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AROMATIC RADICAL CATION COUPLING IN BIOMIMETIC ALKALOID SYNTHESISJaunbergs, Janis 24 September 2002 (has links)
No description available.
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Effects of Hydroxycinnamates and Exogenous Yeast Assimilable Nitrogen on Cider Aroma and Fermentation PerformanceCairns, Paulette Anne 08 July 2019 (has links)
Heritage apple cultivars for cider-making are often distinguished by a high concentration of tannins (phenolic compounds), and/or acid. The phenolic content of some cider apples far exceeds that of white wine, however most cider fermentation practices are directly taken from white winemaking, not accounting for effects of high concentrations of phenolic compounds on yeast fermentation. The objective of this study was to determine the impact of ferulic acid, p-coumaric acid, and chlorogenic acid—at concentrations reported in apples—and their interactions with yeast assimilable nitrogen (YAN) on fermentation kinetics and cider aroma. Our hypothesis was that the phenolic compounds present in high-tannin cider apples would negatively impact fermentation kinetics, but not alter the aroma, and that added YAN would reduce these effects. Ferulic acid negatively affected fermentation performance (p < 0.05), but p-coumaric acid and chlorogenic acid did not. p-Coumaric acid led to the greatest changes in cider aroma. Differences were also detected for different concentrations of ferulic acid. Chlorogenic acid did not affect aroma. Yeast strain influenced fermentation performance and cider aroma. Finally, addition of exogenous YAN improved fermentation performance for the low concentration ferulic acid condition, but not for the high concentration. Adding YAN also changed cider aroma in the presence of p-coumaric acid. / Master of Science in Life Sciences / Hard cider is increasingly popular in the United States. Heritage apple cultivars are traditional cider apples, often distinguished by a high concentration of tannins (phenolic compounds), and/or acid, unlike dessert apples that are typically higher in sugar than tannins. While the phenolic content of some cider apples far exceeds that of white wine, most cider fermentation practices are directly taken from white winemaking, and do not account for the effects of high concentrations of phenolic compounds on fermentation performance. The objective of this study was to determine whether three phenolic compounds—ferulic acid, p-coumaric acid, and chlorogenic acid—at concentrations reported in apples, would inhibit fermentation or alter the aroma of the cider, and if adding yeast assimilable nitrogen (YAN), a yeast nutrient, would reduce these effects. Our hypotheses were that the phenolic compounds present in high-tannin cider apples would negatively impact fermentation performance, but not alter the aroma, and that added YAN would reduce these effects. Ferulic acid negatively affected fermentation performance (p < 0.05), but p-coumaric acid and chlorogenic acid did not. Addition of nitrogen improved fermentation performance for the low concentration ferulic acid condition, but not for the high concentration. p-Coumaric acid led to the greatest changes in cider aroma, with differences in aroma also detected for ferulic acid ciders. Chlorogenic acid did not affect aroma or fermentation performance. Yeast strain and YAN addition also influenced fermentation performance and aroma.
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Novel Novolac-Phthalonitrile and Siloxane-Phthalonitrile Resins cured with low melting Novolac Oligomers for Flame Retardant Structural ThermosetsHardrict, Shauntrece Nicole 15 January 2004 (has links)
The chemical modification of low molecular weight novolac oligomers and siloxane/silane-containing monomers has led to novel phthalonitrile derivatives with low glass transition temperatures, ranging from -25 to 75 ºC. Multi-functional, low molecular weight phenol-formaldehyde novolac resins were blended with these novel phthalonitrile derivatives to achieve low viscosity resin blends. Moderate temperatures and rapid curing cycles were employed (200 ºC, 1 h and 225 ºC, 4h) to produce networks with high glass transition temperatures (> 250 ºC). A decrease in the sharp band at 2230 cm⁻¹, attributed to the nitrile functionality of the phthalonitrile resin, was monitored in FTIR studies and indicated the progress of the reactions. Ninety percent conversion was achieved within ~ 30 min.
