People from Brač, emigrant press in Chile and newspaper Domovina - from the late 19th century to the beginning of World War I

Cilj je rada postaviti ishodišta za proučavanje povijesti hrvatskog iseljeničkog novinstva u Čileu od najranijeg razdoblja doseljenja Hrvata do kraja 1914. godine, među kojima je brojčano dominantnu grupaciju činilo stanovništvo s Brača. Radilo se prvenstveno o ekonomskoj migraciji uzrokovanoj ekonomskim promjenama u društvu općenito, ali i ekonomskim promjenama kao posljedicama političkih kretanja. U novu domovinu donose tradicionalnu potrebu organiziranja u razna društva, ali i svijest o vlastitoj nacionalnoj pripadnosti s vlastitim jezikom. Neobično brza asimilacija (već u prvoj generaciji) dovodi u pitanje opstojnost te potrebu očuvanja baštine. Iseljeničke novine u kojima surađuju, uređuju ih i pokreću Bračani – novinari, među kojima se ističu Ivan Krstulović i Luka Bonačić s novinama „Domovina“ iz Punta Arenasa, u dosadašnjoj literaturi sagledavane su gotovo isključivo s aspekta političke orijentacije i borbe. Cilj je rada kroz primjer rubrike „Iz mjesta i okolice“, koja je održala kontinuitet tijekom cijelog razdoblja izlaženja lista „Domovina“ i čijim je sastavnim dijelom bila, prikazati, s aspekta socijalne povijesti, da su lokalne novine odražavale i bilježile pojave i događanja značajna za svakodnevni život zajednice sa svrhom očuvanja njezina identiteta.The topic of this paper is to set the starting point for studying the history of Croatian emigrant journalism in Chile from the earliest period of the settlement of Croats until the end of 1914, including the dominant population group from Brač. It was primarily the economic migration, which was caused by economic changes in the society in general, and economic changes as a consequence of political movements. The immigrants had the need for organizing themselves in various societies in the new country, and they also had the awareness of their own nationality and language. The unusually rapid assimilation (already in the first generation) calls into question the viability and the need to preserve heritage. Immigrant newspapers edited and run by Brač emigrant journalists, most notably Ivan Krstulović and Luka Bonačić, with the newspaper Domovina from Punta Arenas, were in the current literature perceived almost exclusively in terms of political orientation and struggle. The aim of this paper is to show that the local newspaper Domovina reflected and recorded phenomena and events significant for the daily life of the community with the intention of preservation its identity from the perspective of social history, especially in the section From the town and surrounding areas

Computational Assessment of Relative Sites Stabilities and Site-Specific Adsorptive Properties of Titanium Silicalite‑1

Titanium Silicalite-1 (TS-1), because of its crystalline structure and its well-defined Ti sites, represents the prototype of a single site catalyst. According to this fundamental aspect and to the relevant role of TS-1 as selective catalyst in important industrial partial oxidation reactions, TS-1 has been widely characterized through both experimental and computational techniques. Still, several fundamental aspects of its structural and catalytic properties have to be addressed. Among these, an intriguing topic is the Ti location in the various sites of the MFI framework. The independent sites are generally considered to be 12, following the <i>Pnma</i> space group of TS-1 at high Ti loading. However, when Ti loading is lower than 2 atoms per unit cell, diffraction showed that the system must be described by the <i>P</i>2₁/<i>n</i> space group, thereby allowing 24 independent sites. With respect to previous studies, this work aims to exploit this datum to give a more accurate description of the TS-1 system at low Ti loadings, adopting a state of the art methodology (all electron periodic B3LYP-D2 calculations). The relative stabilities of the 24 Ti sites have been evaluated, showing a good agreement with previous studies. The simulation of adsorption energies for ammonia (present as reactants in some of the most important industrial reactions catalyzed by TS-1) over the most stable sites have been computed as well, in order to validate the obtained models. Additionally to binding energies, adsorption enthalpies and Gibbs free energies have been obtained through an approximate reduced Hessian scheme. The improved local description of the Ti sites (in combination with the adducts stabilities given by the energetic data) allowed the deep understanding of subtle effects, such as the number of molecular ligands each Ti atom can actually host upon adsorption. These results, showing only few sites can efficiently host two ligands in the neighborhoods of STP conditions, allowed for the first time the heterogeneity in the experimental outcomes reported over the last two decades to be rationalized

