Articles publicats en revistes (Química Inorgànica i Orgànica)

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Kinetic and Mechanistic Studies of Native Chemical Ligation with Phenyl α-Selenoester Peptides
(ACS Publications, 2024-10-30) Sánchez Campillo, Iván; Blanco Canosa, Juan B.
Native chemical ligation (NCL) ligates two unprotected peptides in an aqueous buffer. One of the fragments features a C-terminal α-thioester functional group, and the second bears an N-terminal cysteine. The reaction mechanism depicts two steps: an intermolecular thiol–thioester exchange resulting in a transient thioester, followed by an intramolecular S-to-N acyl shift to yield the final native peptide bond. Although this mechanism is well established, the direct observation of the transient thioester has been elusive because the fast intramolecular rearrangement prevents its accumulation. Here, the use of α-selenoester peptides allows a faster first reaction and an early buildup of the intermediate, enabling its quantification and the kinetic monitoring of the first and second steps. The results show a correlation between the steric hindrance in the α-thioester residue and the rearrangement rate. In bulky residues, the S-to-N acyl shift has a significant contribution to the overall reaction rate. This is particularly notable for valine and likely for other similar β-branched amino acids.
Computational Study of a Copper-Catalyzed Synthesis of Fluoroalcohols from Alkylboranes and Ketones
(American Chemical Society, 2025-09-03) Gómez-Mudarra, Francisco A.; Aullón López, Gabriel; Jover Modrego, Jesús
Fluoroalcohols are a class of organic compounds containing one or more fluorine atoms together with an alcohol group in their molecular structure. These fluorinated species have a wide range of applications due to their unique properties and are used in medicine and electronics. Herein, we propose a new synthetic procedure, promoted by a copper(I) catalyst, for preparing fluoroalcohols from alkylboranes and symmetric ketones. The reaction has been computationally explored to propose a plausible mechanism, which allows identifying the rate-limiting step and quantitatively evaluating the electronic effects of each substrate on the overall reactivity. These DFT calculations suggest that the combination of electron-poor ketones with electron-rich alkylboranes produce the most efficient catalytic systems for preparing fluoroalcohols. Microkinetic modeling of the studied systems allow the prediction of the activation barrier limit to achieve fully functional reactions and multilinear regression techniques provide a methodology to estimate the overall reaction barriers in a simple manner, opening the way for proposing new catalytic systems.
Crystallographic and Computational Analysis of Oxyma B Cocrystals with Nitrogen-Containing Coformers: The Relevant Role of n → π* Interactions in Their Diverse Supramolecular Architectures
(American Chemical Society) Jemai, Mahdi; Barbas Cañero, Rafael; Barceló-Oliver, Miquel; Marouani, Houda; Albericio Palomera, Fernando; Frontera, Antonio; Prohens López, Rafael
Three new cocrystals of Oxyma-B, an important racemization suppressor for peptide synthesis, with 6-methylquinoline (I), 2,3,5,6-tetramethylpyrazine (II), and 1,10-phenanthroline (III) were synthesized and their single crystal structures analyzed. They show a rich network of noncovalent interactions, including classical and nonclassical hydrogen bonds (CH···O, OH···N, CH···N), CH···π, π-stacking, and, notably, lone pair···π (n → π*) interactions. Distinctive supramolecular synthons were identified, including the R22(7) motif found in both 6-methylquinoline/Oxyma-B and 2,3,5,6-tetramethylpyrazine/Oxyma-B cocrystals. In 1,10-phenanthroline/Oxyma-B, larger ring motifs such as R44(20) and R55(24) were observed, further supported by additional synthons of types R12(5) and R12(6). Hirshfeld surface analysis and density functional theory (DFT) calculations, including MEP surface, QTAIM, and NCIplot analyses, were carried out to quantify the intermolecular contributions and rationalize the experimental findings with a focus on the cooperative role of hydrogen bonding, π-stacking, and lone pair···π (n → π*) interactions in stabilizing and shaping the architectures of these new multicomponent crystalline materials.
