High-pressure study of a 3d – 4f heterometallic CuEu – organic skeleton

We prepared a 3d – 4f heterobimetallic CuEu – organic framework NBU-8 with a density of 1921   kg   m − 3 belonging to the family of dense packing materials (dense metal – organic frameworks or MOFs). This MOF material was prepared from 4-(pyrimidin-5-yl)benzoic acid (HPBA) with a bifunctional ligand site as a tripodal ligand and Cu2+ and Eu3+ as the metal centres; the molecular formula is Cu3Eu2(PBA)6(NO3)6 · H2O. This material is a very promising dimethylformamide (DMF) molecular chemical sensor. Systematic high-pressure studies of NBU-8 were carried out by powder X-ray diffraction, high-pressure X-ray diffraction and molecular dynamics simulation. The high-pressure experiment shows that the (006) diffraction peak of the crystal structure moves toward a low angle with increasing pressure, accompanied by the phenomenon that the d-spacing increases, and as the pressure increases, the (10\overline{2}) diffraction peak moves to a higher angle, the amplitude of the d-spacing is significantly reduced and finally merges with the (006) diffraction peak into one peak. The amplitude of the d-spacing is significantly reduced, indicating that NBU-8 compresses and deforms along the a-axis direction when subjected to uniform pressure. This is caused by tilting of the ligands to become more vertical along the c direction, leading to its expansion. This allows greater contraction along the a direction. We also carried out a Rietveld structure refinement and a Birch – Murnagh...

Source: Acta Crystallographica Section C - January 31, 2024 Category: Chemistry Authors: Yang, K. Yang, Y. Yao, Z. Cheng, S. Cui, X. Wang, X. Han, Y. Yi, F. Mo, G. Tags: metal – organic framework MOF high pressure X-ray diffraction Rietveld refinement bulk modulus DMF sensor molecular dynamics research papers Source Type: research