Gases, molecular recognition

The study of the interactions between organic compounds and aUtali-metal cations, in the gas phase, is related to many topics such as ion solvation, catalysis and molecular recognition. Furthermore, mass spectrometry has been used for the analyses of organolithium compounds and supramolecular assemblies that contain lithium cations. Alkali cationization is an important ionization technique, implemented for the analyses of a wide range of organic compounds. Finally, gas-phase studies are also useful for the quantitative determination of lithium cation affinity. The interaction between lithium cation and organic substances is thus related to different aspects of gas-phase chemistry and mass spectrometry. 

The all-important finding that carboxylate-appended sapphyrins can self-assem-ble was confirmed in the case of the sapphyrin monocarboxylate 6. ° For both compounds the self-assembly phenomena were shown to take place not only in the solid state, but also in solution and in the gas phase (see Section 3.3). This meant that the carboxylate-binding properties of the sapphyrins could be used as the key molecular recognition basis for engendering the spontaneous self-assembly of appropriately designed supramolecular ensembles. 

C.A. Schalley, Supramolecular chemistry goes gas phase The mass spectrometric examination of non-covalent interactions in host-guest chemistry and molecular recognition. Int. J. Mass Spectrom. 11, 11-39 (2000)... 

R. Abuja, P.L. Caruso, D. Mdbius, W. Paulus, H. Ringsdorf, G.G. Wildbimg, Formation of Molecular Strands by Hydrogen-Bonds at the Gas-Water Interface - Molecular Recognition and Quantitative Hydrolysis of Barbitm-ic Acid Lipids , Angew. Chem. Int. Ed., 32, 1033 (1993)... 

A host-guest molecular recognition process of L-tryptophan, with the above various triangular, bowl-shaped Cp Rh-nucleobase/nucleoside/nucleotide cyclic trimer molecular receptors, was also detected in a gas phase by electrospray ionization mass spectrometry.In this case, the supramolecular complex formation was found to occur predominately via non-covalent tt-tt interactions non-covalent hydrophobic forces apparently being weak or nonexistent. Trp-Met-Asp-Phe tetrapeptide with the trimeric-rhodium host [Cp Rh(2 -deoxyadenosine)]3[OTf]3 also formed a host-guest complex in water that is detected in the gas phase. 

Legon AC, Millen DJ (1993) Molecular recognition involving small gas-phase molecules. In Buckingham AD, Legon AC, Roberts SM (eds) Principles of molecular recognition. Blackie, London, pl7... 

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