Kinetico-mechanistic insights into the photodynamic process of AuI complexes with the CNC6H4NNC6H5 (iso-Ph) azobenzene ligand
(Royal Society of Chemistry, 2025-01) Raïch Panisello, Ot; Jover Modrego, Jesús; Puigjaner, Cristina; Ferrer García, Montserrat; Martínez López, Manuel, 1957-
A family of neutral isocyanide monoazo AuI complexes [AuCl(iso-Ph)], [Au(C6F5)(iso-Ph)] and [Au(C[triple bond, length as m-dash]Cpy)(iso-Ph)] (iso-Ph being CN–C6H4–N[double bond, length as m-dash]N–Ph) and a closely related cationic bisazo symmetrical derivative, [Au(iso-Ph)2](OTf), have been prepared. All the compounds have been structurally characterized using the conventional techniques HRMS, NMR, UV-Vis and IR spectroscopy. Moreover, the structure of the [AuCl(iso-Ph)] compound has been determined by XRD. These compounds undergo more efficient trans-to-cis photoisomerisation upon irradiation at 365 nm than that of the free iso-Ph ligand. The reverse cis-to-trans thermal process has been investigated using different solvents, temperatures and pressures to determine the values of the activation parameters and thus, the corresponding isomerisation mechanism. A change in the operating mechanism (from charge-separated rotational to inversional) has been observed upon going from the monoazo to the bisazo compounds. This effect has been attributed to the difference in the electronic density at the AuI centre in the transition state between the unsymmetrical and the symmetrical species.
Confronting positions: para- vs. meta-functionalization in triindole for p-type air-stable OTFTs
(Elsevier, 2024-05-01) Cuadrado Santolaria, Alba; Bujaldón Carbó, Roger; Fabregat, Clara; Puigdollers i González, Joaquim; Velasco Castrillo, Dolores
The 5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole core, namely triindole, is well-known for its prominent hole-transporting properties and air stability. The functionalization of this core is also rather versatile, which allows the modulation of its properties by anchoring targeted scaffolds to different positions, e.g. 3,8,13 (para with respect to the nitrogens), 2,7,12 (analogously meta) or the nitrogen heteroatoms. Therefore, triindole excels as a pivotal semiconductor to be exploited in long-lasting organic thin-film transistors (OTFTs). This report aims to shed light on the effect of functionalizing whether para or meta positions with sulfurated moieties, in the pursuit of an enhanced performance in OTFTs. Remarkably, meta-substituted derivatives outshone their para- counterparts in terms of thermal, optical, intermolecular arrangement and semiconductor properties, claiming mobility values up to 2 × 10−3 cm2 V−1 s−1 and a shelf lifetime beyond the analyzed period of 5 months. Analysis of the thin films by grazing incidence X-ray diffraction (GIRXD) and atomic force microscopy (AFM) revealed that the meta-substitution also induces a higher degree of order and better morphology, further corroborating the potential of this structural approach.
On-the-Fly Synthesis of Freestanding Spin-Crossover Architectures With Tunable Magnetic Properties
(Wiley-VCH, 2025-06-13) Ngo, Anh Tuan; Aguilà Avilés, David; Vale, João Pedro; Sevim, Semih; Mattera, Michele; Díaz-Marcos, Jordi; Pons, Ramon; Aromí Bedmar, Guillem; Jang, Bumjin; Pané, Salvador; Mayor, Tiago Sotto; Palacios-Corella, Mario; Puigmartí-Luis, Josep
Spin-crossover (SCO) molecular-based switches have shown promise across a range of applications since their discovery, including sensing, information storage, actuators, and displays. Yet limited processability remains a barrier to their real-world implementation, as traditional methods for integrating SCO materials into polymer matrices are often complex, expensive, and prone to producing uneven material distributions. Herein, we demonstrate how 3D flow-focusing chemistry enables unprecedented control for the direct fabrication of SCO composite materials, addressing key challenges in processability, scalability, and cost. By using a 3D coaxial flow-focusing microfluidic device, we simultaneously synthesize [Fe(Htrz)2(trz)](BF4) and achieve its homogeneous incorporation into alginate fibers in a continuous manner. The device’s versatility allows for precise manipulation of the reaction-diffusion (RD) zone, resulting in SCO composite fibers with tunable physicochemical and magnetic properties. Additionally, we demonstrate the ability to isolate these fibers as freestanding architectures and highlight the potential for printing them with defined shapes. Finally, we show that the 3D control of the RD zone granted by continuous flow microfluidic devices offers precise spatiotemporal control over the distribution of SCO complexes within the fibers, effectively encoding SCO materials into them. SCO-encoded fibers can seamlessly combine adaptability and functionality, offering innovative solutions for application-specific customization.
