Dinis O. Abranches

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Verified

Dinis verified their affiliation via an institutional email.

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• PhD in Chemical Engineering
• Assistant Researcher at University of Aveiro

The combination of machine learning (ML) models with chemistry-related tasks requires the description of molecular structures in a machine-readable way. The nature of these so-called molecular descriptors has a direct and major impact on the performance of ML models and remains an open problem in the field. Structural descriptors like SMILES string...

Electrolytes based on deep eutectic solvents (DESs) coupled with redox active organic molecules have shown potential as a versatile and energy dense electrochemical energy storage system. However, progress in these systems has been held back by a lack of understanding of the irregular behavior displayed when redox active organic molecules are trans...

The solubilities of benzoic acid, (S)-hesperetin, and l-tryptophan in aqueous solutions of ionic liquids (choline glycolate and choline malonate) and the analogous eutectic solvents (choline chloride:glycolic acid and choline chloride:malonic acid) were studied. It is shown that while ionic liquids (IL) and eutectic solvents (ES) were able to incre...

The high tunability of deep eutectic solvents (DESs) stems from the ease of changing their precursors and relative compositions. However, measuring the physicochemical properties across large composition and temperature ranges, necessary to properly design target-specific DESs, is tedious and error-prone and represents a bottleneck in the advanceme...

This review explores how vibrational spectroscopy helps us understand deep eutectic solvents (DESs) by showcasing over 150 studies. It covers various techniques, from common ones like infrared and Raman to advanced methods, highlighting best practices and the powerful combination of spectroscopy with computational chemistry. https://www.tandfonlin...

This work establishes a different paradigm on digital molecular spaces and their efficient navigation by exploiting sigma profiles. To do so, the remarkable capability of Gaussian processes (GPs), a type of stochastic machine learning model, to correlate and predict physicochemical properties from sigma profiles is demonstrated, outperforming state...

This work explores the impact of solute conformers on the conductor-like screening model for real solvents (COSMO-RS) solubility predictions of vanillin and ethyl vanillin in water, short alcohols, and their mixed solvents. Two major conformers of these solutes and changes with solvent polarity were experimentally established by Raman spectroscopy...

The recently proposed category of type V deep eutectic solvents (DESs), composed only of non-ionic species, has attracted great interest in the literature. However, despite their importance in solvent design, measuring the solid–liquid equilibrium (SLE) diagrams of all possible type V DES precursor combinations is unfeasible. Therefore, a reliable...

This work explores the use of thermodynamics‐informed Gaussian processes (GPs) and active learning (AL) to model activity coefficients and construct phase diagrams. Relying on synthetic data generated from an excess Gibbs energy model, GPs were found to accurately describe the activity coefficients of several binary mixtures across large compositio...

With the (re)advent of eutectic mixtures within the field of deep eutectic solvents, special attention has been given to the measurement of solid–liquid equilibrium (SLE) phase diagrams, supported by the relevant information they can provide on the molecular interactions and melting temperature depression of any given system. As such, this work inv...

The solid-liquid phase behaviour of two tertiary alcohols, perfluoro-tert-butanol and tert-butanol, was studied here using experimental (ITC, DSC and density measurements) and theoretical (MD simulations) approaches. The phase diagram of the binary mixture reveals highly negative deviations from ideality at low concentrations, as well as the format...

The Abraham and NRTL-SAC semipredictive models were employed to represent the solubility of (-)-borneol, (1R)-(+)-camphor, l-(-)-menthol, and thymol in water and organic solvents, using data measured in this work and collected from the literature. A reduced set of solubility data was used to estimate the model parameters of the solutes, and global...

Are deep eutectic solvents (DESs) a promising alternative to conventional solvents? Perhaps, but their development is hindered by a plethora of misconceptions. These are carefully analyzed here, beginning with the very meaning of DESs, which has strayed far beyond its original scope of eutectic mixtures of Lewis or Brønsted acids and bases. Instead...

