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| 2. |
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| 3. |
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| 4. |
- Bedoire, Fredric
(författare)
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Förord
- 2017
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Ingår i: Villastan. - Stockholm : Langenskiöld i samarbete med Kungl. Vitterhersakademien. - 9789188439062
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Gaio, Servane, et al.
(författare)
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Nanoceria-nanocellulose hybrid materials for delayed release of antibiotic and anti-inflammatory medicines
- 2022
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 3:19, s. 7228-7234
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Tidskriftsartikel (refereegranskat)abstract
- A novel nanoceria-nanocellulose hybrid material has been developed and evaluated as a potential drug delivery system. Crystalline nanoceria was synthesized in situ in the nanocellulose to obtain a homogenous distribution without extensive particle aggregation. The hybrid materials were loaded with two antibiotic drugs, triclosan and ampicillin, and one anti-inflammatory drug, diclofenac. The bacteriostatic effect on the gram-negative bacteria Escherichia coli was evaluated for the hybrid materials containing triclosan and ampicillin. The nanoceria-nanocellulose hybrid displayed a better retention of ampicillin than triclosan in the disc diffusion test, which is likely due to the presence of the carboxylic acid group in ampicillin that has better affinity for ceria compared to the phenolic group in triclosan. However, drug release studies in solution revealed rapid release of ampicillin and diclofenac, indicative of outer-sphere complexes between ceria and the drugs.
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| 6. |
- Ganji, Suresh, 1984-, et al.
(författare)
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Asymmetric Synthesis of Oxygenated Monoterpenoids of Importance for Bark Beetle Ecology
- 2020
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 83:11, s. 3332-3337
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Tidskriftsartikel (refereegranskat)abstract
- Herein we report the asymmetric syntheses of a number of oxygenated terpenoids that are of importance in the chemical ecology of bark beetles. These are pinocamphones, isopinocamphones, pinocarvones, and 4-thujanols (= sabinene hydrates). The camphones were synthesized from isopinocampheol, the pinocarvones from beta-pinene, and the thujanols from sabinene. The NMR spectroscopic data, specific rotations, and elution orders of their stereoisomers on a chiral GC-phase (beta-cyclodextrin) are also reported. This enables facile synthesis of pure compounds for biological activity studies and identification of stereoisomers in mixed natural samples.
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| 7. |
- Geranmayeh, Fatemeh, et al.
(författare)
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Microglia in gemistocytic astrocytomas
- 2007
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Ingår i: Neurosurgery. - 0148-396X .- 1524-4040. ; 60:1, s. 159-166
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Although gemistocytic astrocytomas, they behave more aggressively than other astrocytomas. Their proliferative potential is low, and it remains an intriguing question why these tumors are so biologically "successful". They show a high mutation rate of the P53 gene, cytological abnormalities, and frequent perivascular mononuclear infiltrates. Microglial cells, a feature of this astrocytoma variant, are of increasing interest in the context of glioma growth. Methods: We selected 23 tumor biopsies from 201 samples obtained from patients with gemistocytic astrocytomas operated at Mayo Clinic between 1985 and 1998. These tumors were formerly anaylzed for P53 mutations, P53 protein, and proliferative activity (9). Immunolabeling for three microglial markers, including CR3/43, Ki-M1P, and iba1, was performed on adjacent tissue sections. In additions, in situ hybridization for the alpha-chain of the major histocompatibility complex (MHC) Class II molecule recognized by the CR3/43 monoclonal antibody was performed. Results: A high number of microglia was detected in gemistoccytic astrocytomas. More microglia were present if the fraction of gemistocytic tumor cells was high (correlation coefficient = 0.699; P < 0.0002). Interestingly, a number of gemistocytes were immunoreactive for MHC Class II molecules, an observation confirmed by in situ hybridization. Importantly, the higher the number of Class II immunoreactive gemistocytes, the fewer Class II positive microglial cell could be detected (correlation coefficient = -0.5649; P < 0.005). Conclusion: Our results support the view that gemistocytic astrocytomas contain unusually high numbers of microglial cells. We propose that the finding of aberrant MHC Class II expression by gemistocytic tumor cells correlates with a loss of immune-competent MHC Class II-expressing microglia. This may be related to the expecially poor prognosis of gemistocytic astrocytomas for which induction of T cell anergy could provide one explanation.
