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A series of lead(II) complexes incorporating benzoate derivative ligands was prepared: [Pb(2MeOBz)2]n (1), [Pb(2MeOBz)2(H2O)]n (2), [Pb2(1,4Bzdiox)4(DMSO)]n (3), [Pb(1,4Bzdiox)2(H2O)]n (4), [Pb(Pip)2(H2O)]n (5), and [Pb(Ac)(Pip)2(MeOH)]n (6) (2MeOBz: 2-methoxybenzoate; 1,4Bzdiox: 1,4-benzodioxan-5-carboxylate; DMSO: dimethylsulfoxide; Ac: acetate; Pip: piperonylate; MeOH: methanol). All compounds were characterized via elemental analysis, ATR-FTIR spectroscopy, and powder XRD. In addition, the crystal structures of some compounds were elucidated. Compounds 1 and 2, involving 2-methoxybenzoate, were closely related, only differing in the presence of one extra aqua ligand found for the latter. However, this implies key changes in the studied properties, e.g., 2 shows solid-state luminescence that displays a different color as a function of the crystal orientation, while 1 does not. The crystal structure of 2 revealed a 1D coordination polymer. A similar relationship was found between compounds 3 and 4, incorporating 1,4-benzodioxan-5-carboxylate. In this pair, only 4, with aqua ligands, displayed a greenish-yellow-color solid-state luminescence. Furthermore, two new lead(II) piperonylate complexes, 5 and 6, were obtained from the reaction between lead(II) acetate and piperonylic acid. In water, all acetate ligands in the metal precursor were displaced and [Pb(Pip)2(H2O)]n (5) was isolated, while in methanol, a mixed acetate–piperonylate complex, [Pb(Ac)(Pip)2(MeOH)]n (6), was precipitated. Considering only conventional Pb-O bonds, the crystal structure of 6 was described as a 1D coordination polymer, although, additionally, the chains were associated via tetrel bonds, defining an extended 2D architecture.

A facile, fast and green strategy based on ethanol is utilized to prepare a new bioMOF, namely, CaSyr-1, with particular characteristics of full biocompatibility given by using just calcium and syringic acid, the latter being a phenolic natural product found in fruits and vegetables, permanent porosity with an outstanding surface area >1000 m2 g−1, and a micropore diameter of 1.4 nm close to mesopore values. Collectively, these data establish CaSyr-1 as one of the most porous bioMOFs reported to date, with high molecular adsorption capacity. The CaSyr-1 adsorptive behavior is revised here through the reversible adsorption of CO2 and the encapsulation of bioactive ingredients in the structure. Remarkably, CaSyr-1 enables the development of triple therapeutic entities, involving bioactive Ca2+, syringic acid and an impregnated drug.

Two copper(II) complexes, both involving the anionic 3,5-bis(trifluoromethyl)benzoate ligand (TFMBz), have been prepared and their structure elucidated by single crystal-X ray diffraction. [Cu(TFMBz)2(ISNA)2] (1) is a mononuclear complex, in which the sphere of coordination of Cu(II) is completed by two neutral isonicotinamide (ISNA) auxiliary ligands. Hydrogen bonding formed between auxiliary ISNA ligands determines the formation of a 2D supramolecular network. [Cu2(TFMBz)4(DMSO)2] (2) is a binuclear complex, in which the four carboxylate ligands define the typical paddle wheel structure often found in copper complexes, containing also the ancillary dimethyl sulfoxide (DMSO) ligand in axial positions. The elucidated crystallographic data provide the static view of the crystal structures, which reveals only non-interconnected voids for both materials. Even that, compound 1 shows an appreciable adsorption of CO2 at 273 K (ca. 1 CO2 molecule/Cu atom at 100 kPa), concomitant with a reduced adsorption of Ar or N2 under similar conditions, which implies a considerable degree of selectivity for CO2. Moreover, 1 does not adsorb N2 or Ar at 77 K and 100 kPa. This behavior suggests that the stablished intermolecular hydrogen bonds rest flexibility and dynamism to 1 at low temperature. Contrarily, increasing the temperature transient porosity is originated, which allows guest molecules to diffuse through the cavities. Compound 2 shows adsorption of N2 and Ar at 77 K, indicating that vibrations in the network and rotation of some CF3 groups, necessary to favor adsorbate diffusion, are still feasible at this low temperature.