Encapsulation Enhances the Quantum Coherence of a Solid‐State Molecular Spin Qubit
(Wiley-VCH, 2025-09-01) Swain, Abinash; Barrios Moreno, Leoní Alejandra; Nelyubina, Yulia; Teat, Simon J.; Roubeau, Olivier; Novikov, Valentin; Aromí Bedmar, Guillem
Spins within molecules benefit from the atomistic control of synthetic chemistry for the realization of qubits. One advantage is that the quantum superpositions of the spin states encoding the qubit can be coherently manipulated using electromagnetic radiation. The main challenge is the fragility of these superpositions when qubits are to partake of solid-state devices. We address this issue with a supramolecular approach for protecting molecular spin qubits against decoherence. The molecular qubit [Cr(ox)3]3− has been encapsulated inside the diamagnetic triple-stranded helicate [Zn2L3]4+ (L is a bis-pyrazolylpyridine ligand). The quantum coherence of the protected qubit is then analyzed with pulsed EPR spectroscopy and compared with the unprotected qubit, both in solution and in the solid state. Crucially, the spin–spin relaxation in the solid state has been examined within diamagnetic crystal lattices of the isostructural ([Al(ox)3]@[Zn2L3])+ or [Al(ox)3]3- assemblies, respectively, doped with the Cr3+ qubit in two different (<10%) concentrations. The study unveils a surprising increase of the phase memory time of the qubit upon encapsulation only in the solid. Spin-lattice relaxation times also exhibit a significant enhancement, as established from inversion recovery pulse sequences and from slow relaxation of the magnetization of the protected qubit, not featured by the free qubit.
New series of mononuclear β-diketonate cerium(iii) field induced single-molecule magnets
(Royal Society of Chemistry, 2024-05-08) Tubau Ribot, Ànnia; Gómez Coca, Silvia; Speed Castro, Saskia; Font Bardia, Ma. Mercedes; Vicente Castillo, Ramón
Five new β-diketonate Ce3+ mononuclear complexes, [Ce(Btfa)3(H2O)2] (1), [Ce(Btfa)3(phen)] (2), [Ce (Btfa)3(bipy)] (3), [Ce(Btfa)3(terpy)] (4) and [Ce(Btfa)3(bathophen)(DMF)] (5), where Btfa− = 4,4,4-trifluoro-1- phenyl-1,3-butanedionate, phen = 1,10-phenanthroline, bipy = 2,2’-bipyridyl, terpy = 2,2’:6’,2’’-terpyridine and bathophen = 4,7-diphenyl-1,10-phenanthroline, have been synthesized and structurally characterized through X-ray diffraction of single crystals. The central Ce3+ atom displays a coordination number of 8 for 1, 2 and 3 and of 9 for 4 and 5. Under a 0 T external magnetic field, none of the given compounds exhibits single molecule magnet (SMM) behaviour. However, a small magnetic field, between 0.02 and 0.1 T, is enough for all the compounds to exhibit slow relaxation of the magnetization. A comprehensive magnetic analysis, with experimental magnetic data and ab initio calculations, was undertaken for all the complexes, and the study highlights the significance of the different spin relaxation mechanisms that must be considered for a Ce3+ lanthanide ion.