Although a theoretically extensive number of hydrophobic eutectic mixtures suitable for solvent extraction are obtainable, to date reported mixtures rely on a limited number of chelating groups, namely phosphine oxide, carboxylic acid, and ketones. Herein, a new family of Type V Deep Eutectic Solvents (DES) based on the polypyridyl ligand 1,10-phen...

Artemisinin is an antimalarial substance very sparingly soluble in water. In the attempt to identify environmental-friendly and non-toxic aqueous-based solvents to extract it from Artemisia annua L., the solubility of artemisinin in aqueous solutions of different hydrotropes was measured at 303.2 K, for hydrotrope concentrations up to 5 M. The abil...

A comprehensive evaluation of the thermal behavior and heat capacities of ChCl and ChCl + H 2 O and the SLE of ChCl + H 2 O is performed. A new structural model that includes small amounts of water in the ChCl crystal structure is proposed.

The formation of deep eutectic solvents (DES) is tied to negative deviations to ideality caused by the establishment of stronger interactions in the mixture than in the pure DES precursors. This work tested thymol and menthol as hydrogen bond donors when combined with different flavonoids. Negative deviations from ideality were observed upon mixing...

This work showcases the remarkable ability of sigma profiles to function as molecular descriptors in deep learning. The sigma profiles of 1432 compounds are used to train convolutional neural networks that accurately correlate and predict a wide range of physicochemical properties. The architectures developed are then exploited to include temperatu...

Inspired by the recently proposed cooperative mechanism of hydrotropy, where water molecules mediate the aggregation of hydrotrope around the solute, this work studies the impact of apolar volume and polar group position on the performance of hydrotropes. To do so, the ability of two different families of alkanediols (1,2-alkanediols and 1,n-alkane...

Type V deep eutectic solvents are a novel class of sustainable solvents. They are prepared by physically mixing solid, non-ionic components and are characterized by strong negative deviations from thermodynamic ideality. This work provides guidelines for the rational design of these solvents and reviews some of their recent applications. Emphasis i...

The differences on the impact of water on the intermolecular interactions present in the deep eutectic solvents betaine/urea and choline/urea are investigated in this work by measuring the solid–liquid phase diagrams of these mixtures with different amounts of added water. These data are analyzed in terms of ternary systems, rather than the usual p...

Mixtures of carbohydrates are often reported in the literature as deep eutectic solvents yet, in most cases, their solid–liquid phase diagrams are poorly characterized and no evidence is available to validate this classification. In this work, the phase diagrams of the binary systems composed of the sugar alcohols mannitol or maltitol and meso-eryt...

Hydrotropy is a well-established strategy to enhance the aqueous solubility of hydrophobic drugs, facilitating their formulation for oral and dermal delivery. However, most hydrotropes studied so far possess toxicity issues and are inefficient, with large amounts being needed to achieve significant solubility increases. Inspired by recent developme...

The efficiency of an ionic hydrotrope is shown to increase with the hydrophobicity of its counterion, challenging the common view that ionic hydrotropes should possess a small, densely charged counterion such as sodium or chloride.

Artemisinin is a sesquiterpenoid lactone peroxide, known for its potent antimalarial activity that can be extracted from Artemisia annua L. This compound is only sparingly soluble in water, making its extraction using environmental-friendly and non-toxic aqueous solvents difficult. In the attempt to overcome this limitation, hydrotropes, which are...

Lignin stands as a promising raw material to produce commodities and specialty chemicals, yet its poor solubility remains a big challenge. Recently, deep eutectic solvents (DES) have been proposed as sustainable solvents with high potential to dissolve and valorize lignin. In the present study, the ability of DES based on cholinium chloride ([Ch]Cl...

Aiming to contribute to drug pre-formulation, new eutectic mixtures were developed. Thymol, coumarin, or quaternary ammonium chlorides as excipients, were combined with the active pharmaceutical ingredients (APIs) acetylsalicylic acid, acetaminophen, ibuprofen, ketoprofen, or lidocaine. Their solid-liquid equilibrium (SLE) binary phase diagrams wer...

