Selective preparation of beta-cyclodextrin clathrates by solid-phase exchange of included tetrahydrofurane for volatile guests in absence of water

© 2014 Akadémiai Kiadó, Budapest, Hungary. Solid-phase guest-exchange products, prepared from dehydrated clathrate of beta-cyclodextrin (bCD) with tetrahydrofurane (THF) by its saturation with vapor of second guest, were studied using thermal analysis by thermogravimetry combined with mass-spectrometric detection of evolved vapors. This guest-exchange procedure was found to be effective for inclusion of volatile guests, which otherwise require a difficult optimization of preparation conditions. Besides, a performed solid-phase exchange without liquid/solid-phase contact is a standard, technologically friendly procedure of clathrate preparation, which does not require further drying to provide an end product. An observed exchange of THF in the absence of water is rather selective, with some hydrophobic guests being unable to replace THF in its dried clathrate with bCD. This selectivity together with low toxicity of THF may be an advantage for practical applications of this guest-exchange method

Using water-mimic organic compounds to activate guest inclusion by initially dry beta-cyclodextrin

© 2016 The Royal Society of Chemistry.Optimal conditions were found enabling anhydrous beta-cyclodextrin (bCD) to include target guests using small monofunctional organic compounds instead of water. Structural criteria were specified for organic substances with such water-mimic behavior. For this, a thermodynamic description of guest and water inclusion by initially dry bCD in binary systems was given using experimentally determined vapor sorption isotherms. These data perform a cooperative inclusion of each water-mimic guest and water with phase transition, and give the values of inclusion and hydration Gibbs energy, respectively. The observed inclusion cooperativity in binary systems with bCD defines a specific size-exclusion effect banning monofunctional organic compounds from entering the dry bCD phase if they exceed a threshold value of molecular size parameter near that of acetone. For larger guests, this threshold was shown to be removed in ternary systems by simultaneous inclusion with water-mimic guests or by solid-phase exchange of such guests. As well as water, water-mimic organic compounds activate the inclusion of target guests by initially dry bCD just by forming ternary clathrates, thus making all other hypotheses on the role of water and its mimics in this inclusion process excessive. These procedures may be useful for practical purposes when the presence of water does not give good results in clathrate preparation with bCD. This may provide a way for developing new techniques for the preparation of beta-cyclodextrin clathrates with various organic compounds

Liquid silyl derivative of beta-cyclodextrin

© ISUCT Publishing. Per-6-O-(tert-butyl)(diphenyl)silyl-β-cyclodextrin was found to form metastable liquid phase, which is unusual for cyclodextrin mono-derivatives under ambient conditions. Also, it can exist in a solid amorphous state as a stable molecular glass. Conditions and parameters of phase transitions between crystal, glassy and liquid forms were determined. The studied compound is soluble in various solvents. Crystallization from its solutions and overcooled melt results in formation of two different polymorphs. The liquid mono-derivative of beta-cyclodextrin is amphiphilic and preferable for application in solutions, in pure form or even as a solvent for substrates with various structures

Selective preparation of beta-cyclodextrin clathrates by solid-phase exchange of included tetrahydrofurane for volatile guests in absence of water

© 2014 Akadémiai Kiadó, Budapest, Hungary. Solid-phase guest-exchange products, prepared from dehydrated clathrate of beta-cyclodextrin (bCD) with tetrahydrofurane (THF) by its saturation with vapor of second guest, were studied using thermal analysis by thermogravimetry combined with mass-spectrometric detection of evolved vapors. This guest-exchange procedure was found to be effective for inclusion of volatile guests, which otherwise require a difficult optimization of preparation conditions. Besides, a performed solid-phase exchange without liquid/solid-phase contact is a standard, technologically friendly procedure of clathrate preparation, which does not require further drying to provide an end product. An observed exchange of THF in the absence of water is rather selective, with some hydrophobic guests being unable to replace THF in its dried clathrate with bCD. This selectivity together with low toxicity of THF may be an advantage for practical applications of this guest-exchange method

Selective preparation of beta-cyclodextrin clathrates by solid-phase exchange of included tetrahydrofurane for volatile guests in absence of water

© 2014 Akadémiai Kiadó, Budapest, Hungary. Solid-phase guest-exchange products, prepared from dehydrated clathrate of beta-cyclodextrin (bCD) with tetrahydrofurane (THF) by its saturation with vapor of second guest, were studied using thermal analysis by thermogravimetry combined with mass-spectrometric detection of evolved vapors. This guest-exchange procedure was found to be effective for inclusion of volatile guests, which otherwise require a difficult optimization of preparation conditions. Besides, a performed solid-phase exchange without liquid/solid-phase contact is a standard, technologically friendly procedure of clathrate preparation, which does not require further drying to provide an end product. An observed exchange of THF in the absence of water is rather selective, with some hydrophobic guests being unable to replace THF in its dried clathrate with bCD. This selectivity together with low toxicity of THF may be an advantage for practical applications of this guest-exchange method

