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Dibenzo Crown Ether Layer Formation on Muscovite Mica, Langmuir 30 (2014) 12570-12577

W. de Poel, S. Pintea, A. de Jong, J. Drnec, F. Carla, R. Felici, H. op den Camp,

J.A.A.W. Elemans, W.J.P. van Enckevort, A.E. Rowan, E. Vlieg,

Abstract: Stable layers of crown ethers were grown on muscovite mica using the

potassium−crown ether interaction. The multilayers were grown from solution and from the

vapor phase and were analyzed with atomic force microscopy (AFM), matrix-assisted laser

desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, and surface X-ray

diffraction (SXRD). The results show that the first molecular layer of the three investigated

dibenzo crown ethers is more rigid than the second because of the strong interaction of the first

molecular layer with the potassium ions on the surface of muscovite mica. SXRD measurements

revealed that for all of the investigated dibenzo crown ethers the first molecule lies relatively flat

whereas the second lies more upright. The SXRD measurements further revealed that the

molecules of the first layer of dibenzo-15-crown-5 are on top of a potassium atom, showing that

the binding mechanism of this layer is indeed of the coordination complex form. The AFM and

SXRD data are in good agreement, and the combination of these techniques is therefore a

powerful way to determine the molecular orientation at surfaces.