Inclusion formation

Fig. 4. Chiroselective inclusion formation of racemic l-phenylethylammonium salt ((R/S)-14) using optically active crown compound ((i, 5)-13) [53955-48-9]. The diastereomeric inclusion complex (R)-(14) is more stable than (3, 3)-(13)-(3)-(14) (top views, dotted lines represent hydrogen...

The formation of such materials may be monitored by several techniques. One of the most useful methods is and C-nmr spectroscopy where stable complexes in solution may give rise to characteristic shifts of signals relative to the uncomplexed species (43). Solution nmr spectroscopy has also been used to detect the presence of soHd inclusion compound (after dissolution) and to determine composition (host guest ratio) of the material. Infrared spectroscopy (126) and combustion analysis are further methods to study inclusion formation. For general screening purposes of soHd inclusion stmctures, the x-ray powder diffraction method is suitable (123). However, if detailed stmctures are requited, the single crystal x-ray diffraction method (127) has to be used. 

Selection at inclusion formation (see relative guest excess) is derived from steric as well as from chemical points of view. Hence, high discrimination is found for a combination of potential solvents differing in the functional group characteristic, e.g. if belonging to different classes of substances (see Entries 8-10). But also within the same class of substance, so far as a series of homologues and different substituted or branched compounds are concerned, discrimination is effected in up to a 90% ratio 33). 

Considering the competitive experiments, e.g. from two-component solvent mixtures (see Table 4), it is not surprising that the amines are always favored on inclusion formation (Entries 1—5). A remarkable point is also the ability of 13, properly speaking its crystal lattice, to accommodate relatively voluminous guest molecules, among them many ring compounds (Tables 3 and 4). Hence, 1 and 13 are complementary in their inclusion behavior to some extent. 

Changing of the flexible scissor-like element, as in 7, to an orthogonal and rigid version of this element, as in 22, reduces the activity of inclusion formation to a certain degree. Nevertheless very different guest molecules are readily accommodated in the crystal lattice of 22, they are proton donors (ethanol, 2-propanol) 47, H-bridge acceptors (dimethylformamide, dioxane), or benzene as an unpolar solvent48 ... 

Likewise it is possible to differentiate between substituted and unsubstituted alicycles using inclusion formation with 47 and 48 only the unbranched hydrocarbons are accommodated into the crystal lattices of 47 and 48 (e.g. separation of cyclohexane from methylcyclohexane, or of cyclopentane from methylcyclopentane). This holds also for cycloalkenes (cf. cyclohexene/methylcyclohexene), but not for benzene and its derivatives. Yet, in the latter case no arbitrary number of substituents (methyl groups) and nor any position of the attached substituents at the aromatic nucleus is tolerated on inclusion formation with 46, 47, and 48, dependent on the host molecule (Tables 7 and 8). This opens interesting separation procedures for analytical purposes, for instance the distinction between benzene and toluene or in the field of the isomeric xylenes. 

The hydrocarbons 54 and 5551) which are functional group-free analogues of 26 and 38 display no activities of inclusion formation, either with polar or with apolar solvents371. This result is another proof that mostly for the roof-shaped type of compounds, functional groups play a fundamental role in the construction of a low-density packed crystal lattice. 

In contrast to 1, the related pure host 7 may be obtained in crystalline form 68). The crystal structure of 7 is built via helical chains of alternating intra- and inter-molecular H-bonding through the carboxyl functions. This structure supplies the information that the carboxyl groups are therefore already positioned in an appropriate way to facilitate analogous H-bonding in the known inclusions of 7. As discussed later (Sect. 4.2.2), these are exclusively salt-type associates and as such, intimately interact with the carboxyl groups. Hence one may infer that displacement of the carboxyl functions from position 2 in 1 to position 8 in 7 reduces the ability of inclusion formation. Similar reasons such as the solid-solubility differences observed in the classical naphthalene/chloronaphthalene systems (alpha- vs. beta-substituted derivatives, cf. Ref. 28 may also be applied here. 

