Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.

 

Supramolecular materials: Molecular packing of tetranitrotetrapropoxycalix[4]arene in highly stable films with second-order nonlinear optical properties


Kenis PJA, Noordman OFJ, Schonherr H, Kerver EG, Snellink-Ruel BHM, van Hummel GJ, Harkema S, van der Vorst CPJM, Hare J, Picken SJ, Engbersen JFJ, van Hulst NF, Vancso GJ, Reinhoudt DN
CHEMISTRY-A EUROPEAN JOURNAL
vol 4 issue 7: p1225-p1234 JUL 1998
doi:10.1002/(SICI)1521-3765(19980710)4:7<1225::AID-CHEM1225>3.3.CO;2-Y

Highly stable films of tetranitrotetrapropoxycalix[4]arene (9) with second-order nonlinear optical (NLO) properties and a noncentrosymmetric structure were obtained by a novel crystallization process at 130-140 degrees C in a de electric field. The packing of 9 in these films was elucidated by a combination of X-ray diffraction, angle-dependent second- harmonic generation, and scanning force microscopy (SFM). The experimental results agree well with solid-state molecular dynamics calculations for these films. No crystalline phase was observed for nitrocalix[4]arene derivatives with longer or branched alkyl chains; this explains the limited NLO stability of films of these calixarenes. Scanning force microscopy o­n the aligned films of 9 showed two distinct surface lattice structures: a rectangular lattice (a = 9.3, b = 11.7 Angstrom) and a pseudohexagonal lattice (d approximate to 11.4 Angstrom). The combination of these data with the interlayer distance of 8.9 Angstrom (X-ray diffraction) allowed the packing of molecules of 9 in these structures to be fully elucidated at the molecular level.
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