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σ-hole and lone-pair (lp) hole interactions of trivalent pnicogen-bearing (ZF3) compounds were comparatively scrutinized, for the first time, under field-free and external electric field (EEF) conditions. Conspicuously, the sizes of the σ-hole and lp-hole were increased by applying an EEF along the positive direction, while the sizes of both holes decreased through the reverse EEF direction. The MP2 energetic calculations of ZF3⋯FH/NCH complexes revealed that σ-holes exhibited more impressive interaction energies compared to the lp-holes. Remarkably, the strengths of σ-hole and lp-hole interactions evolved with the increment of the positive value of the considered EEF; i.e., the interaction energy increased as the utilized EEF value increased. Unexpectedly, under field-free conditions, nitrogen-bearing complexes showed superior strength for their lp-hole interactions than phosphorus-bearing complexes. However, the reverse picture was exhibited for the interaction energies of nitrogen- and phosphorus-bearing complexes interacting within lp-holes by applying the high values of a positively directed EEF. These results significantly demonstrate the crucial influence of EEF on the strength of σ-hole and lp-hole interactions, which in turn leads to an omnipresent enhancement for variable fields, including biological simulations and material science.

The present investigation was designed to characterize influence of doping with Al or Mg ions on nature and acidity of sulfate species dispersed on tetragonal-zirconia. Pure and doped zirconias were prepared by the citrate method. Sulfating of the thus produced zirconias was carried out by impregnation with aqueous solutions of (NH4)2SO4. The material bulk structure was elucidated by X-ray powder diffractometry and Laser Raman spectroscopy, whereas the surface sulfate was characterized via thermal and mass spectrometric analyses, and Fourier-transform infrared spectroscopy. The sulfate acidity was probed by IR νCCN spectra of adsorbed pyridine, and TPD of adsorbed n-propylamine. Results obtained showed the Al-doping to improve sulfate monolayer at the expense of overlayer structure, as well as its acidity. In contrast, Mg-doping influenced favorable bonding sites for polydentate sulfate of high thermal stability but of insignificant acidity.

HCl and CO2 are active participant molecules in the re-modeling phase of bone materials of vertebrates, wherein old bone is dissolved (resorbed) by osteoclast cells (HCl acid and collagenase secreting cells) and new bone becomes deposited (mineralized) by osteoblast cells. The mineralization process results in the deposition of mature (i.e., non-carbonated) or immature (i.e., partially carbonated) hydroxyapatite (HAP), which may involve CO2-carbonation, depending on the function of the perceived bone (e.g., non-dissolvable tooth enamel bone or dissolvable skeletal bone). The present investigation adopted a surface chemical approach to examine impacts of interfacial interactions of wet HCl vapor (at 673 K) and CO2 gas molecules (at 298 K) on the chemical composition and particle morphology of synthetic and biological apatite (AP) materials of varied contents of mature HAP. Studies employing X-ray powder diffractometry, Fourier-transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray micro-probing were carried out. Accordingly, high relative crystallinity, extent of hydroxylation and Ca/P atomic ratio were found to discern synthetic from biological APs. Furthermore, results obtained helped revealing that (i) compositional (atomic ratios, and extents of hydroxylation and carbonation) and morphological (particle shape and agglomeration) parameters are more diagnostic to the HAP maturity than the geometric structural (crystallization and crystallinity) parameters, (ii) the higher the maturity of the contained HAP, the higher is the resistance of chemical integrity and morphology of the AP material particles to the HCl-acidification, and (iii) a preceding CO2-carbonation lessens HAP-maturity of the AP materials thus rendering them more vulnerable to retrogressive chemical and morphological consequences of the acidification.

