Solid-state inclusion complexes

Solid-state inclusion complexes of parent calixarenes with neutral molecules... 

Clathrate A solid-state inclusion complex where the guest is held in a cavity, or channel in the crystal lattice of the host. A clathrate is destroyed when the crystal is dissolved. 

The work reported here has shown that inclusion complexation of organic and organometallic chromophores by thiourea, TOT and cyclodextrins can induce second harmonic generation capability in the polar crystals which result, even when the original bulk materials are themselves incapable of SHG. Structural evidence has been presented to show tht the solid state inclusion structures are acentric, and a simple electronic picture t0 the polarization response of these materials within the two-state modeP ° has been discussed. In an earlier section we remarked that of the many complexes we have made, only one has NOT been acentric. This result was not anticipated. We postulate that it is a natural tendancy in such materials, rather that an exception. If we consider a dipolar molecule in isotropic solution, we can imagine that if it were to aggregate, it would do so in a head to tail fashion in order to minimize electrostatic repulsion. The situation is illustrated in Scheme 3. The arrangement that would result is centrosymmetric. 

Cyclotriveratrylene is a trimeric, bowl-shaped molecular skeleton, known to form solid-state inclusion compounds. A variety of cyclotriveratrylene derivatives, e.g. 96 and 97, resulted from r-complexation of the aromatic nuclei with one, two, or three Ru( / -arene) (arene = CeHe, p-MeC6H4Pr ) and Ir( -C5Me5) organometallic moieties [195-197], Some of their structures were established by X-ray diffraction. 

Walliman, P., Mattel, S., Seiler, P. Diederich, F. (1997) New cyclophanes as initiator cores for the construction of dendritic receptors Host-guest complexation in aqueous solutions and structures of solid-state inclusion compounds, Helv. Chim. Acta, 80, 2368-2390. 

Potrzebowski MJ, Kazmierski S (2005) High-Resolution Solid-State NMR Studies of Inclusion Complexes. 246 91-140 Poulin P, see Loudet JC (2003) 226 173-196 Raghuraman K, see Katti KV (2003) 229 121-141... 

A regio- and stereoselective Beckmann rearrangement utilized diastereose-lective host guest interactions of the inclusion complexes 225 and 228 in a solid state reaction. Initially, a 1 1 mixture of the chiral host 223 and the racemic oximes 224 and 227, respectively, was treated with ultra sound in the solid state to induce the optical resolution. Then H2SO4 was added to start the Beckmann rearrangement, the corresponding c-caprolactams 226 and 229 were isolated in 68 % and 64 % yields and ee of about 80 % and 69 % (determined by HPLC analysis on chiracel OC) (Scheme 43) [46]. 

When a solution of 10a and 11 in ether was kept at room temperature for 12 h, a 2 1 inclusion complex of 10a and 11 was obtained as colorless prisms (m.p. 134-137 °C) in 72% yield. When a powdered mixture of the inclusion crystal and 7 was kept at room temperature in the solid state for 3 days, (+)-trans-1,2-dibromocyclohexane (12) of 12% ee was obtained in 56% yield by distillation of the reaction mixture [3]. Much more efficient enantioselective reactions in the solid state are described in Sect. 6. 

Enantioselective Br2 addition to cyclohexene (11) was accomplished by the solid-state reaction of a 2 1 inclusion complex of 10b and 11 with 7, although the optical yield was low (Sect. 2.1). However, some successful enantioselective solid-state reactions have been reported. For example, reaction of a 1 1 complex of 68 and acetophenone (64a) with borane-ethylenediamine complex (130) in the solid state gave the (i )-(+)-2-hydroxyethylbenzene (65a) of 44% ee in 96%... 

An enantioselective Michael addition reaction was also accomplished in an inclusion complex with a chiral host compound. Treatment of a 1 1 complex of 10c and 66b with 2-mercaptopyridine (137) in the solid state gave (+)-138 of 80% ee in 51% yield. By a similar method, 3-methyl-3-buten-2-one (139) gave (+)-140 of 49% ee in 76% yield [30]. 

By way of contrast, irradiation for 6 h in the solid state of the 1 2 inclusion complex 12a composed of 1 and 11a which has been prepared by recrystallization of the two components from a solvent gave the syn-head-to-tail dimer 13a selectively in 90% yield 7,8>. Similar irradiation of the 1 2 inclusion complexes 12b-12d composed of 1... 

Table 2. Reaction time, products, and yields of photocycloaddition reactions of inclusion complexes involving 11,17, and 21 in the solid state...

The freeze of equilibrium by the complexation method is also applicable to some other compounds. 2-Mercapto substituted tropone 32 has been reported to exist as an equilibrium mixture of 2-mercaptotropone (32 a) and 2-hydroxytropothione (32 b), and the latter is predominant both in solution 17) and in the solid state 18). The equilibrium is frozen and the former was isolated by inclusion complexation with 1. When a solution of 1 and 32 in petrol ether was kept, a 1 1 complex 33 composed of 1 and 32a was obtained in 90% yield as orange prisms of mp 101 to 103 °C19). The structure of 32a in 33 was elucidated by IR spectroscopy which showed vSH at 2482 cm-1 33 gave also absorptions of a strongly hydrogen-bonded hydroxyl group at 3270 cm 1. 

An enantioselective photoreaction of a guest compound is expected when an inclusion complex of the guest with an optically active host compound is irradiated in the solid state. 

When 8 a is used instead of 2a for complexation with 50a, two kinds of 1 1 inclusion complexes 57 were obtained one (57a) is photoreactive and the other (57b) is photostable. Thus when a solution of 8a and an equimolar amount of 50a in benzene was kept at room temperature for 10 h, a 1 1 inclusion complex between both (57a) was obtained as colorless fine needles of mp 110 to 123 °C which upon irradiation in the solid state for 49 h gave (1 R,5S)-(+)-52a of 3.6% ee in 30% yield 13). However, recrystallization of 57a from benzene gave a different kind of 1 1 inclusion complex (57b) as colorless needles of mp 123-125 °C which is photostable. Photocyclization of 50a in 57b is probably prevented by a steric hindrance. The different behavior of 57a and 57b may be clarified in future by X-ray structural studies. 

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