Cyrene is an emerging bio-based green solvent that has been shown to have the ability to increase the solubility of hydrophobic substances in water. Even though the water-Cyrene system is an attractive solvent, its applications are hampered by difficulties in the understanding of its solvation mechanism, caused by a delicate chemical equilibrium es...

Cyrene, a recently introduced bio-based green solvent, behaves as a hydrotrope, greatly increasing the aqueous solubility of hydrophobic substances in water. Moreover, water, when present in small quantities, has also been shown to increase the solubility of hydrophobic substances in Cyrene. Albeit of large practical importance, the understanding o...

The mechanism of formation of betaine‐based deep eutectic solvents (DES) is presented for the first time. Due to its polarity unbalance, it was found that betaine displays strong negative deviations from ideality when mixed with a variety of different organic substances. These results pave the way for a comprehensive design of novel deep eutectic s...

Trial and error remain the most common method to select the right solvent for the extraction of natural products, in particular when dealing with novel, poorly studied solvents such as deep eutectic solvents (DES). This can lead to either a lengthy or a suboptimal selection of solvents. COSMO-RS, a quantum chemistry-based thermodynamic model, was a...

A recent proposal attributes the origin of hydrotropy to the water-mediated aggregation of hydrotrope molecules around the solute. Experimental evidence for this phenomenon is reported for the first time in this work, using 1H-NMR. A new computational technique to quantify apolarity is introduced and is used to show that apolarity of both solute an...

The criterion to distinguish a simple eutectic mixture from a deep eutectic solvent (DES) lies in the deviations to thermodynamic ideality presented by the components in the system. In this work, the current knowledge of the molecular interactions in types III and V DES is explored to liquefy a set of three fatty acids and three fatty alcohols, her...

The use of glycerol ethers (with alkyl side chain ranging from one to six methyl groups) as hydrotropes to enhance the solubility of gallic and syringic acids in water was here studied. These compounds were selected by their intrinsic interest and for serving as models for lignin fractions. The results obtained were compared against traditional co-...

Aiming to extend the yet limited knowledge on phase equilibria and physical-chemical properties of quaternary alkylammonium halides and their aqueous binary systems, the solubilities of ten salts in water were measured in this work in the temperature range between 293.2 K and 348.2 K along with their densities. The PC-SAFT equation of state was the...

It was recently shown that tetramethylammonium chloride presented negative deviations to ideality when mixed with tetraethylammonium chloride or tetrapropylammonium chloride, leading to a strong decrease of the melting points of these salt mixtures, in a behavior akin to that observed in the formation of deep eutectic solvents. To better rationaliz...

Deep eutectic solvents (DES) present interesting properties, mostly connected to their solvation ability, and have been subject to much research in the recent past. Currently, the discovery of new eutectic solvents is accomplished by experimentally measuring the eutectic point of random systems, often using choline chloride as a hydrogen bond accep...

Natural products can be the basis for the development of green solvents, relevant for the advancement of new, more sustainable, processes and products. In this work, ten binary mixtures constituted by terpenes are prepared and characterized. Their solid-liquid phase diagrams show that room temperature solvents can be prepared from solid terpenes in...

Mixtures of non-ionic compounds have been reported as DES but most are just ideal mixtures. In the thymol–menthol system, an abnormal strong interaction was identified stemming from the acidity difference of the phenolic and aliphatic hydroxyl groups. This type of interaction is found to be the key to prepare non-ionic DES, that may be classified a...

There is a lack of fundamental knowledge on deep eutectic solvents, even for the most extensively studied mixtures, such as the mixture of cholinium chloride and urea, that prevents a judicious choice of components to prepare new solvents. The objective of this work is to study and understand the fundamental interactions between cholinium chloride...

The high melting point of a large number of organic salts with potential ionic liquid-like properties, hinders their applicability as solvents. Considering the success of cholinium chloride on lowering the melting temperature of several substances and its success on forming deep eutectic solvents, this work studies its mixing with organic chlorides...