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Commercial nanopowders of MgB2 were characterized from the viewpoint of granulometric distribution, structure, microstructure, and pH behavior in water. The powders are very different: a higher amount of the MgB2 phase with a lower tendency for agglomeration determines a higher rate of pH-increase. A higher rate of pH-increase usually produces a stronger antimicrobial activity against Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Candida parapsilosis reference strains. The variation of the pH-increase rate suggests the possibility of temporo-spatial control of MgB2 bioactivity, although the contribution of other factors should not be neglected. Remarkably, the efficiency of the MgB2 powders is higher against biofilms than on microbes in the planktonic state. Further, our experiments confirm the antimicrobial efficiency of MgB2 in the in vitro tests against 29 methicillin resistant clinical S. aureus isolates and 33 vancomycin resistant E. faecium/faecalis strains, but in this case the biofilms are more resistant than planktonic cells. The MgB2 treatment of infected mice led to a significant decrease of E. coli colonization in liver, spleen and peritoneal liquid and it also caused changes in the intestinal microbiota. The activity of powders on HeLa and HT-29 tumor cell lines was assessed by inverted microscopy, flow cytometry, and evaluation of the cellular cycle. MgB2 inhibits tumor cell growth influencing DNA synthesis (S-phase). The obtained results indicate that the tested powders could provide promising solutions for the development of large-spectrum multifunctional antimicrobial and anti-biofilm agents, and/or for anti-cancer therapies.

Abstract Three commercial powders of MgB2 were tested in vitro by MTS and LDH cytotoxicity tests on the HS27 dermal cell line. Depending on powders, the toxicity concentrations were established in the range of 8.3–33.2 µg/ml. The powder with the lowest toxicity limit was embedded into polyvinylpyrrolidone (PVP), a biocompatible and biodegradable polymer, for two different concentrations. The self-replenishing MgB2-PVP composite materials were coated on substrate materials (plastic foil of the reservoir and silicon tubes) composing a commercial urinary catheter. The influence of the PVP-reference and MgB2-PVP novel coatings on the bacterial growth of Staphylococcus aureus ATCC 25923, Enterococcus faecium DMS 13590, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, in planktonic and biofilm state was assessed in vitro at 6, 24, and 48 h of incubation time. The MgB2-PVP coatings are efficient both against planktonic microbes and microbial biofilms. Results open promising applications for the use of MgB2 in the design of anti-infective strategies for different biomedical devices and systems.

Azurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO 3 ·Cu(OH) 2 ), is one of the Middle Ages' most common blue pigments. Why paintings originally coated with azurite appear blackened today remains debated. Using a non-invasive multi-analytical approach, the study analysed several unexpectedly black-appearing details (objects such as books or clothing such as veils, robes, or mantles) in Antoine de Lonhy's works. The aim was to investigate if the black colour was due to intentional iconographic reasons, incautious restoration work, or painting deterioration. The analytical results displayed the presence of the blue pigment azurite, therefore, the expected original colour of various areas should be blue. To shed light on the discussion regarding the blackening, several other Renaissance paintings with similar black details were analysed, all from the same period and geographic area as de Lonhy's works and conserved under identical conditions. The reasons why the blackening takes place are still unclear. However, the combined use of X-ray fluorescence spectrometry (XRF), UV-visible diffuse reflectance spectrophotometry with optical fibres (FORS), portable X-ray diffraction (XRD), and the elemental mapping based on the XRF data revealed that these blackened areas were originally painted with azurite, suggesting they were once blue. This finding significantly changes the overall appreciation of these artworks.

Background: The volatile composition of Ruché, a red wine produced from a native grape in Piedmont (Italy), was investigated using headspace-solid phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC/MS). The main volatile compounds of the wine were identified and quantified. Chemometric techniques were applied to identify features and possible clusters among the different samples., Results: Forty volatile compounds were unambiguously identified in the 36 wine samples from different producers. The aroma profile was mainly composed of different alcohols and esters but also featured appreciable concentrations of terpenes, aldehydes, and octanoic acid. 2-Methyl benzaldehyde was identified for the first time. A high concentration of isoamyl alcohol significantly contributed to the aroma complexity. Differences between producers are highlighted., Conclusion: The present work is the first report about the volatile profile of Ruché wines investigated by chemometric methods with quantitative results. Multivariate exploratory approaches revealed minor but distinct differences among the studied wines, likely attributable to variations in winemaking procedures. This study could be developed in future by investigating possible differences between wines according to different production vintages. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

