Understanding the formation of deep eutectic solvents: betaine as a universal hydrogen bond acceptor

© 2020 Wiley-VCH GmbH 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 solvents. A connection to biologically relevant systems was made using betaine (osmolyte) and urea (protein denaturant), showing that these two compounds formed a DES, the molecular interactions of which were greatly enhanced in the presence of water.This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES, and CIMO-Mountain Research Center, UIDB/00690/2020, financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement.info:eu-repo/semantics/publishedVersio

Application of PEG400 in the one-pot synthesis of 7-[4-alkyl- or (hetero) aryl-1H-1,2,3-triazol-1-yl]thieno[3,2-b]pyridines via SNAr and Cu(I)- Catalyzed Azide-Alkyne Cycloaddition and preliminary evaluation of their anti-tumour activity

Several novel 7-[4-alkyl- or (hetero)aryl-1H-1,2,3-triazol-1-yl]thieno[3,2-b]pyridines were prepared in good to high yields, using the environmentally friendly solvent PEG400 in a one-pot procedure from 7- chlorothieno[3,2-b]pyridine to form the corresponding azide via SNAr with NaN3, followed by Cu(I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) using different types of alkynes. This one-pot reaction in PEG400 starting from a halogenated heteroaromatic system is reported for the first time and demonstrated a wide scope of application for alkynes. Preliminary anti-tumour activity on human tumour cell lines using the prepared 1,4-di(hetero)aryl-1,2,3-triazoles was evaluated, together with their toxicity in non-tumour cells. Among the tested compounds the most promising one was a 2-ethynylpyridine derivative.Fundação para a Ciência e Tecnologia (FCT)–Portugal financially supports CQUM (UID/QUI/686/2019), CIMO-IPBragança (UID/ AGR/690/2019), the research project PTDC/QUI-QFI/28020/2017 (POCI-01-0145-FEDER-028020) also financed by European Regional Development Fund (ERDF), COMPETE2020 and Portugal2020, the PTNMR network also supported by Portugal2020 and the PhD grant of J.M.R. (SFRH/BD/115844/2016) also financed by ESF (European Social Fund) and HCOP (Human Capital Operational Programme).info:eu-repo/semantics/publishedVersio

Physico-chemical characterization of aqueous solutions of superbase ionic liquids with cellulose dissolution capability

Superbase-based ionic liquids 7-methyl-1,5,7-triazabicyclo[4.4.0]dec‑5-enium acetate, [mTBDH][OAc], and 5-methyl-1,5,7-triaza-bicyclo[4.3.0]non-6-enium acetate, [mTBNH][OAc], are good candidates to produce high performance cellulose fibres while presenting much easy spinnability and good recyclability, than the state-of-the-art ionic liquids. Nevertheless, the recovery of the IL from the aqueous spinning bath and its purification, which are both an economical and environmental necessity, are important aspects that are still not solved. Aiming to gather knowledge to recover and recycle superbase-ILs, the main goal of this work is the physicochemical characterization of the binary systems water + [mTBDH][OAc] or [mTBNH][OAc]. Measurements performed include solid-liquid equilibria, vapor-liquid equilibria, water activity, Kamlet−Taft solvatochromic parameters, densities, and viscosities. An experimental screening on possible hydrophobic extractants for the recuperation of the ionic liquids from aqueous solution was performed. Using butanol, an extraction efficiency of 37% for [mTBDH][OAc] was achieved. Better extraction efficiencies were achieved with chlorinated solvents, however, they seem to react with the ILs anion.publishe

Fire behaviour of ecological soil-cement blocks with waste incorporation

Tecnologias construtivas com elevado caráter sustentável vêm se tornando cada vez mais uma necessidade da sociedade atual. Neste contexto, métodos construtivos que valem-se de terra como matéria-prima, bem como o reaproveitamento de resíduos industriais, mostram-se em ascenção. Sendo assim, o presente trabalho tem por objetivo caracterizar o comportamento de blocos de terra compactados perante situações de incêndio. Para tal, utilizou-se tanto abordagens experimentais quanto modelagem computacional.info:eu-repo/semantics/publishedVersio

Infinite dilution activity coefficients in the smectic and isotropic phases of tetrafluoroborate-based ionic liquids

Inverse gas chromatography was used to obtain the activity coefficients at infinite dilution (γ13∞) of several organic solutes and water in the thermotropic ionic liquid crystal phases of both [C12mim][BF4] and [C14mim][BF4] and their isotropic phases. In the smectic to isotropic transition, a change in the linear representation of the natural logarithm of γ13∞ with the reciprocal temperature was observed for [C14mim][BF4], and was more evident for alkanes, alkylbenzenes, esters, and alcohols, that can be related to structural modifications of the stationary phase. Results are interpreted in terms of the enthalpic and entropic contributions of solute-IL interactions. Selectivities and capacities of important separation problems, such as octane/benzene and cyclohexane/benzene, were calculated and compared with literature values for separating agents such as N-methyl-2-pyrrolidinone, sulfolane, and ionic liquids presenting the [BF4]− anion combined with several imidazolium-based cations. It is shown that to achieve maximum separation efficiency, imidazolium cations with short alkyl chain lengths such as [C2mim][BF4] should be used, whereas high capacities require larger alkyl chain lengths.publishe

Non-Ideality in Thymol + Menthol Type V Deep Eutectic Solvents

The nonionic Type V deep eutectic solvent (DESs) thymol + menthol is experimentally and computationally studied aiming to clarify the relation between its liquid phase structure and its thermodynamic nonideality. 1H NMR, Raman, and X-ray scattering analysis of the thymol + menthol system, supported by molecular dynamics simulations, show complex intermolecular interactions dominated by sterically hindered H-bonded clusters. For temperatures greater than or equal to room temperature, a quasi-linear evolution of the eutectic system properties between the pure compounds is observed, suggesting the absence of a magic stoichiometric composition in the eutectic solvent. However, temperature dependent Raman spectroscopy indicates a notable increase in thymol–menthol H-bonding as temperatures approach the eutectic point. This study shows that nonionic Type V DESs present an important temperature-dependent nonideality originating from the change in the intermolecular H-bonding with temperature. These findings have significant implications for the design and growing application of Type V DESs