Synthesis and characterization of 1,4-di(1H-imidazol-1-yl) butane dihydrate and 1,4-di(1H-2-methylimidazol-1-yl) butane tetrahydrate: A study of the methyl group effect on spectroscopic data, thermal properties, and the crystal structures

• Main Authors: Johari, Suzaimi, Halim, Siti Nadiah Abdul, Johan, Mohd Rafie, Khaligh, Nader Ghaffari
• Format: Article
• Published: ELSEVIER 2022
• Subjects: QD Chemistry
• Online Access: http://eprints.um.edu.my/46119/; https://doi.org/10.1016/j.molstruc.2022.133823

Two bis(imidazole) derivatives, 1,4-di(1H-imidazol-1-yl) butane dihydrate (DImB center dot 2H(2)O) and 1,4-di(1H-2-methylimidazol-1-yl) butane tetrahydrate (DMImB center dot 4H(2)O were synthesized. The crystallization was performed from an aqueous ethanol by slow evaporation technique. X-ray crystallography was used to confirm the molecular structures of both crystals. The results from crystal structure analysis displayed that DImB center dot 2H(2)O was crystallized in the orthorhombic crystal system and Pbca space group with a = 14.7805(4) angstrom, b = 5.22600(10) angstrom, and c = 15.6110(4) angstrom. The molecule lies in the center of inversion, making the asymmetric unit consist of half of the parent molecule with one unit of the water molecule, whereas DMImB center dot 4H(2)O displayed the triclinic crystal system and R-3 space group with a = 21.526(3) angstrom, b = 21.526(3) angstrom, and c = 9.3333(12) angstrom. Themoleculeliesonacenterofinversion, makingtheasymmetric molecules consist of half of the parent molecule with two units of the water molecules. The effect of replacing hydrogen atoms at C-2 of two imidazole rings with the methyl groups on spectroscopic properties was investigated using FTIR, MS, H-1, and C-13 NMR. The infrared spectrum demonstrated the presence of water molecules in DMImB center dot 4H(2)O, which showed a more intense O-H group peak than DImB center dot 2H(2)O. The effect of methyl groups was studied on the chemical shifts, multiplicity, and coupling constants of hydrogen atoms, and carbon chemical shifts of imidazole rings. Mass spectra of both compounds showed M+ Na]+ and 2M+ Na]+ in positive ion mode (ESI+). In addition, the thermal phase transitions and thermal stability of the bis(imidazole) derivatives were studied using the DSC and TGA/DTG. The crystalline structures of DImB and DMImB recorded and the methyl effect was investigated on the size of molecules, arrangement of molecules in the crystal lattice, lattice planes, solvent void, length, angle, and torsion. (C) 2022 Elsevier B.V. All rights reserved.