Hydrogen-bond directed assembly

The first step of the catalytic process is the hydrogen bond directed assembly and orientation of the reactants. In this example, the azlactone and methanol form a ternary starting complex with the organocatalyst (Fig. 1) [39]. The pseudo-Lewis acidic thiourea forms two bifurcated, nearly symmetric hydrogen bonds (2.147 A, < (0,H,N) = 155.5° and 2.146A, <(0,H,N) = 155.8°) to the carbonyl oxygen atom of the azlactone. 

The first step of the catalyhc process is the hydrogen bond directed assembly and orientation of the reactants. In this example, the azlactone and methanol form... 

C. Aakeroy, A. Beatty, and B. Helfirich, Total synthesis supramolecular style design and hydrogen-bond-directed assembly of ternary supermolecules, Angew. Chem., Int. Ed., 40, 3240-3242 (2001). 

Figure 12 Mesoscopic hydrogen-bond-directed assemblies in organic media, (a) Stacked cyclic 12-mer for 1-17, (b) helically grown tape for 1-17, (c) transmission electron micrograph for 1-18, and (d) a triple-layer membrane formed from the linear hydrogen-bond networks 1-18.

Fig. 10. Electron density projection along -strand direction—hydrogen-bonding direction (a-axis) horizontal, and intersheet direction (c-axis) vertical—and skeletal models of polyGln8 (Q8) and polyGln45 (Q45) assemblies. The unit cell for both peptides was monoclinic, with lattice constants a = 9.73 A, b = 7.14 A, c = 8.16 A, and y = 95.7° for Q8, and a = 9.66 A, b = 7.10 A, c = 8.33 A, and y = 94.0° for Q45. The side chains are nearly overlapped in the hydrogen-bonding direction. This difference in side chain conformation and disorder likely accounts for the differences in observed intensity between their diffraction patterns.

Papaefstathiou, G. S. Kipp, A. J. MacGillivray, L. R. Exploiting Modularity in Template-Controlled Synthesis a New Linear Template to Direct Reactivity Within Discrete Hydrogen-Bonded Molecular Assemblies in the Solid State. Chem. Commun. 2001, 2432-2433. 

The packing pattern of BABI is mostly conserved in PhBABI, despite the substantial difference in their lengths, because they form different 7T-stacking cant angles relative to the direction of their 7T-stack axes, and because void spaces between the PhBABI molecules in the lattice are occupied by solvent molecules that are probably important filler to help bilayers to form (Fig. 26). Even the thickness of a bilayer from aminoxyl chain to aminoxyl chain is nearly the same in the two - 11.1 A in BABI and 11.2 A in PhBABI, both room-temperature crystal structures. The driving force of the BIm unit for hydrogen-bonded chain assembly is clearly strong. 

Fig. 14.26 2-Aminopyrimidine-functiona-lized anthracene (36) and the cavities formed by the hydrogen bond-directed self-assembly of this molecule (top right). These cavities...

Scheme 10.6 Self-assembly of the hydrogen bond-directed [2]catenane formation by Leigh and coworkers.

Papaefstathiou. G.S. Kipp, A.J. MacGilliviay, L.R. Exploiting modularity in template-directed synthesis A new linear template to control reactivity within discrete hydrogen-bonded molecular assemblies in the solid state. Chern. Commun. 2001, 2462-2463. 

Wang L, Wang G-T, Zhao X, Jiang X-K, li Z-T (2011) Hydrogen bonding-directed quantitative self-assembly of cyclotriveratrylene capsules and their encapsulation of C o and C70. J Org Chem 76 3531-3535... 

Men Y-B, Sun J, Huang Z-T, Zheng Q-Y (2009) Rational construction of 2D and 3D Borromean arrayed organic crystals by hydrogen-bond-directed self-assembly. Angew Chem Int Ed 48 2873... 

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