A site-specific MiniAp4-Trastuzumab conjugate prevents brain metastasis
(American Chemical Society, 2025-03-03) Masmudi-Martín, Mariam; Oller Salvia, Benjamí; Perea, María; Teixidó Turà, Meritxell; Valiente, Manuel; Giralt Lledó, Ernest; Sánchez-Navarro, Macarena
Monoclonal antibodies (mAbs) are changing cancer treatments. However, the presence of the blood–brain barrier (BBB) and the blood–tumor barrier (BTB) limits the use of mAbs to treat brain cancer or brain metastasis. Molecules that hijack endogenous transport mechanisms on the brain endothelium (brain shuttles) have been shown to increase the transport of large molecules and nanoparticles across the BBB. Among these shuttles, protease-resistant peptides such as MiniAp-4 are particularly efficient. Here, we report the synthesis, characterization, and evaluation of site-specific mAb–brainshuttle antibody conjugates (ASC) based on the anti-HER2 mAb trastuzumab (Tz) and four molecules of MiniAp-4. The ASCs preserve the binding and cell cycle arrest capacity of Tz. MiniAp-4 ASC displays enhanced transport across an in vitro BBB cellular model with respect to Tz and Tz conjugated to Angiopep-2, the brain shuttle that has advanced the most in clinical trials. More importantly, evaluation of Tz-MiniAp4 in a murine brain metastasis model demonstrated that the protease-resistant peptide showed preferential transport across the BBB/BTB, displaying a marked therapeutic effect and protecting against metastasis development. The technology described herein could be applied to any antibody of interest to treat central nervous system-related diseases. MiniAp-4 enhances the brain transport of the monoclonal antibody trastuzumab, preventing brain metastasis.
A Leap from Diradicals to Tetraradicals by Topological Control of π-Conjugation.
(American Chemical Society, 2024-09-20) Betkhoshvili, Sergi; Poater i Teixidor, Jordi; Moreira, Ibério de Pinho Ribeiro; Bofill i Villà, Josep M.
In this work, we explore the series of diradical(oid)s based on 2,2′-(5,11-dihydroindolo[3,2-b]carbazole-3,9-diyl)-dimalononitrile (further referred to as PH). Hydrogen atoms in the central benzenoid (CB) ring of PH are substituted by the seriesof substituents with various lengths of π-conjugated chain and electron-donating or electron-withdrawing properties to study howthey modulate the diradical character of the parent compound. The diradical character of molecules increases up to 88−89% by twogroups doubly bonded to both sides of the CB ring of PH in para relative positions. This breaks the direct π-conjugation betweenunpaired electrons that gives rise to two radical centers and restricts the minimal polyradical identity of the compound todiradical. We show that diradicals and tetraradicals can be designed, and their polyradical character can be modulated by controlling the topology of π-conjugation as long as there is sufficient aromatic stabilization. Henceforth, the bridge between diradicals and tetraradicals is established, leading to the tetraradical(oid) molecule, which has been predicted to have narrow low-spin to high-spin energy gaps in our recent Letter.
A Nanoencapsulated Ir(III)-Phthalocyanine Conjugate as a Promising Photodynamic Therapy Anticancer Agent
(American Chemical Society, 2024-07-23) Bonelli Blasco, Joaquin Daniel; Ortega-Forte, Enrique; Vigueras, Gloria; Follana-Berná, Jorge; Ashoo, Pezhman; Abad-Montero, Diego; Isidro, Neus; López-Corrales, Marta; Hernández, Adrián; Ortiz, Javier; Izquierdo-García, Eduardo; Bosch, Manel; Rocas, Josep; Sastre-Santos, Ángela; Ruiz, José; Marchán Sancho, Vicente
Despite the potential of photodynamic therapy (PDT) in cancer treatment, the development of efficient and photostable photosensitizing molecules that operate at long wavelengths of light has become a major hurdle. Here, we report for the first time an Ir(III)-phthalocyanine conjugate (Ir-ZnPc) as a novel photosensitizer for high-efficiency synergistic PDT treatment that takes advantage of the longwavelength excitation and near infrared (NIR) emission of the phthalocyanine scaffold and the known photostability and high phototoxicity of cyclometalated Ir(III) complexes. In order to increase water solubility and cell membrane permeability, the conjugate and parent zinc phthalocyanine (ZnPc) were encapsulated in amphoteric redox-responsive polyurethane-polyurea hybrid nanocapsules (Ir-ZnPc-NCs and ZnPc-NCs, respectively). Photobiological evaluations revealed that the encapsulated Ir-ZnPc conjugate achieved high photocytotoxicity in both normoxic and hypoxic conditions under 630 nm light irradiation, which can be attributed to dual Type I and Type II reactive oxygen species (ROS) photogeneration. Interestingly, PDT treatments with Ir-ZnPc-NCs and ZnPc-NCs significantly inhibited the growth of three-dimensional (3D) multicellular tumor spheroids. Overall, the nanoencapsulation of Zn phthalocyanines conjugated to cyclometalated Ir(III) complexes provides a new strategy for obtaining photostable and biocompatible red-light-activated nano-PDT agents with efficient performance under challenging hypoxic environments, thus offering new therapeutic opportunities for cancer treatment.
