Structures of two crystal forms of the host-guest complex between trans-3,3'-bis(diphenylhydroxymethyl)azobenzene and acetone

The macro properties of crystalline inclusion compounds depend on their structures. Their thermal stabilities are a function of the strength and the directionality of the various nonbonded interactions occurring in the host-guest assembly. Their lattice energies, as measured by the method of atom-atom potentials, correlate with the thermodynamics of the guest-release reactions and the selectivity that a given host displays for a particular guest. The kinetics of solid-host:vapor-guest reactions and of guest exchange are important in our understanding of catalytic processes. Crystal engineering, in which materials of predetermined properties may be synthesized, is still at the empirical stage.

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“…A number of examples illustrating this phenomenon have appeared in the recent literature. [27][28][29][30]…”

Section: It May Partially Decompose To Yield a New γ-Phasementioning

confidence: 99%

Physicochemical Aspects of Host−Guest Compounds

2003

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“…Previous reports have appeared detailing the possibility of growing inclusion compounds with various host:guest ratios by changing the crystallization temperature. [2][3][4] This technique has also been employed to control the selectivity of isomers of xylene by a dicarboxylic host. 5 We now present the results of variable-temperature crystallization experiments carried out on inclusion compounds formed between the host, H = 2,2'-dihydroxy-1,1'-binaphthyl, and the guest, G = 1,4-dioxane.…”

Section: Introductionmentioning

confidence: 99%

Controlled host:guest ratio in an inclusion compound

Nassimbeni

2000

J. Phys. Org. Chem.

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Drastic Increase in the Flexibility of Open Host Frameworks of a Steroidal Host Compound upon Shortening Its Spacer

et al. 2004

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Nordeoxycholic acid (NDCA), which has a shorter side chain than the steroidal host compound, deoxycholic acid (DCA), forms inclusion crystals with various organic substances at 1:1 or 2:1 host−guest ratios. X‐ray crystallographic studies reveal that four types of host frameworks (bilayer, monolayer, tape, and hexagonal) are generated by NDCA, in stark contrast to the robust and dominant bilayer frameworks formed from DCA, although they have the same functional groups capable of hydrogen bonding. The first three host frameworks are further divided into three, two, and four sub‐types by arrangements of the hydrogen‐bonded host columns, tapes, or layers, respectively. A total of nine types of open host frameworks are observed depending on the nature of the guest compounds. The sizes of the guest compounds induce isomerization of these host frameworks having molecular cavities, which is rationalized by the range of values of PCcavity, which are ratios of the volumes between the guest compound and the host cavities. Such a drastic increase of flexibility of the open host framework by the slight chemical modification from DCA to NDCA deserves attention with respect to crystal engineering. Unique 21 helical assemblies of DCA are linked by the carboxyl group at the side chain to form a robust sheet‐like structural motif. In NDCA, on the other hand, the linkage between the helices becomes impossible because of the shortening of the side chain’s length, which results in destruction of the sheet‐like motif to yield renewed molecular voids among the unique 21 helical assemblies. These remarkable differences in the flexibility of the open host frameworks provide us with a possible strategy for designing of new host compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Structures of two crystal forms of the host-guest complex between trans-3,3'-bis(diphenylhydroxymethyl)azobenzene and acetone

Cited by 8 publications

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Physicochemical Aspects of Host−Guest Compounds

Physicochemical Aspects of Host−Guest Compounds

Controlled host:guest ratio in an inclusion compound

Drastic Increase in the Flexibility of Open Host Frameworks of a Steroidal Host Compound upon Shortening Its Spacer

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