Publications

Abstract This work investigates the potential of betaine as a substitute for choline chloride in the formation of polyol-based DES. The solid-liquid equilibrium (SLE) phase diagrams of binary mixtures of betaine with one polyol (ethylene glycol, 1,3-propanediol, glycerol, meso-erythritol, xylitol, or sorbitol) were studied across the entire composition range. Experimental measurements of the phase diagrams were limited by the thermal degradation of betaine and by the boiling points or high viscosities of some polyols. Overall, betaine exhibited negative deviations from ideality, while most polyols displayed near-ideal behaviour. COSMO-RS, a thermodynamic model, satisfactorily predicts these deviations from ideality and the observed phase behaviour. Mixtures of betaine and polyols yielded a narrower liquid-phase window for room-temperature applications than the corresponding choline chloride systems. The cross-association of betaine with polyols is more favourable than its self-association, and stronger interactions between the polyols and betaine than with choline chloride are expected, leading to more negative deviations; thus, the smaller melting temperature depression must result from a higher enthalpy of fusion of betaine than that of choline chloride.

Abstract The biphasic transfer of Eu(NO3)3 by trioctylphosphine oxide (TOPO) diluted in a molecular diluent or as a component of a hydrophobic eutectic solvent (HES) was studied by two-phase isothermal titration calorimetry and complemented by XAS, FTIR, and NMR spectroscopy. In HES, the solvent intermolecular interactions introduce an enthalpic penalty, which is overcompensated by a reduction of the entropic cost of Eu(III) phase transfer, resulting in enhanced metal partitioning.

Abstract A comprehensive thermodynamic and supramolecular characterization was conducted on a series of phenanthroline-based organic semiconductors and related derivatives, including 1,10-phenanthroline (PHEN), neocuproine (DMPHEN), bathophenanthroline (BPHEN), and bathocuproine (BCP), to elucidate how systematic molecular substitution affects their stability, volatility, and optoelectronic properties. Heat capacity and phase-transition studies, including vapor-pressure measurements, provided a consistent thermodynamic framework for these materials. Analysis of heat capacities revealed that methyl and phenyl groups contribute independently and additively, supporting transferable models for predicting thermal behavior. Thermogravimetric analysis showed that phenyl substitution enhances thermal stability (BPHEN, BCP), whereas methyl substitution slightly decreases it. Differential scanning calorimetry revealed distinct phase behaviors: PHEN is sensitive to hydration, DMPHEN exhibits polymorphism, BPHEN tends to form a glass, and BCP crystallizes reproducibly. Sublimation studies using Knudsen effusion coupled with a quartz crystal microbalance yielded enthalpic and entropic parameters clarifying volatility trends. Complementary supramolecular analysis identified the key pi-pi stacking, C-H & centerdot;& centerdot;& centerdot;N and C-H & centerdot;& centerdot;& centerdot;pi interactions underlying crystal cohesion. UV-vis spectroscopy further provided the band gap energies, which are relevant to optoelectronic performance. By correlating thermodynamic data with supramolecular organization and molecular structure, this study establishes a rigorous framework for the rational design and processing of phenanthroline derivatives in robust and efficient organic electronic devices.

Abstract A systematic investigation of thin films of pyridinium-based ionic liquids (ILs), [C n py][NTf2] (n = 2-9), deposited via physical vapor deposition on ITO and Au/ITO substrates is presented, providing the first comprehensive study of vacuum-deposited films within this homologous series. The influence of evaporation temperature, deposition rate, alkyl chain length, and substrate on thin-film morphology, nucleation and coalescence dynamics, interfacial behavior, and film structure was examined using SEM, optical microscopy, FTIR, and XPS. SEM analyses reveal that higher evaporation temperatures, which increase the deposition rate, lead to larger droplets and enhanced coalescence, resulting in larger microstructures. A comparison of the film morphologies across the IL series shows that longer cation alkyl chains further enhance lateral spreading and wetting, particularly on Au substrates. An odd-even effect on the morphological characteristics of the films is observed across the series, reflecting subtle differences in interfacial interactions. Moreover, a clear distinction in wetting behavior between short- and long-chain pyridinium ILs is evident, consistent with trends previously reported for imidazolium-based ILs. FTIR spectra comparing bulk and thin IL films confirm that the ILs retain their chemical integrity upon film formation. XPS measurements support the morphological observations, highlighting that ILs comprising longer alkyl chains achieve more complete surface coverage. The results of this work provide fundamental insights into the interplay between the cation alkyl chain length of pyridinium-based ILs, substrate interactions, and film formation dynamics, offering guidance for the rational design of IL films for functional surface applications.

