Denna forskningsrapport fokuserar på gymnasieskolans laborationer i kemi och hur dessa förändrats under de senaste 10-20 åren. Motivet till att studera detta är ambitionen att få ökad didaktisk förståelse för laborationen som viktigt inslag i kemiundervisningen. I ett större perspektiv kan detta vara av intresse för att analysera om förändringar av gymnasieskolans kemilaborationer kan utgöra en delförklaring till att svenska universitet upplever ett minskat söktryck för kemi på högskolenivå och om delförklaring kan finnas för att Sverige som nation inte når samma resultat i naturvetenskap som vissa andra länder i internationella kunskapsmätningar. Sex erfarna lärare från sex olika skolor har intervjuats om sina upplevelser av kemilaborationen och vad som påverkat dess utveckling. Ramfaktorteorin har varit grundläggande för detta arbete och som analysmetod har fenomenografin valts. Resultaten visar på en stor variation i vad lärare anser påverkat kemilaborationens förändring. Ökat medvetande och högre krav från lagar och förordningar inom säkerhetsområdet samt att lärare upplever sig ha mindre tillgänglig tid för laborationerna framstår som de tydligaste orsakerna till gjorda förändringar. Även kompensation för försämrade praktiska färdigheter hos elever som lämnar grundskolan framkommer som en bakomliggande faktor. Den nya läroplanen Gy 2011, kostnadsöverväganden och kemi­lokalernas beskaffenhet framkom som mindre avgörande för kemilaborationens utveckling.

<p>Thermodynamic, viscous and structural properties of melts and glasses in the AlCl₃-ZnCl₂ system have been investigated. The two pure components are fundamentally different in the molten state. Both metal atoms are four coordinated, however, ZnCl₂ forms a corner sharing tetrahedral network whereas AlCl₃ is a dimer, Al₂Cl₆. ZnCl₂ is one of two known single component halide glass formers and additions of AlCl₃ have shown to form stable glasses. The glass forming ability remains far into the binary AlCl₃-ZnCl₂ system.</p><p>The phase diagram of the AlCl₃-ZnCl₂ system has been investigated by differential thermal analysis. The system is a simple eutectic system, and the eutectic point was observed at 116±2°C and 0.52±0.05 mole fraction ZnCl₂. The system is highly glass forming in the range from pure ZnCl₂ up to about 0.46 mole fraction ZnCl₂. Glass transition temperatures measured by differential scanning calorimetry (heating rate 10 K/min) were recorded from 115°C for pure ZnCl₂ to -5.5°C for 0.46 mole fraction ZnCl₂. The reduced width of the glass transition ( T_g'-T_g )/T_g showed a maximum at 0.80 mole fraction ZnCl₂ giving a minimum in fragility at this composition.</p><p>The density of AlCl₃-ZnCl₂ melts has been determined using volume measurements in sealed quartz tubes. The molar volumes showed a negative deviation from ideality with a minimum at ~0.33 mole fraction ZnCl2 (ZnAl₂Cl₈). The volume expansion coefficient is strongly reduced from pure AlCl₃ to ZnCl₂, and the excess volume of mixing is strongly increasing with temperature. A simple model using molecular Al₂Cl₆, ZnCl₂ and ZnAl₂Cl₈ units was used to calculate equilibrium constants for the reaction of pure components ZnCl₂ and Al₂Cl₆ to ZnAl₂Cl₈. The density data showed that molecular ZnAl₂Cl₈ became more stable with increasing temperature. The viscosity of molten AlCl₃-ZnCl₂ in the range from pure ZnCl₂ to 0.40 mole fraction ZnCl₂ has been measured as a function of temperature by an oscillation cup method. The melts with ZnCl₂ content higher than 0.60 mole fraction ZnCl₂exhibited non-Arrhenius behavior. The viscosity clearly decreases with increasing AlCl₃ content. However, the viscosity of ZnCl₂is affected less by addition of AlCl₃ compared to addition of ionic chlorides which form terminal chloride bonds. The fragility of the melts obtained from a reduced Arrhenius plot, were observed to decrease with addition of AlCl₃ up to 0.80 mole fraction ZnCl₂. At higher AlCl₃ content the fragility increases in line with the more molecular nature of the melt. The present study has also demonstrated that the oscillation cup viscometer can be applied to record viscosities as high as 3 Pa·s.</p><p>IR spectroscopy has been performed on melts in the whole compositional range of the AlCl₃-ZnCl₂ system. The spectra were recorded using an IR reflection method of thin films (>10 µm). Compensation for any splitting of strong bands was performed by defining a specular reflectance, r*, where a thick melt (2-3 mm)\ was used as reference. For all the mixtures a splitting of the anti-symmetric stretching frequency ν3(F2) for the AlCl₄ tetrahedron into three bands was observed. This indicated a C2v perturbation of the T_d symmetry. From this observation it was proposed that the AlCl₄ units were always terminal consisting of two bridging and two terminal chlorines. The melts with compositions from 0.33 mole fraction ZnCl2 to pure Al2Cl6 are proposed to consist of a mixture of Al₂Cl₆ and ZnAl₂Cl₈. The temperature dependence of the 0.20 mole fraction ZnCl₂ spectra showed that the amount of ZnAl₂Cl₈ increased relative to the amount of Al₂Cl₆with increasing temperature. At 0.40 - 0.60 mole fraction ZnCl₂, the melts were proposed to remain molecular in nature, where the ZnCl₄ tetrahedra were enclosed by edge sharing AlCl₄ terminal units. At higher ZnCl₂ content or higher temperatures the connectivity of the molten structure is shifted from edge sharing AlCl₄ units to corner sharing AlCl₄ units bonded to two ZnCl₄ tetrahedra.</p>