The reaction between 2,4,6-tris(4-pyridyl)-1,3,5-triazine (4-tpt) and copper(II) hexafluoroacetylacetone (Cu(hfa)2) yields two different 1D metal–organic frameworks (MOFs), [(Cu(hfa)2)2(4-tpt)]n (1) and [Cu(hfa)2(4-tpt)]n (2). The Cu:4-tpt ratio in the new MOFs is determined by the reaction medium, particularly, the solvent used. The two compounds have been fully characterized, including crystal structure elucidation. [(Cu(hfa)2)2(4-tpt)]n (1), with a 2:1 Cu:4-tpt ratio, could be precipitated in either 1,1,2-trichloroethane or supercritical CO2. In (1), 4-tpt shows a tritopic coordination mode, but only half of the Cu(hfa)2 subunits act as a node, thus connecting two 4-tpt and giving a 1D network. The other half of Cu(hfa)2 subunits are connected only to one pyridine and thus protrude along the chains. The later Cu(hfa)2 fragments show a labile character and can be dissolved in diethyl ether to give the second MOF [Cu(hfa)2(4-tpt)]n (2), with a 1:1 Cu:4-tpt ratio. The compound (2) has also a 1D structure, with all the incorporated copper atoms acting as nodes. In this case, the packing of the chains defines accessible channels, which are perpendicular to the chain axis. After activation, N2 adsorption/desorption measurements at 77 K confirm the microporous character of (2) with an apparent surface area of 190 m2 g−1. Besides, at 273 K this material clearly shows a significant adsorption of CO2 prompted by noncoordinated nitrogen in the triazine linker.

This paper provides a detailed technological characterization of the Roman opus sectile glasses (second century AD) coming from the renowned Gorga collection. Nine glass samples corresponding to imitations of the porfido verde antico, cipollino rosso, rosso antico, giallo antico, diaspro nero e giallo, semesanto and agate/alabaster stones were studied. The aim of this study was twofold: (i) archaeometric, i.e., to provide valuable data on the production, raw materials and techniques of these refined Roman glasses that mimic precious stones and (ii) methodological, i.e., to highlight the good performance of combining polished thin sections and local probe measurements for the study of glassy microstructures. Based on the nature of the flux used, the glasses from the samples were classified as either natron-type or mixed-type (natron/plant ash). The latter stem from remelted glasses and contain relict grains of wollastonite that were not found in the pure natron samples. Relict wollastonite crystals appear to be a proficient petrographic marker to spot recycled glasses along with the commonly used chemical fingerprints. Different production and colouring techniques were identified, even for a given type of imitated stone. Metallic Cu, Ca antimonates and Pb-Fe antimonates were the three opacifiers used for the opaque glasses. Based on the crystal morphologies, metallic Cu and Ca antimoniates were possibly synthesized in situ simultaneously with the glass, whilst the Pb-Fe antimonates were prepared ex situ. The working temperatures for these glasses were estimated within the 900–1100 °C range based on the presence and known thermal stability of some identified crystal phases.

This paper provides a detailed technological characterization of the Roman opus sectile glasses (second century AD) coming from the renowned Gorga collection. Nine glass samples corresponding to imitations of the porfido verde antico, cipollino rosso, rosso antico, giallo antico, diaspro nero e giallo, semesanto and agate/alabaster stones were studied. The aim of this study was twofold: (i) archaeometric, i.e., to provide valuable data on the production, raw materials and techniques of these refined Roman glasses that mimic precious stones and (ii) methodological, i.e., to highlight the good performance of combining polished thin sections and local probe measurements for the study of glassy microstructures. Based on the nature of the flux used, the glasses from the samples were classified as either natron-type or mixed-type (natron/plant ash). The latter stem from remelted glasses and contain relict grains of wollastonite that were not found in the pure natron samples. Relict wollastonite crystals appear to be a proficient petrographic marker to spot recycled glasses along with the commonly used chemical fingerprints. Different production and colouring techniques were identified, even for a given type of imitated stone. Metallic Cu, Ca antimonates and Pb-Fe antimonates were the three opacifiers used for the opaque glasses. Based on the crystal morphologies, metallic Cu and Ca antimoniates were possibly synthesized in situ simultaneously with the glass, whilst the Pb-Fe antimonates were prepared ex situ. The working temperatures for these glasses were estimated within the 900–1100 °C range based on the presence and known thermal stability of some identified crystal phases.

