Search

Platinum complexes are ubiquitous in chemistry and largely used as catalysts or as precursors in drug chemistry, thus a deep knowledge of their electronic properties may help in planning new synthetic strategies or exploring new potential applications. Herein, the electronic structure of many octahedral platinum “IV” complexes is drastically revised especially when the metal is associated with electronegative elements such as halogens and chalcogens. The investigation revealed that in most of the cases the five d platinum orbitals are invariably full, thus the empty antibonding orbitals, usually localized on the metal, are mainly centered on the ligands, suggesting a questionable assignment of oxidation state IV. The analysis supports the occurrence of the Inverted Ligand Field theory in all cases with the only exceptions of the Pt-F and Pt-O bonding. The trends for the molecular complexes are mirrored also by the Density of States plots of extended structures featuring octahedral platinum moieties in association with chalcogens atoms. Based on the gathered information on the electronic structure of complexes and materials, the oxidative addition of a Se-Cl linkage to a square platinum complex to achieve an octahedral moiety has been revised in the framework of the Inverted Ligand Field.

The CO2 desorption process from a CO2-saturated nonaqueous sorbent, 2-(2-aminoethoxy)ethanol (DGA) in diethylene glycol monomethyl ether (DEGMME), was investigated in the absence and presence of four different metal oxides, namely, V2O5, TiO2, WO3, and ZnO, aiming at identifying acid catalysts with the potential to reduce the energy demand for sorbent regeneration. The desorption performances of the DGA-DEGMME solutions with and without catalysts were evaluated in terms of CO2 desorption rate, overall CO2 desorbed, and thermal energy consumption. The desorption mechanism was understood by the 13C NMR speciation study of the solutions during the regeneration experiments. As a result, metal oxide catalysts, depending on the number and types of acidic sites on their surface, can accelerate the carbamate breakdown and the subsequent CO2 release. In particular, WO3 and TiO2 can be considered good candidates for implementation in CO2 capture processes with nonaqueous sorbents, as they greatly improved the desorption performance, and their structures remain unchanged before and after use. The combination of nonaqueous sorbents with catalysts, here reported for the first time, provides an effective strategy that could inspire the design of advanced sorbents for energy-efficient CO2 capture.

Essential oils (EOs) and oleoresins are complex mixtures mainly made up of terpenes, synthesized by a wide variety of plants. Individual terpenes may show broad-spectrum activity against different plant pathogens, and their combination into EO and oleoresin mixtures enhances plant chemical defense. The interest in EOs has significantly increased due to the trend of using natural products as herbicides, insecticidal and antimicrobial agents. In addition, the use of plant mixtures is an emerging approach to face the problem of antimicrobial resistance in agriculture. This chapter reports guidelines about plant sample collection for the production of EOs and provides protocols to test their activity as antimicrobial agents against bacteria and fungi. It also describes a solvent-free method for the inclusion of EOs into β-cyclodextrins. This type of formulate is prepared to turn liquid EOs into easily manageable water-soluble powders, and to control the release of volatile compounds, aiming to increase EOs' applications in agriculture.

The selective recognition of caffeine in water among structurally related xanthines and purine or pyrimidine bases was achieved by a simple tweezer-shaped receptor featuring sulfonate hydrosolubilizing groups. The remarkable affinity for caffeine, among the highest reported thus far in the literature and larger than that shown by adenosine receptors of all subtypes, stems from a synergistic combination of hydrogen bonding, CH-pi, and pi-stacking interactions.

Gold chemistry has experienced in the last decades exponential attention for a wide spectrum of chemical applications, but the +3 oxidation state, traditionally assigned to gold, remains somewhat questionable. Herein, we present a detailed analysis of the electronic structure of the pentanuclear bow tie Au/Fe carbonyl cluster [Au{η2-Fe2(CO)8}2]- together with its two one-electron reversible reductions. A new interpretation of the bonding pattern is provided with the help of inverted ligand field theory. The classical view of a central gold(III) interacting with two [Fe2(CO)8]2- units is replaced by Au(I), with a d10 gold configuration, with two interacting [Fe2(CO)8]- fragments. A d10 configuration for the gold center in the compound [Au{η2-Fe2(CO)8}2]- is confirmed by the LUMO orbital composition, which is mainly localized on the iron carbonyl fragments rather than on a d gold orbital, as expected for a d8 configuration. Upon one-electron stepwise reduction, the spectroelectrochemical measurements show a progressive red shift in the carbonyl stretching, in agreement with the increased population of the LUMO centered on the iron units. Such a trend is also confirmed by the X-ray structure of the direduced compound [Au{η1-Fe2(CO)8}{η2-Fe2(CO)6(μ-CO)2}]3-, featuring the cleavage of one Au-Fe bond.

The three different solid forms of dexktoprofen trometamol (DK-T_A, DK-T_B, and DK-T_2H2O) have been studied by using X-ray diffraction and calorimetric methods. In the molecular and crystal structure of DK-T_A, the thermodynamically stable form used in the tablets production process, all the potential H-bond donors and acceptors of each trometamol cation are involved in strong H-bonds which hold together the cations as well as the dexketoprofen/trometamol ionic pairs. The dihydrate species is quickly formed starting from DK-T_A apparently without the formation of an amorphous phase, and the process is fully reversible. In addition, the two solids have comparable crystal density (cell parameters and space group of the resulting hydrate were determined by X-ray powder diffraction). We speculate that the anhydrous and hydrate crystal architectures did not suffer upon the hydration/dehydration process and that the hydrate form belongs to the class of the channel hydrates and most probably is a planar hydrate. Finally, the unit cell parameters and space group were determined also for the metastable DK-T_B solid form.

