No abstract

Cyclic phosphazenes with positively charged substituents were investigated as surface modifiers for lanthanide phosphate nanoparticles. Cyclotriphosphazenes bearing aromatic (1, 2) and aliphatic (3‐6) substituents with terminal tertiary amino functions have been synthesized and subsequently quaternized by treatment with methyl iodide. In subsequent tests, their influence as surface modifiers for the lanthanide phosphate‐based nanoparticles was analysed with respect to the resulting particle solubility and the degree of surface interaction. While an interaction of the completely quaternized cyclic phosphazenes 2 and 4 with the nanoparticles leads to an agglomeration, stable nanocrystal‐linker complexes in methanol could be formed with the compounds 5 and 6. Aromatic functions were not suitable due to interference with the UV absorbance of the nanocrystals, while aliphatic side chains allowed a good fluorescence detection of the nanocrystals with UV excitation without any loss of intensity as compared to the untreated particles.

Cyclic phosphazenes with different substituents were synthesised and investigated by liquid chromatography (LC) and electrospray ionisation mass spectrometry (ESI-MS). Hexachlorocyclotriphosphazene was functionalised with aliphatic substituents as alcohols and amines, leading to product mixtures, which were subsequently analysed. In contrast to classical methods of structural analysis such as nuclear magnetic resonance (NMR) spectroscopy or X-ray crystallography, which are restricted to pure compounds, these complex mixtures can favourably be analysed by means of LC/ESI-MS. The main products could be separated from by-products and, moreover, all the components of the unknown mixture were unambiguously identified by accurate mass measurements. For all compounds with different side-chain ratios, remaining chlorine atoms or hydroxyl groups and even for spiro or ansa products, molecular structures could be suggested.

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