Thermal analysis of siloxane-phthalonitrile/novolac networks cured for 1h at 200 ºC and 4h at 225 ºC did not exhibit glass transition temperatures below 250 ºC. In dynamic TGA studies, 5% weight loss temperatures up to 418 ºC were observed, and the materials exhibited 50 to 56 % char at 800 ºC in nitrogen. Networks prepared from a resin blend containing 50 weight% of a phthalonitrile derivative of a 260 g mol⁻¹ novolac oligomer, 50 weight% of the 260 g mol⁻¹ novolac oligomer, and 1.5 mol % triphenylphosphine (based on novolac) (NOV/NOV/TPP) cured at 200 ºC for 1h, did not exhibit a Tg below 250 ºC via DSC. These networks exhibited a 5% weight loss temperature of 350 ºC, and 70 % char at 800 ºC in TGA studies under nitrogen. This degree of char formation makes these materials appealing for use in carbon-carbon composites. Post-curing these networks at 200 ºC for 1h, and then at 225 ºC for 4h, resulted in high thermo-oxidative stability, with a 5% weight loss observed at 447 ºC and 50 % char at 800 ºC.
Blending tetramethyldisiloxane phthalonitrile monomers with 260 g mol⁻¹ novolac oligomers afforded prepolymer resins with low melt viscosities, 560 mPa s at 80 ºC. Such viscosities may allow these resins to be processed via vacuum assisted resin transfer molding (VARTM) at low temperatures and heated at elevated temperatures to produce flame resistant three-dimensional networks. / Master of Science
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Cherries with different geographical origins regulate neuroprotection in a photoperiod-dependent manner in F344 ratsManocchio, F., Bravo, F.I., Helfer, Gisela, Muguerza, B. 08 January 2024 (has links)
Yes / The photoperiod is the main environmental cue that drives seasonal adaptive responses in reproduction, behavior, and metabolism in seasonal animals. Increasing evidence suggests that (poly)phenols contained in fruits can also modulate seasonal rhythms. (Poly)phenol-rich diets are associated with an improvement in cognitive function and neuroprotection due to their anti-inflammatory and antioxidative properties. However, it is unknown whether cherries affect neuroprotection in a photoperiod-dependent manner. To test this, F344 rats were exposed to L6 (6 h light/day), L12 (12 h light/day) and L18 (18 h light/day) photoperiods and fed a standard chow diet supplemented with either a control, lyophilized cherry 1 or cherry 2 with distinctive phenolic hallmarks. Physiological parameters (body weight, eating pattern index (EPI), testosterone, T4/T3) and hypothalamic key genes (Dio2, Dio3, Raldh1 and Ghrh) were strongly regulated by the photoperiod and/or fruit consumption. Importantly, we show for the first time that neurotrophs (Bdnf, Sod1 and Gpx1) in the hippocampus are also regulated by the photoperiod. Furthermore, the consumption of cherry 2, which was richer in total flavonols, but not cherry 1, which was richer in total anthocyanins and flavanols, enhanced neuroprotection in the hippocampus. Our results show that the seasonal consumption of cherry with a specific phenolic composition plays an important role in the hippocampal activation of neuroprotection in a photoperiod-dependent manner. / This work was supported by grant number PID2020-113739RB-I00 funded by MCIN/AEI/10.13039/501100011033 and by Pect-Nutrisalt funded by the European Regional Development Fund of the European Commission through the Operative Program Erdf of Catalonia 2014–2020. The authors thank the British Society for Neuroendocrinology (BSN) for providing a research visit Grant to F.M (Grant number: BSN-2022-1452). F.M. is the recipient of a predoctoral fellowship from Universitat Rovira i Virgili—Martí i Franquès (Grant number: 2019PMF-PIPF-19).
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HPLC method development for the characterisation of the flavonoid and phenolic acid composition of rooibos (Aspalathus linearis) infusionsBeelders, Theresa 12 1900 (has links)
Thesis (MSc Food Sc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Rooibos tea, produced from the endemic South African fynbos plant Aspalathus linearis, has various healthpromoting
benefits which can largely be attributed to its phenolic composition. In this study, the reversedphase
liquid chromatographic (RP-LC) separation of the principal phenolic constituents of aqueous rooibos
infusions was optimised on conventional high-performance liquid chromatography (HPLC) instrumentation.
