Guest-dependent flexible coordination networks with fluorinated ligands

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Crystallography

Background:

• Coordination networks are crystalline materials constructed from metal ions and organic ligands.
• The topology and properties of coordination networks can be tuned by altering the ligand structure and reaction conditions.
• Fluorinated organic ligands offer unique electronic and steric properties that can influence network formation.

Purpose of the Study:

• To investigate the formation of guest-dependent flexible coordination networks using novel fluorinated bis(pyridyl) ligands.
• To explore the impact of different fluorinated ligands and guest molecules on the resulting network topologies.
• To characterize the structural diversity and interpenetration patterns within these coordination networks.

Main Methods:

• Synthesis of coordination networks via solvothermal reactions between cadmium nitrate and four distinct fluorinated bis(pyridyl) ligands: 1,4-bis(4-pyridylmethyl)tetrafluorobenzene (bpf), 4,4'-bis(4-pyridylmethyl)octafluorobiphenyl (bpfb), 2,6-bis(4-pyridylmethyl)hexafluoronaphthalene (2,6-bpfn), and 2,7-bis(4-pyridylmethyl)hexafluoronaphthalene (2,7-bpfn).
• Crystallographic analysis (X-ray diffraction) to determine the precise structures and network topologies.
• Inclusion of various organic guest molecules during synthesis to study their templating effect.

Main Results:

• The ligand bpf yielded one-dimensional cyclic chains, two-dimensional rhombus grid sheets, and three-dimensional diamond frameworks with threefold interpenetration.
• The ligand bpfb primarily formed two-dimensional rhombus grid sheets with twofold parallel interpenetration.
• The ligands 2,6-bpfn and 2,7-bpfn resulted in a variety of one-dimensional and two-dimensional structures, including ladder, twisted grid, herringbone sheets, and sheets with dumbbell-shaped cavities.

Conclusions:

• The choice of fluorinated ligand significantly influences the dimensionality and topology of the resulting coordination networks.
• Guest molecules play a crucial role in directing the formation of specific network architectures and interpenetration modes.
• These findings highlight the potential for designing flexible coordination networks with tunable structures by controlling ligand design and guest inclusion.