Supramolecular Materials: Molecular Packing of Tetranitrotetrapropoxycalix[4]arene in Highly Stable Films with Second-Order Nonlinear Optical Properties

✍ Scribed by Paul J. A. Kenis; Oscar F. J. Noordman; Holger Schönherr; Esther G. Kerver; Bianca H. M. Snellink-Ruël; Gerrit J. van Hummel; Sybolt Harkema; Cornelis P. J. M. van der Vorst; Jeff Hare; Stephen J. Picken; Johan F. J. Engbersen; Niek F. van Hulst; G. Julius Vancso; David N. Reinhoudt

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 396 KB
• Volume: 4
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/(sici)1521-3765(19980710)4:7<1225::aid-chem1225>3.0.co;2-6

✦ Synopsis

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 8C in a dc 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 ) and a pseudohexagonal lattice (d % 11.4 ). The combination of these data with the interlayer distance of 8.9 (X-ray diffraction) allowed the packing of molecules of 9 in these structures to be fully elucidated at the molecular level.