Solution and solid state studies of a triangle-square equilibrium: anion-induced selective crystallization in...

Area of Science:

• Supramolecular chemistry
• Coordination chemistry
• Materials science

Background:

• The self-assembly of discrete supramolecular architectures is a cornerstone of modern chemistry.
• Ditopic ligands offer versatile building blocks for constructing complex molecular structures.
• Platinum(II) complexes are well-established components in supramolecular chemistry.

Purpose of the Study:

• To investigate the formation of supramolecular species from the reaction of trans-bis(4-pyridyl)ethylene and cis-(Me(3)P)(2)Pt(OTf)(2).
• To characterize the resulting triangular and square supramolecular structures in solution and solid state.
• To explore the influence of solvent, water, and counteranions on the supramolecular equilibrium and crystallization.

Main Methods:

• Multinuclear Nuclear Magnetic Resonance (NMR) spectroscopy for solution characterization.
• X-ray crystallography for solid-state structural determination.
• Varying solvent systems and anion ratios to control crystallization.

Main Results:

• Formation of an equilibrium mixture of triangular and square supramolecular species in a 1:1 reaction ratio.
• Complete structural elucidation of both species in solution and solid state.
• Demonstration of selective crystallization of either species by controlling solvent and anion composition.
• Observation that the dominant species in solution does not always correlate with the most prevalent species in the solid state.

Conclusions:

• The reaction between the flexible ditopic donor and acceptor units leads to a predictable equilibrium of distinct supramolecular architectures.
• The supramolecular equilibrium and resulting solid-state structures are sensitive to external factors like solvent and anion identity.
• Careful control over crystallization conditions allows for the isolation of specific supramolecular isomers.