Three distinct nebular phenomena can in principle contribute to the discordant Mg isotopic systematics late formation of individual anorthites followed by gentle compaction of B2 inclusions, selective secondary alteration of anorthites after inclusion formation, and initial heterogeneities in 26A1 similar to those observed in stable isotopes. The fact that data from anorthites in both B2 inclusions are used to construct the two new Al-Mg correlation lines suggests that whatever processes(es) or... 

In conjunction with studies performed by van Leeuwen et al. (135-138), Layfield et al. (263) proposed a novel mechanism that could account for an inhibition of 26S proteasome activity in cases of nonfamilial AD. Mutant forms of ubiquitin may inhibit proteolysis within neurons, predisposing these cells to inclusion formation. Molecular misreading of the UBB gene results in a dinucleotide deletion in UBB mRNA (135-138,264). In AD, an age-related posttranscriptional defect in primary transcript RNA processing may occur, leading to dinucleotide deletions within open reading frames that result in frameshifts and produce abnormal extension proteins, as demonstrated by van Leeuwen and coworkers (138). 

This interesting result strongly suggests that even for the substituted cyclodextrins the capacity of inclusion formation is much the same as for the parent cyclodextrin. Therefore, we may extend the basic concept of the structure of cyclodextrin inclusion to molecular design for the preparation of artificial enzymes having satisfactory substrate specificities and catalytic activities. 

Strong MJ, Gaytan-Garcia S, Jakowec DM. 1995. Reversibility of neurofilamentous inclusion formation following repeated sublethal intracistemal inoculums of A1C13 in New Zealand white rabbits. Acta Neuropathol 90 57-67. 

Tachibana M, Kiba N. Correlation between inclusion formation constant and distribution coefficient in a liquid-liquid extraction system consisting of hydrocarbon solvents and aqueous dimethyl sulfoxide solutions of (1-cyclodextrin. Analyst 1997 122 903-909. 

Smith WW, Margolis RL, Li X, Troncosco JC, Lee MK, et al. 2005. A-Synuclein phosphorylation enhances eosinophilic cytoplasmic inclusion formation in SH-SY5Y cells. J Neurosci 25 5544-5552. 

Box 18.2. Schematic Description of the Induced Fit Mechanism of a-Cyclodextrin Inclusion Formation... 

Chen L, Feany MB (2005) Alpha-synuclein phosphorylation controls neurotoxicity and inclusion formation in a Drosophila model of Parkinson disease. Nat Neurosci 8 657-663... 

Watson E. B. and Brenan J. M. (1987) Fluids in the lithosphere 1. Experimentally-determined wetting characteristics of CO2-H2O fluids and their implications for fluid transport, host-rock physical properties, and fluid inclusion formation. Earth Planet. Set Lett. 85, 497-515. 

Simultaneously with the Harada s report on the first polyrotaxane, Wenz reported the preparation of polyrotaxanes from polyamines and a-cyclodex-trin in an aqueous solution [108]. a-Cyclodextrin forms inclusion complexes with poly(iminoundecamethylene) and poly(iminotrimethylene-iminode-camethylene) (Scheme 17). The rates of the inclusion of poly(iminounde-camethylene) by a-cyclodextrin are slow on the H NMR time scale in D20 at pH<6. The inclusion formation between poly(iminotrimethylene-imin-odecamethylene) and a-cyclo dextrin took 170 h to reach equilibrium. Wenz... 

Minimal values Th-Tn for different samples are between 12 and 20°C. It is mean, that nucleation of vapour phase never observed before overcooling inclusion on 10°C (or smaller) below L-V equilibrium. At average slops of water isochors as 1.5-1.6 MPa per 1°C, it corresponds to nucleation pressures from -20 to -30 MPa. Last values are very similar to cavitation pressures, estimated by other methods (see review Herbert et. al., 2006). By other words, in some fluid inclusions formation of vapour phase begin at the same pressure (rate of tension) as in capillaries, optic or other cells, but in other inclusions with same water density the cavitation take place at much higher tension (larger values of Th-Tn). 

---