A new C(3v)-symmetrical calix[6]azacryptand, that is, calix[6]tmpa (11), was synthesized by efficient [1+1] macrocyclization reactions. Remarkably, both linear and convergent synthetic strategies that were applied lead to equally good overall yields. Calix[6]tmpa behaves as a single proton sponge and appeared reluctant to undergo polyprotonation, unlike classical tris(2-pyridylmethyl)amine (tmpa) derivatives. It also acts as a good host for ammonium ions. Interestingly, it strongly binds a sodium ion and a neutral guest molecule, such as a urea, an amide, or an alcohol, in a cooperative way. A (1)H NMR study indicated that the ligand, as well as its complexes, adopt a major flattened cone conformation that is the opposite of that observed with the previously reported calix[6]cryptands. Characterization of the monoprotonated derivative 11H(+) by X-ray diffraction also revealed the presence of a 1,3-alternate conformation, which is the first example of its kind in the calix[6]arene family. This conformer is probably also present in solution as a minor species. The important covalent constraint induced by the polyaromatic tmpa cap on the calixarene skeleton, and conversely from the calix core onto the tmpa moiety, is the likely basis for the unique conformational and chemical properties of this host.

Qualitative as well as quantitative information is obtained simultaneously by combining thermogravimetry and operando IR spectroscopy with on line mass spectrometry. A microbalance has been adapted to an infrared reactor cell. The weight and IR spectra of a solid sample can be measured together in real time in operando conditions, in a gas flow at temperature between room temperature and 773 K. Molar absorbance coefficients epsilons can be obtained directly. The new technique was first applied to adsorbed water and ammonia on a solid acid catalyst, HY zeolite. Epsilon coefficients for water bands were measured. They are influence by the hydration level, and the nu+delta combination band is shown to be a much better option to determine the amount of adsorbed water on zeolites. Epsilon has also been measured for ammonium ions, and water was shown to greatly influence the spectral response of these ions.