Supramolecular chemistry hydrogen bonding

Wilcox. C.S. Adrian. J.C. Webb. T.H. Zawacki. F.J. Chemistry of synthetic receptors and functional group arrays. 18. Approaches to quantitative supramolecular chemistry. Hydrogen-bond-based molecular recognition phenomena and sigmoidal behavior in multicomponent mixtures. J. Am. Chem. Soc. 1992. 114. 10189-10197. 

Most dendrimers that have been prepared in the years since 1985 have been based on covalent bonds. However, some have employed secondary bonding, such as hydrogen bonding or co-ordination chemistry. Dendrimers of this type can be considered as part of the growing field of supramolecular... 

Co-ordination chemistry is not the only possible approach to the successful preparation of supramolecular dendrimers. Other examples include hydrogen-bonded dendrimers, which have been prepared using tetracar-boxylic acid moieties as the linking species, and others have been prepared where the hydrogen bonds were developed using melamine and cyanuric acid at the focal point (i.e. the point towards which convergent synthesis is directed). 

The complex obtained with ferrocenylmethylpyrazole (9) is noteworthy because the structure [151] shows the molecules associated into pairs via intermolecular Au Au interactions of 3.1204(6) A and these pairs form chains held together by H Au and H F interactions. The 3D supramolecular structure is formed through additional C— H F hydrogen bonds. These types of H F and H Au interactions are not common in pentafluorophenylgold chemistry. 

Although non-covalent interactions of anions are one of the most actively explored areas of supramolecular chemistry [15], the anion sensing and recognition have up to now relied primarily on electrostatic binding or hydrogen bonding to the receptor [16,54-61]. However, recent UV-Vis and NMR spectral studies clearly reveal that complex formation takes place in the solutions between halides and neutral olefinic and aromatic it-acceptors such as those in Fig. 3 [23,62],... 

The design and synthesis of supramolecular architectures with parallel control over shape and dimensions is a challenging task in current organic chemistry [13, 14], The information stored at a molecular level plays a key role in the process of self-assembly. Recent examples of nanoscopic supramolecular complexes from outside the dendrimer held include hydrogen-bonded rosettes [15,16], polymers [17], sandwiches [18, 19] and other complexes [20-22], helicates [23], grids [24], mushrooms [25], capsules [26] and spheres [27]. 

The recognition of hydrogen bonds is an indispensable tool for designing molecular aggregates, in the field of crystal engineering29 as well as in the fields of supramolecular chemistry. 

Ma, Y. Kolomchin, S. V. Zimmerman, S. C. Supramolecular polymer chemistry Self-assembling dendrimers using the DDA AAD (GC-like) hydrogen bonding motif. J. Am. Chem. Soc. 2002,124, 13757-13769. 

It is obvious that these molecular systems can be prepared specially or can form spontaneously as self-assemblies when hydrogen or dihydrogen bonds dictate the processes of molecular aggregation. The latter is particularly importaut in supramolecular chemistry and crystal engineering, where the primary attention is focused on mastering weak intermolecular interactions [1]. 

---