Hydrogen superstructure

Figure 1.9 A superstructure for the manufacture of benzene from toluene and hydrogen incorporating some redundant features. (From Kocis GR and Grossman IE, 1988, Comp Chem Eng, 13 797, reproduced by permission.).

Fig. 12 An example of guanidinium-sulfonate superstructures. The fundamental interaction responsible for both robustness and flexibility is the charge-assisted (+)N-H---0( ) hydrogen bonding between the guanidinium cations and the sulfonate anions, which can be varied in shape and length [44]...

Further studies by the same authors have demonstrated that PFj acts a hydrogen bond-acceptor template in the assembly of several other interwoven structures. In an extensive study aimed at using a combination of hydrogenbonding motifs to self-assemble pseudorotaxanes into more complex structures it was discovered that PFj assists on the organization of the components that yield the final superstructure [74]. Particularly, it was found that this anion dictates the orientation of the two carboxylic acid groups of the [3]pseudorotaxanes 58 and 59 (see Schemes 27 and 28) when these groups are co-directional with respect to each other the formation of discrete hydrogen-bonded dimers is observed. 

Fig. 12 Neat melamine Hekates 40, their 1 1 host-guest complexes 41,42 and the 1 3 aggregates of a melamine core with three arms 43 and 44. The disk-shaped aggregates 41 stack in a Colrd phase [99]. The Janus-type Hekate 42 arrange in a Colh phase with hexagonal superstructure of the nanosegregated semi-perfluorinated chains [105]. The supramolecular Hekate discs 43-45 self-assemble by hydrogen bonding of the three arms around a melamine core...

Oxtoby, N. S., Blake, A. J., Champness, N. R., Wilson, C., Water superstructures within organic arrays, Hydrogen-bonded water sheets, chains and clusters. Chem. Eur. J. 2005, 11, 4643-4654. 

The Cei9034 phase was found when cerium dioxide was reduced by hydrogen in electron microscope. The diffraction pattern in the [211]p direction is given in Figure 35. There are 19 superstructure spots along the direction [4-21]p, and the electron diffraction pattern has the symmetry of the space group, PI. The unit cell is a triclinic with an inversion center as shown in Figure 35. 

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