Computational Assessment of Relative Sites Stabilities and Site-Specific Adsorptive Properties of Titanium Silicalite‑1

Titanium Silicalite-1 (TS-1), because of its crystalline structure and its well-defined Ti sites, represents the prototype of a single site catalyst. According to this fundamental aspect and to the relevant role of TS-1 as selective catalyst in important industrial partial oxidation reactions, TS-1 has been widely characterized through both experimental and computational techniques. Still, several fundamental aspects of its structural and catalytic properties have to be addressed. Among these, an intriguing topic is the Ti location in the various sites of the MFI framework. The independent sites are generally considered to be 12, following the <i>Pnma</i> space group of TS-1 at high Ti loading. However, when Ti loading is lower than 2 atoms per unit cell, diffraction showed that the system must be described by the <i>P</i>2₁/<i>n</i> space group, thereby allowing 24 independent sites. With respect to previous studies, this work aims to exploit this datum to give a more accurate description of the TS-1 system at low Ti loadings, adopting a state of the art methodology (all electron periodic B3LYP-D2 calculations). The relative stabilities of the 24 Ti sites have been evaluated, showing a good agreement with previous studies. The simulation of adsorption energies for ammonia (present as reactants in some of the most important industrial reactions catalyzed by TS-1) over the most stable sites have been computed as well, in order to validate the obtained models. Additionally to binding energies, adsorption enthalpies and Gibbs free energies have been obtained through an approximate reduced Hessian scheme. The improved local description of the Ti sites (in combination with the adducts stabilities given by the energetic data) allowed the deep understanding of subtle effects, such as the number of molecular ligands each Ti atom can actually host upon adsorption. These results, showing only few sites can efficiently host two ligands in the neighborhoods of STP conditions, allowed for the first time the heterogeneity in the experimental outcomes reported over the last two decades to be rationalized

Effect of Ti Speciation on Catalytic Performance of TS‑1 in the Hydrogen Peroxide to Propylene Oxide Reaction

Hydrogen peroxide to propylene oxide (HPPO) reaction is an attractive process exploiting titanium silicalite-1 (TS-1) as a catalyst in combination with aqueous hydrogen peroxide as an oxidizing agent. Beyond the industrial interest, TS-1 represents one of the most widely characterized catalysts due to its unique properties. However, a unified description on the speciation of the different Ti species and their correlation to catalytic performances is missing in the literature. This work aims to exploit spectroscopic techniques (namely, diffuse reflectance UV–vis, Raman, FT-IR, and Ti K-edge XANES) in a qualitative and quantitative way to thoroughly characterize Ti sites in a selected set of industrially relevant TS-1 samples, each one owning a peculiar Ti speciation. The outcomes of this study have been then related to the activity of each catalyst in HPPO reaction, showing its linear correlation with the content of perfect Ti sites (i.e., isomorphously substituting Si in the zeolitic framework). Other Ti species, such as amorphous TiO_<i>x</i> and bulk titania, are instead not involved in the peroxide conversion (neither in a detrimental way)

Insights into Adsorption of NH₃ on HKUST‑1 Metal–Organic Framework: A Multitechnique Approach

We report a careful characterization of the interaction of NH₃ with the Cu­(II) sites of the [Cu₂C₄O₈] paddle-wheel cornerstone of the HKUST-1 metallorganic framework, also known as Cu₃(BTC)₂. The general picture emerging from combining XRPD, EXAFS, XANES, mid- and far-IR, DRUV–vis, and EPR techniques is that the presence of traces of water has relevant consequences on the effect of ammonia on the MOF framework. NH₃ adsorption on the dry system results in a strong chemisorption on Cu­(II) sites that distorts the framework, keeping the crystallinity of the material. Perturbation observed upon NH₃ adsorption is analogous to that observed for H₂O, but noticeably enhanced. When the adsorption of ammonia occurs in humid conditions, a time-dependent, much deeper modification of the system is observed by all of the considered techniques. On a methodological ground, it is worth noticing that we used the optimization of XANES spectra to validate the bond distance obtained by EXAFS

Ligands Make the Difference! Molecular Insights into Cr^VI/SiO₂ Phillips Catalyst during Ethylene Polymerization