The phenolic constituents comprised dihydrochalcones (aspalathin and nothofagin), flavones (orientin,
isorientin, vitexin, isovitexin, luteolin, luteolin-7-O-glucoside and chrysoeriol), flavonols (quercetin,
isoquercitrin, hyperoside and rutin), a hydroxycinnamic acid (ferulic acid) and a phenylpropanoid
(phenylpyruvic acid glucoside, PPAG). A systematic approach towards method development was adopted:
resolution was optimised by simultaneous optimisation of gradient conditions and temperature on a sub-2 6m
phase to exploit the benefits of this phase for fast routine analyses. The developed HPLC method, utilising
photodiode-array (PDA) detection, yielded complete separation of the 15 target analytes on the 1.8 µm C18
column, thermostatted to 37°C, within 37 min (total analysis time: 50 min). The method was successfully
validated and demonstrated its suitability for the fast, quantitative analysis of aqueous infusions of
unfermented and fermented rooibos. Mass spectrometric (MS) and tandem MS detection confirmed peak
purity and permitted the tentative identification of 13 additional phenolic compounds, including a flavonol Odiglycoside
(quercetin-3-O-robinobioside), a luteolin-6-C-pentoside-8-C-hexoside and a novel C-8-hexosyl
derivative of aspalathin reported here for the first time.
The HPLC-PDA method was subsequently applied to a large number of fermented rooibos samples
representative of different production seasons (2009, 2010 and 2011) and quality grades (grades A, B, C
and D) to capture as much potential variation in the phenolic composition as possible. Production season
had no clear effect on the levels of the individual phenolic compounds in ‘cup-of-tea’ rooibos infusions, whilst
high quality tea (grades A and B) was associated with higher levels of phenolic compounds and soluble
solids than low quality tea (grades C and D). Steam-pasteurisation of the plant material, required to obtain a
product of high microbiological quality, induced significant reductions in the mean values of most of the
phenolic compounds in rooibos infusions. The major phenolic constituents of steam-pasteurised, fermented
rooibos were isoorientin and orientin, whilst quercetin-3-O-robinobioside, PPAG and aspalathin were also
present in high concentrations. Representative content values of the major phenolic compounds present in a
typical ‘cup-of-tea’ rooibos infusion were thus obtained and the generated data are suitable for inclusion in
food composition databases.
The application of comprehensive two-dimensional liquid chromatography (LCxLC) was investigated
as an alternative approach for the detailed investigation of rooibos phenolics. The combination of hydrophilic
interaction chromatography (HILIC) in the first dimension and RP-LC in the second dimension offered
different separation selectivities and hence a high degree of orthogonality. HILICxRP-LC provided a
significant improvement in resolution, as is evident from practical peak capacities in excess of 2000 and 800
for the off-line and on-line methods, respectively. Further optimisation, particularly of the first dimension
separation, is however required to improve the LCxLC separation of complex rooibos phenolic fractions. / AFRIKAANSE OPSOMMING: Gebruik van rooibostee, berei vanaf die eg Suid-Afrikaanse fynbosplant Aspalathus linearis, hou verskeie
gesondheidsvoordele in wat grootliks toegeskryf kan word aan sy fenoliese samestelling. Die skeiding van
die hoof fenoliese verbindings van ’n koppie rooibos is in hierdie studie deur middel van omgekeerde-fase
vloeistof chromatografie (RP-LC) op konvensionele hoë-druk vloeistof chromatografiese (HPLC) toerusting
geoptimiseer. Die fenoliese verbindings was verteenwoordigend van dihidrogalkone (aspalatien en
notofagien), flavone (orientien, isoorientien, viteksien, isoviteksien, luteolien, luteolien-7-O-glukosied en
krisoeriol), flavonole (kwersetien, isokwersetrien, hiperosied en rutien), ‘n hidroksiekaneulsuur (ferulasuur) en
‘n fenielpropanoied (fenielpirodruiwesuurglukosied, PPAG). Die ontwikkeling van die metode was sistematies
benader: resolusie is op ‘n geselekteerde 1.8 6m stationêre fase met welombekende kinetiese voordele
geoptimiseer deur die gradiëntkondisies en kolomtemperatuur gelyktydig te optimiseer. Die ontwikkelde
HPLC metode, gekoppel aan ultraviolet-fotodiode deteksie (PDA), het binne 37 min (totale analiese tyd: 50
min) volledige skeiding van die 15 standaard verbindings op die 1.8 µm C18 kolom teen 37°C bewerkstellig.
