Synthesis, structural elucidation, characterization and theoretical DFT study of 1-(o-tolyl)biguanidium chloride

Abstract

The structure of the new salt 1‐(o‐tolyl)biguanidium chloride, C9H14N5+·Cl−, has been determined by single‐crystal X‐ray diffraction. The salt crystallizes in the monoclinic space group C2/c. In this structure, the chloride and biguanidium hydrophilic ions are mostly connected to each other via N—H…N and N—H…Cl hydrogen bonds to form layers parallel to the ab plane around y = and y = . The 2‐methylbenzyl groups form layers between these layers around y = 0 and y = , with the methyl group forming C—H…π interactions with the aromatic ring. Intermolecular interactions on the Hirshfeld surface were investigated in terms of contact enrichment and electrostatic energy, and confirm the role of strong hydrogen bonds along with hydrophobic interactions. A correlation between electrostatic energy and contact enrichment is found only for the strongly attractive (N—H…Cl−) and repulsive contacts. Electrostatic energies between ions reveal that the interacting biguanidium cation pairs are repulsive and that the crystal is maintained by attractive cation…Cl− dimers. The vibrational absorption bands were identified by IR spectroscopy.

Crystal structure and characterization of monascin from the extracts of Monascus purpureus-fermented rice

“…In the monascin molecule, O atoms situated near regions of negative electrostatic potential (red area) tend to act as acceptors (Tables 2 and 3), whereas H atoms adjacent to the regions of positive electrostatic potential (blue area) have potential donor properties (Table 3). In addition, atoms C11, C9 and C15 demonstrate higher electrophilicity and susceptibility towards nucleophilic attack (Kaabi et al, 2020). Consequently, the negative electrostatic potential regions of monascin should be attracted towards more positively charged amino acid residues within target protein cavities (and vice versa).…”