Tape structures, hydrogen-bonded

Far IR spectroscopy is a useful technique to study the structural environment and dynamics of water molecules and ions in the interlayer galleries of LDHs, since it directly probes the intermolecular and hydrogen bonding interactions [223]. Spectra, which can be recorded by pressing small amounts of powder onto one side of a piece of Scotch tape, are often difficult to interpret because of the complex network of intermolecular interactions present and molecular dynamics simulations have been employed in order to assist in the interpretation [223]. 

Figure 5.51 (a) Polymeric tape structure of [Au(SC6H3N202) (PPh3)] and (b) sheet structure of [ Au(SC6H3N202) 2 X-PPh2(CH2)3PPh2 ] formed via N —H- hydrogen bonds. 

Two different of supramolecular synthons have been detected in the two polymorphs of the carbamazepine-saccharin cocrystal system [45]. In the Form-I structure, the carbamazepine molecules formed a homo-synthon, with the saccharine molecules also forming a hydrogen-bonded homodimer. The interaction of these two synthons resulted in formation of a one-dimensional array of molecules in a crinkled tape motif. In the Form-II structure, a heterosynthon is formed by the interaction of a carbamazepine and a saccharin molecule. This latter synthon packs in one-dimensional chains that extended along the crystallographic c-axis. 

Figure 8.57 Supramolecular synthons 8.44 and 8.45 formed to halometallate complexes along with the tape structure formed by 4,4 bipyridinium tetrachloroplatinate(II) via an Rf (4) hydrogen bonded...

Solid-State Structures of Hydrogen-Bond Tapes Based on Cyclic Secondary Diamides [J. C. MacDonald, G. M. Whitesides, Chem. Rev. 1994, 94, 2383]. 

The complex between melamine and cyanuric acid (1 1) was reported in the literature in the late 1970s, but it was only in the early 1990s that the contributions from Whitesides and the concept of self-assembly popularized these systems [45]. Whitesides and co-workers reported the formation of tapes (Fig. 11.11), crinkled tapes and cyclic hexamers (rosettes) formed between barbituric acid and N,N -bis(p-substituted phenyl)melamine [46], In this they effectively blocked one face of melamine and, by manipulating substituents at the para position, different structures were obtained. Whiteside s putative suggestion that melamine/cyanuric acid formed an extended array (Fig. 11.12) was confirmed recently by Rao et al. with the crystal structure [47]. Hamilton and coworkers reported the crystal structure of a 5-substituted isophthalic acid derivative, which forms a cyclic aggregate held together with six pairs of hydrogen bonds, which in a way resembles the trimesic acid (Fig. 11.13) [48]. 

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. 

Zerkowski, J. A., MacDonald, J. C., Seto, C. T., Wierda, D. A. and Whitesides, G. M. (1994). Design of organic structures in the solid state molecular tapes based on the network of hydrogen bonds present in the cyanuric acid melamine complex. J. Am. Chem. Soc. 116, 2382. 

Figure 21 (a) Hydrogen-bonded tape structure of cation in [Pd(dppp)(L)2](CF3S03)2-... 

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