What is a Hydrogen Bond

Strength deserves a more subtle comment, because it brings about the definition of the hydrogen bond. What is a hydrogen bond The answer to this question is controversial and depends on the objective of the investigator. For the purpose of crystal engineering, however, Etter s elaboration of the Linus Pauling definition of ahon is probably the most appropriate ... 

Weinhold F, Klein R (2012) What is a hydrogen bond mutually consistent theoretical and experimental criteria for charararaizing H-bonding interactions. Mol Phys 110 565-579... 

Ihe interaction between atoms and molecules can vary from the weak attraction between a pair of closed-shell atoms (e.g. two rare gas atoms in a molecular beam) to the large energy associated with the formation of a chemical bond. Intermediate between these two extremes are interactions due to hydrogen bonding or electron donor-acceptor processes. In these intermediate cases it is often difficult to determine what factors are important in contributing to the interaction. For example, what can a hydrogen bond be ascribed to ... 

The average molar mass of a hydrogen-bonded pair of nucleotides in a DNA molecule is 625 g-mol Each successive pair is found at a distance of 340 pm along the chain. If the total length of one strand of a DNA molecule is 0.299 m, what is the molar mass of the molecule ... 

What makes this bond so unusual is that the proton-accepting atom is a hydrogen atom, although the topological properties of the electron density at the bond s critical points allow us to distinguish these two types of bonding. 

The hydrogen bonding scheme is identical in both crystals as seen in Fig. 11 and Fig. 12. The molecules pack so as to provide what maybe aptly described as a hydrogen-bonded comb, with a GA 36 backbone and caffeine 35 teeth. In fact, the major difference between the two polymorphs on the secondary level of supramolecular architecture resides in the torsion of the GA 36 aliphatic chain. 

One case, however, where materialization of a specific solvent molecule out of the continuum is indeed critical is when that solvent molecule loses its solvent character. For instance, a water molecule tightly bound as both a hydrogen-bond donor and acceptor in a chain involving two solute functional groups clearly should be regarded as a unique fragment in what is fundamentally a two-piece supermolecule. Unfortunately, it is not always... 

What is released when a hydrogen bond forms between two water molecules ... 

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