Nonlinear Structure−Affinity Relationships for Vapor Guest Inclusion by Solid Calixarenes

Abstract

The structure-affinity relationships were studied for the guest inclusion parameters of solid tert-butylthiacalix-[4]arene (1) and tert-butylcalix [4]arene (2). The inclusion stoichiometry and inclusion free energy were calculated by the sorption isotherms obtained for guest vapor-solid host systems by the static method of headspace gas chromatographic analysis at 298 K. The obtained sorption isotherms have an inclusion threshold for guest thermodynamic activity corresponding to the phase transition between the initial host phase and the phase of inclusion compound. Unlike tert-butylcalix [4]arene, its thia analogue having a larger molecular bowl is able to bind only initial members of each studied homological series. All inclusion compounds of 1 formed upon host saturation by guest vapors have the same 1:1 stoichiometry, while for 2 the inclusion stoichiometry depends on the guest molecular size. A linear correlation between the inclusion free energy (standard state: infinitely dilute guest solution in toluene) and the guest size parameter (molar refraction) was observed for 1: ∆G trans (kJ mol -1 ) ) -12.24 + 0.568MR D (n ) 7, r ) 0.972, RSD ) 0.6). This correlation is regarded as a part of the V-like structure-affinity relationship with a minimum for a guest that is complementary to the host cavity.

Configuration effect of the tert-butylthiacalix[4]arene tetracarboxy derivative on its receptor properties toward vaporous organic compounds

“…Vaporous EtOH is not bound by solid calixarene 4. 7 Similarly to that observed earlier for calixarene 4, the sorption isotherms obtained for methanol and ethanol vapors sorbed by calixarenes 1-3 have the threshold of guest binding by its thermodynamic activity P/P 0 , below which the sorption of the guest is absent or insignificant. When the activity of the guest reaches the threshold value, the cooperative increase in sorption is observed, and further the sorption isotherm achieves saturation corre sponding to the formation of stoichiometric inclusion compounds.…”

“…For comparison we also studied tert butyl thiacalix [4]arene (4), which cannot form intermolecular hydrogen bonds with such proton acceptors as alcohols, nitriles, and ketones. 7 The type of stable conformation (configuration) of the macrocycle is the structural parameter affecting the clathrate forming properties of calixarenes 8 along with the type of substituents, 9,10 the size of the macrocycle, 11 and the type of bridges between units of the calixarene macrocycle. 7 The effect of the type of stable conforma tion of calixarenes on their acceptor properties toward guest vapors have not been studied earlier.…”

Chemistry of Thiacalixarenes

“…The structureaffinity relationships for guest inclusion within solid 2 were studied for a vapour guest-solid host system using headspace gas chromatographic analysis. [91] Scheme 14. The complexation of DABCO Recently, interesting differences in the behaviour of classical-and/or thiacalixarene-based metalloporphyrin conjugates have been observed.…”

Specific vapor sorption properties of phosphorus-containing dendrimers

“…The observed selectivity variation characterizes a molecular recognition ability of the studied receptor when using a suitable standard state [20][21][22].…”