We used humic and fulvic acids extracted from digestate to formulate nanohybrids with potential applications in agronomy. In order to obtain a synergic co-release of plant-beneficial agents, we functionalized with humic substances two inorganic matrixes: hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HP) and silica (SiO₂) nanoparticles (NPs). The former is a potential controlled-release fertilizer of P, and the latter has a beneficial effect on soil and plants. SiO 2 NPs are obtained from rice husks by a reproducible and fast procedure, but their ability to absorb humic substances is very limited. HP NPs coated with fulvic acid are instead a very promising candidate, based on desorption and dilution studies. The different dissolutions observed for HP NPs coated with fulvic and humic acids could be related to the different interaction mechanisms, as suggested by the FT-IR study., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Giordana, Malandrino, Zambon, Lusvardi, Operti and Cerrato.)

This manuscript reports four new gold(I)-silver(I) complexes with 2-(2-pyridyl)-1,8-naphthyridine (pyNP) and terpyridine (terpy) as ancillary ligands, having formulae [Ag(pyNP)(Au(CN) 2 )] 2 (1), [Ag 2 Au 2 (μ-CN) 2 (CN) 2 (pyNP) 2 ] (2), [Ag 2 Au(μ-CN) 2 (terpy) 2 ][Au(CN) 2 ] (3) and [Ag 4 Au 4 (μ-CN) 8 (terpy) 2 (py)] (4). Complexes 1 and 2 are structural isomers obtained from different solvents. The Au(CN) 2 - anion is not coordinated and establishes intramolecular Au⋯Ag,Ag interactions in 1. In contrast, it is monocoordinated to silver atoms via a CN fragment in compound 2 and no metallophilic interaction is observed. In compound 3, one Au(CN) 2 anion bridges two Ag(terpy) fragments. In this complex an infinite array of gold atoms is found, exhibiting aurophilic interactions of 3.415 Å. In complex 4 the 3D architecture observed in the crystal packing is driven by Au⋯Au and Au⋯Ag metallophilic interactions. All compounds have been structurally and vibrationally characterized to better understand the crystal forces. In addition, a solution chemistry study in different solvents by ESI-MS spectrometry was performed to comprehend the speciation and solvent effects. Finally, DFT calculations were carried out to analyze the Ag⋯Au interactions and also the π-stacking interactions that are relevant in the crystal packing of some structures. Special attention has been paid to the bifurcated nature of the Au⋯Ag,Ag interactions in compound 1 that has been analyzed theoretically using the quantum theory of atoms-in-molecules (QTAIM) and the Natural Bond Orbital (NBO) computational tools.

Mixed mercury(II) halogenides have been known for a long time as good NLO (non-linear optic) materials. The NLO properties are due to the halogen disposition in the solid state and the electron distribution among the bonds formed by soft elements. We investigated the possibility of using HgBrI as a asymmetric tecton in the preparation of noncentrosymmetric crystalline compounds, by exploiting the coordinating power of Hg(II) toward N-donor ligands, and seven coordination complexes have been obtained. To unravel the nature of these complex systems we combined the data from different techniques: Raman spectroscopy, SC-XRD and Second Harmonic Generation, supported by a periodic DFT computational approach. In HgBrI crystalline products with low symmetry, the presence of substitutional disorder leads to a lack of the inversion center conferring NLO activity, which is absent in analogous complexes of Hg(II) halogenides. These results indicate HgBrI as an interesting tecton to obtain metallorganic NLO materials.

Pristine high-density bulk disks of MgB 2 with added hexagonal BN (10 wt.%) were prepared using spark plasma sintering. The BN-added samples are machinable by chipping them into desired geometries. Complex shapes of different sizes can also be obtained by the 3D printing of polylactic acid filaments embedded with MgB 2 powder particles (10 wt.%). Our present work aims to assess antimicrobial activity quantified as viable cells (CFU/mL) vs. time of sintered and 3D-printed materials. In vitro antimicrobial tests were performed against the bacterial strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Enterococcus faecium DSM 13590, and Enterococcus faecalis ATCC 29212; and the yeast strain Candida parapsilosis ATCC 22019. The antimicrobial effects were found to depend on the tested samples and microbes, with E. faecium being the most resistant and E. coli the most susceptible.