Selective preparation of beta-cyclodextrin clathrates by solid-phase exchange of included tetrahydrofurane for volatile guests in absence of water

© 2014 Akadémiai Kiadó, Budapest, Hungary. Solid-phase guest-exchange products, prepared from dehydrated clathrate of beta-cyclodextrin (bCD) with tetrahydrofurane (THF) by its saturation with vapor of second guest, were studied using thermal analysis by thermogravimetry combined with mass-spectrometric detection of evolved vapors. This guest-exchange procedure was found to be effective for inclusion of volatile guests, which otherwise require a difficult optimization of preparation conditions. Besides, a performed solid-phase exchange without liquid/solid-phase contact is a standard, technologically friendly procedure of clathrate preparation, which does not require further drying to provide an end product. An observed exchange of THF in the absence of water is rather selective, with some hydrophobic guests being unable to replace THF in its dried clathrate with bCD. This selectivity together with low toxicity of THF may be an advantage for practical applications of this guest-exchange method

Smart Molecular Recognition: From Key-to-Lock Principle to Memory-Based Selectivity

© Copyright © 2020 Gatiatulin, Ziganshin and Gorbatchuk. The formation and decomposition of inclusion compounds with a solid-solid phase transition may be very selective to the guest molecular structure. This selectivity may function in essentially different ways than defined by the classical concept of molecular recognition, which implies the preferential binding of complementary molecules. Solid inclusion compounds may take part as an initial or/and final state in several processes of different types summarized in this review, which selectivity is boosted by cooperativity of participating molecular crystals. Some of these processes resemble switching electronic devices and can be called smart giving practically absolute molecular recognition

Nonlinear effect of two remembered guests in their mixtures on the host memory for guest inclusion and release

© 2016, Akadémiai Kiadó, Budapest, Hungary.Selective memory for volatile guests after their inclusion and removal is a smart property of calixarenes, which are capable to form metastable polymorphs. This property is practically unpredictable, particularly for guest mixtures. In the present work, the mutual influence of the two guests in their binary mixture on this effect for tert-butylcalix[6]arene was studied. The first example was found for an ability of two guests, benzene and tetrachloromethane, which can be remembered separately in binary host–guest systems, to erase the host memory to each of them forming a ternary clathrate with a much higher thermal stability than corresponding binary clathrates. Prepared mixed inclusion compounds perform a unique ability for fractional guest release on the separate steps of clathrate decomposition, which may be used for separation of pure volatile compounds from their mixtures. The clathrates were characterized by TG–DSC method combined with mass-spectrometric analysis of the evolved guest vapors and by X-ray powder diffractometry

Nonlinear effect of two remembered guests in their mixtures on the host memory for guest inclusion and release

© 2016 Akadémiai Kiadó, Budapest, HungarySelective memory for volatile guests after their inclusion and removal is a smart property of calixarenes, which are capable to form metastable polymorphs. This property is practically unpredictable, particularly for guest mixtures. In the present work, the mutual influence of the two guests in their binary mixture on this effect for tert-butylcalix[6]arene was studied. The first example was found for an ability of two guests, benzene and tetrachloromethane, which can be remembered separately in binary host–guest systems, to erase the host memory to each of them forming a ternary clathrate with a much higher thermal stability than corresponding binary clathrates. Prepared mixed inclusion compounds perform a unique ability for fractional guest release on the separate steps of clathrate decomposition, which may be used for separation of pure volatile compounds from their mixtures. The clathrates were characterized by TG–DSC method combined with mass-spectrometric analysis of the evolved guest vapors and by X-ray powder diffractometry

Nonlinear effect of two remembered guests in their mixtures on the host memory for guest inclusion and release

© 2016, Akadémiai Kiadó, Budapest, Hungary.Selective memory for volatile guests after their inclusion and removal is a smart property of calixarenes, which are capable to form metastable polymorphs. This property is practically unpredictable, particularly for guest mixtures. In the present work, the mutual influence of the two guests in their binary mixture on this effect for tert-butylcalix[6]arene was studied. The first example was found for an ability of two guests, benzene and tetrachloromethane, which can be remembered separately in binary host–guest systems, to erase the host memory to each of them forming a ternary clathrate with a much higher thermal stability than corresponding binary clathrates. Prepared mixed inclusion compounds perform a unique ability for fractional guest release on the separate steps of clathrate decomposition, which may be used for separation of pure volatile compounds from their mixtures. The clathrates were characterized by TG–DSC method combined with mass-spectrometric analysis of the evolved guest vapors and by X-ray powder diffractometry