Abstract Fullerenes combine high curvature, symmetry, and multiple reactive sites, making them ideal systems to explore structure-reactivity relationships. This work presents an equilibrium and kinetic study of the Diels-Alder reactions of three fullerenes (C-60, C-70, and IC(60)MA) with the dienes anthracene and 9,10-dimethylanthracene in m-xylene solution, using Ultraviolet-visible (UV-Vis) spectroscopy. Equilibrium constants and rate constants for both the forward and reverse reactions were determined at various temperatures, allowing the calculation of standard molar enthalpies and entropies of reaction as well as activation parameters Delta H-m double dagger and Delta S-m double dagger. The equilibrium constants follow the trend C-60 > C-70 similar to IC(60)MA, with C-60 exhibiting higher reactivity due to both a faster forward reaction and a slower reverse reaction. The results reveal that the reactivities of the fullerenes are predominantly distinguished by entropic rather than enthalpic contributions. We show that molecular symmetry, isomerism, and dynamic surface phenomena, such as addend ring walking (its extent depending on fullerene structure), collectively determine the observed reactivity trends. Kinetic results suggest that the transition states of C-60 and C-70 differ significantly in entropy, a trend consistent with the smoother reactive landscape of C-60 relative to the surface-segmented C-70.

Abstract <jats:p>The formation and stabilization of silver nanoparticles (AgNPs) in thin films of ionic liquids (ILs) based on long-chain alkylimidazolium cations are demonstrated in this work. IL films were prepared by vacuum thermal evaporation using the Knudsen effusion method onto ITO/glass substrates, leading to the formation of micro- and nanosized structures distributed across the surface. The investigated ILs were symmetrical dialkylimidazolium-based systems: [C7C7im][NTf2], [C8C8im][NTf2], and [C10C10im][NTf2]. Increasing the alkyl side-chain length of the imidazolium cation resulted in larger droplet domains. AgNPs were subsequently deposited onto the IL films by sputtering. The formation of AgNPs was confirmed by scanning electron microscopy (SEM), ultraviolet (UV)–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results show that increasing the alkyl side-chain length promotes more effective confinement and stabilization of AgNPs, leading to improved nanoparticle formation and a narrower size distribution. The temporal stability of the Ag-containing IL films was evaluated under both air exposure and inert argon storage, revealing a strong influence of the surrounding atmosphere on nanoparticle evolution. Among the ILs studied, [C10C10im][NTf2] exhibited the most favorable behavior for AgNP formation and stabilization, providing a more stable and homogeneous nanoparticle distribution over time.</jats:p>

Abstract The purpose of this article is to present and discuss a historical house project that was transposed into virtual reality, to be preserved as digital cultural heritage. The Matosinhos House, in Portugal, is part of a residential project designed by the architect Alvaro Siza Vieira in 1955-56, is the historical house that was chosen as case study. The article displays the historical significance of the project, as well as the method applied to transpose it into virtual reality. The goal is to promote access to digital cultural heritage based on reliable and accurate interpretation of the collected data.

