Cody Williams

Lipids are essential components of all living cells. In an oenological context, the supply of unsaturated lipids in grape juice allows the yeasts to grow and ferment, despite very low levels of oxygen. The current study proposes a systematic optimization procedure for the analysis of fatty acids and sterols relevant to the grape fermentation process, including both extracellular and intracellular (i.e., yeast cells) lipids. Even though it was extensive, the sample preparation yielded reproducible results for all compounds of interest. The stability of the analyzed compounds was also tested to offer some implementation flexibility for the extensive procedure. The performance parameters (i.e., selectivity, linearity, limit of detection and quantitation, accuracy, and precision) indicated that the method was suitable for future practical implementation. The proof of concept also suggests that the list of compounds of interest can be expanded if additional peaks are identified. Given the large variation in concentrations, the dilution of the matrix needs to be carefully considered in order to ensure that the lipids of interest are still within the dynamic range and not below the limit of detection and/or quantification.

Metallodendrimers can be systematically classified according to the location of the metal centres within the dendritic framework. Dendrimers can be functionalized with various metals on the periphery through many suitable end groups, in their core, along their branches, and in the cavities that exist within their framework. These different structures possess unique architectures and topologies with associated specific functions, with potential in a myriad of fields. This chapter summarizes the recent developments in the synthesis and functionalization of dendrimers with various metal centres.

The aroma profile is an important marker for wine quality. Various classes of compounds are responsible for the aroma of wine, and one such class is terpenoids. In the context of this work, a validated gas chromatography–mass spectrometry (GC–MS) method for the quantitation of terpenoids in red and white wine using headspace solid-phase microextraction (HS–SPME) and solid-phase extraction (SPE) was established. Calibrations were performed in the respective base wine using both sample preparation methods. The linearity, precision and accuracy evaluated for the respective matrices were excellent for both sample preparations. However, the HS–SPME approach was more sensitive and more accurate. For both sample preparations, the quantification limits were lower than the odor thresholds in wine. The terpenoid concentrations (µg/L) were evaluated for 13 white wines using both sample preparation methods. Importantly, the online HS–SPME approach was more sensitive than the offline SPE method. The major terpenoids identified in the white wines evaluated were linalool (0.2–63 µg/L), geraniol (nd–66 µg/L) and α-terpineol (nd–85 µg/L).

A series of organometallic dendrons containing N,O-salicylaldimine entities at the focal point were synthesised by reacting the N,O-salicylaldimine-functionalised Fréchet dendrons (G₀, G₁ and G₂) with a [Rh(μ-Cl)(η²:η²-COD)]₂ dimer to yield the corresponding Rh(COD) [COD = cyclooctadiene] complexes. These Rh(COD) complexes were exposed to an atmosphere of CO to yield a new class of rhodium carbonyl organometallic dendrons with Rh(CO)₂ units at the focal point. All the compounds were characterised using standard spectroscopic and analytical techniques, these include nuclear magnetic resonance, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction for compounds 1, 4 and 7. All of the complexes were evaluated in the hydroformylation of 1-octene, with excellent conversion and chemoselectivity towards aldehydes. The G₀-(CO)₂ catalyst precursor (7) was active in the hydroformylation of 1-octene, styrene, 7-tetradecene, methyl oleate, triolein, D-limonene and R-citronellal. The conversion and chemoselectivity towards aldehydes for 7-tetradecene, methyl oleate, triolein and D-limonene were promising. Across a particular dendron series, an increase in chemoselectivity was observed due to the dendritic effect. Mercury drop tests were performed for the G₀-analogues and these confirm that the hydroformylation can be attributed to a combination of homogeneous and heterogeneous catalysis.