Die metode is suksesvol gevalideer en het sy toepaslikheid vir vinnige, kwantitatiewe analiese van
ongefermenteerde en gefermenteerde rooibos gedemonstreer. Piek suiwerheid is deur middel van massa
spektrometrie (MS) en tandem MS bevestig, wat ook die identifikasie van 13 addisionele verbindings
toegelaat het, insluitende ‘n flavonol O-diglukosied (kwersetien-3-O-robinobiosied), ‘n luteolien-6-Cpentosied-
8-C-heksosied en ‘n unieke C-8-heksosiel afgeleide van aspalatien wat vir die eerste keer hier
gemeld is.
Die geoptimiseerde HPLC-PDA metode is gevolglik toegepas vir die analiese van ‘n groot aantal
gefermenteerde rooibos monsters, verteenwoordigend van verskillende produksie seisoene (2009, 2010 en
2011) en kwaliteitsgrade (A, B, C en D). Hierdie lukraak-geselekteerde monsters het soveel as moontlik
potensiële variasie in die fenoliese samestelling verseker. Produksie seisoen het geen definitiewe effek op
die vlakke van die individuele fenoliese verbindings in ’n koppie rooibos gehad nie, terwyl hoë kwaliteit
rooibos (grade A en B) geassosieër was met hoër vlakke van die individuele fenoliese verbindings en
oplosbare vastestowwe in vergelyking met lae kwaliteit rooibos (grade C en D). Stoompasteurisasie van
rooibos plantmateriaal, noodsaaklik om ‘n produk van hoë mikrobiologiese gehalte te verseker, het gelei tot
‘n betekenisvolle afname in meeste fenoliese verbindings in ’n koppie rooibos. Die hoof fenoliese verbindings
van ‘n koppie stoom-gepasteuriseerde, gefermenteerde rooibos was orientien en isoorientien, terwyl
kwersetien-3-O-robinobiosied, PPAG en aspalatien ook in noemenswaardige hoeveelhede aanwesig was.
Verteenwoordigende waardes van die hoof fenoliese verbindings aanwesig in ‘n tipiese koppie rooibos is
derhalwe verkry en die data is geskik vir insluiting in voedsel-samestelling databasisse.
Die analiese van rooibos fenole met omvattende twee-dimensionele vloeistof chromatografie
(LCxLC) is bestudeer as ‘n alternatiewe metode om verdere insig tot hierdie komplekse fenoliese fraksie te
verkry. Die kombinasie van hidrofiliese interaksie chromatografie (HILIC) in die eerste dimensie en RP-LC in
die tweede dimensie het ‘n uiters gesogte lae graad van korrelasie verskaf. HILICxRP-LC het ‘n besonderse
toename in resolusie teweeg gebring, gekenmerk deur praktiese piek kapasiteite hoër as 2000 en 800 vir die
af-lyn en aan-lyn metodes, onderskeidelik. Verdere optimisering, veral van die eerste dimensie skeiding, is
egter nodig om die LCxLC skeiding van rooibos fenole te verbeter.
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Degradation of Phenolic Acids by Azotobacter Species Isolated from Sorghum FieldsAl-Hadhrami, Mohamed N. (Mohamed Nasser) 08 1900 (has links)
Sorghum plants excrete phenolic acids which reduce subsequent crop yields. These acids accumulate in field soil by combining with soil and clay particles to form stable complexes which remain until degraded by bacterial metabolism. The amount of phenolic acids in soil samples were obtained by gas chromatography measurements, while Azotobacter populations were obtained by plate counts in 40 sorghum field samples from Denton County, Texas. One can conclude that increasing the Azotobacter population in the soil increased the degradation rate of phenolic acids proportionally. It is proposed that seed inoculation will introduce selected strains of Azotobacter into the soil. The presence of Azotobacter should increase crop size in subsequent plantings.