Abstract The effect of the anion on the electrical conductivity of ionic liquids was explored by a high-precision study of the temperature dependence (283–333 K) of the electrical conductivity of ten ILs based on the 1-butyl-3-methylimidazolium cation, [C4C1im]+. The following trend was observed for the molar conductivity at the reference temperature of 298.15 K: Ac < PF6− < BETI < OTf < TFA < BF4− < FAP < NTf2 < FSI < DCA. The molar conductivity at infinite temperature, AΛ, and the energy barrier, EΛ, derived from the Vogel–Fulcher–Tammann equation (VFT) fitting were found to correlate well with the shape/size/dynamics and cohesive energy/charge localization of the studied ions. An extensive revision and comparison with the available experimental electrical conductivity data for the studied ionic liquids is also presented. Additionally, this work presents a detailed description, testing, and evaluation of performance results of a new system/methodology for the high-precision measurement of the electrical conductivity of ionic fluids, designed to minimize the size of the ionic liquid sample and in situ degassing of the sample. The measuring system is based on a high-precision LCR meter and a conductivity cell system designed to ensure the vacuum and gastightness of the sample container. The high-precision temperature control is ensured by a customized thermal chamber based on a heating and cooling Peltier system. The electrical conductivity data were corrected for the effect of solution polarization by extrapolating the resistance to infinite frequency. The accuracy and resolution of the system were evaluated by measuring the conductivity of the reference ionic liquid, [C6C1im][NTf2] which was found to be in excellent agreement with the recommended data. © 2025 The Author(s)

Abstract This study demonstrates the efficacy of ionic liquid (IL)-assisted vapor deposition in achieving high-quality and distinctive crystal film growth of two organic semiconductors (OSCs): a carbazole derivative (TCB) and a phenylamine derivative (TDAB). ILs with different wetting properties (short-chain [C2C1im][NTf2] and long-chain [C8C1im][NTf2]) and engineered shapes (microdroplets and coalesced film) were utilized as solvents in a vacuum. Through a meticulously designed experimental strategy, encompassing both sequential and simultaneous deposition of the IL and the OSC, this study unveils the pivotal role of ILs in shaping the crystallization behavior of the organic compound. Differential scanning calorimetry, polarized light microscopy, high-resolution scanning electron microscopy, and X-ray diffraction were employed for the films' thermal, morphological, and structural characterization. Thin films of TDAB exhibit crystallinity and a greater tendency to grow tridimensionally, forming giant pillars. However, the typical vertical growth of TDAB on solid substrates is altered when deposition occurs on surfaces coated with ILs. The IL promotes the lateral growth of nanostructures. The experimental results reveal variations in film morphology and coverage influenced by the cation alkyl chain length of the IL. In contrast to TDAB, TCB films are amorphous when thermally evaporated on solid substrates. Notably, IL-assisted vapor deposition induces the crystallization of TCB. Furthermore, TCB films deposited on coalesced IL films exhibit enhanced crystallinity and homogeneous horizontal growth, representing a significant finding in the context of thin film deposition and semiconductor device fabrication.

Abstract Extensive research has focused on films formed by pure ionic liquids (ILs). However, growing interest in IL mixtures and their synergistic properties presents new opportunities for targeted applications and fundamental scientific investigations. This study explores the morphology of films composed of mixtures of two ILs, [C2C1im][OTf] and [C8C1im][OTf], co-deposited via physical vapor deposition (PVD)/vacuum thermal evaporation. The primary objective was understanding how varying the IL ratio influences droplet formation, surface coverage, and overall film structure. Thin-film growth was examined on glass substrates coated with indium tin oxide (ITO) and ITO/glass surfaces coated with metallic films (Au and Ag). Film morphology was characterized using optical and high-resolution scanning electron microscopy (SEM), while elemental composition was analyzed via X-ray photoelectron spectroscopy (XPS). The results show that IL mixture morphology is strongly influenced by both IL composition and substrate type. Increasing [C8C1im][OTf] content led to larger microstructures due to improved wetting, particularly on Au surfaces, resulting in nearly fully coalesced films. Metallic surfaces near ITO significantly impacted droplet behavior, with ILs exhibiting a strong affinity for metals, especially when the long-chain IL dominated the mixture. The IL-assisted crystallization of rubrene, a high-performance organic semiconductor (OSC) that typically exhibits poor crystallinity when deposited via PVD, highlights the potential of IL mixtures to enhance organic film quality. X-ray diffraction (XRD) confirmed that [C2C1im][OTf] and [C8C1im][OTf] mixtures significantly improved rubrene crystallinity, demonstrating their potential to create an optimal environment for OSC solubility and crystallization.