Nazzal, Joanna; Kałamagad, Agnieszka; Gómez, Elvira; Vendrell, Xavier; Serrà i Ramos, Albert
Pharmaceutical residues are increasingly persistent in aquatic environments due to their chemical stability andresistance to conventional wastewater treatment. To address this, we developed a two-step, performance-guidedsynthesis of TiO₂- and CeO₂-based photocatalysts: first doped with transition metals (Fe, Ni, Cu, Mo, Pd) andsubsequently modified with 2D Ti₃C₂ MXene to enhance peroxymonosulfate (PMS) activation under UV andvisible light. Among the dopants, Fe and Ni imparted the most favorable physicochemical features, includingnarrowed optical band gaps, increased oxygen vacancy concentrations, and reduced photogenerated chargerecombination, as evidenced by UV–vis, XPS, and photoluminescence analyses. Post-synthetic MXene integrationimproved interfacial charge separation and visible-light absorption, achieving >99 % total organic carbon (TOC)mineralization of a ternary pharmaceutical mixture (tetracycline, levofloxacin, and paracetamol) in real tapwater under UV irradiation. Comprehensive structural (XRD, Raman, TEM), optical (UV–vis DRS, PL), andsurface (XPS) characterizations identified the Ni–CeO₂–MXene composite as the most efficient, showing optimaldefect structure, redox activity, and electronic conductivity. The catalyst maintained >95 % activity over fivereuse cycles, with minimal leaching confirmed by ICP-OES. Post-reaction XPS revealed moderate surfacemodification (Ce4+/Ce3+ and Ni2+/Ni3+ ratios shift) without signs of structural degradation. Kinetic analysisconfirmed pseudo-first-order degradation with high rate constants and short half-lives, highlighting theirapplicability for rapid pharmaceutical mineralization. This study proposes a rational and selective approach forcoupling metal doping and 2D conductive interfaces, enabling the scalable design of stable and efficient photocatalystsfor PMS-driven advanced oxidation processes (AOPs) in water purification
MXenes: Multifunctional 2D materials for hydrogen evolution, energy storage, and carbon capture applications
(Elsevier B.V., 2025-11-01) Serafin, Jarosław; Chaitoglou, Stefanos; Farid, Ghulam; Ma, Y.; Dziejarski, Bartosz; Sánchez Niubò, Albert; Vendrell, Xavier; Amade Rovira, Roger
Ti₃C₂Tₓ MXene was synthesized by selective etching of Ti₃AlC₂ MAX phase using HF. Structural and surface properties were assessed via XRD, Raman, SEM, HRTEM, BET, and XPS, confirming Al removal, interlayer expansion, and functionalization with single bondF, –OH, and = O groups. The resulting MXene exhibited a specific surface area of 26.7 m2/g and pore size of 16.2 nm. A single batch was deployed in three applications: as an HER electrocatalyst in 1 M H₂SO₄, achieving −511 mV onset potential, 190 mA cm−2 at −760 mV, and a Tafel slope of 184 mV dec−1; as a supercapacitor electrode in 3 M KOH, with areal capacitance of 411.1 mF cm−2 and 86.9 % diffusion-controlled contribution; as a CO₂ adsorbent, achieving uptakes of 0.80 and 0.66 mmol g−1 at 0 °C and 25 °C, respectively. Adsorption data fitted best to the Radke–Prausnitz isotherm, indicating mixed physisorption–chemisorption. A techno-economic analysis yielded a production cost of ~2.83 €/g. These results demonstrate the multifunctionality and scalability of Ti₃C₂Tₓ MXene as a good material for hydrogen generation, energy storage, and carbon capture.
Coupling TiO2 with Nb carbide-based materials for H2 photoproduction: From 3D carbides to 2D MXenes
(Elsevier B.V., 2025) Sánchez Ruiz, Adrià; Escolano Casado, Guillermo; Bania, Margarita; Koning, Matthijs; Serafin, Jarosław; Ramírez de la Piscina, Pilar; Mino, Lorenzo; Homs Martí, Narcís
In this work we coupled 3D Nb carbide, ternary layered NbMAX, and 2D NbMXene with TiO2, developing new photocatalysts for the renewable H2 production from ethanol aqueous solutions. A new preparation method of Nb2CTx MXene is reported; the hydrothermal method proposed uses NH3(aq) and avoids the utilization of hazardous HF or a strong acid and fluoride salts. After thorough characterization of the structural and physico-chemical features of the materials, their photocatalytic performance has been related to their photoelectrochemical properties. Moreover, the interaction of the reactant molecules with the TiO2-based composites and their evolution under UV irradiation has been investigated by in situ IR spectroscopy. All composites showed a higher H2 production rate and a higher lifetime of photogenerated charges (h+/e-) than TiO2. The Nb2CTx-containing photocatalyst showed the best H2 production yield, both in gas and liquid phase, owing to a very efficient transfer of the photogenerated electrons from the TiO2 conduction band to the MXene phase, decreasing the rate of charge recombination and favoring the H2 formation. The H2 production of NbMXene/TiO2 was more than 3.5 times that of TiO2 and showed a stable behavior at least up to 7 h with light on/light off cycles.
