Supramolecular helical

FIGURE 5.11 Supramolecular, helical architecture and definition of pitch length p of chiral nematic liquid crystals. 

A supramolecular, helical structure was obtained from bridging bis(NHC) ligands and Hg(OAc)2 in acetonitrile. ... 

These results illustrate how extended supramolecular-polymolecular entities build up through molecular recognition directed polyassociation of complementary components. They also show that molecular chirality is transduced into supramolecular helicity, which is expressed at the level of the material on nanometric and micrometric scales, amounting to a sort of size amplification of chirality. 

Barbera J, Cavero E, Lehmann M, Serrano J-L, Sierra T, Vazquez JT (2003) Supramolecular helical stacking of metallomesogens derived from enantiopure and racemic polycatenar oxazolines. J Am Chem Soc 125 4527-4533... 

Supramolecular Metal Complexes Chiral Self-Assembled Supramolecular Helicates Since the first introduction of the term helicate by Lehn et al. in 1987,58 there have been a number of investigations of self-assembled supramolecules with... 

V. Percec, M. Glodde, T. K. Bera, Y. Miura, I. Shiyanovskaya, K. D. Singer, V. S. K. Balagurusamy, P. A. Heiney, I. Schnell, A. Rapp, H.-W. Spiess, S. D. Hudson, H. Duan, Self-organization of Supramolecular Helical Dendrimers into Complex Electronic Materials, Nature 2002, 419, 384-387. 

Biological macromolecules such as DNA and proteins are typical polyelectrolytes, which further hierarchically self-assemble into complicated supramolecular structures such as coiled coil (helix bundle) superstructures, which are responsible for their sophisticated functions [152,153]. Therefore, with implications for biological superstructures and functions, the design and synthesis of supramolecular helical assemblies with a controlled helicity have attracted great interest. 

A large number of chromophoric, helical macromolecules and oligomers, and supramolecular helical assemblies have been constructed by utilizing vari-... 

Hanessian, S., Gomtsyan, A., Simard, M., and Roelens, S., Molecular recognition and self-assembly by weak hydrogen bonding Unprecedented supramolecular helicate structures from diamine/diol motifs, J. Am. Chem. Soc. 116, 4495 496 (1994). 

Finally, the possibility of pure optical switching has been demonstrated in principle by photoinducing supramolecular helical arrangements of smectic domains in some liquid crystal azo polymer films." The photoinduced chirality is pronounced and stable (our oldest sample is still fairly young), but the process is again slow, because it requires reorientation of whole domains. 

Supramolecular helical mesomorphic materials with different proportions of 2,4,6-triarylamino 1,3,5-triazine and (/ )-3-methyladipic acid have been described <05JA458>. 

Numerous examples of supramolecular helical sfrucfures are docu-menfed for exfended ID, 2D, or 3D metal-organic frameworks, essentially built up from H-bond networks. An amazing variety of sfrucfures have... 

Peptides composed of various coded and noncoded amino acid residues self-assemble to form various types of supramolecular architectures, including supramolecular helices and sheets, nanotubes, nanorods, nanovesicles, and nanofibers. The higher-order self-assembly of supramolecular (3-sheets or supramolecular helices composed of short synthetic acyclic peptides leads to the formation of amyloid-like fibrils. Synthetic cyclic peptides were used in supramolecular chemistry as molecular scaffolding for artificial receptors, so as to host various chiral and achiral ions and other small neutral substrates. Cyclic peptides also self-assemble like their acyclic counterparts to form supramolecular structures, including hollow nanotubes. Self-assembling cyclic peptides can be served as artificial ion channels, and some of them exhibit potential antimicrobial activities against drug-resistant bacteria. 

Fig. 1 Packing diagram of individual columns of the tripeptide Boc-Leu-Aib-Phe-OMe in the projection, illustrating the formation of a highly ordered supramolecular helical assembly via van der Waals interactions.

Fig. 2 The packing diagram of the tetrapeptide Boc-Leu-Aib Phe Aib-OMe showing a higher-ordered supramolecular helical assembly as determined by x-ray crystal structure analysis along the b axis. Hydrogen bonds are shown as dotted lines. Side chains of Lue. Phe, and nonhydrogen-bonded hydrogen atoms are omitted for clarity.

Fig. 4 Space-filling model of the supramolecular helical array of the tetrapeptide Boc-Aib-Val-Aib-p-Ala-OMe showing the staking of subunits maintaining proper registry, generating a helical structure as determined by x-ray crystallographic analysis. Nitrogen atoms are blue, oxygen atoms are red. and carbon atoms are gray. Hydrogen atoms are omitted for clarity. View this art in color at www.dekker.com.)...

Haidar, D. Maji, S.K. Sheldrick, W.S. Banerjee, A. First crystallographic signature of the highly ordered supramolecular helical assemblage from a tripeptide containing a non-coded amino acid. Tetrahedron Lett. 2002, 43. 2653-2656. 

Hanessian utilized N—H-. -O interactions between frani-l,2-diaminocyclohexane and 1,2-diols to construct supramolecular helicate structures that, depending on the chirality of the diols. can be left-handed or right-handed. An example is given in Fig. 2. which shows the left-handed helical structure formed by the self-assembly of (R,R)-l,2-diaminocyclohexane with (R,R)-2,3-butanediol via N—H-. O hydrogen bonds. 

Farina, A. Meille, S.V. Messina, M.T. Metrangolo, P. Resnati, G. Vecchio. G. Resolution ofracemic 1.2- dibromo-hexafluoropropane through halogen-bonded supramolecular helices. Angew. Chem.. Int. Ed. 1999, 38. 2433-2436. 

D. Pijper, M.G.M. Jongejan, A. Meetsma, B.L. Feringa, Light-controlled supramolecular helicity of a liquid crystalline phase using a helical polymer functionalized with a single chiroptical molecular switch. J. Am. Chem. Soc. 130, 4541 552 (2008)... 

All the HBC nanotubes and nanocoils described above are composed of helically rolled-up bilayer tapes and possess a supramolecular helical chirahty as an essential structural element. This is quite interesting, since most HBC molecules examined are devoid of stereogenic centers. Conductive nanotubes... 

Other triorganotin phosphinates self-assemble into chain-like, supramolecular helical arrays, 176 these include trimethyltin dimethylphosphinate, Me3Sn02PMe2, and dichlorophosphate, Me3Sn02PCl2 [529], and tri-n-butyltin diphenylphosphinate, Bu3Sn02PPh2 [530]. The self-assembly of tributyltin derivatives of phosphorus oxyacids (orthophosphates, phosphonates, and phosphinates), (Bu3Sn) 0 P(0)-Ph3 , n = 0-2, has been investigated by " Sn and P NMR and " Sn Moss-bauer spectroscopy results are indicative of intermolecular association both in solution and in the solid state [531]. On the basis of spectroscopic evidence associated structures in the solid state and in solution have also been suggested for tri-... 

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