<p>Syftet med denna studie var att se närmare på gymnasieelevers vilja och lust för fortsatta studier i kemi. Studien genomfördes med kvalitativa intervjuer av tio gymnasieelever på det naturvetenskapliga programmet på en mindre ort i Sverige. Resultatet visade på att alla dessa elever ville läsa vidare efter gymnasiet, men enbart två kunde tänka sig en kemiutbildning. Övriga elever hade antingen redan bestämt sig för någon annan utbildning eller blivit avskräckta från att läsa kemi på grund av sättet undervisningen var upplagd i skolan. De elever som möjligen skulle vilja läsa vidare inom kemiområdet kände, liksom flera av de andra eleverna, att skolan inte givit tillräcklig information kring möjliga yrken inom de olika naturvetenskapliga områdena.</p>

<p>Capillary electroseparation methods<b> </b>are exciting new techniques with very broad application areas and vast potential in pharmaceutical and biomedical analysis.</p><p> To improve the limit of detection (LOD) capillary zone electrophoresis (CZE) has been combined with isotachophoretic (ITP) preconcentration in a single capillary. Using the ITP-CZE combination the LOD can be improved at least 100-fold. Laser-induced fluorescence (LIF) detection is more sensitive and more selective than the most common detection technique, UV, and the intensity and focusing capability of LIF fits well with the small dimensions in CZE. The total sensitivity enhancement attained for a new acetylcholinesterase inhibitor, NXX-066, by using ITP-CZE-LIF was more than 5500-fold compared to CZE-UV.</p><p> Capillary electrochromatography (CEC) combines the high separation efficiency of CZE with the vast possibilities to improve selectivity of HPLC. We have examined different ways to solve the problem of extensively tailing peaks and studied the influence of the mobile phase composition on the electrochromatographic performance for a number of tricyclic antidepressants and related quaternary ammonium compounds. (1) Adding aliphatic amines to the mobile phase in reversed phase CEC. The effect on the chromatographic performance was coupled to the hydrophobicity of the additive and the amine of our choice was dimethyloctylamine. (2) Silica-based cation exchangers with different pore sizes. The large-pore materials promoted pore flow, but this had no positive influence on the performance. The small-pore (highest surface area) particles gave the best selectivity. (3) Designing special continuous beds. As the bed is covalently attached to the capillary wall, problems related to retaining frits are avoided. The stationary phase most suitable for our analytes had a molar ratio of 1:80 between the functional ligands, vinyl sulphonic acid and isopropyl groups, respectively. The LOD was lowered 26000-fold by dissolving the sample in a low-conducting medium.</p>