New UB006 derivatives with a higher solubility and cytotoxic activity in ovarian cancer cells
(MDPI, 2025-01-31) Reina del Pozo, Manuel; Ariza Piquer, Xavier; Serra i Cucurull, Dolors; García Gómez, Jordi; Herrero Rodríguez, Laura
Background/Objectives: The compound (±)-UB006 ((4SR,5SR)-4 (hydroxymethyl)- 3-methylene-5-octyldihydrofuran-2(3H)-one) is a promising anti-cancer molecule. The enantiomer (–)-UB006 displays a potent cytotoxic effect in several tumor cell lines, particularly the ovarian cancer OVCAR-3 cell line, with a 40-fold increase in potency compared with the fatty acid synthase (FAS) inhibitor C75. Furthermore, in vivo, (–)-UB006 reduced the tumor burden in neuroblastoma xenografts. This effect was attributed to FAS inhibition and upregulation of apoptotic markers. However, CoA adducts of UB006 presented low solubility. Methods: We synthesized several (±)-UB006 derivatives by elongating the carbon chain of the primary alcohol and/or by adding hydroxyl groups with the aim of finding more potent and soluble anti-cancer compounds. Results: Our results showed a decrease in cytotoxicity when the carbon chain was elongated by more than two carbons. However, ethyl or propyl polyhydroxylated four-branched compounds showed an increased or maintained potency and solubility. The most promising compound was (±)-UB035 (IC50: 2.1 ± 0.2 µM), with a 2.5-fold increase in cytotoxicity in the OVCAR-3 cell line and a >4-fold increase in solubility (>2 mM) compared with (±)-UB006.
Conformational free energy landscape of β-glucose in the gas phase and aqueous solution: Energetic, structural, and electronic changes
(American Chemical Society, 2025-05-09) Liao, Qinghua; Morais, Manuela; Rovira i Virgili, Carme; Nin Hill, Alba
The conformational flexibility of β-glucose is critical for the enzymatic breakdown of carbohydrates such as cellulose and starch. Detailed knowledge of its ring conformations supports the rational design of therapeutic agents and functional molecules, including glucosidase activity-based probes. Although quantum mechanical methods have been employed to study β-glucose conformations, a comprehensive analysis of the Cremer–Pople conformational space, particularly accounting for solvent effects, remains incomplete. Using density functional theory (DFT), we systematically characterize β-glucose conformations in both gas and aqueous phases. We apply three metadynamics approaches ─ standard, well-tempered, and parallel bias ─ using Cremer–Pople polar coordinates and ring dihedral angles as collective variables. Consistent conformational stability trends are observed across methods and environments. In both gas and aqueous phases, the free energy landscape (FEL) identifies the 4C1 chair as the global minimum, followed by equatorial conformers and the inverted 1C4 chair, which is less stable in solution than in the gas phase. In the gas phase, the most stable distorted conformers (in the 2SO –B3,O – 1S3 region) exhibit structural and electronic features characteristic of an oxocarbenium ion, including a high C1–O1/C1–O5 bond length ratio, a pronounced anomeric effect, and negative charge accumulation at O1 and O5. These features are significantly diminished in aqueous solution, suggesting that the gas-phase FEL better reflects the conformational preferences of the saccharide at the -1 subsite in enzyme–substrate complexes of glucosidases. These findings provide a valuable framework for investigating saccharide conformations, establishing β-glucose as a model system for computational and methodological benchmarking.
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.
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.
The Coordinate Reaction Model: An Obstacle to Interpreting the Emergence of Chemical Complexity
(Wiley-VCH, 2021-07-14) Ribó i Trujillo, Josep M.; Hochberg, David
The way chemical transformations are described by models based on microscopic reversibility does not take into account the irreversibility of natural processes, and therefore, in complex chemical networks working in open systems, misunderstandings may arise about the origin and causes of the stability of non-equilibrium stationary states, and general constraints on evolution in systems that are far from equilibrium. In order to be correctly simulated and understood, the chemical behavior of complex systems requires time-dependent models, otherwise the irreversibility of natural phenomena is overlooked. Micro reversible models based on the reaction-coordinate model are time invariant and are therefore unable to explain the evolution of open dissipative systems. The important points necessary for improving the modeling and simulations of complex chemical systems are: a) understanding the physical potential related to the entropy production rate, which is in general an inexact differential of a state function, and b) the interpretation and application of the so-called general evolution criterion (GEC), which is the general thermodynamic constraint for the evolution of dissipative chemical systems.

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