Molecular Recognition at a Monolayer Interface: 2,4-Diaminopyrimidine - Succinimide Host - Guest Partners

Molecular recognition at a 2,4-diaminopyrimidine terminated monolayer 1 (host) by a succinimide derivative (guest) has resulted in the formation of bilayers. The bilayers were prepared either from solution or by transfer from the air-water interface to the monolayer substrate. The preorganized 2,4-diaminopyrimidine is oriented for recognition with a molecule of complementary hydrogen bonding ability, succinimide 2. The resultant bilayer 3 is stabilized by the formation of three hydrogen bonds per host-guest pair. We present an example of a self-assembling process, wherein a relatively weak hydrogen bonding interaction (molecular recognition) leads to the formation of bilayers. The bilayer structures and the hydrogen bonding interactions were analyzed by external-reflection Fourier transform infrared spectroscopy (FTIR), ellipsometry, and X-ray photoelectron spectroscopy (XPS).