<p>This thesis is divided into two parts based on a total of 8 papers: Part 1: <i>Synthesis, physicochemical and biochemical studies of chemically modified oligonucleotides and their duplexes and triplexes</i>. Potency of the chromophore conjugated DNA oligonucleotides as antigene and antisense gene repressors was evaluated. The effect of geometry, bulk and ¥ð-electron density of a series of chromophores, tethered at the 5'-end of oligonucleotides, as well as the effect of the linker nature, length and the attachment site of the chromophore to the oligo were explored based on the stability of the duplexes and triplexes. A dramatic improvement in the triplex stability with <i>ara</i>-U linked phenazine oligo (potent antigene) was achieved (¥ÄT_m = 16.5¢ª C). A number of selected phenazine and dipyridophenazine tethered antisense oligos (AONs) and their phosphorothioate analogues were shown to form the AON/RNA hybrid duplexes with enhanced thermal stability. CD experiments revealed that these duplexes have the global structure unaltered from that of the native counterpart. RNase H degradation studies on three RNA targets having different degrees of folded structures showed that tethering of phenazine and dipyridophenazine increases the hydrolysis rates (potent antisense) of the target RNA, and that chemical nature of the chromophore influences the RNase H cleavage pattern. Further investigation at the RNA saturated conditions revealed that 3'-tethered chromophores influence the substrate recognition, and the kinetics of the cleavage by RNase H. Conjugation of different chromophores, charged polyaromatic systems and metal complexes with polyaromatic ligands at different sites of the AON revealed that RNase H is very sensitive to any modifications in the middle region of the AON/RNA duplex. On the contrary, any modification at the 3'-end of the AON regardless of the bulk of the substituent or presence of positive charge can be easily tolerated by the enzyme. Sensitivity of the RNase H towards the local structural changes in the AON/RNA hybrid was probed with a number of AONs containing a single 1-(1',3'-O-anhydro-©¬-<u>D</u>-psicofuranosyl)thymine with locked 3'-<i>endo</i> sugar conformation at different sites of AON. RNase H degradation studies revealed that the local conformational changes brought by the constrained nucleoside, although invisible by CD, span in the hybrid as far as 5 nucleotides toward the 5'-end of the AONs (3'-end of RNA), showing the unique transmission of the structural distortion from a single modification site. The results also showed that the structural requirements for the substrate binding and substrate cleavage by RNase H appear to be different. Part 2: <i>Preparation of biologically important isotope labelled oligo-RNAs for the NMR structure determination in solution</i>. Synthesis of the non-uniformly ¹³C₅ labelled 29mer HIV-1 TAR RNA was achieved by solid-phase synthesis using ¹³C₅ labelled ribonucleosides from ¹³C₆-<u>D</u>-glucose). Two hammerhead forming RNAs (16mer and 25mer) were synthesized according to the Uppsala NMR-window strategy, where the sugar residues of the nucleosides forming stem I, II and the loop of the stem III of the resulting hammerhead complex were deuterated. UV melting and high resolution NMR structural studies showed that the 16mer RNA under quasiphysiological condition folds to a very stable hairpin structure, which prevents formation of a hammerhead RNA with the 25mer, primarily owing to thermodynamic reasons.</p>

<p>Capillary electrophoresis-mass spectrometry has been used successfully for the analysis of a wide range of analytes such as chiral local anaesthetics, sulphonated reactive dyes and endogenous neurotransmitters and neuropeptides.</p><p>The partial filling technique was used in CE-MS for chiral separation of bupivacaine and ropivacaine using the non-volatile selector β-cyclodextrin. By only partially filling the capillary with selector and using capillaries coated with polyacrylamide to suppress the electroosmotic flow, introduction of the selector into the mass spectrometer was avoided. An impurity of 0.25% of the R-enantiomer of ropivacaine in the S-form could be detected.</p><p>The partial filling technique was developed further using CE employing two different selectors in separate plugs in the capillary. This enhanced the separation efficiency and offered greater flexibility in controlling the separation.</p><p>By using transient-isotachophoresis (tITP)-CE-MS it was possible to concentrate and detect classical neurotransmitters and neuropeptides with masses ranging from 104 Da to 1642 Da. γ -Aminopropyltriethoxysilane coated capillaries were used to minimize adsorption of the peptides onto to capillary surface. Endogenous dopamine, glutamate, γ-aminobutyric acid (GABA), acetylcholine, methionine-enkephalin and substance P 1-7 were detected in the striatum of marmoset monkey.</p><p>Sulphonated dyes obtained from single textile fibres were analysed using CE-MS. Capillary electrophoresis was found to be a good way of removing the excess amounts of glucose present in the sample that would otherwise interfere with the electrospray ionisation. </p><p>Automatic function switching, originally developed for use together with liquid chromatography, was found to be a great method for acquiring MS/MS data when doing infusion experiments saving both time and sample without decreasing the quality of the MS/MS data. It was also found to be a more time efficient way than using the precursor ion scanning mode on the Q-TOF to obtain precursor ion data.</p>

