Hydrogen bonds are of paramount importance for biological processes, they are energetically weaker than covalent bonds, and their cumulative effect strengthens the three-dimensional shape of macromolecules and maintains their structure. The weakness of these bonds is responsible for the flexibility and conformational dynamics that are necessary for the flexibility of biomolecules, which gives them their recognition capacity and therefore their very high specificity.

New compounds have been obtained by proton transfer reactions between organic compounds of type nitrogenous substance and dicarboxylic acid. These reactions present interesting aspects for the realization of molecular systems whose properties can be monitored by X-ray diffraction.

In recent literature there are many examples of organic molecules functionalized with hydrogen bond donor-acceptor groups. Carboxylic acids are a few examples which illustrate excellent model systems for the preparation of new compounds with proton transfer, hence our interest in studying new organic compounds based on creatinine and organic acids which form complexes with many organic molecules

In this study, we shed light on the structural study of a new proton transfer compound. In this crystal structure, creatinine is protonated by two hydrogens of fumaric acid, forming a new organic compound, Bis Creatinium fumarate fumaric acid, that is rich in strong hydrogen bonds.