Breast cancer resistance protein (ABCG2) is a human ATP-binding cassette (ABC) that plays a paramount role in multidrug resistance (MDR) in cancer therapy. The discovery of ABCG2 inhibitors could assist in designing unprecedented therapeutic strategies for cancer treatment. There is as yet no approved drug targeting ABCG2, although a large number of drug candidates have been clinically investigated. In this work, binding affinities of 181 drug candidates in clinical-trial or investigational stages as ABCG2 inhibitors were inspected using in silico techniques. Based on available experimental data, the performance of AutoDock4.2.6 software was first validated to predict the inhibitor-ABCG2 binding mode and affinity. Combined molecular docking calculations and molecular dynamics (MD) simulations, followed by molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations, were then performed to filter out the studied drug candidates. From the estimated docking scores and MM-GBSA binding energies, six auspicious drug candidates—namely, pibrentasvir, venetoclax, ledipasvir, avatrombopag, cobicistat, and revefenacin—exhibited auspicious binding energies with value < −70.0 kcal/mol. Interestingly, pibrentasvir, venetoclax, and ledipasvir were observed to show even higher binding affinities with the ABCG2 transporter with binding energies of < −80.0 kcal/mol over long MD simulations of 100 ns. The stabilities of these three promising candidates in complex with ABCG2 transporter were demonstrated by their energetics and structural analyses throughout the 100 ns MD simulations. The current study throws new light on pibrentasvir, venetoclax, and ledipasvir as curative options for multidrug resistant cancers by inhibiting ABCG2 transporter.

Solid acids are desirable heterogeneous catalysts for green chemistry, with zirconia and its sulfated analogues offering tunable Lewis/Bronsted character. A new route to sulfated ZrO2, and Al-substituted ZrO2 (SO4/AlxZrO2), via carbonization and calcination of metal citrate gels and their subsequent sulfation by (NH4)2SO4 is reported. Structural and acidic properties of these materials were characterized by XRD, Raman, XPS, TGA-MS, N2 porosimetry, and propylamine and pyridine titration. Parent and sulfated materials all adopted the tetragonal zirconia phase, with Al-substitution (evidenced by contraction of the zirconia lattice parameter) at between 0.38–3.50 wt% increasing the surface area but decreasing acid strength, accompanied by an overall increase in total acid site loading and Lewis character. Low Al concentrations enhance α-pinene isomerization activity by up to 50% due to the increased acid site loading, however the Turnover Frequency (TOF) remained constant indicating a common active site. The TOF decreased for Al concentrations >3.5 wt% due to a further fall in acid strength, manifest as higher selectivity to polycyclic versus monocyclic products.

ABCG2 is a substantial member of the ABC transporter superfamily that plays a significant role in multidrug resistance in cancer. Until recently, the 3D structure of ABCG2 has not been resolved, which resulted in the limitation of developing potential ABCG2 inhibitors using structure-based drug discovery. Herein, eMolecules, ChEMBL, and ChEBI databases, containing >25 million compounds, were virtually screened against the ABCG2 transporter in homodimer form. Performance of AutoDock4.2.6 software to predict inhibitor-ABCG2 binding mode and affinity were validated on the basis of available experimental data. The explored databases were filtered based on docking scores. The most potent hits with binding affinities higher than that of experimental bound ligand (MZ29) were then selected and subjected to molecular mechanics minimization, followed by binding energy calculation using molecular mechanics-generalized Born surface area (MM-GBSA) approach. Furthermore, molecular dynamics simulations for 50 ns, followed by MM-GBSA binding energy calculations, were performed for the promising compounds, unveiling eight potential inhibitors with binding affinities

The present investigation was designed to assess the credibility of methylbutynol (MBOH) as an infrared (IR) reactive probe molecule for surface acid–base properties of metal oxides. Accordingly, pure alumina was systematically modified with varied amounts (0.5–10 wt.%) of K + or SO 4 2 − additives. Then, the influence of nature and amount of the additive on the following alumina properties were examined: (i) bulk composition and structure by X-ray powder diffractometry and ex-situ IR spectroscopy, (ii) surface area and net charge by N 2 sorptiometry and pH-metry, respectively, and (iii) nature and strength of exposed surface acid sites by in-situ IR spectroscopy of adsorbed pyridine at ambient and higher temperatures. Results obtained were correlated with IR-identified product distribution of MBOH catalytic decomposition/conversion at 200 °C. It is thereby concluded that MBOH is superior to conventional IR inactive probe molecules in gauging sensitively the prevailing acid or base character, availability of base sites, relative population of Bronsted to Lewis acid sites, and strength and reactivity of the sites exposed on metal oxide surfaces. Hence, all that is needed to get this information is to handle IR spectra taken from the gas phase, a task that is experimentally much more accessible than taking spectra from adsorbed species of irreactive probe molecules.