Organocatalytic Asymmetric Allylic Benzylborylation via Fluoride-Assisted Catalytic Generation of α-Boryl Carbanionic Intermediates
(American Chemical Society, 2024-10-04) Duran, Jordi; Rodríguez, Paula; Vermeer, Ward; Companyó Montaner, Xavier
Herein we describe the organocatalytic asymmetric allylic benzylborylation of allyl fluorides with α-silyl benzylboronic esters. The catalytic protocol leverages the singular features of fluoride as an unconventional leaving group, enabling the catalytic generation of reactive α-boryl carbanion species through desilylative activation. It allows the construction of a wide set of homoallylic benzylated organoboronates bearing two contiguous stereocenters. The chiral boronate installed in the products serves as a synthetic lynchpin to construct complex chemical architectures in a stereospecific manner.
Field-Induced Slow Relaxation of the Magnetization in Two Families of [MIILnIII] Complexes
(American Chemical Society, 2024-07-03) Costa Villén, Ernesto; Font Bardia, Ma. Mercedes; Mayans Ayats, Júlia; Escuer Fité, Albert
A family of discrete dinuclear complexes [MIILnIII] (M = Cu, Ni and Ln = Ce, Gd, Tb, Dy, Er, Yb) has been synthesized from the use of the compartmental Schiff base ligand H4L (3,3′-((1E,1′E)-(ethane-1,2-diylbis- (azaneylylidene)) bis(methaneylylidene))bis(benzene-1,2-diol)), obtained from the condensation of ethylenediamine and 2,3-dihydroxybenzaldehyde. All of the complexes have been structurally and magnetically characterized. The dynamic magnetic measurements show that the [CuIILnIII] and [NiIILnIII] derivatives exhibit ac response as a function of the d-cation. Noteworthily, the isotropic GdIII complexes exhibit a slow relaxation of magnetization.
Unexpected E-to-Z Isomerizations during the Negishi-Type Homocoupling of E-Iodoalkenes
(American Chemical Society, 2024-12-01) Crovara, Fernanda A.; Marti Ribas, Josep; Costa, Ana Maria; Vilarrasa, Jaume
The direct insertion of Zn into olefin–halide bonds is a challenge. When (E)-alkenyl iodides were treated with a very large excess of Zn nanoparticles, in the presence of Pd(PPh3)4, the dimerization was observed but, unexpectedly, yielding mainly Z,E-1,3-dienes. This apparently contrathermodynamic E-to-Z isomerization of organometallic intermediates is predicted to be general and is explained with the aid of DFT [principally M06/6-311+G(d,p)], MP2, and CCSD(T) calculations.
