Publications

Abstract The determination of the reliable thermodynamic properties of 2-benzoxazolinone derivatives is the main goal of this work. Some correlations are established between the energetic properties determined and the structural characteristics of the title compounds, and the reactivity of this class of compounds is also evaluated. Static-bomb combustion calorimetry and high-temperature Calvet microcalorimetry were used to determine, respectively, the standard molar enthalpies of formation in the solid state and the standard molar enthalpies of sublimation, both at T = 298.15 K. Using the results obtained for each compound, the respective gas-phase standard molar enthalpy of formation was derived. High-level quantum chemical calculations were performed to estimate the same property and the results evidence good accordance. Moreover, the gas-phase relative thermodynamic stability of 2-benzoxazolinone derivatives was also evaluated using the respective gas-phase standard molar Gibbs energy of formation. In addition, the relationship between the energetic and structural characteristics of the benzoxazolinones is presented, evidencing the enthalpic increments associated with the presence of a methyl and a nitro groups in the molecule, and this effect is compared with similar ones in other structurally related compounds.

Abstract An experimental study based on the thermal analysis of 5-methyl-1H-benzotriazole and 5,6-dimethyl-1H-benzotriazole was developed, by using differential scanning calorimetry. Additionally, a summary of the experimental techniques and computational methodology being performed, in order to complement the energetic study of both compounds, is described. The knowledge of the thermochemical, thermophysical and structural properties of functionalized benzotriazoles is relevant for the evaluation of their chemical behaviour, as well as in the prediction of the reactivity of similar compounds that have not been thermodynamically characterized. © 2022, Universidade do Porto - Faculdade de Engenharia. All rights reserved.

Abstract Scientific literacy is an important skill for students' success, given the characteristics of today's society. However, not all students have a natural predisposition toward science, chemistry in particular. Considering the relevance of transdisciplinary learning, schools should foster the scientific abilities for which students may have less aptitude or interest by taking advantage of areas and subjects that they have more inclination and knowledge. The use of analogies through comparisons between familiar and unfamiliar domains can potentiate the learning of abstract, unknown, or complex chemistry concepts. This article describes a case study regarding the use of a marching band analogy that was developed to teach kinetic-molecular theory. The study involved a convenience sample of 50 Portuguese seventh grade students attending a middle school music course, from four specialized music education schools. Data was collected through a questionnaire and an interview. Results reveal that the marching band analogy for kinetic-molecular theory, considering the students' profile, is didactic and suitable, enhances their attention and interest, and promotes their chemistry learning. In order to benefit chemistry education, we recommend the development and use of analogies between chemistry and music with students of similar profiles or the use of different areas and subjects for other student profiles.

Abstract The active participation of citizens in scientific research, through citizen science, has been proven successful. However, knowledge on the potential of citizen science within formal chemistry learning, at the conceptual and procedural levels, remains insufficiently explored. We developed a citizen science project - PVC: Perceiving the Value of Chemistry behind water and microplastics - which sought to involve students in monitoring the physicochemical parameters of coastal water quality, through the detection of microplastics in these waters, in addition to the qualitative identification of plastic contaminants on beaches. The project was conducted throughout the 2018/2019 school year and involved 442 middle school students (Key Stage 3 (KS3) aged 12-14, in Portuguese schools) and 9 chemistry teachers, in the northern coastal region of Portugal. The data on learning outcomes was collected through knowledge tests, applied after project conclusion, and was then compared to data collected up to six months later (retention test). In addition, interviews were conducted with participants, and researchers' field notes were recorded and analyzed. Data analysis suggests the PVC project promoted conceptual chemistry learning related to the analysis of physicochemical water parameters (pH, temperature, turbidity, salinity, nitrate and nitrite concentrations and dissolved oxygen), as well as polymers (polymer types, formation and structure). A positive knowledge retention was registered a few months after the project conclusion. At a process level, participants learned laboratory techniques (sieving, gravity and reduced pressure filtrations and crystallization) and the handling of laboratory materials. Furthermore, teachers recognized that their students' participation in the PVC project fostered the development of their argumentation skills, as well as their reflexive and critical thinking skills. The ability to communicate ideas and results, along with the development of students' digital skills, was also mentioned.

Abstract This work constitutes a new contribution for understanding the relationship between the metal-ligand bonding and, indirectly, the inherent reactivity of metallic complexes with tetradentate N2O2 Schiff base ligands, being reported the energetic characterization of two transition metal complexes - (N,AT c -bis(salicylaldehydo)tetramethylenediiminate)nickel(II) and (N,N' -bis(salicylaldehydo)propylenediiminate)copper(II). The standard molar enthalpies of formation of these complexes were determined by solution-reaction calorimetry measurements. Their standard molar enthalpies of sublimation, at T = 298.15 K, were obtained by an effusion method. From these studies, the gas-phase enthalpies of formation of Ni(II) and Cu(II) complexes, at T = 298.15 K, were derived. Differences between the metal-ligand and mean hydrogen-ligand bond dissociation enthalpies were derived and discussed in structural terms, in comparison with identical parameters for complexes of the same metals with analogous tetradentate Schiff bases. High-level quantum chemical calculations have also been conducted, complementing the results obtained experimentally.