Heterostructures of single- and few-layer black phosphorus (2D bP) functionalized with gold nanoparticles (Au NPs) have been recently reported in the literature, exploiting their intriguing properties and biocompatibility for catalytic, therapeutical and diagnostic applications. However, a deeper insight on the structural and electronic properties at the interface of the 2D bP/Au NP heterostructure is still lacking. In this work, 2D bP is functionalized with Au nanoparticles (NPs) through in situ deposition–precipitation heterogeneous reaction. The smallest realized Au NPs have a diameter around 10 nm as revealed by atomic-force and scanning electron microscopy, and are partially positively charged as revealed by X-ray Photoelectron Spectroscopy (XPS). XPS, UV-vis and Raman spectroscopy, supported by density functional theory (DFT) calculations, confirmed that while the structural and electronic properties of 2D bP are overall preserved, a soft-pairing between P atoms at the surface of 2D bP and Au atoms at the surface of Au NPs occurs, leading to a partial charge transfer at the 2D bP/Au interface, with a positive charge being localized on the Au atoms directly bonded to 2D bP. DFT calculations also predicted a band gap lowering, by 0.8 eV, for phosphorene functionalized with a tetranuclear Au cluster. Larger effects are expected as the Au cluster nuclearity (and coverage) increases., Computational analysis and electronic, structural and morphological properties of a heterostructure of 2D bP with Au nanoparticles formed in situ.

Since its first reported exfoliation in 2014, the interest in 2D black phosphorus (2D BP) and its chemical functionalization has grown dramatically [1], though a satisfactory structural description of the modified materials is seldom achieved. Herein, the functionalization of 2D BP starting from molecular Pd precursors is presented, leading either to supported Pd NPs (Pd/BP) or to interlayer Pd-Pd discrete units (Pd2/BP). An in-depth solid-state characterization of the new materials was carried out by means of XPS, HAADF-STEM, XRD, NMR MAS and XAS. Remarkably, XAS analysis, backed up by DFT modelling, was crucial in revealing the existence of Pd2 moieties stacked amidst BP layers in Pd2/BP. The potential application of these heterogeneous systems as catalysts was demonstrated in distinct processes, namely the selective hydrogenation of chloronitrobenzene to chloroaniline and the hydrogen evolution reaction (HER) from acidic medium.

The main role of the Ruthenium metal in the stepwise demolition of the P4 ligand upon the reaction with I2 is to enhance the basicity of the phosphorus atoms. The first step of reaction goes through the η2 coordination of the P4 moiety. The bounded phosphorus atoms are able to interact with the di-iodine molecule allowing the formation of tri-iodide anions. The latter, once released, may exert their nucleophilic action toward the transient unsaturated coordinated phosphorus centre. Such a vacancy is partially fulfilled by the metal through the formation of a partial Ru=P double bond. A detailed analysis of the evolution of the electronic structure at the various intermediates allows to discriminate in between the possible different initial adducts and to predict the most stable product. In contrast with the unassisted reaction, no concerted mechanism has been pointed out but the process evolves through a stepwise cleavage of the three P P bonds involving the coordinated phosphorus up to the final PI3 ligand formation and a cyclo-P3I3 moiety.

The solid-state investigation of the diastereomeric salts (S)-ibuprofen (S-Ibu), (S)-naproxen, (S-Nap), and (S)-ketoprofen (S-Ket) with (R)-(+)- and (S)-(-)-1-phenylethylamine, R-PEA, and S-PEA respectively, has been carried out by using a combination of experimental and in-silico tools. The focus was on their crystal packing and on the stability/transformation of their solid forms under different experimental conditions with the final aim of extracting useful information on the forces/features which could be exploited for the chiral separation of the corresponding racemic compounds. All the salts are 21-column crystals, each column consisting of API and 1-phenylethylamine ions assembled via the 1-phenylethylammonium-carboxylate supramolecular heterosynthon which originates a R43 (10) pattern, the intercolumns contacts being definitely weaker. In spite of an overall similarity in the crystal packing forces and motifs of the anhydrous salts, the temperature stability range suggests that the homochiral species are the most stable. The fact that the homochiral salt of S-Ket (S-Ket_S-PEA) is stable toward the hydration, at variance with the heterochiral one (S-Ket_R-PEA), further confirms this hypothesis. On the other hand, preliminary sorption tests show that S-Ket and S-Ibu preferentially capture the homochiral PEA (S-Nap is not selective). This behavior has been correlated to the almost planar boundary surfaces which characterize and differentiate the 21 sheets in S-Ket_S-PEA and S-Ibu_S-PEA salts with respect to the corresponding heterochiral ones.

The chemical functionalization of 2D exfoliated black phosphorus (2D BP) continues to attract great interest, although a satisfactory structural characterization of the functionalized material has seldom been achieved. Herein, we provide the first complete structural characterization of 2D BP functionalized with rare discrete Pd2 units, obtained through a mild decomposition of the organometallic dimeric precursor [Pd(?3-C3H5)Cl]2. A multitechnique approach, including HAADF-STEM, solid-state NMR, XPS, and XAS, was used to study in detail the morphology of the palladated nanosheets (Pd2/BP) and to unravel the coordination of Pd2 units to phosphorus atoms of 2D BP. In particular, XAS, backed up by DFT modeling, revealed the existence of unprecedented interlayer Pd-Pd units, sandwiched between stacked BP layers. The preliminary application of Pd2/BP as a catalyst for the hydrogen evolution reaction (HER) in acidic medium highlighted an activity increase due to the presence of Pd2 units.

Functionalization is one of the most powerful tools in materials science for the development of new and innovative materials with tailored properties purposefully designed to enhance the overall stability of the system. This is particularly true for exfoliated black phosphorus, which suffers from easy decomposition by air and moisture, hampering its highly desirable applications, especially in electronics. The present work suggests an innovative approach to the functionalization process of this 2D-material based on the selective introduction of chalcogen atoms on the material surface through a reaction with suitable molecular precursors such as stibine chalcogenides (R3Sb(X), X = O or S; R = organyl group). These molecules may readily act as chalcogen-transfer agents and, upon releasing the chalcogen atom atop the bP surface, leave stable stibines (R3Sb) as byproducts, which may be easily removed from the functionalized bP surface. The work provides an overview of all the possible structural, electronic and energy aspects associated with the chalcogen-atom transfer from the stibine to phosphorus based compounds, exemplified by trialkyl phosphines and single layer exfoliated black phosphorus, i.e. phosphorene, Pn. In both cases the oxygen transfer is more exergonic than the sulfur transfer, with the associated free energy barrier for the phosphine process being higher. Although the sulfur transfer for the Pn is found to be endergonic (ca. +3.6 kcal mol-1), the process may surely occur at high temperature. The evolution of the band structure upon the chalcogen transfer has been depicted in detail.