Herein we explore the opportunities arising from combining bicyclic amine cations with halometallate anions to build organic–inorganic hybrid materials. We will use the crystal engineering approach in these materials, focusing on the tuning of the organic cation, which is mainly responsible for obtaining both new plastic states at high temperature and electrical behaviour below the plastic temperature. Precisely, this work explores the influence of the ketonization of the bicyclic quinuclidine molecule (C7H13N)+, which, combined with the tetrachloroferrate(1-) anion, gives the compound (3-oxoquinuclidinium)[FeCl4]. Interestingly, crystallization in the presence of humidity is enough to obtain an isostructural hydrate phase of formula (3-oxoquinuclidinium)[FeCl4]·H2O. Although the organic–inorganic layered structure is the same in both compounds, the three-dimensional magnetic ordering disappears after the intercalation of crystallization water molecules. A heat treatment above 400 K allows the removal of water obtaining the non-hydrate phase. Finally, the temperature evolution of the electric and magnetic behaviour will be compared with other previously reported hybrid organic–inorganic materials built with tetrachloroferrate ions and quinuclidinium-based cations.

The reaction of [Co2(H2O)(TFMBz)4(py)4] (1) (TFMBz: 3,5-bis(trifluoromethyl)benzoate; py: pyridine) with 4,4'-bipyridine (bpy) in different solvents yields four coordination polymers with unlikely structures but with the same stoichiometry. Three of them contain similar ladder chains consisting of binuclear nodes "Co2(TFMBz)4", in which two of the TFMBz ligands show bidentate bridge coordination, double linked to each adjacent node by bpy but packed in different fashions. The different packing affects the compound porosity; thus, [Co2(TFMBz)4(bpy)2]n (2), precipitated using low-polarity solvents such as supercritical CO2 (scCO2), n-butyl acetate, or heptane and also in acetonitrile, is microporous, with a surface area of 330 m2 g-1, showing the N2 adsorption/desorption isotherm at 77 K with a gate-opening effect at low relative pressures (P/P0 = 0.05). The isomer [Co2(TFMBz)4(bpy)2]n (3), synthesized in ethoxyethanol, presents a surface area of 230 m2 g-1. A third chain packing isomer, [Co2(TFMBz)4(bpy)2]n (4), is obtained in acetone and has only non-interconnected voids. Finally, precursor 1 is combined with bpy in a highly polar solvent such as water to give [Co(TFMBz)2(bpy)]n (5). In this isomer, all the carboxylate units act as bidentate bridging ligands, generating chains that are interlinked by bpy, leading to a 2D network, which after packing yields a non-porous structure. The resolution of structures 2-5 is only possible with the recently developed 3D electron diffraction method based on the collection of diffraction patterns on sub-micron-sized single crystals. The variation of magnetic susceptibility as a function of temperature is also measured. Overall, our work provides insightful information on the complex landscape of metal-organic framework solids that are formed by crystallization using different solvent media.

