Hydrogen-Bonding Assembly of Coordination Polymers Showing Reversible Dynamic Solid-State Structural Transformations

Abstract

We herein report the synthesis, single-crystal structures of coordination polymers, and structural transformations of complexes employing 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile (tdpd2−) and pyrazine (pyz) as bridging ligands. {[M(H2O)4(pyz)][M(tdpd)2(pyz)]·6(H2O)}n, [1·10H2O and 2·10H2O where M = Co (1) and Zn (2)], consists of two types of crystallographically independent one-dimensional (1D) structures packed together. One motif, [M(tdpd)2(pyz)]2− (A), is an anionic infinite pyz bridged 1D array with chelating tdpd2− ligands, and the other motif is a cationic chain, [M(H2O)4(pyz)]2+ (B), which is decorated with four terminal water molecules. The 1D arrays (A) and (B) are arranged in parallel by multi-point hydrogen-bonding interactions in an alternate (A)(B)(A)(B) sequence extending along the c-axis. Both compounds exhibit structural transformations driven by thermal dehydration processes around 350 K to give partially dehydrated forms, 1·2H2O and 2·2H2O. The structural determination of the partially dehydrated form, 2·2H2O, reveals a solid-state structural transformation from a 1D chain structure to a two-dimensional (2D) coordination sheet structure, [Zn2(tdpd)2(H2O)2(pyz)]n (2·2H2O). Further heating to 500 K yields the anhydrous form 2. While the virgin samples of 1·10H2O and 2·10H2O crystallize in different crystal systems, powder X-ray diffraction (PXRD) measurements of the dehydrated forms, 1·2H2O and 2·2H2O, are indicative of the same structure. The structural transformation is irreversible for 1·10H2O at ambient conditions. On the other hand, compound 2·10H2O shows a reversible structural change. The solid-state structural transformation for 1·10H2O was also confirmed by monitoring in-situ magnetic susceptibility, which is consistent with other thermally-induced measurements.

A Self‐Assembly of New Cobalt Coordinating Polymer Based on Fluorinated Secondary Building Unit and Pyrazine

“…have 1D‐polycations and dinuclear anions based on Co‐pyz‐Co fragment [39] . Another ‘hybrid’ structure with the same cationic subsystem {[Co(H 2 O) 4 (pyz)] 2+ } n was published in 2018 [40] . The anionic part of this structure is also presented by 1D coordination polymer, {Co(tdpd) 2 (pyz) 2− } n .…”

“…Subsystems are isolated from each other by [39] Another 'hybrid' structure with the same cationic subsystem {[Co-(H 2 O) 4 (pyz)] 2 + } n was published in 2018. [40] The anionic part of this structure is also presented by 1D coordination polymer, {Co(tdpd) 2 (pyz) 2À } n . (where tdpd 2À is 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile).…”

Structure, Optical and Magnetic Properties of Two Isomeric 2-Bromomethylpyridine Cu(II) Complexes [Cu(C6H9NBr)2(NO3)2] with Very Different Binding Motives

“…For the development of new interesting materials based on coordination compounds, polytopic or polyfunctional ligands are interesting candidates [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Both types can help to selectively assemble discrete mononuclear or polynuclear complexes [ 1 , 2 , 3 , 4 , 7 , 8 , 9 ], clusters [ 6 , 7 ], or coordination polymers [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ] including metal-organic frameworks (MOFs) [ 8 , 10 ] either by providing more than one coordination site (polytopic) or other functionalities (polyfunctional) enabling secondary interactions such as hydrogen bonds, halogen bonds, π-stacking, or hydrophobic van der Waals interactions [ 11 , 12 , 13 , 14 , 15 , 16 ]. Additionally, the nature of the ligand combined with the h ard and s oft a cids-and b ases principle (HSAB) help in taming the quite flexible geometries of many 3D transition metals.…”

Noncentrosymmetric Supramolecular Hydrogen-Bonded Assemblies Based on Achiral Pyrazine-Bridged Zinc(II) Coordination Polymers with Pyrazinedione Derivatives

“…(Scheme 1). We have been working on H 2 CN 2 pyzdione to develop coordinationand hydrogen-bond supported metal-CN 2 pyzdione 2coordination materials and have reported topological and physico-chemical properties [7][8][9]. Scheme 1.…”