An Extension of the Stern–Volmer Equation for Thermally Activated Delayed Fluorescence (TADF) Photocatalysts
(American Chemical Society, 2024-10-11) Limburg, Bart
Fluorescence quenching experiments are essential mechanistic tools in photoredox catalysis, allowing one to elucidate the first step in the catalytic cycle that occurs after photon absorption. Thermally activated delayed fluorescence (TADF) photocatalysts, however, yield nonlinear Stern–Volmer plots, thus requiring an adjustment to this widely used method to determine the efficiency of excited state quenching. Here, we derive an extension of the Stern–Volmer equation for TADF fluorophores that considers quenching from both the singlet and triplet excited states and experimentally verify it with fluorescence quenching experiments using the commonly employed TADF-photocatalyst 4CzIPN, and multiple-resonance TADF-photocatalyst QAO with three different quenchers in four solvents. The experimental data are perfectly described by this new equation, which in addition to the Stern–Volmer quenching constants allows for the determination of the product of intersystem and reverse intersystem crossing quantum yields, a quantity that is independent of the quencher.
An Unusual His/Asp Dyad Operates Catalysis in Agar-Degrading Glycosidases
(American Chemical Society, 2024-11-01) Sagiroglugil, Mert; Nin Hill, Alba; Ficko-Blean, Elizabeth; Rovira i Virgili, Carme
Agarose motifs, found in agars present in the cell walls of red algae, consist of alternating units of d-galactose (G) and α-3,6-anhydro-l-galactose (LA). Glycoside hydrolases from family 117 (GH117) cleave the terminal α-1,3-glycosidic bonds, releasing LA units. Structural studies have suggested that these enzymes use unconventional catalytic machinery, involving a histidine (His302) as a general acid rather than a carboxylic residue as in most glycosidases. By means of quantum mechanics/molecular mechanics metadynamics, we investigated the reaction mechanism of Phocaeicola plebeius GH117, confirming the catalytic role of His302. This residue shares a proton with a neighbor aspartate residue (Asp320), forming a His/Asp dyad. Our study also reveals that, even though the sugar unit at the –1 subsite (LA) can adopt two conformations, 4C1 and 1,4B, only the latter is catalytically competent, defining a 1,4B → [4E]‡ → 1,4B (→ 4C1) conformational itinerary. This mechanism may be applicable to similar enzymes with a His/Asp dyad in their active sites, such as GH3 β-N-acetylglucosaminidase and GH156 sialidase. These insights enhance our understanding of glycosidase catalytic strategies and could inform the engineering of enzymes for the more efficient processing of seaweed.
A fast method to monitor tyrosine kinase inhibitors mechanisms
(American Chemical Society, 2024-11-08) Fernández, Alejandro; Gairí Tahull, Margarida; González, Maria Teresa; Pons Vallès, Miquel
Methionine residues within the kinase domain of Src serve as unique NMR probes capable of distinguishing between distinct conformational states of full-length Src, including alternative drug-inhibited forms. This approach offers a rapid method to differentiate between various inhibition mechanisms at any stage of drug development, eliminating the need to resolve the structure of Src-drug complexes. Using selectively 13C-methyl-enriched methionine, spectra can be acquired in under an hour, while natural abundance spectra with comparable information are achievable within a few hours.
A Cartesian encoding graph neural network for crystal structure property prediction: application to thermal ellipsoid estimation
(Royal Society of Chemistry (RSC), 2025-12-01) Sole Gomez, Jaume Alexandre; Mosella-Montoro, Albert; Cardona, Joan; Gómez Coca, Silvia; Aravena Ponce, Daniel Alejandro; Ruiz Sabín, Eliseo; Ruiz-Hidalgo, Javier
In the diffraction resolution of crystal structures, thermal ellipsoids are a critical parameter that is usually more difficult to determine than atomic positions. These ellipsoids are quantified through Anisotropic Displacement Parameters (ADPs), which provide critical insights into atomic vibrations within crystalline structures. ADPs reflect the thermal behaviour and structural properties of crystal structures. However, traditional methods to compute ADPs are computationally intensive. This paper presents CartNet, a novel graph neural network (GNN) architecture designed to predict properties of crystal structures efficiently by encoding the atomic structural geometry to the Cartesian axes and the temperature of the crystal structure. Additionally, CartNet employs a neighbour equalization technique for message passing to help emphasise the covalent and contact interactions and a novel Cholesky-based head to ensure valid ADP predictions. Furthermore, a rotational SO(3) data augmentation technique has been proposed during the training phase to generalize unseen rotations. To corroborate this procedure, an ADP dataset with over 200 000 experimental crystal structures from the Cambridge Structural Database (CSD) has been curated. The model significantly reduces computational costs and outperforms existing previously reported methods for ADP prediction by 10.87%, while demonstrating a 34.77% improvement over the tested theoretical computation methods. Moreover, we have employed CartNet for other already known datasets that included different material properties, such as formation energy, band gap, total energy, energy above the convex hull, bulk moduli, and shear moduli. The proposed architecture outperformed previously reported methods by 7.71% in the JARVIS dataset and 13.16% in the Materials Project dataset, proving CarNet's capability to achieve state-of-the-art results in several tasks. The project website with online demo available at: https://www.ee.ub.edu/cartnet.
