News
13/05/2024 NEW PAPER
Our paper titled "The binding energy distribution of H2S: why it is not the major sulphur reservoir of the interstellar ices" has been published on Monthly Notices of the Royal Astronomical Society and is now available here!
Despite hydrogen sulfide (H2S) has been predicted to be the major reservoir of S-bearing species on the icy mantles of interstellar grains, no solid H2S has been detected so far. A crucial parameter that governs whether or not a species remains frozen onto the grain mantles is its binding energy (BE). We present a new computational study of the H2S BE on a large amorphous water ice surface, constituted by 200 water molecules. The resulting H2S BE distribution ranges from 57 K (0.5 kJ/mol) to 2406 K (20.0 kJ/mol), with the average μ = 984 K (8.2 kJ/mol). We discuss the reasons why the low bound of the newly computed BE distribution, which testifies to the very weak interaction of H2S with the ice surface, has never been found by previous theoretical or experimental works before. In addition, the low H2S BEs may also explain why frozen H2S is not detected in interstellar ices. Following previous molecular dynamics studies that show that the energy of reactions occurring on ice surfaces is quickly absorbed by the water molecules of the ice and conservatively assuming that 10% of the HS + H → H2S formation energy (-369.5 kJ/mol) is left to the newly formed H2S, its energy is more than twice the largest BE and 5 times the average BE and, hence, H2S will most likely leave the water surface.
16/04/2024 NEW PAPER
Our paper titled "Unveiling the synergy: a combined experimental and theoretical study of β-cyclodextrin with melatonin" has been published on J. Mater. Chem. B and is now available here!
Melatonin (MT) is a vital hormone controlling biorhythms, and optimizing its release in the human body is crucial. To address MT's unfavorable pharmacokinetics, we explored the inclusion complexes of MT with β-cyclodextrin (β-CD). Nano spray drying was applied to efficiently synthesize these complexes in three molar ratios (MT : β-CD = 1 : 1, 2 : 1, and 1 : 2), reducing reagent use and expediting inclusion. The complex powders were characterized through thermal analyses (TGA and DSC), Fourier transform infrared spectroscopy (FTIR), and in vitro MT release measurements viahigh-performance liquid chromatography (HPLC). In parallel, computational studies were conducted, examining the stability of MT : β-CD complexes by means of unbiased semi-empirical conformational searches refined by DFT, which produced a distribution of MT : β-CD binding enthalpies. Computational findings highlighted that these complexes are stabilized by specific hydrogen bonds and non-specific dispersive forces, with stronger binding in the 1 : 1 complex, which was corroborated by in vitro release data. Furthermore, the alignment between simulated and experimental FTIR spectra demonstrated the quality of both the structural model and computational methodology, which was crucial to enhance our comprehension of optimizing MT's release for therapeutic applications.
15/04/2024 NEW PAPER
We are glad that our paper titled "Experimental and Theoretical Studies of the LiBH4-LiI Phase Diagram" has been published on RSC Advances and is now available here!
The hexagonal structure of LiBH4 at room temperature can be stabilised by substituting the BH4− anion with I−, leading to high Li-ion conductive materials. A thermodynamic description of the pseudo-binary LiBH4–LiI system is presented. The system has been explored investigating several compositions, synthetized by ball milling and subsequently annealed. X-ray diffraction and Differential Scanning Calorimetry have been exploited to determine structural and thermodynamic features of various samples. The monophasic zone of the hexagonal Li(BH4)1−x(I)x solid solution has been experimentally defined equal to 0.18 ≤ x ≤ 0.60 at 25 °C. In order to establish the formation of the hexagonal solid solution, the enthalpy of mixing was experimentally determined, converging to a value of 1800 ± 410 J mol−1. Additionally, the enthalpy of melting was acquired for samples that differ in molar fraction. By merging experimental results, literature data and ab initio theoretical calculations, the pseudo-binary LiBH4–LiI phase diagram has been assessed and evaluated across all compositions and temperature ranges by applying the CALPHAD method.
19/03/2024 NEW PAPER
A new paper titled "Synthesis of amine derivatives from furoin and furil over a Ru/Al2O3 catalyst" has been published on Catal. Sci. Technol. and is now available here!
The direct/reductive amination of carbohydrate-based furoin and furil with NH3/H2 was investigated to access amine derivatives. In the sole presence of NH3, cyclic amines, i.e. 2,3,5,6-tetra(furan-2-yl)pyrazine and 2,2′-bipyridine-3,3′-diol, were generated as the main products from furoin and furil, respectively. Over Ru/Al2O3 under NH3/H2, 2-amino-1,2-di(furan-2-yl)ethan-1-ol (i.e. alcohol–amine) was generated as the main product with 47% yield at 140 °C for 2 h starting from furoin. The catalyst could be recycled for at least three consecutive runs. An alcohol–imine was the main intermediate that underwent tautomerization to alcohol–enamine/keto–amine leading to cyclic by-products by self-condensation. DFT calculations, complementing the experimental observations, provided detailed molecular-level insight into the reactivity of the alcohol–imine intermediate. Its preferential adsorption on Ru centers via the NH group, with the OH group pointing away from the surface, was found to direct its hydrogenation towards the alcohol–amine as main product. By combining Ru/Al2O3 and a silica-anchored N-heterocyclic carbene (NHC) catalyst, the alcohol-amine could be accessed with 42% overall yield in a single reactor.