White bronzes are ternary alloys composed by Cu, Zn and Sn, named after their bright whitish colour. This class of alloys share excellent hardness, corrosion and tarnishing resistance, and is commonly adopted in galvanic industrial processes as technological grade coating, to obtain layers with particular aestethical and/or anticorrosive properties. Despite the widespread employment of white bronzes in fashion and electronics industry, recent literature lacks a characterization of these electrodeposited alloys in respect to more common binary (Cu-Sn) white bronzes. In this presentation, a thorough characterization of a commercial ternary Cu-Zn-Sn white bronze, produced by electrodeposition, is reported. Structural, Chemical and Physical characteristics of the deposited coating were investigated by various techniques (e.g. FIB/SEM, XRF, XRD, EDX, microhardness, colour and corrosion tests). Results were compared with a similar set of measures obtained from a binary electrodeposited Cu-Sn white bronze (with a high tin content), in order to shed some light on the influence of Zn in the coating properties.

Dexketoprofen trometamol is the tromethamine salt of dexketoprofen [(2S)-2-(3-benzoylphenyl)propanoic acid-2-amino-2-(hydroxymethyl)propane-1,3-diol], a nonsteroidal anti-inflammatory drug (NSAID) used for the treatment of moderate- to strong-intensity acute pain. The crystal structure of the hitherto sole known hydrate phase of dexketoprofen trometamol (DK-T_2H2O), as determined by single-crystal X-ray diffraction, is presented. The water molecules are arranged in dimers included in isolated sites and sandwiched between piles of trometamol cations. The molecular and crystal structures of DK-T_2H2O are analyzed and compared to those of the parent anhydrous crystal form DK-T_A. In both the crystal structures, all the potential H-bond donors and acceptor of the dexketoprofen and trometamol ions are engaged, and both the species crystallize in the P21 space group. However, during the DK-T_A&agrave, DK-T_2H2O hydration process, the unique symmetry axis is not conserved, i.e., the ions are arranged in a different way with respect to the screw axis, even if the two crystal structures maintain structural blocks of DK anions and T cations. Quantum mechanical solid-state calculations provide some hints for the possible intermediate structure during the crystalline&ndash, crystalline hydration/dehydration process.

Anisotropic lattice expansion could be a source of misunderstanding in powder pattern recognitions, especially in the case of organic crystals where for the interpretation of room temperature patterns single crystal data at low temperature are usually used. Trying to rationalize the thermal lattice expansion, we studied two close related &beta, blocker molecules with similar packing in the solid state but with different thermal behavior. Solid state calculations, using the fast and accurate HF-3c method and the quasi harmonic approximation for the simulation of the lattice expansion, were able to reproduce the experimental trends with good accuracy. The complete analysis of the calculated thermal expansion of the two structures, as well as of other structures with similar packing found in a database survey, revealed the primary role of the hydrogen bonds. Secondary non-covalent interactions in the plane perpendicular to the hydrogen bond system could also play a role.

White bronzes are electrodeposited coatings applied on brass as surface finishes. We report a comparative study on the corrosion resistance in chloride aqueous environment of two white bronzes, a Zn-bearing and a Zn-free. Corrosion tests showed that both materials provide protection to brass, but the Zn-free is more cathodic and performs better in the test environment, following a different corrosion mechanism. We also explored the effect of the coating thickness on the corrosion parameters. We found that the more cathodic OCPs were achieved with coatings exceeding 1 μm, while the 0.5 μm coatings show OCPs closer to the brass substrate.

Metal-organic frameworks (MOFs) have gained widespread attention due to their modular construction that allows the tuning of their properties. Within this vast class of compounds, metal carboxylates containing tri- and tetravalent metal ions have been in the focus of many studies due to their often high thermal and chemical stabilities. Cerium has a rich chemistry, which depends strongly on its oxidation state. Ce(iii) exhibits properties typically observed for rare earth elements, while Ce(iv) is mostly known for its oxidation behaviour. In MOF chemistry this is reflected in their unique optical and catalytic properties. The synthetic parameters for Ce(iii)- and Ce(iv)-MOFs also differ substantially and conditions must be chosen to prevent reduction of Ce(iv) for the formation of the latter. Ce(iii)-MOFs are usually reported in comprehensive studies together with those constructed with other RE elements and normally they are isostructural. They exhibit a greater structural diversity, which is reflected in the larger variety of inorganic building units. In contrast, the synthesis conditions of Ce(iv)-MOFs were only recently (2015) established. These lead selectively to hexanuclear Ce-O clusters that are well-known for Zr-MOFs and therefore very similar structural and isoreticluar chemistry is found. Hence Ce(iv)-MOFs exhibit often high porosity, while only a few porous Ce(iii)-MOFs have been described. Some of these show structural flexibility which makes them interesting for separation processes. For Ce(iv)-MOFs the redox properties are most relevant. Thus, they are intensively discussed for catalytic, photocatalytic and sensing applications. In this perspective, the synthesis, structural chemistry and properties of Ce-MOFs are summarized.

Novel materials based on mixtures of immiscible polymers, namely poly (3-hexylthiophene-2,5-diyl) and poly (methyl methacrylate) (P3HT/PMMA), with dispersed phosphorene (2D-bP), obtained by liquid-phase exfoliation (LPE) of black phosphorus (bP) or by in situ polymerization technologies, were prepared for the first time. The new materials were characterized by Raman, UV–Vis, solid state 31P NMR spectroscopies, X-ray diffractometry (XRD), size exclusion chromatography (SEC), morphological (SEM), topographical (AFM) and thermal analysis (DSC and TGA) to investigate the physio-chemical features of both components, polymers and phosphorene owing the composites preparation. Good distribution of the nanoflakes, which preserve their structure and resulted intercalated and partially exfoliated, was achieved thanks to established interactions at the interface between the 2D-bP flakes and the polymers, especially with the P3HT phase, changing the morphology and topography of the mixtures. The preferential allocation of 2D-bP in P3HT, besides inducing a particular polymers phase segregation (a vertical phase separation with P3HT continuous phase onto the surface) encouraged testing these materials as an active layer in Organic Field Effect Transistor (OFET) devices. The data collected showed that the introduction of 2D-bP in P3HT/PMMA polymer mixtures is somewhat promising, giving an increase in mobility up to an order of magnitude with respect to the corresponding 2D-bP-free mixture.