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Design and Synthesis of Potential Anticancer AgentsZhang, Weihe January 2010 (has links)
No description available.
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Specific mold filling characteristics of highly filled phenolic injection molding compoundsScheffler, Thomas, Englich, Sascha, Gehde, Michael 08 March 2016 (has links) (PDF)
Thermosets show excellent mechanical properties and chemical resistance (for most automotive fluids) even at high temperatures up to 300 °C. Furthermore they can be highly efficient processed by injection molding. So they should be particularly suited for e.g. under the bonnet applications. However, the reality shows that thermosets are, except fiber reinforced composites, heavily underrepresented in technical applications. E.g. thermosetting components only account 0,2 % to a vehicle’s weight. Therefore reasons can be found in limited knowledge, e.g. relating mold filling behavior.
The objective of the study is to analyze the influence of the mold filling behavior during injection molding of highly filled phenolic compounds on mechanical properties. Injection molding filling studies, mechanical testing and optical microscopy were done while varying mold geometry (injection gate and cavity height), mold temperature and injection rate during injection molding a highly filled phenolic compound. It was found that the mold filling behavior varies with altered injection molding parameters as well as the mold geometry. In consequence of this the mechanical properties change according to the resulting reinforcement orientation. The results can help to improve part and mold design for optimal load transmission.
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The effect of maturity and crop load on the browning and concentration of phenolic compounds of Thompson Seedless and Regal SeedlessKamfer, De Witt 12 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Thompson Seedless and Regal Seedless are two white seedless table grape
cultivars widely produced in South Africa. Both cultivars are susceptible to berry
browning, especially Regal Seedless. Browning leads to annual financial losses for
table grape growers. Although a correlation between harvest maturity and the
occurrence of browning seems to exist, it is still unclear whether maturity levels are
the actual contributing factor. The aim of the study was to establish if harvest
maturity and crop load could influence the occurrence of browning of both cultivars.
The impact of harvest maturity and crop load on phenolic compound concentration in
the berry skin of both cultivars was also investigated. Total external browning of
Regal Seedless and Thompson Seedless occurred in much higher percentages than
internal browning. Regal Seedless showed a tendency to decreased total external
browning with harvest maturity. The main reason for this is that net-like browning,
which is the greatest contributor to total external browning, decreased with harvest
maturity, in all three seasons. External browning of Thompson Seedless increased
with harvest maturity in both seasons. Contact browning was the greatest contributor
to total external browning of Thompson Seedless. Crop load did not significantly
influence berry browning of Regal Seedless or Thompson Seedless grapes. The
flavan-3-ol concentration (catechin, epicatechin, procyanidin B1 and procyanidin B2)
in Regal Seedless generally increased with harvest maturity, whereas in Thompson
Seedless the general tendency was a decrease in the flavan-3-ol concentration with
harvest maturity. The development of phenolic compound concentration with