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| 8. |
- Lakic, Marijana, et al.
(författare)
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Uptake and separation of rare earth elements and late transition metal cations by nanoadsorbent grafted with diamino ligands
- 2023
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 323
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Tidskriftsartikel (refereegranskat)abstract
- Recycling of magnetic materials based on Rare Earth Elements (REE) is of major interest in the view of growing clean energy production and transportation. One of the major challenges in its realization is the need to separate smaller amounts of Late Transition Metals (LTM) from REE. Hybrid adsorbents are very attractive in finding such a solution. Here, novel silica-based nanoadsorbents were synthesized by grafting the surface of dense silica nanoparticles with a diamino functional ligand grafted via an arene linker to improve selectivity towards LTM. The produced adsorbent materials were characterized using SEM, TEM, AFM, XPS, FTIR, and TGA in its pure form and by DLS in suspension, and tested for the adsorption and separation of LTM (Co2+ and Ni2+) and REE (Sm3+ and Nd3+) in single and mixed solutions. Prepared organo-silica material showed rapid uptake of all tested cations with higher affinity towards LTM. Adsorption capacities reached values of 1.18-1.45 mmol/g for Co2+ and Ni2+, respectively, with a 1:1 metal-to-ligand stoichiometry for Ni cations. Investigation of reusability demonstrated the potential of the prepared materials as an environmentally friendly alternative in specific separation of LTM to conventional separation techniques. Investigations of the molecular structures of the Ni2+ complex with the selected molecular function and of Co3+ with a closely related tris-aminoethyl amine ligand in combination with XPS data for corresponding surface complexes helped explaining the molecular mechanisms for adsorption and desorption of the LTM cations.
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| 9. |
- Lindahl, Göran, et al.
(författare)
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Centrala Jönköping : Den Nordiska Trästaden
- 1972
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Rapport (populärvet., debatt m.m.)abstract
- Konsthögskolans Arkitektur skola har under studieåret 1971-72 behandlat förnyelseproblemen i centrala Jönköping. Huvudvikten har lagts vid de problem som uppstått vid över gången från 60-talets överhettade konjunktur till 70-talets mera dämpade. I denna situation framstår det som naturligt att begränsa eller hejda den omdaningsprocess i Jönköpings centrala delar, som i så hög grad varit ett uttryck för de expansiva årens förväntningar. Denna typ av restriktiv planering förutsätter en mycket detaljerad kunskap om den befintliga bebyggelsen och dess utnyttjande. Föreliggande arbete bygger således på inventeringar, genomförda på platsen, och på tillgängligt utredningsmaterial som förmedlats av kommunens tjänstemän. Studierna har koncentrerats till två områden i staden, som representerar var sitt skede i Jönköpings byggnadshistoria, och som också bedömts möjliga att bevara.
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| 10. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 11. |
- Movert, Elin, et al.
(författare)
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Interplay between human STING genotype and bacterial NADase activity regulates inter-individual disease variability
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Variability in disease severity caused by a microbial pathogen is impacted by each infection representing a unique combination of host and pathogen genomes. Here, we show that the outcome of invasive Streptococcus pyogenes infection is regulated by an interplay between human STING genotype and bacterial NADase activity. S. pyogenes-derived c-di-AMP diffuses via streptolysin O pores into macrophages where it activates STING and the ensuing type I IFN response. However, the enzymatic activity of the NADase variants expressed by invasive strains suppresses STING-mediated type I IFN production. Analysis of patients with necrotizing S. pyogenes soft tissue infection indicates that a STING genotype associated with reduced c-di-AMP-binding capacity combined with high bacterial NADase activity promotes a ‘perfect storm’ manifested in poor outcome, whereas proficient and uninhibited STING-mediated type I IFN production correlates with protection against host-detrimental inflammation. These results reveal an immune-regulating function for bacterial NADase and provide insight regarding the host-pathogen genotype interplay underlying invasive infection and interindividual disease variability.