Bi/Fe-citrate xerogel, prepared by sol-gel processing, was first carbonized and, then, calcined at 300–700 °C for 1 h. The gel and its calcination products were characterized by thermal analyses (TG/DTA), X-ray powder diffractometry (XRD), Fourier-transform infrared spectrophotometry (FTIR), BET-specific surface area measurement (SBET), and Ultraviolet–Visible diffuse reflectance spectrometry (UV–Vis DRS). It was found that the carbonization step helps to subside the effects of a glowing thermal decomposition event, thus suppressing the formation of parasitic phases (such as Fe2O3 and Bi2Fe4O9). Rhombohedral-BiFeO3 yielded at 500 °C was found to assume qualifying properties for photo-assisted applications.

Halogen bond effectively contributes to inhibitor⋅⋅⋅receptor binding affinity. Several critical questions remain about the nature of halogenated inhibitor⋅⋅⋅receptor interactions. In the current study, the role and nature of the halogen bonding in halo-derivatives of benzimidazole in complex with casein kinase-2 (CK2) protein was clarified from molecular mechanical perspective. The molecular mechanics/generalized Born surface area (MM-GBSA) binding energy was calculated for the energetically minimized halogenated inhibitor⋅⋅⋅CK2 complexes and compared to the experimental data. The results were further assessed with the help of halogen bond test (–σ-hole test) at AMBER-molecular mechanical (MM) level. A molecular mechanical estimation of the halogen’s atomic parameter contribution (e.g., electrostatic and van der Waals contributions) was performed to characterize the nature of the halogen bonding using our previously proposed atomic parameter contribution to molecular interaction (APCtMI) approach. In accordance with the results, the inhibitor⋅⋅⋅CK2 binding energy increased with increasing the charge value of halogen’s σ-hole in the order iodo- > bromo- > chloro-derivative. One unanticipated finding was the disability of chloro-derivative to form a halogen bonding with the hinge region of the CK2 protein. APCtMI results revealed that halogen’s negative charge has no significant contribution to the total MM-GBSA binding energy. Furthermore, van der Waals interactions have a significant impact on the halogenated inhibitors⋅⋅⋅receptor binding energy. The APCtMI results were assessed by evaluating the binding energies of several hydrogen-substituted derivatives of tetrabromo-benzimidazole with CK2. These results should further the role of halogens for the purpose of drug discovery and development.

New insight was gained into the acidity-reactivity relationships of sulfated zirconia (SZ) catalysts prepared via (NH4)2SO4 impregnation of Zr(OH)4 for propanoic acid esterification with methanol. A family of systematically related SZs was characterized by bulk and surface analyses including XRD, XPS, TGA-MS, N2 porosimetry, temperature-programmed propylamine decomposition, and FTIR of adsorbed pyridine, as well as methylbutynol (MBOH) as a reactive probe molecule. Increasing surface sulfation induces a transition from amphoteric character for the parent zirconia and low S loadings

The amount of 10 wt%-WO3 was supported on alumina, titania or silica by impregnation with aqueous solution of ammonium paratungstate and subsequent calcination at 500 °C for 10 h. Tungstate-related chemical and physical changes in the calcination products were resolved by ex-situ infrared (IR) spectroscopy. Nature of exposed surface acid sites were probed by in-situ IR spectroscopy of adsorbed pyridine (Py) molecules at room temperature (RT). The relative strength of the acid sites thus probed was gauged by combining results of temperature-programmed desorption (TPD) measurements of the RT-adsorbed Py with those communicated by in-situ IR spectra of residual Py on the surface after a brief thermoevacuation at high temperatures (100–300 °C). Reactivity of the surface acid sites was tested toward 2-propanal catalytic decomposition, and observed by in-situ IR gas phase spectra. Results obtained were correlated with predominant structures assumed by the supported tungstate species. Accordingly, polymerization of the supported tungstate into 2-/3-dimensional structures, was found to be relatively most advanced on favorable locations of titania surfaces as compared to the case on alumina or silica surfaces. Consequently, the Lewis acidity was strengthened, and strong Bronsted acidity was evolved, leading to a 2-propanol dehydration catalyst (tungstate/titania) of optimal activity and selectivity. Strong tungstate/support interfacial interactions were found to hamper the formation of the strongly acidic and catalytically active polymeric structures of the supported tungstate (i.e., the case on alumina or silica).

