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. The induced microporosity was further investigated by affinity comparisons of aromatic analytes with high fundamental frequency quartz crystal microbalances.
The cover picture shows the reversible change in the shape of a blowfish between its flat and inflated forms. This picture is a suitable metaphor for the reversible conformational change of an oligospirobifluorene derivative into an open structure in aromatic solvents. The flexible biaryl axis linking the spirobifluorene moieties is crucial to the conformation change, which arises from the strong attraction between the host and the solvent guest molecules. Details are given in the Communication by S. R. Waldvogel and co‐workers on page 1116 in Issue 8, 2017 (DOI: 10.1002/cplu.201600583).
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. Read the full text of the article at 10.1002/cplu.201600583.
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