Coordination polymers from silver(I) and bifunctional pyridyl ligands

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Flexible bis(2-pyridyl) ligands are versatile building blocks in coordination chemistry.
• Silver(I) triflate (AgCF3SO3) is a common precursor for forming coordination polymers and metal-organic frameworks.
• Controlling the self-assembly of ligands and metal ions is crucial for designing novel supramolecular architectures.

Purpose of the Study:

• To investigate the formation of coordination polymers and macrocycles using flexible bis(2-pyridyl) ligands and silver triflate.
• To explore how ligand structure and reaction stoichiometry influence the resulting supramolecular structures.
• To understand the role of non-covalent interactions in stabilizing these coordination compounds.

Main Methods:

• Synthesis of coordination compounds through reactions of specific flexible bis(2-pyridyl) ligands (L1-L5) with silver triflate.
• Varying the stoichiometry of ligands and silver ions to control structure formation.
• Single-crystal X-ray diffraction for structural elucidation of coordination polymers and macrocycles.
• Analysis of intermolecular interactions, particularly aromatic ring interactions, within the crystal structures.

Main Results:

• Formation of 1D chain coordination polymers with ligands L2, L4, and L5 at a 1:1 stoichiometry.
• Synthesis of a 2D porous network using ligand L2 at a 2:1 ligand-to-silver ratio.
• Generation of a novel 1D ABAB type coordination copolymer from a mixture of L1 and L2.
• Isolation of a bimetallic macrocycle using ligand L3 at a 1:1 ratio, instead of a polymer.
• Identification of significant aromatic ring interactions contributing to the stability of the polymeric structures.

Conclusions:

• The self-assembly of flexible bis(2-pyridyl) ligands with silver triflate is highly sensitive to ligand structure and reaction stoichiometry.
• Diverse coordination architectures, including 1D polymers, 2D networks, copolymers, and macrocycles, can be selectively obtained.
• Aromatic interactions play a critical role in the stabilization of the resulting coordination polymers.