Two samples (S1 and S2) of magnetite were synthesized, using two different methods, and characterized by means of X-ray powder diffractometry, infrared and Mossbauer spectroscopy, N2 sorptiometry and electron microscopy. Particles of sample-S1 were found to be loosely agglomerated, micro-sized spheroids (200–350 nm) composed almost solely of highly aggregated (fused) crystallites (size averaged at 35 nm) of cubic-Fe3O4. In contrast, particles of sample-S2 were strongly agglomerated, nano-sized spheroids (25–30 nm) composed of slightly aggregated crystallites (size averaged at 11 nm) of cubic-Fe3O4 and noncrystalline domains made-up of FeO(OH) species. Temperature-programed reduction (TPR) profiles obtained for the two samples were similar in monitoring two peaks at >450 °C assignable to a two-step reduction of Fe3O4 (→FeO→Fe), but different in monitoring a peak at

Titania-supported molybdena catalyst was prepared by calcination at 773 K of ammonium heptamolybdate-impregnated TiO 2 pellets with the equivalent of 5 monolayers of MoO 3 . Then, potassium-modified versions of the catalyst were prepared at 0.5–5 wt%-K. The modified and unmodified catalysts were characterized, before and after H 2 -reduction at 673 K, by means of ISS, XPS, UPS and FT-IR spectroscopy techniques. Results obtained enabled revealing the presence of density of states (DOS) at the Fermi level and, hence, metallic properties related to the deformed rutile structure of MoO 2 . On the other hand, Bronsted (Mo OH) acidic function was found to form on the surface of the MoO 2 structure, thereby producing a metal-acid (bifunctional) MoO 2− x (OH) y catalyst. The presence of Bronsted acid Mo OH groups was evidenced by in situ IR spectra of adsorbed pyridine molecules. On the other hand, the K-modification was found to enhance the molybdena dispersity and reducibility, but to suppress the surface acidity by transforming the bifunctional MoO 2− x (OH) y species into the monofunctional MoO 2− x (OK) y species. Subsequent catalytic measurements employing hydrotreating reactions of 1-hexene and n-hexane could confirm the exposure of bifunctional or monofunctional sites on the catalysts tested. The combination of research methods adopted in the present investigation has shown competency in unravelling the nature of active sites on heterogeneous catalysts.

The surface properties of sol–gel synthesized anatase titania (TiO2) nanoparticles are probed by sorptiometry, infrared absorption spectroscopy, UV–vis diffuse reflectance spectroscopy and high resolution transmission electron microscopy. The results reveal strong correlations of the surface area, porosity, pyridine adsorption capacity and strength, and catalytic methylbutynol decomposition activity.

Summary. The influence of the type of precursor, the phosphate content, as well as the source of phosphate ions on the surface texture, acidity, and catalytic activity of phosphated aluminas has been described. Phosphated alumina catalysts were prepared by impregnating two different precursors with two different sources of phosphate in different loading levels w ¼ 3, 6, and 10% PO4 3� . The characterisation of the catalyst was performed using X-ray powder diffraction (XRD), thermal analysis (TG), and nitrogen adsorption–desorption methods at 77 K. The surface acidity of the catalysts has been studied by FT-IR spectroscopy of adsorbed pyridine at different temperatures. Moreover, the activity in the catalytic decomposition of isopropanol (2-PrOH) has been investigated at 520 K. Investigation of the surface properties shows that the addition of phosphate ions does not change the crystal phase (� -phase) and the samples prepared from gel and phosphoric acid have the highest surface area. An FT-IR study of pyridine adsorption shows both Lewis and Bronsted acid sites on the surface of the samples prepared from gel, while only Lewis acid sites are detected on the samples prepared from crystalline oxide. The catalytic activity by 2-PrOH conversion shows that the conversion of 2-PrOH as well as the selectivity towards propene formation increases from w ¼ 3t o 6% followed by a decline for w ¼ 10%. Moreover, the strongest activity was detected in case of phosphated alumina gel with w ¼ 6% which gives 97.3% propene and 96.1% conversion of 2-PrOH.