A High Temperature Synchrotron Radiation X-Ray Powder Diffraction experiment was performed to determine the manganese compounds formed during the heating and cooling of 70 wt% PbO – 30 wt% SiO2 mixture or the equivalent glass plus 10 wt% of MnO. The effect of adding calcite, dolomite and kaolinite were also studied. All mixtures were fired between 690 ¿C and 1020 ¿C in oxidizing conditions and analysed by Scanning Electron Microscopy. A sequence of manganese phases are formed during firing: bixbyite (Mn2O3), barysilite ((Pb,Mn)Si2O7), kentrolite (Pb2Mn2Si2O9) and braunite (Mn7SiO12). Kentrolite and braunite crystallise with different crystal habits during the heating and the cooling. If dolomite is present diopside ((Ca,Mg,Mn)2Si2O6) is formed. If calcite is present, ganomalite (Pb3(CaMn)2Si3O11), margarosanite (Pb(Ca,Mn)2Si3O9) and wollastonite ((Ca,Mn)SiO3) are also formed. Wollastonite can incorporate enough manganese to transform into bustamite ((Mn,Ca)3Si3O9) at high temperatures. This leaves less manganese available for the crystallisation of kentrolite and braunite., Peer Reviewed, Postprint (author's final draft)

The reaction of [Co2(H2O)(TFMBz)4(py)4] (1) (TFMBz: 3,5-bis(trifluoromethyl)benzoate; py: pyridine) with 4,4′-bipyridine (bpy) in different solvents yields four coordination polymers with unlikely structures but with the same stoichiometry. Three of them contain similar ladder chains consisting of binuclear nodes "Co2(TFMBz)4", in which two of the TFMBz ligands show bidentate bridge coordination, double linked to each adjacent node by bpy but packed in different fashions. The different packing affects the compound porosity; thus, [Co2(TFMBz)4(bpy)2]n(2), precipitated using low-polarity solvents such as supercritical CO2(scCO2), n-butyl acetate, or heptane and also in acetonitrile, is microporous, with a surface area of 330 m2g-1, showing the N2adsorption/desorption isotherm at 77 K with a gate-opening effect at low relative pressures (P/P0= 0.05). The isomer [Co2(TFMBz)4(bpy)2]n(3), synthesized in ethoxyethanol, presents a surface area of 230 m2g-1. A third chain packing isomer, [Co2(TFMBz)4(bpy)2]n(4), is obtained in acetone and has only non-interconnected voids. Finally, precursor 1 is combined with bpy in a highly polar solvent such as water to give [Co(TFMBz)2(bpy)]n(5). In this isomer, all the carboxylate units act as bidentate bridging ligands, generating chains that are interlinked by bpy, leading to a 2D network, which after packing yields a non-porous structure. The resolution of structures 2-5 is only possible with the recently developed 3D electron diffraction method based on the collection of diffraction patterns on sub-micron-sized single crystals. The variation of magnetic susceptibility as a function of temperature is also measured. Overall, our work provides insightful information on the complex landscape of metal-organic framework solids that are formed by crystallization using different solvent media.

Different iron oxide catalysts supported on mesoporous silica were prepared by several techniques including assembly of pre-synthesized nanoparticles, coprecipitation in the presence of the support or impregnation. Characterization showed that iron oxide nanoparticles were dispersed either at the surface of the SiO2 material or within the pores when prepared by dry impregnation. The catalytic performance of these materials for Fenton chemistry was evaluated through kinetic tests in the presence of coumarin as a radical trap for the quantification of the HO˙ radicals produced. The first tests concerned the production of HO˙ radicals from H2O2 by a Fenton-like reaction. The results show that catalysts prepared by dry impregnation in an ethanolic solution show the highest activity toward the production of HO˙ radicals. These catalysts were also engaged in a reaction without external H2O2 using a cold atmospheric pressure plasma jet treatment with the successful purpose of increasing the production of HO˙ radicals in aqueous solution at room temperature and near-neutral pH. Our best catalysts outperformed others reported in the literature in reactions carried out with soluble species or at acidic pH. Moreover, a synergetic effect between the heterogeneous catalyst and the plasma for HO˙ radical production was highlighted. These radicals could be easily used for biomedical or wastewater treatment applications.

