Solid–Gas Phase Synthesis of Coordination Networks by Using Redox‐Active Ligands and Elucidation of Their Oxidation Reaction. Issue 49 (7th August 2019)

• Record Type: Journal Article
• Authors: Den, Taizen; Usov, Pavel M.; Kim, Jaejun; Hashizume, Daisuke; Ohtsu, Hiroyoshi; Kawano, Masaki
• Is Part Of: Chemistry. Volume 25:Issue 49(2019)
• Page Start: 11512
• Page End: 11520
• Publication Date: 2019-08-07
• Subjects: cyclic voltammetry -- redox chemistry -- structure elucidation -- synthesis design -- X-ray diffraction; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201902105
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Formation of coordination networks is a complex process affected by a multitude of factors. Many synthetic strategies have been developed that attempt to control these factors and direct the structure of the final product. Coordination bond formation and structural assembly processes, however, typically take place either in the solution or solid states. In comparison, gas‐phase network synthesis remains largely unexplored. Herein, two new two‐dimensional coordination networks are obtained from the solid–gas phase reaction between ZnX2 (X=I, Br) and the redox‐active 2, 5, 8‐tri(4‐pyridyl)1, 3‐diazaphenalene (HTPDAP) ligand. Their structures were solved by ab initio powder X‐ray diffraction analysis and feature a novel Zn halide trimeric cluster. This strategy is contrasted with a conventional solvothermal synthesis, which led to a one‐dimensional coordination polymer instead. The intrinsic electroactive properties of these materials were probed by solid‐state cyclic voltammetry measurements, which revealed the presence of HTPDAP and halide‐based processes. Chemical oxidation of the two‐dimensional networks by using NOPF6 agent, unexpectedly, led to the formation of a nitrated analog of HTPDAP, the PF6 − salt of diprotonated 4, 6, 7, 9‐tetranitro‐2, 5, 8‐tris(4‐pyridyl)diazaphenalene cation (denoted N ‐TPDAP), which was isolated and characterized. These results provide deeper insights into the oxidation process of HTPDAP‐containing networks and uncover unique redox‐induced chemical transformations. Abstract : Solid–gas phase synthesis : A series of redox‐active coordination networks were obtained by using a highly energetic solid–gas phase synthetic approach. The structure was solved from Rietveld refinement of the X‐ray powder diffraction data. Cyclic voltammetry showed the presence of redox processes owing to both the diazaphenalene skeleton and the constituent halides. Chemical oxidation by using nitrosonium resulted in an unprecedented nitrated diazaphenalene cation.