Ladder structures, hydrogen-bonded

The isomerization from 10 to 11 in the crystalUne state requires not only the movements of atoms but also a change in the crystal symmetry and the reconstruction of the hydrogen bond network pattern. In the crystals of these primary ammonium carboxylates, ID ladder-type hydrogen bonds are observed. The isomerization from the ZZ to EE form is associated with the rotation of carbonyl groups and the change in the hydrogen bond structure in this case. The quantitative transformation of 10 to 11 in the crystalUne state suggests that the molecular motion in the crystals occurred cooperatively with the minimum movement of atoms in the crystals via a phase transition from the crystal of 10... 

Liu and coworkers [138] studied Co(NIA)2(H20)4 (NIA = nicotinate), a transition- metal organic-inorganic composite compound with a novel three-dimensional supramolecular cavity structure witii ladder-type hydrogen-bond chains. The formation of this special structure is attributed to it having two carboxylates and four water molecules, which are strong donor/acceptors in hydrogen bond interactions. 

The structure of DNA resembles a ladder that has been twisted around itself. The rungs of the ladder are composed of bases (guanine, thymine, cytosine, and adenine) that form hydrogen bonds. 

The simple diols R2Si(OH)2 (R = Pr , Bul, c-C6Hn, and o-tolyl) form similar, but not identical, hydrogen-bonded chains. The structures of the Pr1 (305), Bu (40, 278), and c-C6Hn (292) compounds are very similar in that they comprise ladder chains of the general type 65, in which pairs of molecules are linked to form dimers and then further hydrogen bonds link the dimers to form the chains. [It has also been... 

Fig. 22 Hydrogen bonded ladder structure of ((NH2)3C)(CH3CN n CTV)[Co(C2B9Hn)2] 41 with N-H...OMe hydrogen bonding between guanidinium cations and CTV [90]... 

Figure 8.43 (a) Chicken wire and (b) ladder motifs for saturated hydrogen bonded structures. The... 

Bile acids, which have carboxylic acid groups at their side-chains, form salts with various amines. Salts of DCA and CA with various primary amines [23] show bilayer structures with a one-dimensional ladder hydrogen-bonding network. These salts act as host compounds and will include small alcohols. 

The close similarity between the structures of the amine phosphate and the final product of the reaction of the amine phosphate with metal (Zn2+) is shown in Fig. 7.24. The amine phosphate consists of a hydrogen-bonded network with water molecules and resembles the loosely hydrogen-bonded structures involved in the synthesis of aluminosilicates. The mechanism of formation of the initial ladder phosphate can be understood in terms of the displacement of the water molecules from the amine phosphate by the Zn2+ ions. 

Adjacent ladders are cross-linked by strong O—H O hydrogen bonds via the water molecules. Incorporation into 19 of pyromellitic dianhydride (PMDA) 21 produces [DTPO]2[PMDA] which has a similar ladder structure, but in this case the PMDA molecules are also able to associate via C—H O hydrogen bonds (synthon XIII) to form tapes (Fig. 12.1 lb). In the absence of water molecules, adjacent ladders are bound via additional C—H O bonds. The overall structure, therefore, consists of a three-dimensional, C—H O bound DTPO network, threaded by PMDA tapes also bound via C—H O interactions (Fig. 12.1 lc). This fascinating structure represents a solid-state polypseudorotaxane mediated entirely by weak C—H O hydrogen bonds. 

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