We report for the first time on the antimicrobial activity of MgB 2 powders produced via the Reactive Liquid Infiltration (RLI) process. Samples with MgB 2 wt.% ranging from 2% to 99% were obtained and characterized, observing different levels of grain aggregation and of impurity phases. Their antimicrobial activity was tested against Staphylococcus aureus ATCC BAA 1026, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. A general correlation is observed between the antibacterial activity and the MgB 2 wt.%, but the sample microstructure also appears to be very important. RLI-MgB 2 powders show better performances compared to commercial powders against microbial strains in the planktonic form, and their activity against biofilms is also very similar.

The behavior in solution of the dicyanoaurate anion in the presence of other metal centers has so far been little explored, despite its importance in material science. The design and synthesis of systems with controlled coordination behavior, using chelating ligands and Zn II , has allowed us to detect self-assembly and oligomerization in solution. This phenomenon has been studied with 13 C and 1 H NMR, absorption and emission UV-vis spectroscopy, ESI-MS, and XAS at both the Au L 3 -edge and Zn K-edge: all of these techniques confirm the presence of Au-Zn aggregation products. These fragments, resembling structural units in the solid state, reveal that coordination of dicyanoaurate to free sites around metal centers can occur at a lower concentration than those at which crystals start to form and at which aurophilic interactions are observed, forming the connection between solution species and solid-state architectures.

X-ray nanofabrication has so far been usually limited to mask methods involving photoresist impression and subsequent etching. Herein we show that an innovative maskless X-ray nanopatterning approach allows writing electrical devices with nanometer feature size. In particular we fabricated a Josephson device on a Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) superconducting oxide micro-crystal by drawing two single lines of only 50 nm in width using a 17.4 keV synchrotron nano-beam. A precise control of the fabrication process was achieved by monitoring in situ the variations of the device electrical resistance during X-ray irradiation, thus finely tuning the irradiation time to drive the material into a non-superconducting state only in the irradiated regions, without significantly perturbing the crystal structure. Time-dependent finite element model simulations show that a possible microscopic origin of this effect can be related to the instantaneous temperature increase induced by the intense synchrotron picosecond X-ray pulses. These results prove that a conceptually new patterning method for oxide electrical devices, based on the local change of electrical properties, is actually possible with potential advantages in terms of heat dissipation, chemical contamination, miniaturization and high aspect ratio of the devices.

High-T c superconducting cuprates (HTSC) such as YBa 2 Cu 3 O 7 - x (YBCO) are promising candidates for solid-state THz applications based on stacks of intrinsic Josephson junctions (IJJs) with atomic thickness. In view of future exploitation of IJJs, high-quality superconducting YBCO tape-like single crystals (whiskers) have been synthesized from Ca-Al-doped precursors in the presence of Te. The main aim of this paper is to determine the importance of the simultaneous use of Al, Te and Ca in promoting YBCO whiskers growth with good superconducting properties (T c = 79-84 K). Further, single-crystal X-ray diffraction (SC-XRD) refinements of tetragonal YBCO whiskers (P4/mmm) are reported to fill the literature lack of YBCO structure investigations. All the as-grown whiskers have also been investigated by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Our results demonstrate that the interplay of Ca, Te and Al elements is clearly necessary in order to obtain superconducting YBCO whiskers. The data obtained from SC-XRD analyses confirm the highly crystalline nature of the whiskers grown. Ca and Al enter the structure by replacing the Y and the octahedral coordinated Cu1 site, respectively, as in other similar orthorhombic compounds, while Te does not enter the structure of whiskers but its presence in the precursor is essential to the growth of the crystals.