<p>The aim of this work was to explore the structural and functional diversity of polypeptides that are found in plants. Expanding knowledge of simililarities between plant use of these compound and animal use promises exceptional opportunities for finding, from plant research, new structures with biomedical and biotechnological potential.</p><p>A fractionation protocol was developed and applied to many plant species, providing fractions enriched in polypeptides, amenable to chemical and biological evaluation. From one species, the common field pansy (<i>Viola arvensis</i>), a 29-amino-acid residue polypeptide was isolated, named varv A, which revealed a remarkable macrocyclic structure (i.e., N- and C-termini are joined) stabilised by three knotted disulfides<i>. </i></p><p>Varv A, together with an increasing number of homologous peptides, form the currently known peptide family of cyclotides. Their stable structure makes them an attractive scaffold for protein engineering. In addition, they display a wide range of biological activities (e.g., antimicrobial, cytotoxic, and insecticidal). As a part of this work, the cytotoxic effects of varv A and two other isolated cyclotides were evaluated in a human cell-line panel: all were active in the low µM range. Most likely, these effects involve pore formation through cell membranes.</p><p>Cyclotides were found to be common in the plant family<i> Violaceae; </i>with eleven cyclotides isolated and sequenced from V. arvensis, V. cotyledon, and<i> Hybanthus parviflorus. </i>For six members of the genus <i>Viola</i>, cyclotide expression profiles were examined by liquid chromatography-mass spectrometry (LC-MS): all expressed notably complex mixtures, with single species containing more than 50 cyclotides. These profiles reflect the evolution of the genus<i>.</i></p><p>To assess these mixtures, a rational strategy for MS based amino acid sequencing of cyclotides was developed, circumventing inherent structural problems, such as low content of positively charged amino acids and the macrocyclic structure. This was achieved by aminoethylation of cysteines, which, following tryptic digestion, produced fragments of size and charge amenable to MS analysis. This method was also modified and used for mapping of disulfide bonds<i>. </i></p><p>Methods for isolation and characterisation developed in this work may prove useful not only for further studies on macrocyclic polypeptides from plants, but also for other plant peptides and disulfide-rich peptides from animals.</p>

<p>Solvolysis reactions of a range of tertiary substrates in largely aqueous solvents were studied in such respects as β-deuterium kinetic isotope effects, linear free energy relationships and stereochemistry.</p><p>Solvolysis of the fluorene derivatives 9-methyl–9-(2´-X-2´-propyl)fluorene (<b>1-X,</b> X = Cl, Br, OOCCF₃) involves a very short-lived carbocation intermediate. The fraction of alkene is increased by addition of general bases, which can be expressed by a Brφnsted parameter β = 0.07. The kinetic deuterium isotope effects vary with solvent composition in a way which is not consistent with a common carbocation intermediate which has time to choose between dehydronation and addition of a solvent water molecule. </p><p>In the absence of bases, the reaction of 4-chloro-4-(4´-nitrophenyl)pentan-2-one (<b>2-Cl</b>) proceeds through a short-lived carbocation intermediate yielding 4-(4´-nitrophenyl)-2-oxopent-4-ene (<b>2-</b><b>t</b>-ne)as the main elimination product. Addition of acetate ion and other weak bases results in the base-promoted E2 (or E1cb) reaction to give (<i>E</i>)-4-(4´-nitrophenyl)-2-oxopent-3-ene (<b>2-</b><b>E</b>-ne) and (<i>Z</i>)-4-(4´-nitrophenyl)-2-oxopent-3-ene(<b>2-</b><b>Z</b>-ne). There is no evidence for a water-promoted E2 (or E1cb) reaction.</p><p>The stereochemistry studies of elimination from (<i>R,S</i> and <i>S,R</i>)-[1-(3´-fluoro)phenyl-2-methyl]cyclopentyl-<i>p-</i>nitrobenzoate (<b>3-PNB</b>) and its (<i>R</i>,<i>R</i> and <i>S,S</i>)isomer <b>3´-PNB</b> and (<i>R,S</i> and <i>S,R</i>)-[1´-(3´´-fluoro)phenyl-2´-methylcyclopentyl]-2,2,2-trifluoroacetate(<b>3-OOCCF</b><b>3</b>) exclude the concerted pericyclic elimination mechanism for formation of the alkene 1-(3´-fluoro)phenyl-2-methylcyclopentene(<b>3-</b><b>m</b>-ne). The effects of added thiocyanate ion and halide ions on the solvolysis reaction are discussed.</p><p>Mass spectrometry analysis showed complete incorporation of the labeled oxygen from solvent water into the product 2-hydroxy-2-phenyl-3-butene (<b>4-OH</b>), confirming that it is the tertiary carbon-oxygen bond that is broken in the acid-catalyzed solvolysis of 2-methoxy-2-phenyl-3-butene (<b>4-OMe</b>). The mechanism for the dominant formation of the less stable <b>4-OH</b> is discussed.</p>

