Solvent-Adaptive Behavior of Oligospirobifluorenes at the Surface of Quartz Crystal Microbalances- A Conformational Process.

Invited for this month's cover are the groups of Siegfried R. Waldvogel at the Johannes Gutenberg University Mainz and of Josef Salbeck at the University Kassel (both Germany). The image shows the swelling of a blowfish to represent the reversible conformational change of an oligospirobifluorene derivative upon solvation.

Solvent-Adaptive Behavior of Oligospirobifluorenes at the Surface of Quartz Crystal Microbalances-A Conformational Process.

Oligospirobifluorenes represent promising building blocks for the generation of microporous sensor materials based on their restricted flexibility. The contact with specific solvents leads to a change of the three-dimensional spirobifluorene structure. The single fluorene moieties unfold to an open structure with an increased volume due to intermolecular interactions with the solvent, detectable by NMR spectroscopy.

Novel supramolecular affinity materials based on (-)-isosteviol as molecular templates.

The readily available ex-chiral-pool building block (-)-isosteviol was combined with the C 3-symmetric platforms hexahydroxytriphenylene and hexaaminotriptycene providing large and rigid molecular architectures. Because of the persistent cavities these scaffolds are very potent supramolecular affinity materials for head space analysis by quartz crystal microbalances. The scaffolds serve in particular as templates for tracing air-borne arenes at low concentration.

Surface pretreatment boosts the performance of supramolecular affinity materials on quartz crystal microbalances for sensor applications.

A Teflon-like coating is the key for the boost in sensitivity of quartz microbalances for the tracing of airborne analytes. Since the undesired signals for the interfering compounds are suppressed and the ones for the targeted compounds (e.g.