Competition in Coordination Assemblies: 1D-Coordination Polymer or 2D-Nets Based on Co(NCS)₂ and...

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Terpyridine ligands are versatile building blocks in coordination chemistry.
• Cobalt complexes with thiocyanate ligands exhibit diverse structural motifs.
• Understanding metal-ligand interactions is crucial for designing functional materials.

Purpose of the Study:

• To synthesize and characterize 4'-(4-methoxyphenyl)-3,2':6',3″-terpyridine (2).
• To investigate the coordination behavior of ligand 2 with cobalt(II) thiocyanate.
• To explore the formation of coordination polymers and pseudopolymorphs.

Main Methods:

• Synthesis and characterization of the terpyridine ligand.
• Crystallization experiments using varying molar ratios of cobalt(II) thiocyanate and ligand 2.
• Single-crystal X-ray diffraction to determine crystal structures.
• Powder X-ray diffraction (PXRD) to confirm bulk sample composition.

Main Results:

• The 1D-coordination polymer [Co(2)(NCS)2(MeOH)2] was successfully synthesized.
• Pseudopolymorphs, specifically (4,4)-nets [{Co(2)2(NCS)2}·3MeOH] and [{Co(2)2(NCS)2}·2.2CHCl3], were also obtained.
• PXRD confirmed the 1D-coordination polymer as the dominant product in bulk samples.

Conclusions:

• Ligand 2 forms diverse coordination structures with cobalt(II) thiocyanate.
• Crystallization conditions influence the formation of 1D-coordination polymers versus higher-dimensional nets.
• The study highlights the tunability of coordination polymer structures based on metal-ligand ratios and crystallization times.