Intramolecular association

Most of the other compounds that have been studied usually have an oligomethylene bridge and have been studied by Dakternieks s group. They give tetradistannoxanes by intramolecular association examples of these compounds are given in Table 6, and more are to be found in Chandrasekhar s review.347... 

As a surfactant, ICG exists predominantly in a monomeric form at low concentrations (< 5 pM) but rapidly aggregates at higher concentrations (100 pM) [132]. Although administration of low ICG concentrations is preferred for in vivo applications in order to avoid aggregation, the rapid binding of ICG to plasma proteins prevents intramolecular association in vivo and may favor the use more concentrated ICG samples, if needed. 

Beak and Siegel studied the protodelithiation of the lithioanisole isomers by ethanol in di-n-butyl ether solution. As are phenyl lithium in diethyl ether solution and o-lithioanisole in dibutyl ether solution, the p- and m-lithioanisoles also were presumed to be predominately dimeric in the di-n-butyl ether solution. As dimers, the o-isomer is some 35 kJ mop more stable than the nearly isoenergetic m- and p-isomers, consistent with intramolecular association between the lithium and oxygen. That the inductive effect is small in comparison with association is shown by the nearly identical enthalpies of protodelithiation of the p- and m-lithioanisoles. 

Red-purple colors in the flowers of orchids have been shown to be derived from altogether 15 cyanidin and peonidin glycosides, with aromatic acylated sugars attached at both the 7- and 3 -positions (Table Intramolecular associations between these... 

Our laboratory conducted the most extensive investigation of the 2,3,1-benzodiazaborines reported to date. We analyzed 25, l,2-dihydro-l-hydroxy-2,3,l-benzodiazaborine (26), and certain derivatives related to 26 by multisolvent H, C, "B, and NMR using isotopically-enriched ( C, N) compounds <97JA7817>. The X-ray crystal structures of 25 and 26 were obtained first, and that of the 2-methyl derivative 39 was determined soon thereafter <98AX(C)71>. The topography (internal geometry, intramolecular associations) of 39 was found to be most similar to 26, but some subtle 25-like characteristics were found. All three boron heterocycles were shown to exist in planar form in protic solution just like they do in the... 

As pointed out in CHEC-II(1996), most of the parent l,4-(oxa/thia)-2-azoles are unknown, except for 1,3,4-oxathia-zol-2-one, l,4,2-dithiazol-5-one, and 1,4,2-dithiazolium perchlorate <1996CHEC-II(4)505>. All other known compounds are generally heavily substituted, so generalizations about their inter- and intramolecular associations or chromatographic behavior are not available. However, details about their chromatographic separation and isolation are given in the experimental sections of the published articles without comments. 

Figure 23 Equilibrium constants of intramolecular association-dissociation dynamics.

Compounds 10a 13c), 11 (13e), 12 (13g), and 13 (13), while monomeric, have the same general geometrical features as those found in 5-9, and can be regarded as examples of intramolecular association. That is, two lithium atoms are involved in a symmetrical double-bridging arrangement between benzylic (10a and 11) and aryl (12 and 13) sp carbon atoms, respectively. 

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