Consequences of the loading level of sulfate ions (3, 6, and 10-wt%) as well as the source of sulfate (H2SO4 or (NH4)2SO4) on the structural, textural, and surface acid–base properties as well as the impacts on catalytic activity towards 2-propanol conversions on γ-Al2O3 and on aluminum hydroxide gel is described. Structural investigations of the catalysts by XRD revealed that the sulfation processes do not remarkably affect the γ-phase of alumina irrespective of the sulfate content or source. N2-adsorption at 77 K indicated that sulfated gel catalysts exhibit the highest S BET areas and, in general, S BET for all catalysts were found to decrease with the increase of sulfate content, such a decrease is more pronounced for the 10% loaded catalysts. Pyridine adsorption as followed by FTIR indicated that sulfation of alumina increases the strength of its Lewis acid sites and creates Bronsted acidity in the case of highly loaded catalysts. The catalytic decomposition of 2-propanol in the gas phase indicated that, amongst all the catalysts investigated, the 6% loaded ones exhibited 100% activity (2-propanol conversion) and the highest propene (dehydration product) selectivity.

Ketonization of acetic acid vapour over polycrystalline MgO was examined both kinetically and spectroscopically from room temperature to 480 °C. The kinetic study was performed with the use of a flow-reactor and gas chromatography, whereby the reaction rate and the catalyst selectivity were determined. The spectroscopic study was carried out by means of in situ infrared (IR) absorption measurement. Nature and products of adsorptive and absorptive interactions with the catalyst not only of the acid, but also of products of the reaction (acetone and CO 2 ) were identified by in situ IR spectroscopy, and quantified by thermogravimetric analysis. Moreover, adsorption and surface reactions of methylbutynol molecules were observed by IR spectroscopy and utilized to probe specifically the availability on MgO surfaces of strong, reactive base (O 2− ) sites. The results could help to reveal the strong catalyst tendency towards absorption of the acid and CO 2 molecules, and consequent formation of magnesium acetate and carbonate bulk phases, respectively. This unexpected behaviour of MgO, which enjoys high lattice (Mg O bond) energy, was considered to be driven by the strong catalyst basicity (ionicity). Accordingly, the ketonization of acetic acid over MgO was found to occur via overlapping catalytic and pyrolytic routes. Reactive species and reaction pathways involved in each route were proposed.

FT-IR spectroscopy of adsorbed probe molecules of pyridine and CO2, has been used to characterize adsorption sites (acidic and basic sites) on holmium oxide. Ho2O3, was obtained by calcination of holmium nitrate penta hydrate [Ho(NO3)3·5H2O] at 970 K for 1 h in static air. The adsorption and surface reaction of 2-propanol on the test oxide were also examined using IR spectroscopy. The results of adsorbed pyridine and CO2 revealed that the surface of Ho2O3 exposes Lewis acid sites (cus Ho3+) and highly reactive basic sits (O2− and/or OH−). The results also revealed that 2-propanol is irreversibly adsorbed at 300 K giving rise to different surface species. The results revealed that Ho2O3 is a dual functioning catalyst ≥520 K, and that 2-propanol decomposes thereon via dehydration into propene and dehydrogenation into acetone. At ≥570 K, the acetone was used up in a secondary surface reaction, giving rise to gas phase isobutene, methane and carbon dioxide.

Supported ceria and lanthana catalysts on alumina and silica were prepared by impregnating two different supports (SiO 2 and Al 2 O 3 ) with an aqueous solution of lanthanum nitrate or diammonium hexanitratocerrate, to yield final materials containing 3 and 10 wt.% of CeO 2 or La 2 O 3 catalysts. The products thus obtained were calcined at 650 °C for 2 h in static air for supported La 2 O 3 catalysts and at 500 °C for 2 h for supported ceria catalysts. X-ray powder diffractograms and nitrogen adsorption isotherms (at −196 °C) obtained on the support and supported catalysts were investigated. The pore volume was calculated from the adsorption branch to explore the modification of the porosity of unsupported and supported catalysts. The results suggest formation of highly dispersed lanthana on the surfaces of alumina and silica up to 10 wt.%, leading to pore narrowing. In contrast, a poor dispersion of ceria on alumina (higher than 3 wt.%) and silica (at 3 wt.%) in the form of small CeO 2 crystallites was observed and found to lead to pore blocking. These conclusions can be rationalized on the basis of the different surface chemical properties of the oxide supports and nature of oxide supported. It is revealed that nitrogen adsorption data offer valuable qualitative information on the dispersion of supported oxide materials.