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| 12. |
- Svensson, Fredric, et al.
(författare)
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Adsorption and Photo-Degradation of Organophosphates on Sulfate-Terminated Anatase TiO2 Nanoparticles
- 2023
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Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption and photocatalytic degradation of trimethyl phosphate (TMP) and triethyl phosphate (TEP), two environmentally relevant model pollutants, have been studied on commercial anatase TiO2 and sulfate-terminated anatase TiO2 nanoparticles by means of operando diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and 2D correlation spectroscopy (2D COS). It is concluded that both TMP and TEP adsorb dissociatively on anatase TiO2, while on the sulfate-terminated anatase TiO2, TMP and TEP adsorb associatively. Upon UV illumination, TMP and TEP are completely oxidized on sulfate-terminated anatase TiO2, as evidenced by the evolution of the IR bands characteristic for water and carbon dioxide. In contrast, on anatase TiO2, UV illumination leads to the formation of stable surface-coordinated carboxylate products, which impedes complete oxidation. 2D COS analysis suggests that parallel reaction pathways occur during oxidation under UV illumination, viz. methoxide/ethoxide (ads) -> carboxylates (ads) and methoxide/ethoxide (ads) -> aldehydes (ads) -> carboxylates (ads). A parallel reaction occurs on sulfated TiO2 that yields CO2 and H2O by direct radical reactions with the methoxide groups with little, or no, formation of surface-coordinated intermediates. Sulfated TiO2 favor the formation of aldehyde intermediates, with reaction rates 10 times and 30 times faster for TMP and TEM, respectively, compared with commercial anatase TiO2. About 37% (33%) and 32% (24%) of TMP (TEP) were degraded on sulfated-terminated TiO2 and pure TiO2, respectively, after the first 9 min of UV illumination. We show that the sulfate-functionalization of TiO2 has two main functions. First, it prevents the formation of strongly bonded bridging carboxylates, thereby alleviating deactivation. Second, it promotes full oxidation of the organic side-chains into carbon dioxide and water. Improved electron-hole separation by the electrophilic S(VI) in combination with the blocking of bridging reaction intermediates is proposed to contribute to the improved activity. The presented results give insights into how acidic surface modifications change adsorbate surface chemistries, which can be used to increase the sustained activity of low-temperature photocatalysts.
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| 13. |
- Svensson, Fredric G., et al.
(författare)
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Hemocompatibility of Nanotitania-Nanocellulose Hybrid Materials
- 2021
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- In order to develop a new type of improved wound dressing, we combined the wound healing properties of nanotitania with the advantageous dressing properties of nanocellulose to create three different hybrid materials. The hemocompatibility of the synthesized hybrid materials was evaluated in an in vitro human whole blood model. To our knowledge, this is the first study of the molecular interaction between hybrid nanotitania and blood proteins. Two of the hybrid materials prepared with 3 nm colloidal titania and 10 nm hydrothermally synthesized titania induced strong coagulation and platelet activation but negligible complement activation. Hence, they have great potential as a new dressing for promoting wound healing. Unlike the other two, the third hybrid material using molecular ammonium oxo-lactato titanate as a titania source inhibited platelet consumption, TAT generation, and complement activation, apparently via lowered pH at the surface interface. It is therefore suitable for applications where a passivating surface is desired, such as drug delivery systems and extracorporeal circuits. This opens the possibility for a tailored blood response through the surface functionalization of titania.
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| 14. |
- Svensson, Fredric G., et al.