The ammonium salt of monoethyloxalate (AmEtOx) was investigated as a novel precursor for the conservation of carbonate stone substrates, such as biomicritic limestone and marble. Full characterization of treated and untreated authentic stone samples was carried out by means of SEM, X-ray powder diffraction, synchrotron tts-µXRD measurements, mercury intrusion porosimetry, determination of water transport properties, and pull-off tests. The improved solubility (1.49 M, 20.1% w/w) of AmEtOx as compared to that of ammonium oxalate (AmOx; 0.4 M, 5% w/w) results in the formation of microcrystalline phases 30–50 and 200–500 µm thick of calcium oxalate mono-(whewellite) or dihydrate (weddellite), on marble and biomicrite samples, respectively, after treatment with AmEtOx 5% and 12% w/w aqueous solutions. As a result, a reduction in the porosity of the stone samples and an enhancement of their cohesion are observed. DFT calculations, carried out to investigate the hydrolysis reaction leading from AmEtOx to AmOx, showed that the localization of the Lowest Unoccupied Molecular Orbital (LUMO) and the natural charge distribution account nicely for the tendency to hydrolyse observed experimentally, eventually leading to the formation of whewellite and weddellite on the stone surface., Peer Reviewed, Preprint

The materials, painting techniques and conservation state of the enamelled stain glass of the Catalan Modernist workshops operating in Barcelona are studied. It is known for its creativity and artistic value where textured, flashed, coloured and enamelled glasses concur. In the late 19th century, Catalan workshops used a new type of ready-to-be-used enamels (lead-zinc borosilicate glass) incorporating pigment particles and colourants. Although humidity, pollutants and solar irradiation are the main causes of corrosion, the microstructure of the enamels plays a role- Enamels that contain large particles close to the surface appear more corroded than those that are fully amorphous. Lixiviation of lead, boron and zinc produced a hydrated layered silica rich fragile glass and the subsequent precipitation of lead, sodium and calcium compounds on the surface, cracks around particles and inside the bubbles decrease the chemical and mechanical stability. The practices of some workshops produced enamels with reduced stability., Peer Reviewed, Postprint (author's final draft)

Cobalt was used since the early antiquity to tinge glass and glazes in blue. The presence of arsenic in blue decorated glazes since ~1500 onwards and absence beforehand, observed in Europe, might be related to the processing of the ore: roasting of the cobalt mineral (saffre) and obtaining a glass adding sand and potash (smalt) or as by-product of other metallurgical processes, e.g. silver smelting slag. We have replicated the roasting of cobalt arsenide ore (CoAs3) and the processing of silver smelting as described in historical treatises following the transformations by in situ variable temperature SR-XRD, PIXE and SEM. Our laboratory tests have proved that roasting cobalt arsenide ore either alone or mixed with fluxes (PbO, CaF2), CaCO3, SiO2 and kaolinite was unable to remove the arsenic completely. Roasting cobalt arsenide ore (saffre) alone explains the presence of arsenic in the cobalt blue glasses and glazes after 1520. The product obtained as described by Agricola contains less arsenic forming calcium arsenates, lead arsenates (Pb5(AsO4)3F, Pb8As2O13) and calcium lead arsenates (Ca,Pb)5(A-sO4)3(F,Cl,OH) with an hedyphane structure, while cobalt is incorporated into a glassy matrix. As the physical separation of the arsenic free cobalt vitreous phase does not seem possible, these processes can explain the variable content of arsenic shown by the historical blue glazes but not the arsenic free glazes. In this case, the use of an arsenic free cobalt ore such as linnaeite is the most likely source., Peer Reviewed, Postprint (author's final draft)