<p>The actual signal recorded with an analytical instrument is not always a true reflection of the analysed sample. In this thesis a further insight of the atmospheric pressure ionisation processes electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) has been endeavoured, to provide a deeper understanding of and ways to minimize this bias.</p><p>A response model for ESI has been modified and used to study the influence of solvent composition on the observed mass spectrometric signal. The response model divides the response into an analyte partitioning coefficient and an instrumental response factor. A number of experimental parameters influencing the response were investigated including spray position relative to the orifice, spray potential, nebulizer and curtain gas flow rates, ionic strength and organic content of the sprayed solution. The history of the generated droplets turned out to be of significant importance to both the partitioning coefficients and the instrumental response factor. Furthermore, it was found that the total ionic strength and not only the electrolyte concentration will influence the instrumental response factor.</p><p>In addition, based on the importance of hydrophobicity and electrophoretic mobility, a model was proposed for the ion distribution within the electrosprayed droplets.</p><p>The coupling of an electrochemical (EC) cell to a mass spectrometric (MS) system has been evaluated. The coupling of the EC cell to the MS was made to decouple the cell from the high voltage circuit of the ESI. The feasibility for analyte ionisation, sample pre-concentration and solvent exchange as well as studying redox reaction products was shown.</p>

<p>The Ru(arene)[(1<i>S</i>, 3<i>R</i>, 4<i>R</i>)-3-(Hydroxymethyl)-2-azabicyclo[2.2.1]heptane catalyst was optimized as ligand in the asymmetric transfer hydrogenation of ketones and resulted in increased activity and enantioselectivity of the catalyst. Dioxolane substitution at the rear end of the amino alcohol ligand and introduction of a (<i>R</i>)-methyl substituent yielded a catalyst that reduced acetophenone in 96% enantiomeric excess in 90 minutes with a substrate to catalyst molar ratio of 5000. A diversity of substituted aromatic ketones was reduced with excellent rate and enantioselectivity. Based on experimental and computational results, a study of the origin of the enantioselectivity was conducted. A combination of electrostatic, steric, dispersion forces and solvation effects was suggested to be the cause of the stereo discrimination. A set of amino sulfides built upon the 2-azabicyclo and the cyclohexane structures were prepared and tested as ligands in the enantioselective transfer hydrogenation of acetophenone with [IrCl(COD)]₂ as metal precursor. With this type of catalysts, the reaction rates were good but the enantioselectivity unsatisfactory with 70% as the highest obtained enantiomeric excess. The first enantioselective reduction of aromatic 2<i>H</i>-azirines was accomplished by using the asymmetric transfer hydrogenation protocol. Aromatic azirines were reduced to yield chiral aziridines with up to 72% enantiomeric excess and good yields. The enantioselectivity and reactivity of the reaction were strongly influenced by substituents on the aromatic and aliphatic moiety of the substrate.</p>