The ibuprofen alkaline-earth compounds Ibuprofen-Mg and Ibuprofen-Ca were investigated by using combined solid state and solution studies. The molecular and crystal structures of the calcium (Ca_Ibu_Hy, a 1D-coordination polymer based on ibuprofen) and magnesium (Mg_Ibu_Hy_RT and Mg_Ibu_Hy_LT) ibuprofen dihydrate salts have been analyzed in depth by using X-ray diffraction (both single crystal and powder) and in-silico tools. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), variable temperature X-ray diffraction experiments were carried out to study the stability of the solid forms under different temperature conditions. The Mg_Ibu_Hy_LT → Mg_Ibu_Hy_RT transition, which occurs between 250 and 300 K, is fully reversible and consists of a mild rearrangement of the crystal structure. Upon raising the temperature, dehydration of the Mg_Ibu_Hy_RT phase occurs, which leads to a completely amorphous phase at T > 340 K. As a consequence, the RT phase of the MgII compound is stable in a quite narrow temperature range. The calcium salt, in turn, gives a partially crystalline anhydrous phase with rising temperature. The coordination behavior of ibuprofen towards MgII, CaII and SrII in a water–ethanol mixture has been studied by means of potentiometric titrations. Based on the almost identical formation constants for CaII- and MgII-Ibuprofen complexes and on the well-known great affinity of MgII-for water molecules, we speculated the formation of solvent-shared ion pairs in the latter case, where the MgII-carboxylate interaction is of the outer-sphere type.

Dexketoprofen [(2S)-2-(3-benzoylphenyl)propanoic acid], C16H14O3, is the S-enantiomer of ketoprofen, a nonsteroidal anti-inflammatory drug (NSAID) that has analgesic, antipyretic and anti-inflammatory properties, and finds applications for the short-term treatment of mild to moderate pain. A new crystalline phase of dexketoprofen is reported. Its solid-state structure was determined by single-crystal X-ray diffraction (SCXRD). The molecular structure of the two independent molecules found in the asymmetric unit of this new phase (DXKP-β) were compared to those of the already known crystal form of dexketoprofen (DXKP-α) and with the S-enantiomer of the racemic compound. The three different conformers of dexketoprofen found in DXKP-α and DXKP-β were then investigated by computational methods. The optimized structures are very close to the corresponding starting geometries and do not differ significantly in energy. The crystal packing of DXKP-β was studied by means of Hirshfeld surface (HS) analysis; interaction energies were also calculated. A comparison with DXKP-α shows close similarities between the two crystal forms, i.e. in both cases, molecules assemble through the catemer O—H...O synthon of the carboxylic acid stabilized by additional C—H...O contacts and, accordingly, the interaction energies, as well as the contributions to the HS area, are very similar. Finally, the thermal behaviour of the two polymorphs of dexketoprofen was assessed by means of XRD (both from single crystal and microcrystalline powder) and differential scanning calorimetry (DSC); both crystal forms are stable under the experimental conditions adopted (air, 300–350 K for DXKP-α and 300–340 K DXKP-β) and no solid–solid phase transition occurs between the two crystal forms in the investigated temperature range (from 100 K up to ca 350 K).

Caffeine is a competitive inhibitor of adenosine receptors and possesses wide pharmacological activity. Artificial receptors recognizing caffeine potentially have a wide range of biomedical and industrial applications. Herein, we describe two structurally related and readily available artificial receptors: 1) a macrocyclic receptor, which binds caffeine with the unprecedented affinity of 9.3 microM, though with poor selectivity; and 2) a tweezers-like structure, showing an affinity of 26 microM and a 4.5-fold and 6-fold selectivity toward theophylline and theobromine, respectively. Binding affinities were measured by 1H NMR titrations and were confirmed by isothermal titration calorimetry. The X-ray structure of the complex between caffeine and the acyclic receptor revealed the origin of the recognition, explained the selectivity, and shed light on the role of hydrogen bonding and CH-pi/pi-pi interactions.

[Image: see text] We studied the chemical–physical nature of interactions involved in the formation of adducts of two-dimensional black phosphorus (2D BP) with organoboron derivatives of a conjugated fluorescent molecule (pyrene). Time-resolved fluorescence spectroscopy showed a stabilization effect of 2D BP on all derivatives, in particular for the adducts endowed with the boronic functionalities. Also, a stronger modulation of the fluorescence decay with oxygen was registered for one of the adducts compared to the corresponding organoboron derivative alone. Nuclear magnetic resonance experiments in suspension and density functional theory simulations confirmed that only noncovalent interactions were involved in the formation of the adducts. The energetic gain in their formation arises from the interaction of P atoms with both C atoms of the pyrene core and the B atom of the boronic functionalities, with a stronger contribution from the ester with respect to the acid one. The interaction results in the lowering of the band gap of 2D BP by around 0.10 eV. Furthermore, we demonstrated through Raman spectroscopy an increased stability toward oxidation in air of 2D BP in the adducts in the solid state (more than 6 months). The modification of the electronic structure at the interface between 2D BP and a conjugated organic molecule through noncovalent stabilizing interactions mediated by the B atom is particularly appealing in view of creating heterojunctions for optoelectronic, photonic, and chemical sensing applications.