maturity could not be correlated with the occurrence of berry browning. Crop load did
not affect flavan-3-ol concentration. When the flavan-3-ol concentration of Regal
Seedless and Thompson Seedless were compared at different harvest maturities the
concentrations of flavan-3-ols were clearly much higher in the skin of Regal Seedless than in the skin of Thompson Seedless (for both the 2008 & 2009
seasons). Comparison of the browning incidence with harvest maturity for these two
cultivars (see above) clearly reveals that external browning of Regal Seedless
occurred in much higher percentages than on Thompson Seedless. Regal Seedless
had much higher levels of external browning than Thompson Seedless. The
concentration of flavan-3-ols in the skin of white seedless cultivars may be an
indication of the cultivar’s susceptibility to external browning. / AFRIKAANSE OPSOMMING: Thompson Seedless en Regal Seedless is twee wit pitlose tafeldruif kultivars wat
ekstensief in Suid-Afrika verbou word. Verbruining kan ‘n probleem wees by beide
kultivars, spesifiek Regal Seedless. Die faktore wat aanleiding gee tot verbruining is
nog nie duidelik bepaal nie. Alhoewel dit lyk of daar ‘n korrelasie tussen
rypheidsgraad van die oes en verbruining kan wees is dit steeds onduidelik of
oesrypheidsvlakke die werklike oorsaak van verbruining is. Die doel van die studie
was om vas te stel of die rypheidsgraad van die oes en oeslading verbruining van
beide kultivars kan beïnvloed. Die effek van oes rypheidsgraad en oeslading op
konsentrasie van fenoliese verbindings in die korrelskil van beide kultivars is ook
ondersoek. Totale eksterne verbruining van Regal Seedless en Thompson Seedless
het in baie hoër persentasies voorgekom as interne verbruining. Daar was ‘n
tendens by Regal Seedless dat totale eksterne verbruining verminder het soos die
oes ryper geraak het as gevolg van netagtige verbruining, wat die grootste bydrae tot
totale eksterne verbruining veroorsaak het. Netagtige verbruining se voorkoms het
verminder oor al drie seisoene. Eksterne verbruining van Thompson Seedless het
toegeneem met oes rypheid in beide seisoene. Kontak verbruining het grootste
byrdae gelewer tot totale eksterne verbruining van Thompson Seedless. Oeslading
het nie ‘n betekenisvolle invloed op verbruining van Regal Seedless en Thompson
Seedless gehad nie. Die flavan-3-ol (katesjien, epikatesjien, prosianidien B1 en
prosianidien B2) konsentrasie van Regal Seedless het met oes rypheid toegeneem.
By Thompson Seedless was daar ‘n afname in die flavan-3-ol konsentrasie met oes
rypheid. Daar was geen korrrelasie tussen die konsentrasie van fenoliese verbinding
en die voorkoms van verbruining vir beide kultivars. Oeslading het nie ‘n
betekenisvolle effek op die konsentrasie van fenoliese verbindings gehad nie.
Vergelyking van die flavan-3-ol konsentrasie van Regal Seedless en Thompson
Seedless by verskillende rypheidsgrade wys dat die konsentrasie baie hoër in die korrel skil van Regal Seedless as in die van Thompson Seedless (vir beide 2008 &
2009 seisoene). Die vergelyking van die voorkoms van verbruining met oesrypheid
van beide kultivars wys duidelik dat eksterne verbruining van Regal Seedless in baie
hoër persentasies voorkom as in Thompson Seedless. Flavan-3-ol konsentrasie in
die skil van wit pitlose kultivars kan ‘n aanduiding wees van die kultivar se moontlike
risiko vir die voorkoms van eksterne verbruining.
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Building MIII clusters with derivatised salicylaldoximesMason, Kevin January 2012 (has links)