(författare)
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Rare-Earth-Modified Titania Nanoparticles : Molecular Insight into Synthesis and Photochemical Properties
- 2021
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 60:19, s. 14820-14830
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Tidskriftsartikel (refereegranskat)abstract
- A molecular precursor approach to titania (anatase) nanopowders modified with different amounts of rare-earth elements (REEs: Eu, Sm, and Y) was developed using the interaction of REE nitrates with titanium alkoxides by a two-step solvothermal-combustion method. The nature of an emerging intermetallic intermediate was revealed unexpectedly for the applied conditions via a single-crystal study of the isolated bimetallic isopropoxide nitrate complex [Ti2Y((PrO)-Pr-i)(9)(NO3)(2)], a nonoxo-substituted compound. Powders of the final reaction products were characterized by powder X-ray diffraction, scanning electron microscopy-energy-dispersive spectroscopy, Fourier transform infrared, X- ray photoelectron spectroscopy, Raman spectroscopy, and photoluminescence (PL). The addition of REEs stabilized the anatase phase up to ca. 700 degrees C before phase transformation into rutile became evident. The photocatalytic activity of titania modified with Eu3+ and Sm3+ was compared with that of Degussa P25 titania as the control. PL studies indicated the incorporation of Eu and Sm cations into titania (anatase) at lower annealing temperatures (500 degrees C), but an exclusion to the surface occurred when the annealing temperature was increased to 700 degrees C. The efficiency of the modified titania was inferior to the control titania while illuminated within narrow wavelength intervals (445-465 and 510-530 nm), but when subjected to a wide range of visible radiation, the Eu3+- and Sm3+-modified titania outperformed the control, which was attributed both to doping of the band structure of TiO2 with additional energy levels and to the surface chemistry of the REE-modified titania.
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| 15. |
- Svensson, Fredric G.
(författare)
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Structural diversity in transition metal-doped titanium oxo-alkoxy complexes : Potential sol-gel intermediates for doped titania nanoparticles and complex titanates
- 2022
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Ingår i: Journal of Sol-Gel Science and Technology. - : Springer Nature. - 0928-0707 .- 1573-4846. ; 103:2, s. 595-615
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Tidskriftsartikel (refereegranskat)abstract
- Since the discovery of its photocatalytic properties, titanium dioxide has remained one of the most popular and widely used metal oxide photocatalysts. Its major drawback, however, lies in the narrow region (UV) of sunlight necessary to produce reactive oxygen species. This have been countered by sensitizing with organic dyes to red-shift the absorption spectrum but also with doping of other metals and non-metals. Volume doping or surface modification have demonstrated improved photocatalytic efficiency, mainly via red-shifted absorption by introduction of intermediate energy states between the valence band (VB) and conduction band (CB) and increased number of surface hydroxyl groups (which can form reactive hydroxyl radicals) from charge compensation, and in some cases by improved surface-adsorption of organic molecules. Doped titania and complex titanates have traditionally been produced via, for instance, co-precipitation of mixed metal salts or via solid-state synthesis. While these methods usually are simple, they offer limited control over size, shape, and phase composition. An alternative is the use of single-source precursors (SSPs), i.e., molecules already containing the desired metal ratio in a homogenous distribution. The last one or two decades have seen an increased number of reported transition metal-doped titanium oxo-alkoxides (TOA), particularly for the first-row transition metals as potential single-source precursors (SSP) for doped titania and complex titanates. This review aims at providing an overview of TM-doped TOAs, focusing on first and second row TM elements, with special emphasis on their synthesis, photochemical properties, and their applications as SSPs.
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| 16. |
- Svensson, Fredric, et al.
(författare)
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Hybrid Drug Delivery Patches Based on Spherical Cellulose Nanocrystals and Colloid Titania-Synthesis and Antibacterial Properties
- 2018
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H2SO4. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus. It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents.
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| 17. |
- Svensson, Fredric
(författare)
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Hybrid nano titania: molecular formation mechanisms and applications in nanotechnology.
