Synthesis, Ab Initio X-ray Powder Diffraction Crystal Structure, and Magnetic Properties of Mn₃(OH)₂(C₆H₂O₄S)₂ Metal–Organic Framework

Abstract

A new hydroxythiophenedicarboxylate metal-organic framework based on Mn(II) cations has been obtained by an aqueous two-step procedure including hydrothermal treatment. The structure of Mn(3)(OH)(2)(C(6)H(2)O(4)S)(2) has been determined ab initio from synchrotron X-ray powder diffraction data and consists of infinite inorganic ribbons which are interlinked by 2,5-thiophenedicarboxylate (tdc) molecules (monoclinic, space group P2(1)/c, a = 3.4473(1) Å, b = 19.1287(1) Å, c = 11.0069(1) Å, β = 97.48(1)°, V = 719.65(1) Å(3), and Z = 2). Each ribbon is built of three vertex-sharing chains of edge-sharing MnO(6) octahedrons. These ribbons are bridged together by the carboxylate functions of the tdc molecule to form a pseudo-2D inorganic subnetwork, while this molecule develops in the third dimension to pillar these pseudo-2D layers. An unprecedented hexadentate symmetric bridging mode is adopted by tdc which bridges two chains of a ribbon on one side and two ribbons of a pseudo-2D inorganic subnetwork on the other side. Magnetic measurements suggest that the titled compound is antiferromagnetic below T(N) = 17.7 K. Heat capacity measurements confirm the existence of a magnetic phase transition toward a 3D long-range ordered state. These C(P)(T) data have also been used for the calculation of the thermal variations of both the adiabatic temperature change ΔT(ad) and magnetic entropy change ΔS(m) of the material, namely its magnetocaloric effect.

Chemistry of Metal-organic Frameworks Monitored by Advanced X-ray Diffraction and Scattering Techniques

“…Many MOF structures have been recently determined using the conventional ab-initio procedures based on the classical high-resolution synchrotron powder X-ray data with the typical approach of pattern indexing, intensity integration, structure solution and Rietveld refinement. [51][52][53][54][55][56][57][58][59][60][61][62] Herein, the more nonconventional strategies and improvement overcoming the challenges of the X-ray powder diffraction structure determination of MOFs will be overviewed.…”

Spin-glass state in Ni 5 (OH) 6 (C n H 2n−4 O 4 ) 2 metal-organic frameworks ( n = 6, 8, 10, 12)

“…The resulting solution was placed into a home-made 50 mL plastic reactor under constant argon bubbling flow in order to avoid the formation of nickel oxide impurities during the hydrothermal treatment of the mixture. This hermetic reactor was used in the past for the synthesis of other MOFs [19,20], it is equipped with two injectors, a pH electrode and magnetic stirring. Peristaltic pumps from Ismatec were used for the simultaneous injection of NiCl 2 $6H 2 O (2 mmol in 10 mL water) and NaOH (0.1 M) solutions into the hermetic reactor via the two injectors.…”