Different variation of one crystallographic axis respect the other ones leds to the so called anisotropic lattice expansion. It could be visualized as a significant shift of a family of peaks during a temperature dependent X-Ray Powder Diffraction experiment. Wrong conclusions on the purity and/or composition of a crystalline phase could be drawn looking to the diffractogram without considering the effect of anisotropic expansion. We first observed anisotropic lattice expansion in metoprolol succinate salt ( metoprolol = (±)-1-isopropylamino-3-[4-(2-methoxy-ethyl)-phenoxy]-propan-2-ol) salt. It is interesting to note that in the case of the related and structural close, metoprolol tartrate salt no such behavior was found. [1] Also the metoprolol free base is subject to anisotropic expansion while the betaxolol expands isotropically beside few structural differences and close solid state arrangement. [2] At the moment we have no easy rationalization for the phenomena. [1, 2] With the aim to shed some light on this phenomenon and to rationalize the factors responsible for it, we started an investigation using semiempirical HF-3c method. [3] We were able to reproduce the experimental observations at a reasonable computational cost within the standard error in reproducing crystal structures. [4] The method was tested against the DFT B3LYP with dispersion correction. [5] The anisotropic expansion was predicted to be active for the solid structure of other molecules with the metoprolol core.

A

2D materials have attracted the interest of researchers around the world due to their outstanding properties and potential applications in many fields such as optoelectronics and sensing. Among those 2D materials, phosphorene, which consists on a single layer of bulk orthorhombic black phosphorus1, seems to be promising. Yet, the instability of this material in air and its tendency to degrade very quickly via reaction with oxygen and water is a major drawback that impedes its direct application.2 Therefore, for the last years, research efforts have been devoted to the chemical functionalization of this fascinating nanomaterial in order to improve its stability.3 It is known that SiO2 coating is a common process that has been previously used in many nanomaterials, such as carbon nanotubes.4 This kind of coating does not alter its electronic structure significantly and improving their resistance to degradation. In this work, we have studied the reactivity of few-layers black phosphorus with various silane compounds such as TEOS and PDMS. Characterization of the reaction products (IR, Raman, TEM, etc.) shows the layers of BP are containing silicon compounds and that the flakes are free of SiO2 nanoparticles on its surface. Analysis via EDX confirmed the presence of Si whose quantity depends on the reaction conditions. References: [1] , Materials Chemistry and Physics 2017, 189, 215-229. [2] 2D Mater. 2018, 5, 032001. [3] Adv. Mater. 2018, 30, 1704749. [4] Nano Letters 2002, 2, 329. Acknowledgements: Thanks are expressed to the European Research Council (ERC) for funding the project PHOSFUN "Phosphorene functionalization: a new platform for advanced multifunctional materials" (Grant Agreement No. 670173) through an ERC Advanced Grant to M. P. and to the University of Siena.

Phosphorene is a 2D material and it can view as the all phosphorus counterpart of graphene. In our work, we have studied the non covalent functionalization of the phosphorene sheet with pyrene and pyren boronic derivatives. The solid state calculations using Density functional theory at PBE level, augmented with the D3 dispersion correction as implemented in CRYSTAL17 code, dismissed a possible covalent bond between the boron center and the phosphorus lone pairs, confirming the nature of non covalent functionalization. Our results helped to shed light on the NMR and spectroscopic experiments helping to understand better the remarkably stability toward oxidation in air of phosphorene/pyren boronic adducts.

Metal-Organic Nanotubes (MONT) are a class of one dimension coordination polymers with open channels extended in one direction and assembled in crystalline frameworks with non-covalent interactions. [1] In recent years, some of us have reported the first two isoreticular MONTs assembled by Cu(II) metal atoms, diphosphinate and bipyridine ligands of different length. [2] MONTs are a small subset of Metal Organic Frameworks. On the other side we found several ambiguities and confusions on the nature of MONT in the literature and we decide to give a clear definition of MONT based either on topology and on geometrical constraints. The latter are the smallest dimension of the internal cavity as well as the size of the windows in the lateral walls. With our definition, we extracted 35 "true" MONT from 28000 1D coordination polymers in the CSD database finding that most of the classified MONTs failed to fulfil our geometrical constraint.

The anisotropic lattice expansion is a different variation of one crystallographic axis respect the other ones. In a temperature dependent X-Ray Powder Diffraction experiment, the anisotropic lattice expansion can be visualized as a significant shift of a set of peaks while others practically did not move. As a consequence, the anisotropic expansion could lead wrong conclusions on the purity and/or composition of a crystalline phase. We observed anisotropic lattice expansion for metoprolol succinate salt ( metoprolol = (±)-1-isopropylamino-3-[4- (2-methoxy-ethyl)-phenoxy]-propan-2-ol) salt. For the related and structural close, metoprolol tartrate salt no such behavior was found. [1] Moreover also the metoprolol free base is subject to anisotropic expansion while the related betaxolol, with similar solid state arrangement and very small structural difference, expands isotropically. [2] In this work, we show that semiempirical HF-3c method [3] is able to reproduce the experimental observations at a reasonable computational cost within the standard error in reproducing crystal structures. [4] Our protocol could help to shed some light on the anisotropic lattice expansion in organic crystals and to rationalize the factor responsible for the phenomenon. [1] P. Paoli, P. Rossi, E. Macedi, A. Ienco, L. Chelazzi, G. L. Bartolucci, B. Bruni Cryst. Growth Des. 2016, 16, 789. [2] P. Rossi, P. Paoli, L. Chelazzi, L. Conti, A. Bencini Acta Cryst. 2019, C75, 87. [3] R. Sure, S. Grimme J. Comput. Chem. 2013, 34, 1672. [4] M. Cutini, B. Civalleri, M. Corno, R. Orlando, J. G. Brandenburg, L. Maschio, P. Ugliengo J. Chem. Theory Comput. 2016, 12, 3340.