Operando-sensitive spectroscopic techniques were employed for investigating the changes in the molecular structure of the Cr sites in the Cr^VI/SiO₂ Phillips catalyst during ethylene polymerization. Practically, the most arduous barrier to be overcome was the separation of the chromates reduction carried out by ethylene from the subsequent polymerization. By carefully tuning the experimental parameters we succeeded in observing these two events separately. We found that the sites involved in ethylene polymerization are mainly divalent Cr ions in a 6-fold coordination, in interaction with the oxygenated byproduct (mostly methylformate, generated from the disproportionation of two formaldehyde molecules). Unreduced Cr^VI species are also present during ethylene polymerization as well as reduced Cr species (either Cr^II or Cr^III) acting as spectators. Our results challenge the old vision of “naked” chromium species (i.e., low coordinated) as the active sites and attribute a fundamental role to external (and flexible) oxygenated ligands that resemble the ancillary ligands in homogeneous polymerization catalysis

Detailed Structure Analysis of Atomic Positions and Defects in Zirconium Metal–Organic Frameworks

We report the structure of the Zr metal–organic frameworks (MOFs) UiO-66 and UiO-67 to very fine detail using synchrotron single-crystal X-ray diffraction and the synthesis method used to obtain single crystals. Zr terephthalate MOF UiO-66 is known to have missing linkers, and the nature of these are shown to be coordinating water and solvent molecules. Single crystals of the isoreticular material UiO-67 does not show such missing linker defects

Detailed Structure Analysis of Atomic Positions and Defects in Zirconium Metal–Organic Frameworks

We report the structure of the Zr metal–organic frameworks (MOFs) UiO-66 and UiO-67 to very fine detail using synchrotron single-crystal X-ray diffraction and the synthesis method used to obtain single crystals. Zr terephthalate MOF UiO-66 is known to have missing linkers, and the nature of these are shown to be coordinating water and solvent molecules. Single crystals of the isoreticular material UiO-67 does not show such missing linker defects

The Cu-CHA deNO_<i>x</i> Catalyst in Action: Temperature-Dependent NH₃-Assisted Selective Catalytic Reduction Monitored by Operando XAS and XES

The small-pore Cu-CHA zeolite is today the object of intensive research efforts to rationalize its outstanding performance in the NH₃-assisted selective catalytic reduction (SCR) of harmful nitrogen oxides and to unveil the SCR mechanism. Herein we exploit operando X-ray spectroscopies to monitor the Cu-CHA catalyst in action during NH₃-SCR in the 150–400 °C range, targeting Cu oxidation state, mobility, and preferential N or O ligation as a function of reaction temperature. By combining operando XANES, EXAFS, and vtc-XES, we unambiguously identify two distinct regimes for the atomic-scale behavior of Cu active-sites. Low-temperature SCR, up to ∼200 °C, is characterized by balanced populations of Cu­(I)/Cu­(II) sites and dominated by mobile NH₃-solvated Cu-species. From 250 °C upward, in correspondence to the steep increase in catalytic activity, the largely dominant Cu-species are framework-coordinated Cu­(II) sites, likely representing the active sites for high-temperature SCR

Selective Catalytic Olefin Epoxidation with Mn^II-Exchanged MOF‑5

Partial substitution of Zn^II by Mn^II in Zn₄O­(terephthalate)₃ (MOF-5) leads to a distorted all-oxygen ligand field supporting a single Mn^II site, whose structure was confirmed by Mn K-edge X-ray absorption spectroscopy. The Mn^II ion at the MOF-5 node engages in redox chemistry with a variety of oxidants. With ^<i>t</i>BuSO₂PhIO, it produces a putative Mn^IV-oxo intermediate, which upon further reaction with adventitious hydrogen is trapped as a Mn^III–OH species. Most intriguingly, the intermediacy of the high-spin Mn^IV–oxo species is likely responsible for catalytic activity of the Mn^II-MOF-5 precatalyst, which in the presence of ^<i>t</i>BuSO₂PhIO catalyzes oxygen atom transfer reactivity to form epoxides from cyclic alkenes with >99% selectivity. These results demonstrate that MOF secondary building units serve as competent platforms for accessing terminal high-valent metal–oxo species that consequently engage in catalytic oxygen atom transfer chemistry owing to the relatively weak ligand fields provided by the SBU