Guanidinium amphiphile

Kunitake and coworkers experimentally investigated the effect of interface size on molecular recognition efficiency with a guanidinium-phosphate interaction (Fig. 2.4). Binding constants of aqueous phosphates such as adenosine monophosphate (AMP) to a monolayer of a guanidinium amphiphile were determined to be in the range of 106... 

The de Mendoza group synthesized caUx[4]arene 34 (Figure 13). This supramolecular host is a highly structured amphiphile it presents four cationic guanidinium... 

Lu et al. used calix[4]arene derivatives with two ammonium (25) or guanidinium functionalities (26) at opposite sides of the lower rim to form stable monolayers. Inside the layer the amphiphiles are orientated orthogonal to the air-water interface (Fig. 24.10). With their cationic moieties immersed in the water phase the calixarene derivatives are able to recognize nucleotides in the subphase. The properties of the monolayer along with the recognition potential for 5 -AMP and 5 -GMP were analyzed at the film balance by means of surface pressure-area tz-A) isotherms and relaxation experiments as well as UV, CD, TR-IR spectra and X-ray photoelectron spectra. Due to their strong molecular interactions nucleotides can even be transferred onto solid substrates along with the monolayers. The... 

In seeking to realise this notion, we chose carboxylates as substrates for two reasons. Firstly, we could avail of the well-known carboxylate-guanidinium recognition motif, as in 11, to establish and dominate complex formation.Secondly, the amphiphilic nature of carboxylates allowed us to aim for enantioselective phase transfer, an easy phenomenon to detect and potentially very useful for the large scale resolution of racemates. ... 

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