The role of comics in science communications has been subject of a number of recent papers. While some debate on an accepted definition of what constitutes a science comics is still ongoing, the role of comics in science outreach is now universally recognized. [1] Here we present the Comics&Science comic books published by CNR Edizioni and edited by Roberto Natalini and Andrea Plazzi. The Comics&Science concept was implemented in the first place as a section of the Lucca Comics&Games festival, followed by the printed series in 2013. Comics&Science's philosophy is to have science elements, ideas and "bits" integrated into cartoons by the best professional writers and artists. The story must be fun, entertaining and overall artistically and aesthetically significant. Each issue is completed by articles and pieces about and around the topics touched by the story. A Comics&Science issue almost always starts with the cartoonist visiting a research lab/facility. Tipically, the artist has little or no formal scientific background and up to now this has proved to be an effective starting point for exchanging opinions and a cross-debate of sorts. Following the Comics&Science "protocol", Italian hugely popular cartoonist Zerocalcare (millions of books sold in the last few years) visited the Elettra and Fermi light sources prior to working to his "Light Issue", co-edited by the Istituto di Struttura della Materia-CNR (ISM- CNR) and Elettra Sincrotrone Trieste. The upcoming Comics&Science issue (Fall 2019) will be featuring a Periodic Table-inspired story by writer Giovanni Eccher and artist Sergio Ponchione, as a joint venture between the Department of Chemical Science and Technology of Materials (CNR-DSCTM) and the Young Chemists Group and the Group for the Diffusion of the Chemistry Culture of the Italian Chemical Society.

The Co6C(CO)(12)(AuPPh3)(4) carbide carbonyl cluster was obtained from the reaction of [Co6C(CO)(15)](2-) with Au(PPh3)Cl. This new species was investigated by variable-temperature P-31 NMR spectroscopy, X-ray crystallography, and density functional theory methods. Three different solvates were characterized in the solid state, namely, Co6C(CO)(12)(AuPPh3)(4) (I), Co6C(CO)(12)(AuPPh3)(4).THF (II), and Co6C(CO)(12)(AuPPh3)(4).4THF (III), where THF = tetrahydrofuran. These are not merely different solvates of the same neutral cluster, but they contain three different isomers of Co6C(CO)(12)(AuPPh3)(4). The three isomers IIII possess the same octahedral [Co6C(CO)(1)2(]4) carbidocarbonyl core differently decorated by four [AuPPh3]+ fragments and showing a different Au(I)...Au(I) connectivity. Theoretical investigations suggest that the formation in the solid state of the three isomers during crystallization is governed by packing and van der Waals forces, as well as aurophilic and weak pi-pi and pi-H interactions. In addition, the closely related cluster Co6C(CO)(12)(PPh3)(AuPPh3)(2) was obtained from the reaction of [Co8C(CO)(18)](2) with Au(PPh3)Cl, and two of its solvates were crystallographically characterized, namely, Co6C(CO)(12)(PPh3)(AuPPh3)(2).toluene (IV) and Co6C(CO)(12)(PPh3)(AuPPh3)(2).0.stoluene (V). A significant, even if minor, effect of the cocrystallized solvent molecules on the structure of the cluster was observed also in this case.

This paper is a comparative outline of the potential acid–base adducts formed by an unsaturated main group or transition metal species and P atoms of phosphorene (Pn), which derives from black phosphorus exfoliation., This paper is a comparative outline of the potential acid–base adducts formed by an unsaturated main group or transition metal species and P atoms of phosphorene (Pn), which derives from black phosphorus exfoliation. Various possibilities of attaining a realistic covalent functionalization of the 2D material have been examined via DFT solid state calculations. The distribution of neighbor P atoms at one side of the sheet and the reciprocal directionalities of their lone pairs must be clearly understood to foreshadow the best possible acceptor reactants. Amongst the latter, the main group BH3 or I2 species have been examined for their intrinsic acidity, which favors the periodic mono-hapto anchoring at Pn atoms. The corresponding adducts are systematically compared with other molecular P donors from a phosphine to white phosphorus, P4. Significant variations emerge from the comparison of the band gaps in the adducts and the naked phosphorene with a possible electronic interpretation being offered. Then, the Pn covalent functionalization has been analyzed in relation to unsaturated metal fragments, which, by carrying one, two or three vacant σ hybrids, may interact with a different number of adjacent P atoms. For the modelling, the concept of isolobal analogy is important for predicting the possible sets of external coligands at the metal, which may allow the anchoring at phosphorene with a variety of hapticities. Structural, electronic, spectroscopic and energy parameters underline the most relevant pros and cons of some new products at the 2D framework, which have never been experimentally characterized but appear to be reasonably stable.

Semiconducting two dimensional black phosphorus (2D BP) has recently attracted a lot of interest thanks to its peculiar properties, which render it suitable for applications in materials science.1 In particular, the surface functionalization of 2D BP and the formation of heterostructures is particularly promising for electrical, optoelectronic and photocatalytic applications. In addition, being 2D BP a potential good ligand for metals, its application in the field of catalysis is also possible. Herein, we bring two examples of easy non-covalent functionalization of 2D BP. In a first study, we investigate the chemical-physics and the nature of the interactions involved in the formation of heterostructures of 2D BP with organoboron derivatives of a conjugated fluorescent molecule (pyrene). NMR experiments in suspension and DFT simulations confirm that only non-covalent interactions are involved. The energetic gain in the formation of the heterostructures arises from the interaction of P atoms with both C atoms of the pyrene core and with B atom of the boronic functionality. We demonstrate through Raman spectroscopy an increased stability towards oxidation in air of 2D BP (more than three months), accompanied by a band-gap lowering by around 0.10 eV, while time-resolved fluorescence spectroscopy shows a stabilization effect also of the organic moieties, in the heterostructures. The second study focuses on 2D BP functionalized in situ with Au nanoclusters through a deposition-precipitation solid-liquid heterogeneous reaction. This reaction leads to the desired 2D support/metal intimacy of contact and also the desired Au nano-morphology. Spectroscopic and morphological characterization, supported by DFT calculations, prove the effective functionalization of 2D BP with Au nanoclusters with nanometric size and non-full metallic character, and the total preservation of 2D BP structure and functionality. In particular, XPS analysis on these systems gives experimental evidence of the soft-pairing/coordination of surface P atoms with the Au(I) atoms on the surface of the nanoclusters. The photonic properties of the 2D BP/Au system are investigated through Surface Plasmon Enhanced (SPR) Raman studies. The authors thank the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 670173) for funding the project PHOSFUN by an ERC Advanced Grant to MP. References [1]M. Peruzzini, R. Bini, M. Bolognesi, M. Caporali, M. Ceppatelli, F. Cicogna, S. Coiai, S. Heun, A. Ienco, I. Iglesias Benito, A. Kumar, G. Manca, E. Passaglia, D. Scelta, M. Serrano-Ruiz, F. Telesio, S. Toffanin, M. Vanni, Eur. J. Inorg. Chem. 2019, 2019, 1476-1494.