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanomaterials are defined as materials with one dimension smaller than 100 nm. At this size, exotic properties start to emerge, making them interesting for a wide range of applications including catalysis, electronics, theranostics, and “smart materials”. Particularly engineered metal oxide nanoparticles have found advanced applications in medical therapy and catalysis. Because of the small size and required homogeneity of these materials, bottom-up synthesis starting from molecular precursors is often the preferred way of production. The present work was initiated with the main purpose to bring insight in the whole chain in materials design and application – from precursor chemistry in the synthesis to physical chemical and biological characteristics of the resulting nanomaterials. It is thus an interdisciplinary project, covering the fields of both chemistry and biology. The chemical part presents synthesis, self-assembly, and chemical characterization of titania nanopowders, hollow titania spheres, and nanotitania-nanocellulose hybrid materials. The biological part primarily evaluates titania-nanocellulose hybrid materials for drug delivery applications using in vitro bacterial cultures and immunological (coagulation-related) responses in human whole blood. Not unexpectedly, titania-nanocellulose hybrids generally induced strong coagulation via the contact activation system. An extensive part of the thesis is dedicated to the solution behavior, stability, and transformation of heteroleptic titanium oxo-alkoxides into nanotitania, using a variety of characterization techniques. The observations support the MTSAL mechanism for formation of metal oxide nanoparticles. No hydrolytic stability, however, from ligandmodification of titanium (oxo-) alkoxides could be observed.
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| 18. |
- Svensson, Fredric, et al.
(författare)
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Interaction between dopamine and the [HPW12O40](2-)Keggin ion-an X-ray and NMR study
- 2021
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860. ; 1226
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Tidskriftsartikel (refereegranskat)abstract
- A novel complex between the [HPW12O40](2-) Keggin ion and the biomolecule dopamine (C8H11NO2), [HPW12O40(dop)(2)] center dot 4H(2)O (1) was crystallized and structurally characterized by single crystal X-ray diffraction and infrared spectrometry. Dopamine interacts via hydrogen bonding between its ammonium group and a W=O oxygen atom in [HPW12O40](2-). NMR analyses (H-1 DOSY) suggests that the [HPW12O40(dop)(2)] complex dissociates in D2O. (C) 2020 Elsevier B.V. All rights reserved.
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| 19. |
- Svensson, Fredric, et al.
(författare)
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Mixed-Ligand Titanium "Oxo Clusters": Structural Insights into the Formation and Binding of Organic Molecules and Transformation into Oxide Nanostructures on Hydrolysis and Thermolysis
- 2017
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-0682. ; , s. 4117-4122
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Tidskriftsartikel (refereegranskat)abstract
- We present the structure of a new tetranuclear titanium oxo complex containing the antibacterial agent triclosan. This provides a good model for the interaction between triclosan and titania, which may be used for drug-delivery applications. The antibacterial activity of the hydrolyzed complex against Staphylococcus aureus is investigated. Thereafter, we use the obtained titanium oxo complex to demonstrate its susceptibility towards hydrolysis, contrary to the widespread belief that titanium oxo complexes are water-stable, and demonstrate that it transforms into titania (anatase) on contact with water. Both hydrolysis and thermolysis of the complex yield titania particles, of very uniform size and shape, that connect into 3D nanostructures; this is of interest for practical applications.
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| 20. |
- Svensson, Fredric, et al.
(författare)
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Modeling metal oxide nanoparticle GABA interactions: Complexation between the Keggin POM and gamma-aminobutyric acid in the solid state and in solution influenced by additional ligands
- 2021
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 526
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Tidskriftsartikel (refereegranskat)abstract
- Phosphotungstic acid (POM) was crystallized together with the neurotransmitter gamma-aminobutyric acid (GABA) in acidic medium to form [(HGABA)3PW12O40], compound 1. The latter would only crystalize in the presence of dopamine, while dopamine itself did not become a part of the complex, but crystallized separately as [(Hdopamine)2HPW12O40], compound 2, as previously reported. GABA interacts with POM via hydrogen bonding between the protonated amino group and a terminal oxygen on POM and also via protonated carboxylic acid group. Based on structural information from the crystal structures of 1 and 2 together with complementary studies using other catechols we attempted to provide molecular insight into the well-known structure-directing effect of dopamine. Strong hydrogen bonding between dopamine and POM, together with formation of "dopamine dimers" in the packed structure by interactions between the aromatic rings and intermolecular hydrogen bonding might be important factors for them in directing the self-assembly of polyoxometalates into complex hierarchal structures. Interaction between dopamine and GABA in solution was investigated by diffusion ordered spectrometry (DOSY) NMR in MilliQ-water and in 0.1 M HCl.
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| 21. |
- Svensson, Fredric, et al.
