Nonlinear structure - Affinity relationships for vapor guest inclusion by solid calixarenes

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: ΔGtrans (kJ mol-1) = -12.24 + 0.568MRD (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

Morphogenesis in Vitro in Maize Inbred Lines from the Lancaster Heterotic Group

The genotypic specificities of morphogenesis and regeneration have been studied in vitro in five maize inbred lines from the breeding-promising Lancaster heterotic group, compared with the representatives of other heterotic groups, that is, PLS61, A188, and Chi31. It has been shown that the ratio between the types of morphogenesis, such as organogenesis and embryoidogenesis, in a callus culture is predetermined by the explant genotype and sucrose concentrations in the medium for callusogenesis. The frequency of embryoidogenesis as the most efficient type of morphogenesis, considering further regeneration, was, on average, 40.0 ± 12.8% for maize inbreds from the Lancaster heterotic group and only 14.0 ± 4.0% from other heterotic groups. A sucrose concentration at a level of 30 g/L in the medium for callusogenesis further supported the process of regeneration through embryoidogenesis in inbreds of the Lancaster heterotic group at a level of 26.5 ± 15.4%, while the sucrose concentration of 60 g/L promoted regeneration up to a level of 57.7± 19.8%. Contents of sucrose in the medium for callusogenesis in the inbreds representing other heterotic groups did not affect the process of regeneration, and the level of embryoidogenesis with sucrose at the concentrations of 30 and 60 g/L was, respectively, 11.0 ± 7.0 and 15.0 ± 4.8%

Nonlinear structure - Affinity relationships for vapor guest inclusion by solid calixarenes

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: ΔGtrans (kJ mol-1) = -12.24 + 0.568MRD (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

Nonlinear structure - Affinity relationships for vapor guest inclusion by solid calixarenes

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: ΔGtrans (kJ mol-1) = -12.24 + 0.568MRD (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