La(NO3)3·6H2O was used as a precursor to produce La2O3 at 650°C in an atmosphere of air. Thermal processes occurred were monitored by means of thermogravimetry, differential thermal analysis, and gas-mass spectrometry. Infrared (IR)-spectroscopy, X-ray diffractometry and scanning electron microscopy characterized the intermediates and final solid products. The results showed that, La(NO3)3·6H2O decomposes through nine endothermic weight loss processes. Five dehydration steps occurred at 90, 105, 150, 175 and 215°C, leading to the formation of crystalline nitrate monohydrate, which decomposes to La(OH)(NO3)2 at 410°C. The latter, decomposes to La2O3 at 640°C, via two different intermediates; LaO(NO3) at 440°C, and non-stoichiometric unstable, La(O)1.5(NO3)0.5 at 570°C. The gaseous decomposition products as identified by gas-mass spectroscopy were water vapor, nitric acid and nitrogen oxides (NO, NO2 and N2O5). The final product La2O3 has a large crystalline containing pores, voids and cracks, with a surface area of 23 m2 g−1. Also it possessed Lewis acidic and basic sites, as indicated by Pyridine adsorption.

Thermal processes involved during the decomposition course of hydrated holmium acetate (Ho(CH 3 COO) 3 ·3.5H 2 O) up to 800°C, in an atmosphere of air, were monitored by thermogravimetry and differential thermal analysis. The gaseous decomposition products were identified by IR- spectroscopy. X-ray diffraction and IR-spectroscopy characterized intermediates and final solid products. The results showed that, Ho-acetate, dehydrates completely in two steps then decomposes to Ho 2 O 3 at 570°C, through three noncrystalline unstable intermediates. The oxide obtained at 600 and 800°C possesses a surface area of 31 and 15.0 m 2 g −1 , respectively. The volatile decomposition products from the acetate were water vapor, acetic acid, ketene, acetone, methane and isobutene.

Phosphated zirconia catalysts were prepared by impregnating two different precursors (zirconium hydroxide and crystalline ZrO2) with an aqueous solution of diammonium hydrogen phosphate. X-ray powder diffractograms and nitrogen adsorption isotherms at −196°C on pure and phosphated zirconia catalysts were investigated. The pore volume was calculated from the adsorption branch to explore the modification of porosity for pure and phosphated zirconia. Pore structure analysis shows that phosphated zirconia, resulted from calcination of zirconium hydroxide at low temperature, exhibited high surface area and accessible porosity. Whereas for those calcined at higher temperatures, inaccessible porosity is shown to predominate. Phosphation of crystalline zirconia did not modify either surface area or the porosity, as compared to pure zirconia. The influence of phosphation on the structure of zirconium hydroxide and zirconia during the calcination course was studied.

γ-Al2O3, dried alumina gel, as well as their phosphated forms using (NH4)2HPO4 were prepared by wet impregnation and calcined at 870 K. Resulted samples were subjected to investigate the consequent bulk [X-ray powder diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and infrared spectroscopy (IR)] and surface (texture, N2-adsorption and surface acid properties, pyridine adsorption). Results indicated no detectable bulk phase changes due to phosphation. However, the phosphated gel sample reveals the highest SBET. Surface stabilization of phosphate species by γ-Al2O3 or gel is indicated, leading to modifications on surface hydroxyl and hence surface acidity. The phosphated gel sample exhibits the strongest acidity (both Bronsted and Lewis).

Thulium oxide, Tm2O3, was obtained as a final product of the thermal decomposition of Tm(CH3COO)3·4H2O. The decomposition steps up to 800°C were characterized by TG, DTA, XRD, SEM, GC-MS and gas- and solid-phase IR spectroscopy. The results showed that Tm(CH3COO)3 ·4H2O dehydrates completely in two overlapping steps at 90 and 110°C and decomposes to Tm2O3 at 540°C through a non-crystalline intermediate Tm(OH)(CH3COO)2 at 350°C, Tm(O)(CH3COO) at 375°C and Tm2O2CO3 at 400°C. The oxides obtained at 600 and 800°C were subjected to texture analysis and pyridine adsorption. The results revealed that the oxide obtained at 600°C has a higher surface area of 49.7 m2 g−1 with larger pores than that obtained at 800°C (SBET=32.8 m2 g−1). On the other hand, the oxide obtained at 600°C has a basic surface character and contains at least two different Lewis acid sites as indicated from pyridine adsorption. The gaseous decomposition products as identified by gas-phase IR and GC-MS are water vapour, acetic acid, ketene, acetone and methane.

