In this study, a series of new BF₂-chelated tetraarylazadipyrromethane dyes are synthesized and are shown to be suitable for the preparation of on/off photoinduced electron transfer modulated fluorescent sensors. The new indicators are noncovalently entrapped in polyurethane hydrogel D4 and feature absorption maxima in the range 660–710 nm and fluorescence emission maxima at 680–740 nm. Indicators have high molar absorption coefficients of ∼80 000 M^–1 cm^–1, good quantum yields (up to 20%), excellent photostability and low cross-sensitivity to the ionic strength. pK_a values of indicators are determined from absorbance and fluorescence measurements and range from 7 to 11, depending on the substitution pattern of electron-donating and -withdrawing functionalities. Therefore, the new indicators are suitable for exploitation and adaptation in a diverse range of analytical applications. Apparent pK_a values in sensor films derived from fluorescence data show 0.5–1 pH units lower values in comparison with those derived from the absorption data due to Förster resonance energy transfer from protonated to deprotonated form. A dual-lifetime referenced sensor is prepared, and application for monitoring of pH in corals is demonstrated.

In yeast, as in higher eukaryotic cells, sphingolipids are essential membrane components. The yeast, Saccharomyces cerevisiae, contains three classes of sphingolipids, inositolphosphorylceramide (InsP Cer), mannosylinositolphosphorylceramide (ManInsP Cer) and mannosyldiinositolphosphorylceramide (ManP Ins₂P Cer). As a prerequisite to localize these sphingolipids in subcellular membranes, authentic standards of the respective lipids were isolated and characterized using biochemical methods and electrospray ionization mass spectrometry. The complete set of yeast subcellular membranes was isolated at high purity, and sphingolipids were extracted. InsP Cer, ManInsP Cer, and ManP Ins₂P Cer were separated by thin‐layer chromatography, stained and densitometrically scanned along with the respective standards. These methods enable a complete overview of the subcellular distribution of yeast sphingolipids to be obtained, as far as is known, for the first time. InsP Cer was highly enriched in Golgi and vacuolar membranes, whereas the largest amounts of ManInsP Cer and ManPIns2PCer were found in the plasma membrane. The presence of inositol‐containing sphingolipids in organelles of the protein‐secretory pathway strongly supports the notion that protein secretion and intracellular trafficking of sphingolipids are linked processes.