What question did this study set out to answer?

This research investigates how different counteranions influence the crystal structures and porosity of zinc coordination polymers.

February 23, 2026

Effect of counteranions on the crystal structures of Zn II coordination polymers with 1,3-bis(1 H -imidazol-1-yl)benzene

SGSidan GengXinjiang University JJJiayi JiangXinjiang University JDJIngui DuanNanjing Tech University

Key Points

This research investigates how different counteranions influence the crystal structures and porosity of zinc coordination polymers.
Synthesis of two zinc coordination compounds with varying counteranions: BF4- and [TiF6]2-
Structural characterization of the resulting compounds using crystallography techniques
Comparison of ligand conformations and supramolecular architectures based on counteranion identity.
Both compounds exhibit 1D coordination chains with the same ligand configuration.
BF4- stabilizes an extended ligand conformation leading to a nonporous structure.
[TiF6]2- induces a compact ligand conformation, contributing to a dense layered but porous structure.

Abstract

Two new coordination compounds, catena-poly[[diaquazinc (II) -bisμ-1, 3-bis (1H-imidazol-1-yl) benzene] bis (tetrafluoroborate) ], Zn (C12H10N4) 2 (H2O) 2 (BF4) 2n, 1, and catena-poly[[diaquazinc (II) -bisμ-1, 3-bis (1H-imidazol-1-yl) benzene] hexafluorotitanate], Zn (C12H10N4) 2 (H2O) 2TiF6n, 2, have been synthesized and structurally characterized. Both compounds exhibit analogous cationic 1D coordination chains, Zn (L) 2 (H2O) 22+n, where L is 1, 3-bis (1H-imidazol-1-yl) benzene. However, the identity of the counteranion, i. e. BF4- in 1 and TiF62- in 2, significantly influences the supramolecular architecture and porosity due to differences in size, geometry and charge. In 1, the small monovalent BF4- anion stabilizes an extended conformation of the ligand and occupies channels without causing disruption, facilitating the assembly of a nonporous supramolecular framework through hydrogen-bonding interactions. Conversely, the larger TiF62- dianion in 2 induces a more compact conformation of the ligand, occupies potential pore spaces and promotes inter-chain hydrogen bonds, resulting in a dense layered structure. However, the face-to-face packing of these layers creates an open porous architecture. This study highlights the role of anions as templates in modulating hierarchical assembly, ligand conformation and the resultant porosity in coordination polymers.

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