Researchers have identified a new type of hydrogen bond that exhibits similar or even greater strength than certain covalent bonds. These bonds could be involved in many chemical reactions and used in the field of biology or fuel cells.
It exists in , which results from the pooling of between dos , the where the electrons of a are transferred to a neighboring atom, and the o Van der Waals (al que el ), which are lower than the previous two. These three links are all relatively stable. But researchers have long known that in a chemical reaction there are intermediate states in which atoms can bond together for fractions of a second and are therefore more difficult to observe.three types of connection:
Strong hydrogen bonds
A new study published in the journal managed for the first time to observe one of these intermediate states, revealing a new type of : a but with the force of a covalent bond (in principle, the hydrogen bond is about 20 times weaker). To do this, the researchers dissolved a hydrogen fluoride compound in water and observed how hydrogen atoms and interacted thanks to a spectroscopy device that records the atoms under the light . They found that fluorine atoms were attracted to hydrogen atoms due to an imbalance of positive and negative charges, as in a standard hydrogen bond. In solving bifluoride, each hydrogen atom tends to be “sandwiched” between two fluorine atoms.
But the researchers found that these sandwiches were stronger than typical hydrogen bonds. In these short hydrogen bonds, the atoms join together in a structure , which is normally characteristic of a covalent bond. But the mechanism of the new bond is of the nature This means that the link is still of the Van der Waals nature.
According to the researchers’ measurements, these new links have a45.8 kcal / mol (about 192 kJ / mol), which is higher than some . A re’ it is formed for example by two atoms united by a bond of force 38 kcal / mol. Hydrogen bonds have a binding energy of 1 to 5 kcal / mol. This finding isn’t entirely a surprise, but it blurs the definitions of chemical bonds and molecules. In fact, atoms connected by covalent bonds are considered a molecule, while atoms connected by via a hydrogen bond can remain in independent molecules.
A possible strong bond between water molecules?
(not participating in the study), it is possible that this type of connection , where a hydrogen ion is sandwiched between two water molecules. These links have never yet been conclusively observed because their life would be much shorter than with fluoride. ” The study of these molecules and how they can be oriented in a desired direction could find in the transport of in biology and in technologies such as fuel cell membranes »Say the researchers.