Whitesides rosette structur

As one example, the observation of hydrogen bonding [7] in natural systems such as peptide helices and DNA base pairs led to a theoretical understanding of this phenomenon. This understanding has permitted the use of hydrogen bonding in synthesis, leading to the preparation of such diverse structures as Rebek s capsules [8], Lehn s supramolecular polymers [9], and Whitesides rosettes [10]. 

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]. 

Zerkowski, J. A., Seto, C. T. and Whitesides, G. M. (1992). Solid-state structures of rosette and crinkled tape motifs derived from the cyanuric acid-melamine lattice. J. Am. Chem. Soc. 114, 5473. 

J.P. Mathias, E.E. Simaney, J.A. Zerkowski, C.T. Seto, G.M. Whitesides, Structural Preferences of Hydrogen-Bonded Networks in Organic Solution - The Cyclic CA3M3 Rosette , J. Am. Chem. Soc., 116,4316 (1994)... 

The complementary molecular functionality of substituted melamines and barbituric acids leads to efficient hydrogen bonding between such compounds. This pattern is shown in Figure 6 and has been used by Whitesides, Lehn and others to design various supramolecular structures such as a linear tape, a crinkled tape and a cyclic rosette [68,69]. These structures are also illustrated in... 

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