Cation-pi interactions play an important role in biology. The title compounds are C3-symmetric macrotricycles built from resorcinol, a pi electron-rich arene. They were prepared in up to 18% yield by intramolecular cyclization of 1,3,5-trisubstituted benzene tripods bearing pendant resorcinol groups, with methylene acetal bridges. Positive ESI-MS showed that these receptors recognize NH4+ over K+, and poorly respond to the large t-BuNH3+ cation, suggesting that they bind NH4+ intramolecularly, presumably via cation-pi interactions.

A theoretical description and an experimental validation of the application of a microfluidic chip with high‐velocity stratified flows for determining chemical kinetics for liquid‐liquid extraction are presented. In the case of uranium extraction under PUREX (plutonium and uranium refining by extraction) process conditions, a simple theoretical model demonstrates the need for high velocities and short residence times of around 10 ms. Confocal microscopy observations of the interface were undertaken to insure the flow stability at such high velocities, and the same experimental protocol was carried out to uranium(VI) extraction at two concentrations. Results show an unexpected variation in the phase homogenization depending on the uranium concentration of the extracted phase.

Palladium isolation and refining through solvent extraction suffer from limited stability of commercial reagents or limited availability of robust reagents in nitrate media. Several performing extraction solvents based on diamide reagents have been proposed, but their preparation requires synthetic chemistry skills. In the present work, we propose the use of readily accessible N,N,N',N'-tetrahexylmalonamide (THMA). This reagent revealed superior distribution ratios and selectivity in comparison with previously used diamides for palladium(II) extraction from nitrate media in the frame of palladium recovery from waste. Furthermore, the benefit of excess dihexylamine (DHA) employed during the preparation of THMA was demonstrated through a gain in kinetics performance. Detailed analysis enabled to determine the best performing formulation of extraction solvent, which can be readily prepared from commercially available chemicals without any complex synthesis procedure nor purification step.

Molecular recognition between receptor and substrate is optimized when these compounds show complementary shapes, sizes, and interacting moieties. A family of C 3v -symmetric macrotricycles 1-4 is presented that incorporate resorcinol-and mesitylene-derived "walls" and "cap", respectively. These compounds feature, in principle, a tetrahedral π-basic cavity. This paper reports the effect of substituents in

Significance: In an investigation into the effect of substituents on molecular shape, the authors extend the family of C 3v -symmetric macrotricycles from 9,10 to include 7 and 8. Whereas 7 displays a spherical tetrahedral shape, 8 takes up an elongated/cylindrical tetrahedral shape. Surprisingly, bulky heteroatomic substitution at the lower position of the 'walls' by Br (7) and MeS (8) result in the same shape as persubstitution of the mesitylenederived 'cap' 8.Comment: It was noticed that despite the apparent significant differences between the spherical and cyclindrical tetrahedral structures, they both displayed a selective binding affinity (ESI-MS) for NH 4 + over K + in the gas phase. OH HO OH OH OH HO R 1 MOMO OMOM SH Br Br Br 7 R 1 = Br, R 2 = H 8 R 1 = MeS, R 2 = H 3 R 1 = Br, R 2 = MOM 4 R 1 = MeS, R 2 = MOM a b c Reagents and conditions: a) NaH, THF, 79% yield for 3 , 100% yield for 4 ; b) PTSA, CH 2 Cl 2 -MeOH, 87% yield for 5 , 100% yield for 6 ; c) CH 2 Br 2 , Cs 2 CO 3 , DMF, 60 °C, 4.8% yield for 7 , 6% yield for 8 . 5 R 1 = Br, R 2 = H 6 R 1 = MeS, R 2 = H 2 1 S R