Mechanochemistry of degree two.
(Springer Verlag, 2024-12-05) Quapp, Wolfgang; Bofill i Villà, Josep M.
We simplify some proposed formulas for hydrostatic pressure on a molecule byG. Subramanian, N. Mathew and J. Leiding, J.Chem.Phys. 143, 134109 (2015). Weapply the formulas to an artificial triatom ABC whose potential energy surface isformed by a combination of Morse curves.
Slow magnetic relaxation and luminescence properties in b-diketonate lanthanide(III)complexes. Preparation of Eu(III) and Yb(III) OLED devices
(Royal Society of Chemistry, 2024-05-16) Tubau Ribot, Ànnia; Rodríguez Raurell, Laura; Pander, Piotr; Weatherill, Lucy; Dias, Fernando B.; Font Bardia, Ma. Mercedes; Vicente Castillo, Ramón
La reacció de [Ln(btfa)₃(H₂O)₂] (btfa⁻ = 4,4,4-trifluoro-1-fenil-1,3-butanodionat) amb 4,4'-dinonil-2,2'-bipiridil (4,4'-dinonilbipy) en etanol permet l’aïllament de complexos mononuclears [Ln(btfa)₃(4,4'-dinonilbipy)], amb Ln = Sm (1-Sm), Eu (2-Eu), Tb (3-Tb), Dy (4-Dy), Er (5-Er) i Yb (6-Yb).
Els complexos 1-Sm, 2-Eu, 3-Tb i 4-Dy emeten luminescència eficient en la regió visible, mentre que 1-Sm, 5-Er i 6-Yb ho fan en l’NIR. L’energia es transfereix de manera efectiva des del lligand 4,4,4-trifluoro-1-fenil-1,3-butanodionat cap a l’ió central Ln³⁺ en tots els compostos.
Els complexos 2-Eu i 6-Yb es van utilitzar com a emissors en OLEDs multicapa dipositats en buit, aconseguint eficiències quàntiques d’electroluminescència (EQE) del 2,1% per a 2-Eu (λEL = 614 nm) i del 0,1–0,2% per a 6-Yb (λEL = 977 nm). La màxima emittància radiant per a les emissions associades als lantànids va ser de 135 mW cm⁻² per a 2-Eu i de 121 mW cm⁻² per a 6-Yb, valors inusualment alts per a aquest tipus d’emissors.
Els estudis magnètics van revelar comportament de Single Molecular Magnet (SMM) per a 4-Dy i relaxació lenta de la magnetització induïda per camp per als complexos 3-Tb, 5-Er i 6-Yb. Per a 4-Dy, les barreres d’energia d’anisotropia i els factors pre-exponencials són ΔE = 91,1 cm⁻¹, τ₀ = 7,2 × 10⁻⁹ s (sense camp) i ΔE = 109,3 cm⁻¹, τ₀ = 9,3 × 10⁻¹⁰ s (amb 0,1 T). Per a 5-Er, ΔE = 24,6 cm⁻¹, τ₀ = 8,7 × 10⁻⁸ s (amb 0,07 T). A més, per als complexos 3-Tb i 6-Yb, la relaxació de la magnetització no segueix el procés d’Orbach.

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