Inclusion with Mixed Guests: Structure and Selectivity

Abstract

The structures of the inclusion compounds formed by the host 9-(2-naphthyl)-9H-xanthen-9-ol (H) with 1,4-dioxane (DIOX), cyclohexanol (CYOL), and cyclohexanone (CYONE) have been elucidated. The selectivity profile of the host with respect to the guest pairs dioxane/cyclohexanol and dioxane/cyclohexanone have been analyzed, as well as the mixed guest compound H·½DIOX·1CYONE. Thermal analysis and kinetics of desorption of these inclusion compounds have been performed and correlated with the structures.

Concomitant Metal Organic Frameworks of Cobalt(II) and 3-(4-Pyridyl)benzoate: Optimized Synthetic Conditions of Solvatochromic and Thermochromic Systems

“…previously reported in the literature, where activation energies are reported over the range 75 -160 kJ mol -1 . [44][45][46] Furthermore, the values of the activation energy obtained for the desorption of DMF for 1 and 2 concur with the conclusions drawn from the thermal analyses and the features of the crystal networks whereby the DMF molecules were described as tightly held inside the framework of 1 while those entrapped in the framework of 2 were held more loosely as a result of the 2D-layers which may glide past one another. The compound 1d was obtained after heating 1 at 150 ºC for 10 h under vacuum.…”

Concomitant formation of two different solvates of a hexa-host from a binary mixture of solvents

“…In a recent report by Nassimbeni et al, it was shown that the solvates obtained by crystallization of a particular host from a binary mixture of solvents depend on the nature and relative proportions of the solvents. 13 Apart from this passing reference to the concomitant occurrence of mixed crystals of solvates, there is, to the best of our knowledge, no other report of this phenomenon.…”

“…The separated concomitant solvates were analyzed by NMR spectroscopy for further confirmation of different solvent inclusion by 1. 13 C NMR spectra show the characteristic peaks of the methyl carbon atoms of methanol and acetonitrile at 49.3 ppm and 1.87 ppm, respectively (see ESIw). The cyano carbon atom of acetonitrile is confirmed by a peak at 118.7 ppm.…”

Selectivity by benzopinacol

“…in which the host H, generally a solid, is dissolved in a liquid guest G, or is exposed to the vapour of the guest, and yields an inclusion compound which crystallises with the guest : host stoichiometry n. A quantitative measure of the molecular recognition may be obtained by measuring the equilibrium constant of this reaction, but in the case where the product is a solid, this is experimentally laborious, in that it requires accurate measurement of the solubility of the solid inclusion compound in the mother liquor. 1 When the host is exposed to two or more guests then the thermodynamic selectivity is defined as the ratio of the equilibrium constants, 2 and selectivity may be regarded as a differential form of molecular recognition. In order to monitor this, we have adopted the concept of a selectivity coefficient K A : B first propounded by Ward 3 and defined as:…”

“…4 Various selectivity curves may arise, depending on whether one guest is preferred over the other over the whole mixture composition range, or whether the selectivity is concentration dependent. 1 The overall aim of such experiments is to rationalise the selectivity profiles with other parameters, such as specific molecular properties of the guests, the structures of the inclusion compounds formed, their lattice energies and their solubilities. We now present the results of the selectivity by the host 1,1,2, 2-tetraphenylethane-1,2-diol, H, for tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylacetamide (DMA).…”