Strontium‐Carboxylate‐Based Coordination Polymers: Synthesis, Structure and Dielectric Properties

Solvothermal reaction of strontium ions with selected N‐containing and/or V‐shaped carboxylates led to the crystallization of six new coordination polymers: [Sr( 2‐PZC ) 2 ] ( 1 ), [Sr( 2,5‐PDC )(DMF)] ( 2 ), [Sr( 2,5‐PDC )(DMA)] ( 3 ), [Sr( IDA ) 2 ] ( 4 ), [Sr( SBA )(H 2 O) 2 ].DMF ( 5 ) and [Sr 2 ( FBA ) 2 (H 2 O) 2 (DMA) 2 ].DMA ( 6 ) where, 2 ‐ PZC =2‐pyrazinecarboxylate, 2,5 ‐ PDC =2,5‐pyridinedicarboxylate, IDA =iminodiacetate, SBA =4,4′‐sulfonyldibenzoate and FBA= 4,4′ (hexafluoroisopropylidene)bis(benzoate). Crystal structures were determined by single‐crystal X‐ray diffraction analysis and further characterized by powder X‐ray diffraction, elemental analysis, IR spectra, and TG analyses. Single crystal of 1 shows the occurrence of distorted rings made of twelve strontium carboxylate polyhedra connected in 3D. The structures of 2 , 3 , 5 and 6 are characterized by the presence of strontium carboxylate columns made of edge‐sharing SrO n polyhedra but connected differently to each other through organic linkers. The solids 2 and 3 are isostructural and contain rhombic channels which are occupied by the coordinated solvents. In solid 4 , strontium occurred in a rare octahedral geometry bridged by IDA 2− extending into 2D sheets. The structural features of 5 and 6 synthesized using V‐shaped ligands show 2D square‐shaped channel network. All the solids showed dielectric constants in the range 8–20. The solvent‐less 1 showed a relatively low dielectric constant (∼8) in comparison to 2 , 3 and 4 . The solids 5 and 6 with flexible ligands showed higher dielectric constants (∼17 and ∼20 respectively).