Black phosphorus (bP) has been recently investigated for next generation nanoelectronic multifunctional devices. However, the intrinsic instability of exfoliated bP (the bP nanoflakes) toward both moisture and air has so far overshadowed its practical implementation. In order to contribute to fill this gap, we report here the preparation of new hybrid polymer-based materials where bP nanoflakes (bPn) exhibit a significantly improved stability. The new materials have been prepared by different synthetic paths including: (i) the mixing of conventionally liquid-phase exfoliated bP (in dimethyl sulfoxide, DMSO) with poly(methyl methacrylate) (PMMA) solution; (ii) the direct exfoliation of bP in a polymeric solution; (iii) the in situ radical polymerization after exfoliating bP in the liquid monomer (methyl methacrylate, MMA). This last methodology concerns the preparation of stable suspensions of bPn-MMA by sonication-assisted liquid-phase exfoliation (LPE) of bP in the presence of MMA followed by radical polymerization. The hybrids characteristics have been compared in order to evaluate the bP dispersion and the effectiveness of the bPn interfacial interactions with polymer chains aimed at their long-term environmental stabilization. The passivation of the bPn is particularly effective when the hybrid material is prepared by in situ polymerization. By using this synthetic methodology, the nanoflakes, even if with a gradient of dispersion (size of aggregates), preserve their chemical structure from oxidation (as proved by both Raman and 31P-solid state NMR studies) and are particularly stable to air and UV light exposure. The feasibility of this approach, capable of efficiently exfoliating bP while protecting the bPn, has been then verified by using different vinyl monomers (styrene and N-vinylpyrrolidone), thus obtaining hybrids where the nanoflakes are embedded in polymer matrices with a variety of intriguing thermal, mechanical, and solubility characteristics.

The palladium complexes with dibenzylidenacetone (dba) ligand (Pd 2 (dba) 3 or Pd(dba) 2 ) are used as precursors of Pd(0) for cross coupling reaction (Heck, Suzuki, Stille and Buckwald coupling reactions) in combination with phosphine ligands. The real tridimensional structure of these palladium catalyst is dubious and in particular the difference between Pd(dba) 3 , Pd(dba) 2 and Pd 2 (dba) 3 is not so clear. 1 Moreover, some catalytic tests showed that the activity of Pd(dba) 2 and Pd 2 (dba) 3 were almost the same 2 and the difference can be due to the quantity of dba present in the reaction medium that can be involve in the catalytic cycle. 3 We found, using XRD, NMR, IR and theoretical calculation, that the tridimensional supramolecular structural arrangement of the different form of palladium complex with dba is the same: it is formed by three molecules of dba with two site for the coordination of the metal as reported for Pd 2 (dba) 3.1,4 The two coordination have different energy and the site with higher energy could be only partially occupied. In conclusion, we can propose a unified formulation for all palladium dba catalysts.

A detailed mechanism of the I2-induced transformation of white phosphorus into PI3 emerges from a DFT analysis. This multi-step process implies that at any stage one P-P and two I-I bonds cleavages, associated with the formation of two P-I bonds plus an in situ generated brand new I2 molecule. Significant electron transfer between the atoms is observed at any step, but the reactions are better defined as concerted rather than redox. Along the steepest descent to the product, no significant barrier is encountered except for the very first P4 activation, which costs +14.6 kcal mol-1. At the atomic level, one first I2 molecule, a typical mild oxidant, is first involved in a linear halogen bonding interaction (XB) with one P donor, while its terminal I atom is engaged in an additional XB adduct with a second I2. Significant electron transfer through the combined diatomics allows the external I atom of the dangling I3 grouping to convey electrons into the ?* level of one P-P bond with its consequent cleavage. This implies at some point the appearance of a six-membered ring, which alternatively switches its bonding and no-bonding interactions. The final transformation of the P2I4 diphosphine into two PI3 phosphines is enlightening also for the specific role of the I substituents. In fact, it is proved that an organo-diphosphine analogue hardly undergoes the separation of two phosphines, as reported in the literature. This is attributable to the particularly high donor power of the carbo-substituted P atoms, which prevents the concertedness of the reaction but favors charge separation in an unreactive ion pair. © 2018 The Royal Society of Chemistry.

The syntheses of the new triple-decker complexes [(triphos)Co(μ,η 3:3 -P 3 )Ru(triphos)](BPh 4 ) 2 ; ( CoP 3 Ru )(BPh 4 ) 2 , [(triphos)Co(μ,η 3:3 -P 3 )Os(triphos)](BPh 4 ) 2 ; ( CoP 3 Os )(BPh 4 ) 2 and [(triphos)Ru(μ,η 3:3 -P 3 )Ru(triphos)]PF 6 ·(CH 3 ) 2 CO; ( RuP 3 Ru )PF 6 ·(CH 3 ) 2 CO, three new members of the [(tripod)M(μ-P 3 )M′(tripod)] n+ ( MP3M ′ n+ ) family are described. The structure of the homodinuclear complex ( RuP 3 Ru )PF 6 ·(CH 3 ) 2 CO is also reported. This latter compound has a structure similar to that of the other members of the series and shows an M⋯M separation among the longest hitherto found in these compounds. An electrochemical study shows that they are stable in various oxidation states with a VEN value ranging between 28 and 34. A reasoning around the redox data shows a progressive shift of two pairs of redox processes, corresponding to the VEN variation 30/31-31/32 and 32/33-33/34, which almost rigidly moves in the cathode direction as the overall charge of the homoelectronic compound decreases.