(författare)
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One-Step Synthesis of Sulfate-Modified Titania Nanoparticles with Surface Acidic and Sustained Photocatalytic Properties via Solid-State Thermolysis of Titanyl Sulfate
- 2022
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Ingår i: ChemCatChem. - : John Wiley & Sons. - 1867-3880 .- 1867-3899. ; 14:20
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Tidskriftsartikel (refereegranskat)abstract
- Titania nanoparticles surface-functionalized with sulfate were prepared by thermal degradation of titanyl sulfate. At 600 degrees C pure anatase phase is obtained. X-ray photoelectron spectroscopy (XPS) showed 1.4 at.% sulfur in the +6 oxidation state. At 700 degrees C anatase was still present, which is attributed to the presence of small amounts of stabilizing sulfate groups only detectable by high-resolution XPS, segregating to the nanoparticle interfaces. Adsorption and photocatalytic degradation of acetaldehyde reactions were studied by in situ diffuse reflectance Fourier transform spectroscopy and 2D correlation spectroscopy, and compared with pure anatase nanoparticles. Aldol condensation of acetaldehyde and subsequent accumulation of crotonaldehyde was lower on sulfate-modified titania. Butanoate was identified as an intermediate, which forms after dimerization and aldol condensation. Much more carboxylates and carbonates accumulated on pure anatase catalysts compared with sulfate-modified anatase during photocatalysis. It is conjectured that surface acidic photocatalysts could be beneficial for achieving sustained activity for photodegradation of organic pollutants.
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| 22. |
- Svensson, Fredric, et al.
(författare)
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Self-Assembly of Asymmetrically Functionalized Titania Nanoparticles into Nanoshells
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Titania (anatase) nanoparticles were anisotropically functionalized in water-toluene Pickering emulsions to self-assemble into nanoshells with diameters from 500 nm to 3 mu m as candidates for encapsulation of drugs and other compounds. The water-phase contained a hydrophilic ligand, glucose-6-phosphate, while the toluene-phase contained a hydrophobic ligand, n-dodecylphosphonic acid. The addition of a dilute sodium alginate suspension that provided electrostatic charge was essential for the self-limited assembly of the nanoshells. The self-assembled spheres were characterized by scanning electron microscopy, elemental mapping, and atomic force microscopy. Drug release studies using tetracycline suggest a rapid release dominated by surface desorption.
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| 23. |
- Svensson, Fredric, et al.
(författare)
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Solid-state structure and solution behavior of two titanium oxo-alkoxide complexes with phenylphosphonate ligands
- 2020
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Ingår i: Polyhedron. - : Elsevier BV. - 0277-5387. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- A novel titanium phenylphosphonate alkoxide complex, [Ti-6(mu(3)-O)(2)(mu-OEt)(6)(mu(2)-OEt)(6)(mu(3)-PPA)(4)]center dot 0.5C(7)H(8) (1) was synthesized by solvothermal processing and its structure was determined by single crystal Xray diffraction. The solution stability was characterized in solution by H-1 NMR, C-13 NMR and P-31 NMR and 1H DOSY NMR and compared with a previously reported titanium phenylphosphonate alkoxide complex [(Ti4O(OEt)(12)PPA] (2) of similar size. According to the NMR analyses, the solid-state structure is predominantly retained in solution for both 1 and 2. P-31 NMR and H-1 DOSY NMR of the mother liquor from the synthesis of 2 indicated presence of traces of at least two other complexes which could not be isolated in pure form. (C) 2019 Elsevier Ltd. All rights reserved.
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| 24. |
- Svensson, Fredric, et al.