This thesis describes the synthesis of a host of polynuclear iron complexes synthesised with phenolic oxime ligands, fundamentally developing the coordination chemistry of iron with these ligands. The metallic cores that occur within iron phenolic oxime clusters were found to contain almost exclusively oxo-centred triangles and oxo-centred tetrahedra. We found that we could alter the reaction conditions or derivatise the ligands and develop these basic building blocks into more elaborate arrays, exerting a degree of control over creating larger or smaller clusters. Chapter one describes the syntheses, structures and magnetic properties of new iron complexes alongside previously synthesised related complexes (4, 5, 8, 9 and 15) containing salicylaldoxime (saoH2) or derivatised salicylaldoximes (RsaoH2). These are [Fe3O(OMe)(Ph-sao)2Cl2(py)3]·2MeOH (1·2MeOH), [Fe3O(OMe)(Ph-sao)2Br2(py)3]·Et2O (2·Et2O), [Fe4(Ph-sao)4F4(py)4]·1.5MeOH (3·1.5MeOH), [Fe6O2(OH)2(Et-sao)2(Et-saoH)2(O2CPh)6] (4), [HNEt3]2[Fe6O2(OH)2(Et-sao)4(O2CPh(Me)2)6]·2MeCN (5·2MeCN), [Fe6O2(O2CPh)10(3-tBut-5-NO2-sao)2(H2O)2]·2MeCN (6·2MeCN), [Fe6O2(O2CCH2Ph)10(3-tBut-sao)2(H2O)2]·5MeCN (7·5MeCN), {[Fe6Na3O(OH)4(Me-sao)6(OMe)3(H2O)3(MeOH)6]·MeOH}n (8·MeOH) and [HNEt3]2[Fe12Na4O2(OH)8(sao)12(OMe)6(MeOH)10] (9). The predominant building block appears to be the triangular [Fe3O(R-sao)3]+ species which can self-assemble into more elaborate arrays depending on reaction conditions. The four hexanuclear and two octanuclear complexes of formulae [Fe8O2(OMe)4(Mesao) 6Br4(py)4]·2Et2O·MeOH (10·2Et2O·MeOH), [Fe8O2(OMe)3.85(N3)4.15(Mesao) 6(py)2] (11), [Fe6O2(O2CPh-4-NO2)4(Me-sao)2(OMe)4Cl2(py)2] (12), [Fe6O2(O2CPh-4-NO2)4(Et-sao)2(OMe)4Cl2(py)2]·2Et2O·MeOH (13·2Et2O·MeOH), [HNEt3]2[Fe6O2(Me-sao)4(SO4)2(OMe)4(MeOH)2] (14) and [HNEt3]2[Fe6O2(Etsao) 4(SO4)2(OMe)4(MeOH)2] (15) all are built from series of edge-sharing [Fe4( μ4- O)]10+ tetrahedra. Complexes 10 and 11 display a new μ4-coordination mode of the oxime ligand and join a small group of Fe-phenolic oxime complexes with nuclearity greater than six. Chapter three then introduces co-ligands to the reaction scheme to compete with the salicylaldoxime ligands for metal coordination sites. Five tetranuclear and two nononuclear complexes are stabilised with salicylaldoxime (saoH2) or derivatised salicylaldoximes (R-saoH2) in conjunction with either 1,4,7- triazocyclononane (tacn), 2-hydroxymethyl pyridine (hmpH) or 2,6-pyridine dimethanol (pdmH2), [Fe4O2(sao)4(tacn)2]·2MeOH (16·MeOH), [Fe4O2(Mesao) 4(tacn)2]·2MeCN (17·2MeCN), [Fe4O2(Et-sao)4(tacn)2]·MeOH (18·MeOH), [Fe9NaO4(Et-sao)6(hmp)8]·3MeCN·Et2O (19·3MeCN·Et2O), [Fe4 (Etsao) 4(hmp)4]·Et-saoH2 (20·Et-saoH2), [Fe4(Ph-sao)4(hmp)4]·2MeCN (21·2MeCN) [Fe9O3(sao)(pdm)6(N3)7(H2O)] (22). Chapter four straps two salicylaldoxime units together in the 3-position, using ligands with aliphatic a,W-aminomethyl links, allowing the assembly of the polynuclear complexes [Fe7O2(OH)6(H2L1)3(py)6](BF4)5·6H2O·14MeOH (23·6H2O·14MeOH), [Fe6O(OH)7(H2L2)3][(BF4)3]·4H2O·9MeOH (24·4H2O·9MeOH) and [Mn6O2(OH)2(H2L1)3(py)4(MeCN)2](BF4)5(NO3)·3MeCN·H2O·5py (25·3MeCN·H2O·5py). In each case the metallic skeleton of the cluster is based on a trigonal prism in which two [MIII 3O] triangles are tethered together via three helically twisted double-headed oximes. The latter are present as H2L2- in which the oximic and phenolic O-atoms are deprotonated and the amino N-atoms protonated, with the oxime moieties bridging across the edges of the metal triangles. Both the identity of the metal ion and the length of the straps connecting the salicylaldoxime units have a major impact on the nuclearity and topology of the resultant cage, with, perhaps counter-intuitively, the longer straps producing the “smallest” clusters.
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