We describe the first use of a novel photoresist-free X-ray nanopatterning technique to fabricate an electronic device. We have produced a proof-of-concept device consisting of a few Josephson junctions by irradiating microcrystals of the Bi2Sr2CaCu2O8+δ (Bi-2212) superconducting oxide with a 17.6 keV synchrotron nanobeam. Fully functional devices have been obtained by locally turning the material into a nonsuperconducting state by means of hard X-ray exposure. Nano-XRD patterns reveal that the crystallinity is substantially preserved in the irradiated areas that there is no evidence of macroscopic crystal disruption. Indications are that O ions have been removed from the crystals, which could make this technique interesting also for other oxide materials. Direct-write X-ray nanopatterning represents a promising fabrication method exploiting material/material rather than vacuum/material interfaces, with the potential for nanometric resolution, improved mechanical stability, enhanced depth of patterning, and absence of chemical contamination with respect to traditional lithographic techniques.

The X-ray irradiation of binary mixtures of alkyl iodides R-I (R=CH3 , C2 H5 , or i-C3 H7 radicals) and NF3 produces R-NF2 and R-F. Based on calculations performed at the CCSD(T), MRCI(SD+Q), G3B3, and G3 levels of theory, the former product arises from a bimolecular homolytic substitution reaction (SH 2) by the alkyl radicals R, which attack the N atom of NF3 . This mechanism is consistent with the suppression of R-NF2 by addition of O2 (an efficient alkyl radical scavenger) to the reaction mixture. The R-F product arises from the attack of R to the F atom of NF3 , but additional contributing channels are conceivably involved. The F-atom abstraction is, indeed, considerably more exothermic than the SH 2 reaction, but the involved energy barriers are comparable, and the two processes are comparably fast., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Al(+3)-doped (Y,Ca)Ba2Cu3O(7-y) (YBCO) whiskers have been synthesized using a solid-state reaction technique. These materials are promising candidates for solid-state THz applications based on sequences of Josephson Junctions (IJJs). Alumina addition was systematically varied and the effect of aluminium incorporation on the structure has been investigated using single-crystal X-ray diffraction. Aluminium only replaces Cu atoms in the O-Cu-O-Cu chains and a gradual transition from orthorhombic to tetragonal space group occurs, thus increasing the Al content. A gradual modification of the coordination sphere of the copper site has also been observed. The Ca(2+) ion substitutes mainly the Y(3+) ion and also, to a small extent, the Ba(2+) ion.

The germyl cations F(2)Ge(SH)(+), FGe(SH)(2)(+) and Ge(SH)(3)(+) were obtained from ionized mixtures of GeF(4) and H(2)S. Ion trap mass spectrometry revealed the occurrence of three consecutive addition-HF elimination reactions between GeF(3)(+), F(2)Ge(SH)(+) and FGe(SH)(2)(+) and H(2)S. The structure and the mechanism of formation of the observed F(n)Ge(SH)(3-n)(+) (n = 0-2) were investigated by ab initio calculations performed at the MP2 and coupled cluster level of theory. It was also possible to note regular trends in the geometries and Lewis acidities of the F(n)Ge(SH)(3-n)(+) (n= 0-3).

The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (ΔH and ΔG) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The gas-phase ion chemistry of GeF(4) and of its mixtures with water, ammonia and hydrocarbons was investigated by ion trap mass spectrometry (ITMS) and ab initio calculations. Under ITMS conditions, the only fragment detected from ionized GeF(4) is GeF(3)(+). This cation is a strong Lewis acid, able to react with H(2)O, NH(3) and the unsaturated C(2)H(2), C(2)H(4) and C(6)H(6) by addition-HF elimination reactions to form F(2)Ge(XH)(+), FGe(XH)(2)(+), Ge(XH)(3)(+) (X = OH or NH(2)), F(2)GeC(2)H(+), F(2)GeC(2)H(3)(+) and F(2)GeC(6)H(5)(+). The structure, stability and thermochemistry of these products and the mechanistic aspects of the exemplary reactions of GeF(3)(+) with H(2)O, NH(3) and C(6)H(6) were investigated by MP2 and coupled cluster calculations. The experimental proton affinity (PA) and gas basicity (GB) of GeF(4) were estimated as 121.5 ± 6.0 and 117.1 ± 6.0 kcal mol(-1), respectively, and GeF(4)H(+) was theoretically characterized as an ion-dipole complex between GeF(3)(+) and HF. Consistently, it reacts with simple inorganic and organic molecules to form GeF(3)(+)-L complexes (L = H(2)O, NH(3), C(2)H(2), C(2)H(4), C(6)H(6), CO(2), SO(2) and GeF(4)). The theoretical investigation of the stability of these ions with respect to GeF(3)(+) and L disclosed nearly linear correlations between their dissociation enthalpies and free energies and the PA and GB of L. Comparing the behavior of GeF(3)(+) with the previously investigated CF(3)(+) and SiF(3)(+) revealed a periodically reversed order of reactivity CF(3)(+) < GeF(3)(+) < SiF(3)(+). This parallels the order of the Lewis acidities of the three cations., (Copyright © 2011 John Wiley & Sons, Ltd.)