(författare)
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Titanium phosphonate oxo-alkoxide "clusters": solution stability and facile hydrolytic transformation into nano titania
- 2020
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 10, s. 6873-6883
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Tidskriftsartikel (refereegranskat)abstract
- Titanium (oxo-) alkoxide phosphonate complexes were synthesized using different titanium precursors and tert-butylphosphonic acid (tBPA) as molecular models for interaction between phosphonates and titania surfaces and to investigate the solution stability of these species. Reflux of titanium(iv) ethoxide or titanium(iv)(diisopropoxide)bis(2,4-pentadionate) with tert-butylphosphonic acid in toluene-ethanol mixture or acetone yielded seven titanium alkoxide phosphonate complexes; [Ti-5(mu(3)-O)(mu(2)-O)(mu-HOEt)(2)(mu-OEt)(3)(mu(2)-OEt)(mu(3)-tBPA)(3)(mu(3)-HtBPA)(mu(2)-tBPA)(2)(mu(2)-HtBPA)]center dot 3EtOH, 1, [Ti4O(mu-OEt)(5)(mu(2)-OEt)(7)(mu(3)-tBPA)], 2, [Ti-4(mu(2)-O)(2)(mu-OEt)(2)(mu-HOEt)(2)(mu(2)-tPBA)(2)(mu(2)-HtPBA)(6)]center dot 4EtOH, 3, [Ti-4(mu(2)-O)(2)(mu-OEt)(2)(mu-HOEt)(2)(mu(2)-tPBA)(2)(mu(2)-HtPBA)(6)]center dot 2EtOH, 4, [Ti-6(mu(2)-O)(mu(3)-O)(2)(mu(2)-OEt)(5)(mu-OEt)(6)(mu(3)-tBPA)(3)(mu(3)-HtBPA)], 5, [Ti-4(mu-(OPr)-O-i)(4)(acac)(4)(mu(2)-tBPA)(4)], 6 and [Ti-5(mu(4)-O)(mu(2)-O)(3)(mu(2)-OEt)(4)(mu-OEt)(6)(mu-HOEt)(mu(3)-tBPA)](2), 7. The binding mode of tBPA to the titanium oxo-core were either double or triple bridging or a combination of the two. No monodentate or chelating coordination was observed. P-31 NMR spectrometry of dissolved single crystals indicates that 1 and 5 retain their solid-state structures in solution, the latter even on moderate heating, while 6 and 7 dissolved into several other forms. The complexes were found to be sensitive towards hydrolysis, proceeding in a topotactic fashion with densification of the material into plates and lamellae resulting finally in "core-shell" nanoparticles with a crystalline core (anatase) and an amorphous outer shell upon contact with water at room temperature as observed by HRTEM and AFM analyses. P-31 NMR data supported degradation after addition of water to solutions of the complexes. Hydrolysis under different conditions affords complex oxide structures of different morphologies.
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| 25. |
- Svensson, Stefan, 1985-, et al.
(författare)
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ESEM as a Tool for Studying High Temperature Electronics
- 2011
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Ingår i: IMAPS High Temperature Electronics Network (HiTEN 2011), July 18-20, 2011 ,Oxford, UK.
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Konferensbidrag (refereegranskat)abstract
- Researchers studying materials and processes at high temperatures are often restricted to do evaluation afterwards and at room temperature using e.g. scanning electron microscopy (SEM). Limited by high vacuum, outgassing and non-conducting samples are difficult to study with SEM. For such samples, environmental scanning electron microscope (ESEM) is an alternative that is particularly suited also for high temperature in-situ studies. The electron detector in the ESEM make use of otherwise unwanted scattering of electrons as an amplifier of the signal, and by using differential pumping, it is possible to introduce several mbar of either oxygen, water vapor, or a gas of choice into the sample chamber while still maintaining the high-vacuum in the electron column. The auxiliary gas neutralizes surface charges built up by the electron beam, which makes it possible to image non-conductive and outgassing samples, thus making it possible to study e.g. polymeric and high temperature materials. Our ESEM, FEI XL30, have a heating stage making it possible to reach temperatures up to 1500°C. Equipped with electrical feed- throughs, the instrument can be used to study high temperature phenomena on electrically activated components.ESEM is an instrument that has found its use for biological and organic samples. However, less work has been done using it for high temperature processes. Here, we show real-time imaging of the sintering of dielectric and Ag thick-film prints on AlN substrates. The use of the electrical feed-throughs to activate electrical components and study them at high temperatures is also demonstrated. ESEM is a versatile tool for high temperature studies and in-situ analysis of electrical components, solder processes and different die-attach materials.
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