Silica supported cobalt oxides were prepared by the impregnation method, using an aqueous solution of cobalt nitrate hexahydrate (Co(NO3)2 · 6H2O), then calcined at different temperatures (510, 620 and 870 K). Characterization of the samples was carried out by X-ray diffraction, N2-adsorption at −196°C, UV–Vis diffuse reflectance spectroscopy and KBr-IR spectroscopy of the calcination products. The surface acidity was studied by IR spectroscopy of adsorbed pyridine at different temperatures (300, 370, 470 and 570 K). Results indicated that Co3O4 is the stable phase on silica, however, dispersion of minor amount of cobalt oxide could not be ruled out. Results also indicated that the crystallinity of the formed Co3O4 increased by increasing the loading level and/or the calcination temperature. Furthermore, the surface area of the support was decreased by increasing the loading level and the calcination temperatures. It has been also found that the surface of the supported catalysts exposed strong different Lewis acid sites.

The impact of the addition of phosphate and sulphate salts to aluminas, viz. γ-alumina and dried alumina gel, on their surface textures is described. This has been achieved through an analysis of nitrogen adsorption data for structurally characterised test samples. Modification through impregnation by phosphate and sulphate salts did not result in detectable bulk changes, the structure remaining very similar to that of γ-alumina in all cases. However, as far as the texture was concerned, the addition of both phosphate and sulphate salts resulted in a ca. 15% reduction in the S BET value for γ-alumina due to changes in the porosity. Modified alumina gel exhibited a higher surface area than either pure or modified γ-alumina. Thus, for the purposes of obtaining catalytically important acidified aluminas with higher surface areas, it is recommended that phosphates or sulphates be added to the parent alumina gel prior to calcination.

Phosphated zirconia samples were prepared by an impregnation method, using an aqueous solution of diammonium hydrogen phosphate and two different zirconia precursors (monoclinic ZrO2 and Zr(OH)4). The dried impregnated samples were calcined at 770, 870 and 970 K for 1 h in static air. The samples of phosphated zirconia obtained were characterized by X-ray diffraction, Raman and IR spectroscopy and N2 adsorption. The results revealed that the presence of phosphate ions causes the tetragonal ZrO2 phase to form at low temperature (≤970 K) and the surface area to stabilize, when Zr(OH)4 was the precursor used. However, using monoclinic ZrO2 as precursor no such effects were observed. At least two different surface phosphate species were observed, namely pyrophosphate and [(Zr–O)2 PO2H] species.

X-ray diffractometry and UV-Vis diffuse reflectance spectroscopy revealed that fluorite-structured CeO 2 crystallites (mean size 22.3 nm) are dispersed on silica surfaces (CeSi) into microcrystallites (11.2-8.1 nm) and dispersed further on alumina surfaces (CeAl) into nanocrystallites ( x monolayers. Consequently, IR spectroscopy of adsorbed pyridine found Lewis acid sites to be far more strengthened on CeAl. Bronsted acid sites (proton-donors) were probed exclusively on CeAl. On the other hand, IR spectroscopy of adsorbed deuterated chloroform (CDCl 3 ) showed the originally moderate Lewis base sites (low-coordinated OH − and O 2− ) to be weakened on CeSi, but markedly strengthened on CeAl. Lewis base sites exposed on ceria surfaces assume a strong nucleophilic reactivity.

n-butane isomerization on sulfated zirconia was studied in the temperature range 393–473 K. Rapid deactivation occurs, when the reaction is carried out in He carrier gas. In contrast, stable stationary activity was observed in H2 carrier gas. In situ Raman and UV-VIS diffuse reflectance spectroscopy and ESR showed that the deactivation is caused by the formation of allylic and polyenylic cations and polycyclic aromatic compounds, the formation of which is largely prevented in the presence of H2. Deactivated catalysts can be fully regenerated by treatment at 723–753 K in flowing O2. The regeneration process was also followed by in situ spectroscopies.

The acid properties of pure and sulfated zirconias were studied by FTIR spectroscopy of adsorbed CO and NH3 as probe molecules. Whereas pure monoclinic zirconia shows only Lewis acidity, sulfation of tetragonal and monoclinic zirconia creates new bridging OH groups. Two types of Bronsted-acidic centers and two types of Lewis-acidic centers with enhanced acid strength were identified. A communication between the different types of Lewis-acidic sites and the related adsorbed sulfate molecules could be shown. The coordination of basic molecules such as CO onto Lewis-acid sites induces a decrease of the intrinsic Bronsted-acidity of the bridging OH groups. These effects are discussed on the basis of a model of the acidic centers that was previously proposed.