The synergic effect due to chemical interactions between polymer and nanostructured fillers is the key parameter to provide materials with excellent performance and widespread applications. Improvements in mechanical, thermal, and barrier performance as well as new light-responsiveness or antimicrobial and antifouling features can be obtained by dispersing different 2D nanofillers at the nanoscale level. With reference to the particular class of 2D nanofillers used for optoelectronic devices (graphite and transition metal dichalcogenides), the specific interactions with a polymer matrix can be used to improve the performance of devices and to protect the nanostructures from aging. Black phosphorus (bP) has been extensively investigated for both electronic and photonic applications. However, the difficulty in engineering large scale exfoliation procedures and the intrinsic instability of exfoliated bP towards both moisture and air has so far overshadowed its possible applications. Here, polymer-based hybrid materials containing dispersed black phosphorus nanoflakes (bPn) are prepared, and their structural characteristics analysed and compared, to evaluate the bP dispersion degree and the effectiveness of bPn interfacial interactions with polymer chains aimed at their environmental stabilization. In particular, the polymethyl methacrylate (PMMA) passivation results particularly effective for the hybrid material prepared by polymerization in-situ of MMA, after the direct liquid phase exfoliation in the monomer (without solvent and by operating in ambient conditions). The procedure yields hybrids where the bPn, even if with a gradient of dispersion (size of aggregates), preserve their chemical structure from oxidation and even after UV exposure. The feasibility of this methodology, capable of efficiently exfoliating bP by protecting its structure, is verified using different vinyl monomers: styrene (S) and N-vinylpyrrolidone (NVP) and even by building PS-block-PMMA copolymers. The PMMA-based hybrid is used to design a device without the need of a glove box in any stage of the fabrication, where the nanoflakes show resistance and mobility comparable with electronic-grade liquid phase exfoliated bP. This result proves that the methodology here realized provides hybrid materials as suitable platforms for devices fabrication in the field of optoelectronics. References E. Passaglia et al, Chem. Mat, 30, 2036, (2018) F. Telesio et al., Nanotechnology 29, 295601, (2018) Acknowledgments The authors thank the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 670173) for funding the project PHOSFUN "Phosphorene functionalization: a new platform for advanced multifunctional materials" through an ERC Advanced Grant

The trans heterodiphosphane Ru-based compound of the formula [Ru(OAc)2(CO)2(PnBu3)(PPh3)] proved to be a suitable precatalyst for imine hydrogenation in 2,2,2-trifluoroethanol (TFE) without the addition of an external base. High-pressure (HP) NMR investigations combined with a DFT-study, carried out on a related model precatalyst, were indicating the formation of a cationic Ru-monohydride-2,2,2-trifluoroethanol (TFE) species that catalyzes the imine hydrogenation by a TFE-assisted outer-sphere reaction mechanism.

The linear tetraphosphine 1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane (tetraphos-1, P4) was used as its rac and meso isomers for the synthesis of both molecularly defined and in situ formed Fe(II) complexes. These were used as precatalysts for sodium bicarbonate hydrogenation to formate and formic acid dehydrogenation to hydrogen and carbon dioxide with moderate to good activities in comparison to those for literature systems based on Fe. Mechanistic details of the reaction pathways were obtained by NMR and HPNMR experiments, highlighting the role of the Fe(II) monohydrido complex [FeH(rac-P4)]+ as a key intermediate. X-ray crystal structures of different complexes bearing rac-P4 were also obtained and are described herein.

The compound H(PEt3)(3)Pt-3(mu-PPh2)(3) is the unique example of a 46e(-) phosphido-bridged triangular cluster, but its X-ray assigned stereochemistry appears questionable. In particular, the H-free P3Pt3(mu-P)(3) metal core is identical to that of the 46e(-) cation [(PEt3)(3)Pt-3(mu-PPh2)(3)](+) in two salts of the same publication. Also, the lack of a distortional effect due to the upright and strongly-bound hydride ligand is suspicious and intriguing aspects emerge from the inconsistent electronic structure. Although H(PEt3)(3)Pt-3(mu-PPh2)(3) is fully validated by IR and NMR spectra, DFT optimizations never reproduced the reported structure but highlighted a different stereochemistry not in contrast with the spectroscopic response. Here, a formal Pt(II) ion is almost separated with an essential square-planar coordination, completed by two trans-axial ligands (H and Et3P) perpendicular to the Pt-3 plane. Provided the chemical reliability of the in silico molecule, the crystals of the experimental structure have likely contents other than the hydridic cluster and the co-crystallized Ph2PH molecule. As a working hypothesis, the Pt-H and P-H linkages of the distinct components may have reacted together with H-2 release, and subsequent crstallization of the salt [(PEt3)(3)Pt-3(mu-PPh2)(3)](+)/[Ph2P]. This would explain the equal geometries of the putative 46e(-) cluster and the H-free 46e(-) cation. In the lack of any experimental X-ray dataset, the proposed crystal formulation could not be fully validated, but various aspects support its reliability. Essentially, the problem may arise from the misplacement of two H atoms (those of the mentioned Pt-H and P-H linkages), which does not affect the structural refinement but determines the chemical inconsistency. (C) 2014 Elsevier B.V. All rights reserved.

The aromatic methylene blue cation (MB+) shows unprecedented ligand behavior in the X-ray structures of the trigonal-planar (TP) complexes MBMCl2 (M = Cu-I, Ag-I). The two isostructural compounds were exclusively synthesized by grinding together methylene blue chloride and MCl solids. Only in the case of AuCl did the technique lead to a different, yet isoformular, Au-I derivative with separated MB+ and AuCl2- counterions and no direct N-Au linkage. While the density functional theory (DFT) molecular modeling failed in reproducing the isolated Cu and Ag complexes, the solid-state program CRYSTAL satisfactorily provided for Cu the correct TP building block associated with a highly compact pi stacking of the MB+ ligands. In this respect, the dispersion interactions, evaluated with the DFT functional, provide to the system an extra energy, which likely supports the unprecedented metal coordination of the MB+ cation. The feature seems governed by subtle chemical factors, such as, for instance, the selected metal ion of the coinage triad. Thus, the electronically consistent Au-I ion does not form the analogous TP building block because of a looser supramolecular arrangement. In conclusion, while a given crystalline design is generally fixed by the nature of the building block, a peculiarly efficient supramolecular packing unattainable metal complex.