The positive ion chemistry occurring in SiH(4)/GeF(4) gaseous mixtures was investigated by ion trap mass spectrometry and ab initio theoretical calculations. The GeF(3)(+) cation, the only fragment obtained from ionized GeF(4), was unreactive towards SiH(4). All the primary ions SiH(n)(+) (n = 0-3) react instead with GeF(4) so to form SiF(+) or SiH(2)F(+). The latter species reacts in turn with SiH(4) and GeF(4) so to form SiH(3)(+) and SiHF(2)(+), respectively. The potential energy profiles conceivably involved in these reactions were investigated by ab initio calculations performed at the MP2 and coupled cluster (CCSD(T)) level of theory.

The gas-phase reaction of CH(3)(+) with NF(3) was investigated by ion trap mass spectrometry (ITMS). The observed products include NF(2)(+) and CH(2)F(+). Under the same experimental conditions, SiH(3)(+) reacts with NF(3) and forms up to six ionic products, namely (in order of decreasing efficiency) NF(2)(+), SiH(2)F(+), SiHF(2)(+), SiF(+), SiHF(+), and NHF(+). The GeH(3)(+) cation is instead totally unreactive toward NF(3). The different reactivity of XH(3)(+) (X = C, Si, Ge) toward NF(3) has been rationalized by ab initio calculations performed at the MP2 and coupled cluster level of theory. In the reaction of both CH(3)(+) and SiH(3)(+), the kinetically relevant intermediate is the fluorine-coordinated isomer H(3)X-F-NF(2)(+) (X = C, Si). This species forms from the exoergic attack of XH(3)(+) to one of the F atoms of NF(3) and undergoes dissociation and isomerization processes which eventually result in the experimentally observed products. The nitrogen-coordinated isomers H(3)X-NF(3)(+) (X = C, Si) were located as minimum-energy structures but do not play an active role in the reaction mechanism. The inertness of GeH(3)(+) toward NF(3) is also explained by the endoergic character of the dissociation processes involving the H(3)Ge-F-NF(2)(+) isomer., (2009 John Wiley & Sons, Ltd.)

The gas phase ion chemistry of silane/hydrogen sulfide and germane/hydrogen sulfide mixtures was studied by ion trap mass spectrometry (ITMS), in both positive and negative ionization mode. In positive ionization, formation of X/S (X = Si, Ge) mixed ions mainly takes place via reactions of silane or germane ions with H(2)S, through condensation followed by dehydrogenation. This is particularly evident in the system with silane. On the other side, reactions of H(n)S(2)(+) ions with XH(4) (X = Si, Ge) invariably lead to formation of a single X-S bond. In negative ionization, a more limited number of mixed ion species is detected, but their overall abundance reaches appreciable values, especially in the SiH(4)/H(2)S system. Present results clearly indicate that ion processes play an important role in formation and growth of clusters eventually leading to deposition of amorphous solids in chemical vapor deposition (CVD) processes., (2009 John Wiley & Sons, Ltd.)

The positive ion chemistry occurring in silane/nitrogen trifluoride gaseous mixtures has been investigated by ion trap mass spectrometry. Reaction sequences and rate constants have been determined for the processes involving the primary ions SiH(n)(+) (n = 0-3) and NF(x)(+) (x = 1-3) and the secondary ions obtained from their reactions with SiH(4) and NF(3). The SiH(n)(+) efficiently react with NF(3) and undergo cascades of abstraction and scrambling reactions which form the fluorinated and perfluorinated cations SiHF(m)(+) (m = 1, 2), SiH(2)F(+) and SiF(x)(+) (x = 0-3). Fluorinated Si(2)- clusters such as Si(2)H(2)F(+), Si(2)H(3)F(+) and Si(2)H(5)F(+) were also observed. The reaction of both SiH(3)(+) and SiH(2)F(+) with NF(3) produces the elusive fluoronitrenium ion NHF(+). Any NF(x)(+) reacts with SiH(4) mainly by charge transfer. Additional ionic products are, however, observed which suggest intimate reaction complexes. Worth mentioning is the formation of SiNH(2)(+) from the reaction of both NF(+) and NHF(+) with SiH(4). The primary ions NF(2)(+) and SiH(2)(+) are also "sink" species in our observed chemistry.

