Abstract

The design and construction of artificial supramolecular architectures on surfaces is of great current interest and represents an important aspect of molecular self-assembly, because self-assembly offers highly ordered mesoscale structures with desired chemical functionalities and physical properties. The fabrication of polar molecular superstructures proves particularly challenging since polar molecular materials are essential to second-order nonlinear optical (NLO) technologies. Several approaches such as the Langmuir-Blodgett technique and liquid crystals have been reported to generate molecular-based materials with organized polar structures. However, the orientation in these materials is maintained by weak bonding or steric hindrance, which lose the polar alignment over time. Recent developments in self-assembly and host-guest chemistry offer a novel route to ordered materials through the design and synthesis of new molecular building blocks that can be organized into supramolecular assemblies. The synthetic approach here is to fix dipole orientation by structural interlocking of NLO chromophores into cone conformation, and then to utilize them to build polar self-assembled monolayers. In this report, we discuss the molecular design of calixarene-based, NLO molecular "pyramids", their monolayer self-assemblies on oxide surfaces, and their spectroscopic second order NLO properties.

© 1996 Optical Society of America