Quinuclidinium salts and their derivatives are now in the focus of materials science as building units of multifunctional materials. Their properties can be easily switchable, allowing their use in a wide range of physical applications. One type of these kinds of materials, the homochiral hybrid halometallate ferroelectric compounds, is not well understood. In this work, (R)-(-)-3-quinuclidinol hydrochloride was used in the synthesis of ((R)-(-)-3-hydroxyquinuclidium)[FeCl4]. The use of this enantiomeric cation forces crystallographic non-centrosymmetry, which was confirmed by polarimetry and circular dichroism spectroscopy. We studied the physical properties of this compound at different temperatures by single crystal, synchrotron and neutron powder X-ray diffraction, which showed a rich series of structural and magnetic phase transitions. From synchrotron powder X-ray diffraction data, a plastic phase was observed above 370 K (phase I). Between 370 K and ca. 310 K, an intermediate polar phase was detected, solved in a non-centrosymmetric polar space group (C2) (phase II). Below ca. 310 K, the compound crystallizes in the triclinic P1 non-centrosymmetric space group (phase III) which is maintained down to 4 K, followed by phase IV, which shows tridimensional magnetic ordering. The temperature evolution of the neutron diffraction data shows the appearance of new reflections below 4 K. These reflections can be indexed to a commensurate propagation vector k = (0, 0, ½). The magnetic structure below TN was solved in the Ps1 Shubnikov space group, which gives rise to an antiferromagnetic structure, compatible with the magnetometry measurements. Near room temperature, the crystal phase transition is associated with a dielectric change. In particular, the phase transition between phase III (S.G.:P1) and phase II (S.G.:C2) involves an increase of symmetry between two non-centrosymmetric space groups. Therefore, it allows, by symmetry, the emergence of ferroelectric and fer, Postprint (author's final draft)

Soft crystallization routes for the controlled growth of oneand two-dimensional Cu(II)-coordination polymers of the type [(Cu- (hfa)2)x(3-tpt)]n (hfa = hexafluoroacetylacetonate, 3-tpt = 2,4,6-tris(3- pyridyl)-1,3,5-triazine) are described. Three volatile solvents with different protic/aprotic characteristics were chosen as the reaction media, e.g., supercritical CO2, chloroform, and ethanol. Five (1−5) new compounds were crystallized, with different structures and Cu(II)/3-tpt ratios. The structures of 3-tpt and five new coordination polymers were elucidated by single-crystal synchrotron X-ray diffraction. A description of the crystallization pathways followed for the synthesis of the individual compounds is given based on the protic or aprotic character of the used solvents and reagents’ solubility constraints. The main novelty of the work relies in establishing the foundations of 3-tpt isomeric control during crystallization through solvent selection. From the five precipitated new compounds, 3 displays a significant framework flexibility, associated with N2 adsorption at low temperature, presenting a stepwise adsorption isotherm. The N2 adsorption process was followed by in situ synchrotron X-ray powder diffraction

The synthesis of 1D cobalt and zinc monometallic and heterometallic coordination polymers (CPs) was carried out applying one-pot synthetic methods by using either supercritical carbon dioxide or ethanol as the solvent. A collection of four 1D CPs were thus obtained by the combination of a metal (or a mixture of metals) with the linker 1,4-bis(4-pyridylmethyl)benzene. The used metallic complexes were zinc and cobalt hexafluoroacetylacetonate, which can easily incorporate pyridine ligands in the coordination sphere of the metal centre. Independently of the used solvent, the precipitated phases involving Zn(II), i.e., homometallic CP of Zn(II) and bimetallic CP of Zn(II)/Co(II), were isostructural. Contrarily, homometallic CPs of Co(II) were precipitated as an isostructural phase of Zn(II) or with a different structure, depending on the used solvent. All the structures were resolved by XRD using synchrotron radiation. In addition, the magnetic properties of the new CPs involving Co(II) were studied. Remarkably, at low temperatures with the application of an external field, they acted as field-induced single molecule magnets.

The d1Dplot and d2Dplot computer programs have been developed as user-friendly tools for the inspection and processing of 1D and 2D X-ray diffraction (XRD) data, respectively. d1Dplot provides general tools for data processing and includes the ability to generate comprehensive 2D plots of multiple patterns to easily follow transformation processes. d2Dplot is a full package for 2D XRD data. Besides general processing tools, it includes specific data analysis routines for the application of the through-the-substrate methodology [Rius et al. IUCrJ 2015, 2, 452–463]. Both programs allow the creation of a user compound database for the identification of crystalline phases. The software can be downloaded from the ALBA Synchrotron Light Source website and can be used free of charge for non-commercial and academic purposes.