The gas phase ion-molecule reactions in positively and negatively ionized germane/diborane mixtures have been studied by ion trap mass spectrometry. Reaction sequences and rate constants for the most interesting processes have been determined. In positive ionization, formation of Ge-B bonds exclusively occurs through condensation reactions of B(n)H(m)(+) ions with germane, followed by H(2) or BH(3) loss. No reactions of ions from germane with B(2)H(6) were observed under the experimental conditions used here. In negative ionization, the Ge(n)H(m)(-) (n = 1, 2) ion families react with diborane to yield the Ge(n)B(p)H(q)(-) (p = 1, 2) ions, again via dehydrogenation and BH(3) loss, while diborane anions proved to be unreactive. In both positive and negative ionization, Ge-B ions reach appreciable abundances. The present results afford fundamental information about the intrinsic reactivity of gas-phase ions and provide valuable indications about the first nucleation steps ultimately leading to amorphous Ge and B-doped semiconductor materials by chemical vapor deposition methods.

This review essentially deals with positive ion/molecule reactions occurring in gas-phase organometallic systems, and encompasses a period of time of approximately 7 years, going from 1997 to early 2004. Following the example of the excellent review by Eller & Schwarz (1991; Chem Rev 91:1121-1177), in the first part, results of reaction of naked ions are presented by grouping them according to the neutral substrate, while in the second part, ligated ions are grouped according to the different ligands. Whenever possible, comparison among similar studies is attempted, and general trends of reactivities are evidenced., (Copyright 2005 Wiley Periodicals, Inc.)

Silicon clusters are of considerable interest for their importance in astrophysics and chemical vapour deposition processes, as well as from a fundamental point of view. Here, we present a quadrupole ion trap study of the self-condensation ion/molecule reactions of anions of silane. In the high-pressure regime, several ion clusters are formed with increasing size: the largest ions detected are Si5Hn- (n = 0-3). Selective ion isolation and storage allowed detection of the main reaction sequences occurring in the reacting system. The most frequent condensation step is followed by single or multiple dehydrogenation, this latter being particularly observed for the high-mass reactant ions. As a consequence, the most abundant ions in the mass spectra are those with a low content of hydrogen, namely Si2H-, Si3H-, and Si4H-. These results are discussed with reference to literature data on silicon cluster anions and related systems., (Copyright 2006 John Wiley & Sons, Ltd.)

The gas-phase ion chemistry of silane-allene-ammonia, germane-allene (or propyne)-ammonia (or phosphine) systems was studied by ion trap mass spectrometry. Reaction sequences were determined and rate constants were measured for the main processes observed. The mixture containing silane displays higher reactivity with respect to that with germane. Comparison with analogous systems provides useful information about the reactivity of different hydrocarbon molecules and the different affinities of silicon and germanium towards nitrogen and phosphorus. The most interesting product ions observed are those containing Si (or Ge), C and N (or P) elements together, as these ion species may be considered precursors of doped amorphous carbides, which are widely used in semiconductor devices., (Copyright 2005 John Wiley & Sons, Ltd.)