01/03/2024 EuroHPC JU project
The project "Interstellar dust grains coating: water formation on forsterite nanoparticles" has been awarded with 14 000 000 core-hours on the LUMI supercomputer, through the European High Performance Computing Joint Undertaking (EuroHPC JU) Regular Access call
The prebiotic origin of the chemical complexity found on Earth nowadays is a matter of debate in the astrochemical community, in particular because chemical processes start in the molecular clouds, i.e. the first step of a planetary system formation, where the matter is diffuse (101-106 particles/cm3), and the temperatures low (10-100 K). These extreme conditions hinder whatever chemical reaction, thus raising a fundamental question: which is the spark that made possible the elemental reactions that from atomic species led to simple molecules until the most complex living and thinking systems? The dust grains, nanometric particles made by rocky materials, work as concentrators of atomic species that from the gas phase freeze out onto the grains and react among them, thus forming the first simple molecules. Studying such phenomena through laboratory experiments is extremely challenging, and, for this reason, computational chemistry became in the last years a fundamental pillar in the astrochemistry field. The aim of this project is to study the structure and chemical properties of dust grains, as well as the most interesting reactions occurring at their interface. The broader scope of this research is to shed light on the comprehension of our astrochemical heritage, starting from the formation of the simplest molecules by their atomic components.
20/02/2024 NEW PAPER
We are happy that our paper titled "Theoretical prediction of nanosizing effects and role of additives in the decomposition of Mg(BH4)2" has been published on RSC Advances and is now available here!
The energetic transition towards renewable resources is one of the biggest challenges of this century. In this context, the role of H2 is of paramount importance as a key source of energy that could substitute traditional fossil fuels. This technology, even if available in several manufactures, still needs to be optimized at all levels (production, storage and distribution) to be integrated on a larger scale. Among materials suitable to store H2, Mg(BH4)2 is particularly interesting due to its high content of H2 in terms of gravimetric density. Nanosizing effects and role of additives in the decomposition of Mg(BH4)2 were studied by density functional theory (DFT) modelling. Both effects were analyzed because of their contribution in promoting the decomposition of the material. In particular, to have a quantitative idea of nanosizing effects, we used thin film 2D models corresponding to different crystallographic surfaces and referred to the following reaction: Mg(BH4)2 → MgB2 + 4H2. When moving from bulk to nanoscale (2D models), a remarkable decrease in the decomposition energy (10–20 kJ mol−1) was predicted depending on the surface and the thin film thickness considered. As regards the role of additives (Ni and Cu), we based our analysis on their effect in perturbing neighboring borohydride groups. We found a clear elongation of some B–H bonds, in particular with the NiF2 additive (about 0.1 Å). We interpreted this behavior as an indicator of the propensity of borohydride towards dissociation. On the basis of this evidence, we also explored a possible reaction pathway of NiF2 and CuF2 on Mg(BH4)2up to H2 release and pointed out the major catalytic effect of Ni compared to Cu.
11/01/2024 NEW PAPER
We are pleased to announce that our paper titled "Disclosing the true atomic structure of {001} facets in shape-engineered TiO2 anatase nanoparticles" has been published on the Journal of Materials Chemistry A and is now available here!
In the last decade shape-engineering of TiO2 anatase nanoparticles (NPs) has attracted increasing attention owing to the possibility to maximize the presence of {001} facets, which have been reported to show peculiar adsorption, electronic, and (photo)catalytic properties. It is well-known that the anatase (001) surface is prone to reconstruction and several models have been proposed and validated by DFT calculations and single crystal studies. However, its true atomic structure in shape-engineered TiO2 anatase nanoparticles often remains elusive. In this study we shed light on this issue combining IR spectroscopy of CO adsorbed at very low temperature and thorough DFT modelling. Our results show that the thermal treatment in oxygen, performed to remove the capping agents (i.e., fluorides) employed in the synthesis of shape-controlled NPs, leads to a reconstruction of the {001} facets which is compatible with an “add-oxygen” model (AOM) and not with the most commonly reported “add-molecule” model (ADM). These findings can guide future experimental and computational studies highlighting that the AOM reconstruction is the most appropriate model to describe the properties and reactivity of the {001} facets in shape-controlled TiO2nanoparticles after thermal removal of fluorides.