Examples of Hydrogen Bonding

When a hydrogen atom forms a hydrogen bond with an electronegative atom, dipole-dipole attraction occurs. Hydrogen bonds are formed when hydrogen atoms interact with fluorine, oxygen, or nitrogen. Intramolecular bonding, or bonding between atoms within a single molecule, is more common than bonding between atoms of different molecules (intermolecular). 

Here is a list of molecules that exhibit hydrogen bonding

Water (H2O) is a classical  illustration of hydrogen bonding in action. The link is formed between the hydrogen atoms of one water molecule and the oxygen atoms of another water molecule, rather than between two hydrogen atoms (a common misconception).

Hydrogen bonding occurs between hydrogen in one molecule and carbon in another molecule in chloroform (CHCl3).

Hydrogen bonds form between one molecule’s hydrogen and another’s nitrogen in ammonia (NH3). Because each nitrogen atom has only one lone electron pair, the bond formed by ammonia is extremely weak. Methylamine also exhibits this form of hydrogen bonding with nitrogen.

Between hydrogen and oxygen, acetylacetone (C5H8O2) forms intramolecular hydrogen bonds.

Between base pairs in DNA, hydrogen bonds occur.

The strands “unzip” along the hydrogen bonds, giving DNA its double helix form and allowing replication to take place.

Between the repeating units of the polymer, hydrogen bonds can be detected.

The symmetric hydrogen bond formed by hydrofluoric acid (HF) is stronger than the ordinary hydrogen bond. Formic acid makes this type of connection, as well.

Protein folding helps the molecule maintain stability and assume a functional conformation by breaking hydrogen bonds.

Hydrogen bonds can be formed between polymers containing carbonyl or amide groups. The natural polymer cellulose, as well as urea and polyurethane, are examples. These molecules’ tensile strength and melting point are improved by hydrogen bonding.

Hydrogen bonds with hydrogen and oxygen exist in ethanol and other alcohols.

Hydrogen Bonding in Hydrogen fluoride

A hydrogen atom and a fluorine atom make hydrogen fluoride by covalent bonding (electron sharing). Because hydrogen has one electron and fluorine needs one to be stable, the link between the two elements is easily formed when they interact. HF is the chemical formula for hydrogen fluoride. Hydrogen fluoride is a gas at ambient temperature, but as the temperature drops below about 20 degrees Celsius, it condenses into solid crystals.

The molar mass of hydrogen fluoride is 20 g/mol. (A mole of hydrogen fluoride weighs about 20 grams.) It dissolves if it is miscible.

Finally, hydrogen fluoride is a weak acid, which means it will only partially decompose and produce hydrogen ions when mixed with water.

Hydrogen bonding in water

The hydrogen atoms of one water molecule are attracted to the oxygen atom of a neighbouring water molecule, forming hydrogen bonding in liquid water. The oxygen nucleus, with its +8 charge, draws electrons better than the hydrogen nucleus, which has a +1 charge in a water molecule (H2O). As a result, the hydrogen atom is partly positively charged whereas the oxygen atom is partially negatively charged. Hydrogen atoms are attracted to other oxygen atoms as well as covalently bonded to their oxygen atoms. The ‘hydrogen’ bonds are formed from this attraction.

The hydrogen link between water molecules is weak, only about a twentieth of the strength of the O-H covalent bond.

It is, however, sturdy enough to withstand temperature variations both above and below ambient. The O-H bonding electrons’ attraction to the oxygen atom results in a deficiency on the hydrogen atom’s far side relative to the oxygen atom. As a result, when the three atoms are in close proximity to a straight line and the O-atoms are closer than 0.3 nm, the attractive force between the O-H hydrogen and the O-atom of a nearby water molecule is highest.

Hydrogen Bonding in Ammonia

We clarified how ammonia molecules attach to the hydroxyls of the (H,OH)-Si(001) model surface at a temperature of 130 K by combining experimental and ab initio core-level photoelectron spectroscopy (periodic DFT and quantum chemistry calculations). Indeed, theory determined the amount and direction of the N 1s (and O 1s) chemical shifts based on the type (acceptor or donor) of the hydrogen bond, and when tested, the probe molecule made one acceptor and one donor connection with a pair of hydroxyls. The fact that the selected adsorption geometries have the highest binding strength to the surface, as computed using periodic DFT, demonstrates the consistency of our technique. On the surface, minor species were also found. DFT core-level calculations, as in the case of H-bonded ammonia, were crucial in attributing these minority species to datively bonded ammonia molecules, which are associated with isolated dangling bonds remaining on the surface, and dissociated ammonia molecules, which are caused primarily by beam damage. 

Conclusion

A hydrogen bond (or H-bond) is an electrostatic attraction between a hydrogen (H) atom covalently bonded to a more electronegative atom or group and another electronegative atom holding a lone pair of electrons (the hydrogen bond acceptor) (Ac). The solid line symbolises a polar covalent bond, while the dotted or dashed line denotes a hydrogen bond in such an interacting system. Second-row elements nitrogen (N), oxygen (O), and fluorine (F) are the most common donor and acceptor atoms (F).

Many of the strange physical and chemical features of N, O, and F compounds can be attributed to the hydrogen bond. Water’s high boiling point (100 °C) is due to intermolecular hydrogen bonding, which is substantially stronger than the hydrogen bonds seen in other group-16 hydrides. The secondary and tertiary architectures of proteins and nucleic acids are mostly due to intramolecular hydrogen bonding. It’s also vital for the structure of synthetic and natural polymers.