The gas-phase ion chemistry of propyne-phosphine and silane-propyne-phosphine mixtures was studied by ion trap mass spectrometry. For the binary mixture, the effect of different partial pressures of the reagents on the yield of C and P-containing ions was evaluated. Reaction sequences and rate constants were determined and reaction efficiencies were calculated from comparison of experimental and collisional rate constants. In the ternary silane-propyne-phosphine systems, the reaction pathways leading to formation of Si(m)C(n)P(p)H(q) (+) ions were determined and the rate constants of the most important steps were measured. For some ion species, selected by double isolation procedures (MS/MS), the low ion abundances prevented determination of the reaction rate constants. Si, C and P-containing ions are mainly produced in reactions of Si(m)P(p)H(q) (+) ions with propyne, while the reactivity of the Si(m)C(n)H(q) (+) ions towards PH(3) and of the C(n)P(p)H(q) (+) ions towards SiH(4) is very low. The formation of hydrogenated Si--C--P ions is interesting for their possible role as precursors of amorphous silicon carbides doped with phosphorus, obtained in a single step, by deposition from properly activated silane-propyne-phosphine mixtures., (Copyright 2004 John Wiley & Sons, Ltd.)

The gas-phase ion chemistry of allene-phosphine and silane-allene-phosphine mixtures was studied by ion trap mass spectrometry. Rate constants of the main processes were measured and compared with the collisional rate constants to determine the reaction efficiencies. For the binary mixture, the highest yield of C- and P-containing ions is obtained with a 1 : 1 partial pressure ratio among the reagents. In the ternary mixture, formation of ion species containing Si, C and P together is mainly achieved in reactions of Si/P ions with allene, with a lower contribution from reactions of Si/C and C/P ions with phosphine and silane, respectively. The formation of ternary ion clusters is related to their possible role as precursors of amorphous silicon carbides doped with phosphorus, obtained by deposition from properly activated silane-allene-phosphine mixtures., (Copyright 2004 John Wiley & Sons, Ltd.)

This review represents a general overview on the determination of bond energies in gas-phase organometallic systems. The paper focuses on articles published in the last 7 years, whose main scope was to experimentally measure metal ion-ligand binding energies. Therefore, studies of reactivity and characterization of ion complexes are not included, even if some of them display bond energies among the data measured. Bond energies are presented according to the metal ion complexed, in increasing order of atomic number. Periodic trends of binding energies and correlations among the various ligand are discussed. A brief summary of the most used techniques specifically devoted to gather bond energies is also provided., (Copyright 2003 Wiley Periodicals, Inc., Mass Spec Rev 22:407-428, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mas.10065)

The effects of different experimental parameters on rate constant measurements performed by mass spectrometry were investigated with a two-level fractional factorial design. This chemometric technique allows a study of the effects of selected factors and of their interactions on the response of an experiment by performing a limited number of analyses. The selected factors were: sample pressure, energy of the ionising electrons, reaction time and ionisation time. In this work, two mass spectrometric techniques were compared: Fourier transform ion cyclotron resonance (FT-ICR) and quadrupole ion trap (QIT) mass spectrometries. Experimental results were obtained from a study of a reaction system consisting of the condensation between triethylphosphite and its fragment ion (CH(3)CH(2)O)(2)P(+). Apparent bimolecular rate constants are clearly larger when determined by QIT than by FT-ICR, because of collisional stabilisation of the adduct ion by helium buffer gas introduced in the QIT spectrometer. However, the QIT rate constant extrapolated to zero helium pressure is almost identical to the FT-ICR value; this supports the conclusion regarding the buffer gas effect. Minor effects evidenced by the chemometric method were attributed to the sample pressure and to the reaction time.

The gas-phase ion chemistry of propene-ammonia and silane-propene-ammonia mixtures was studied by ion trap mass spectrometry. As far as the binary mixture is concerned, the effect of different molar ratios of the reactants on the trend of ion species formed was evaluated, the ion-molecule reaction processes were identified and the rate constants for the main processes were measured. The results were compared with the collisional rate constants to determine the reaction efficiencies. In the ternary silane-propene-ammonia mixture the mechanisms of formation of Si(m)C(n)N(p)H(q)(+) clusters were elucidated and the rate constants of the most important steps were measured. For some species, selected by double isolation (MS/MS), the low abundance of the ions allowed us to determine the reaction paths but not the rate constants. Ternary ions are mainly formed by reactions of Si(m)C(n)H(q)(+) ions with ammonia, whereas a minor contribution comes from reactions of Si(m)N(p)H(q)(+) ions with propene. On the other hand, the C(n)N(p)H(q)(+) ions showed a very low reactivity and no step leading to ternary ion species was identified. The formation of hydrogenated ternary ions with Si, C and N has a basic importance in relation to their possible role as precursors of amorphous silicon carbides doped with nitrogen obtained by deposition from silane-propene-ammonia mixtures properly activated., (Copyright 2002 John Wiley & Sons, Ltd.)

