Hydrogen bonding amidic

Hagler A T and S Lifson 1974. Energy Functions for Peptides and Proteins. II. The Amide Hydrogen Bond and Calculation of Amide Crystal Properties. Journal of the American Chemical Society 96 5327-5335. 

Cieplak, P., Caldwell, J. W., Kollman, P. A., Molecular mechanical models for organic and biological systems going beyond the atom centered two body additive approximation aqueous solution free energies of methanol and IV-methyl acetamide, nucleic acid base, and amide hydrogen bonding and chloroform/water partition coefficients of the nucleic acid bases, J. Comput. Chem. 2001, 22, 1048-1057... 

D. J. Tobias and C. L. Brooks, Thermodynamics of amide hydrogen bond formation in... 

FIGURE 3.28. 2-methylpropanamide. A. The N—H stretch, coupled, primary amide, hydrogen bonded asymmetric, 3352 cm-1 symmetric, 3170 cm1. B. Aliphatic C—H stretch, 2960 cm-1. C. Overlap C=0 stretch, amide I band, 1640 cm-1 see Table 3.3. 

The amide hydrogen-bonding motif has been shown to support the clipping, threading, and slipping approaches to the formation of rotaxanes. The wide scope of the neutral template synthesis is enriched by the promising possibilities of the non-template synthesis performed in the melt. Numerous rotaxanes were obtained on a preparative scale and are available for further chemistry. 

In contrast to the X-ray results, ab initio calculations of the isolated molecules of primary, and tertiary amides indicated that for these molecules the G+aa structure is favored. The driving force being hydrogen bonds between distal OH and C=0 groups and in the case of the primaiy amide hydrogen bonds with NH groups as donors and proximal OH as acceptors [20,22],... 

The presence of. vyn-postioned hydroxyl groups on the C3 and C5 of the N-octyl-D-gulon-(35a), altron-(37a), allon-(36a), and idon-(38a) amides, makes these compounds water-soluble and therefore does not allow the formation of aggregates. And induced a bent. This bent does not allow the formation of any regular chain amide hydrogen bonds due to the excessive hydration. The crystal structures of D-Gul-8 35a164 and D-Tal-8 34a165 have been reported and shown to contain tail-to-tail bilayers. 

In MeCN solutions, the Soret band of receptor 38 [35] at 425 nm significantly bathochromically shifted upon addition of H2PC>4 and hypsochromically shifted upon addition of Cl", and split into two bands at 430 and 440 nm upon addition of HSOj. Anions formed 1 1 complexes with 38 via favorable amide hydrogen-bonding interactions and electrostatic interactions with four cobal-tocenium moieties. 

Fig. 9. Potential function [U(r), which is the same as Ubb] for the amide hydrogen bond, with e = 5-5 kcal mole"1. Curve A is the analogue of eq. 13, using a Buckingham potential with repulsive part Arep and attractive part Aatt Curve B is eq. 13. In both cases, S(r) is added to either the Buckingham or Lennard-Jones terms to obtain U(r) (Poland and Scheraga, 1967).

As observed for the molecular clips reported above, the chiral scaffold is pivotal in promoting homo- or heterochiral self-discrimination. Amide hydrogen bonds were implemented on helicene chiral scaffolds as well, but in this case dimerization of the monomers was characterized by homochiral enantioselective self-recognition, that is self-association between molecules with the same helicity (Fig. 17B) [44], These species dimerized in solution with association constants of 207 M 1 by means of four non-covalent bonding interactions and, in combination with the peculiar helical shape of the monomers, forms only homochiral dimers. 

The vase conformation can be stabilized by a seam of eight intramolecular amide hydrogen bonds forming a macrocyclic ring (compound 33) that surrounds the open... 

Partitioning of Free Energy Contributions in the Estimate of Binding Constants Residual Motions and Consequences for Amide-Amide Hydrogen Bond Strengths. 

Aakeroy et al. were also able to prepare building blocks based upon Ag(I) centres coordinated in a trigonal planar manner by three isonicotinamide ligands. The isostructural perchlorate and tetrafluoroborate salts of these cationic complexes involve amide-amide hydrogen-bonded links from each cation to six others, resulting in 3D interpenetrated networks that resemble the network found in a-ThSi [53]. 

A more recent example of dynamic coordination chemistry controlled by anion recognition was demonstrated with the series of ligands 2, which formed linear binuclear triple helicates with Co2+ anions (Fig. 4) [16,17]. The asymmetric ligand 2a, functionalized at one end with an amide hydrogen-bond donor group, may form two types of helicate structures head-to-head-to-head (HHH) and head-to-head-to-tail (HHT) isomers. With the weak hydrogen-bond acceptor C104 as counteranion, a 3 1 mixture of HHH HHT isomers was observed. However, with the... 

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