Abstract The CoAstro: @n Astronomy Condo citizen science project engages, in a mediated process, teachers, astronomers, and science communicators in research and science communication/science education practices. In CoAstro, scientific research objectives were aligned with science communication/science education objectives to engage public with low astronomy awareness. One of CoAstro's goals was to understand the effects of the relationships established among the participants, because these are key aspects for engagement. We conducted a case study following the participants during an academic year and collected data through interviews and participant observations. A focus group meeting followed those data collection techniques. The results show the personal benefits of established relationships, institutional effects, changes in the perceived identity roles, and the ability to understand and engage in astronomy research and astronomy communication/ education. Understanding social interactions contributes to increase the scope of citizen science projects' and demonstrates its relevance to engaging scientists, science communicators, and school communities, pointing to a path for community empowerment and engagement with science; i.e., a path to unveil a citizen science that moves from mere citizenship to personal comprehensive development: attitudes but also, knowledge.

Abstract Society needs transdisciplinary citizens with good scientific literacy. One way to achieve this could be through the use of areas or subjects for which students have more affinity and expertise. This study seeks to maximize the chemistry learning of students who want to be musicians, through the use of analogies. Analogies are a powerful tool to explain abstract, unfamiliar, or complex scientific concepts (such as the quantum atomic model) in familiar terms and to promote positive attitudes toward learning science. A case study is presented regarding the use of musical analogies developed to teach the atom concept, subatomic particles, and the atomic structure, according to the quantum mechanical model of the atom. A cohort of 50 Portuguese 12 to 13 year old students, enrolled in the seventh grade of a middle school music course, was selected by convenience sampling from four schools. A questionnaire and interviews were used for data gathering. The results show that the musical analogies used helped to overcome students' difficulties regarding the topics taught, improved chemistry learning, and stimulated attentiveness and interest. The use of analogies between music and chemistry with students of similar characteristics to those of this study, or the use of different areas and subjects for other student backgrounds and tastes, can be fruitful for teaching chemical content.

Abstract The thermochemical study of the 1,3-bis(N-carbazolyl)benzene (NCB) and 1,4-bis(diphenylamino)benzene (DAB) involved the combination of combustion calorimetric (CC) and thermogravimetric techniques. The molar heat capacities over the temperature range of (274.15 to 332.15) K, as well as the melting temperatures and enthalpies of fusion were measured for both compounds by differential scanning calorimetry (DSC). The standard molar enthalpies of formation in the crystalline phase were calculated from the values of combustion energy, which in turn were measured using a semi-micro combustion calorimeter. From the thermogravimetric analysis (TGA), the rate of mass loss as a function of the temperature was measured, which was then correlated with Langmuir's equation to derive the vaporization enthalpies for both compounds. From the combination of experimental thermodynamic parameters, it was possible to derive the enthalpy of formation in the gaseous state of each of the title compounds. This parameter was also estimated from computational studies using the G3MP2B3 composite method. To prove the identity of the compounds, the H-1 and C-13 spectra were determined by nuclear magnetic resonance (NMR), and the Raman spectra of the study compounds of this work were obtained.

Abstract Combined experimental and computational studies were performed aiming the analysis of energetic properties vs structural characteristics of three methyl nitrobenzoate isomers (methyl 2-nitrobenzoate, M2NB, methyl 3-nitro benzoate, M3NB, methyl 4-nitrobenzoate, M4NB). The experimental studies include the determination of the enthalpy of formation in the condensed state (crystal and liquid) of the compounds by static combustion, and the determination of enthalpies of phase transition, using Differential Scanning Calorimetry, high temperature Calvet microcalorimetry and the Knudsen effusion method. These data were combined to derive the enthalpy of formation of the methyl nitrobenzoate isomers in the gaseous phase, at T = 298.15 K. At the computational level, the gas-phase enthalpy of formation of the methyl nitrobenzoate isomers were estimated using theoretical approaches, resorting to the G3(MP2)//B3LYP composite method and to appropriate hypothetical gas-phase reactions. The enthalpies of formation obtained experimental and computationally will be discussed and the energetic structural synergies for the three methyl nitrobenzoate, along with other analogous isomers, will be also analyzed.

Abstract Lipid nanoparticles are currently used to deliver drugs to specific sites in the body, known as targeted therapy. Conjugates of lipids and drugs to produce drug-enriched phospholipid micelles have been proposed to increase the lipophilic character of drugs to overcome biological barriers. However, their applicability at the topical level is still minimal. Phospholipid micelles are amphiphilic colloidal systems of nanometric dimensions, composed of a lipophilic nucleus and a hydrophilic outer surface. They are currently used successfully as pharmaceutical vehicles for poorly water-soluble drugs. These micelles have high in vitro and in vivo stability and high biocompatibility. This review discusses the use of lipid-drug conjugates as biocompatible carriers for cutaneous application. This work provides a metadata analysis of publications concerning the conjugation of cannabidiol with lipids as a suitable approach and as a new delivery system for this drug.