Germane-propane and germane-propene gaseous mixtures were studied by ion trap mass spectrometry. Variations of ion abundances observed under different partial pressure ratios and mechanisms of ion-molecule reactions elucidated by multiple isolation steps are reported. In addition, the rate constants for the main reactions were experimentally determined and compared with the collisional rate constants to obtain the reaction efficiencies. The yield of ions containing both Ge and C atoms is higher in the germane-propene than in the germane-propane system. In the former mixture, chain propagation takes place starting from germane ions reacting with propene and proceeds with the formation of clusters such as Ge(2)C(4)H(n) (+) and Ge(3)CH(n) (+)., (Copyright 2002 John Wiley & Sons, Ltd.)

Propene-phosphine and the silane-propene-phosphine gaseous mixtures were studied by ion trap mass spectrometry. For the binary mixture the variation of ion abundances under different partial pressures and the mechanisms of ion-molecule reactions are reported. Moreover, the rate constants of the main processes were measured and compared with the collisional rate constants to determine the reaction efficiencies. In the ternary silane-propene-phosphine mixture the mechanisms of formation of Si(m)C(n)P(p)H(+)(s) ion clusters were elucidated, but the complexity of the system and the low abundances of the ions usually isolated by successive steps prevented the determination of rate constants. The hydrogenated ternary ions are mainly formed by reactions of Si(r)P(s)H(+)(t) ions with propene, whereas a minor contribution comes from reactions of Si(m)C(n)H(+)(p) ions with phosphine. The C(v)P(w)H(+)(z) ions show very low reactivity with silane. The formation processes of these species are discussed in relation to their possible role as precursors of amorphous silicon carbides doped with phosphorus obtained by deposition from properly activated silane-propene-phosphine mixtures., (Copyright 2001 John Wiley & Sons, Ltd.)

Formation of negative ion clusters from GeH4 has been studied as a function of germane pressure, in the 25-450 mTorr range, by chemical ionisation mass spectrometry. At the lowest pressures, only the GeHn- (n = 0-3) ion family is formed, whilst at increasing pressures GemHn- (m = 1-9) ion clusters of increasing size are observed in the mass spectra. A variable contribution of the ions with different hydrogen content is observed as a function of the pressure of germane in all the GemHn- (m = 1-9) clusters. Increasing pressures induce a general increase of ion species with a low content of hydrogen atoms. In fact, at 450 mTorr, 38% of the ion current is due to the bare Gem- (m = 2-5) clusters and 83% to the sum of abundances of the GemHn- ions without hydrogen (n = 0) and with a number of hydrogen atoms not higher than the number of germanium atoms (n = 0-m). This trend suggests that a contribution of negative clusters to the deposition of the amorphous solid a-Ge:H from gaseous systems containing GeH4, activated by radiolytic methods, can enhance the formation of solids with a low hydrogen content, which show better photoelectrical properties., (Copyright 2001 John Wiley & Sons, Ltd.)

Self-condensation ion-molecule reactions of trimethyl phosphite, triethyl phosphite, dimethyl phosphonate, trimethyl phosphate and 2, 2-dichlorovinyl dimethyl phosphate (dichlorvos) were investigated by ion trap mass spectrometry and Fourier transform ion cyclotron resonance mass spectrometry. Reaction paths for the main processes observed were elucidated by parent ion selection and for reaction times up to 500 ms. In parallel, high-resolution measurements were performed in order to determine the composition of the principal ions. Among the compounds under examination, trimethyl phosphite and triethyl phosphite mainly give [M + H](+) and [M + (RO)(2)P](+) (R = CH(3), C(2)H(5)) adduct ions, whereas trimethyl phosphate and dimethyl phosphonate display [2M + H](+) ions, as the only abundant products, formed by reaction of [M + H](+) and M. 2,2-Dichlorovinyl dimethyl phosphate mostly shows fragmentation processes. The reaction patterns of the compounds examined were related to their different structural features. Gas-phase basicities of the phosphoryl compounds were also determined or re-examined. Copyright 1999 John Wiley & Sons, Ltd.