Nano-particle, pure and CuO x -modified, fluorite-structured cubic-CeO2 were successfully synthesized with surface areas near 240 m2/g applying a microemulsion method with mixed templating surfactants (viz. DDAB and Brij®35). Following calcination at 400–800 °C, the products were characterized by X-ray powder diffractometry, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy, and, then, tested as catalysts for methylbutynol decomposition and CO oxidation in the gas phase. Results obtained showed the pure and CuO x -modified cerias to exhibit comparable activities towards the alcohol decomposition into acetone and acetylene, but the modified ceria exhibited considerably higher activity towards the CO oxidation than the pure one. The calcination product of CuO x -modified ceria at 800 °C was capable of lowering the light-off temperature of the CO oxidation from 300 °C (on the pure) down to 70 °C. Surface chemical consequences of the CuO x -modification, viz. increasing the Ce(III)/Ce(IV) atomic ratio, as well as the establishment of Cu(I) and Cu(II) sites, have been allocated the responsibility of the observed upsurge of the CO oxidation activity.

In situ Fourier transform infrared (FTIR) spectroscopy was employed to characterize the adsorption behavior (as a function of pressure or time) and surface species of CO2 molecules on pure, phosphated, and phosphonated CaO. Carbonate and bicarbonate species were found to form on the pure oxide, whereas on the phosphated and phosphonated oxide samples the carbonate species were found to substitute favorably some of the OH(-) and PO4(3-) groups thereon exposed, respectively. Before and after carbonation, the test samples were further examined by in situ FTIR spectroscopy of adsorbed pyridine species, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Then they were in situ acidified by exposure to a wet atmosphere of HCl vapor at 673 K for 10 min and re-examined similarly to reveal the influence of CO2 adsorption on the chemical and morphological consequences of acidification. The results obtained show the carbonate substitution of PO4(3-) groups to enhance agglomeration of the otherwise fine, longitudinal material particles into much bulkier ones and to render the otherwise more stable phosphonate groups less stable to acid treatment than the phosphate groups. Moreover, the bulky particle agglomerates of the carbonated test samples were detectably eroded following the acid treatment.

Pure, phosphated, and phosphonated CaO samples were prepared and characterized by X-ray powder diffractometry, FTIR spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microprobing. Surface acid–base properties were probed by in situ FTIR spectroscopy of adsorbed CO (at 85 K), CDCl3 (at RT), CO2 (at RT), and methyl butynol decomposition reactions (at 473 K). Results obtained have shown phosphate and, to a larger extent, phosphonate additives to enhance the strength of Lewis acid sites exposed on CaO surfaces, at the expense of the Lewis base site strength. The phosphonation has been found, moreover, to make CaO particles grow in a preferential direction and be less susceptible to rehydration. These findings may establish surface chemical attributes for the application of the methylene bisphosphonate (MBP) class of drugs to hamper acid-induced resorption of bone materials (osteoporosis).

Large 1H chemical shifts are suggestive of protonic superacidity of sulfated zirconia catalysts, this property being related to the structure of surface sulfate species.

Phosphate-modified zirconia was prepared by impregnation of Zr(OH)4 and of m-ZrO2 with an aqueous solution of (NH4)2HPO4. Similar to sulfate and tungstate, phosphate shows a strong stabilizing effect on the specific surface area and the tetragonal phase of zirconia when using Zr(OH)4 as the precursor material. The adsorbed phosphate species were characterized by Raman, DRIFT, and 31P-MAS-NMR spectroscopies as pyrophosphates, chelate-bonded orthophosphates, and oligophosphates. Only a distortion of the geometry of the adsorbed phosphate species was found after dehydration of the materials in contrast to ZrO2/SO4. FT-IR spectroscopy with CO as a probe molecule was used to characterize the acidic properties of ZrO2/PO4. New hydroxyl groups, probably P−OH groups with enhanced protonic acidity as compared to pure zirconia but lower than that of ZrO2/SO4, were observed. In addition basic Zr−OH groups were observed. Furthermore, strong Lewis acidic centers (cus Zr4+), comparable to ZrO2/SO4, are formed by phosph...