Coordination molecular hats binding acetonitrile via C-H...pi interactions

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Crystal Engineering

Background:

• Metallo-macrocycles are complex structures with diverse applications.
• Self-assembly is a key strategy for creating intricate molecular architectures.
• Crown ether and 1,10-phenanthroline ligands offer unique coordination properties.

Purpose of the Study:

• To synthesize and characterize novel [M(3)L(3)](3+) metallo-macrocycles.
• To investigate the self-assembly process and conformational preferences.
• To explore the host-guest chemistry of the macrocyclic cavity.

Main Methods:

• Self-assembly of palladium(II) nitrates with functionalized ligands.
• Synthesis of crown ether functionalized 1,10-phenanthroline and naphthanoimidazole.
• Single-crystal X-ray diffraction analysis to determine structure and conformation.
• Spectroscopic characterization (NMR, IR, UV-Vis).

Main Results:

• Successfully synthesized [M(3)L(3)](3+) metallo-macrocycles with syn, syn, syn conformation.
• Observed self-assembly driven by coordination between Pd(II) and ligands.
• Confirmed the binding of acetonitrile (CH(3)CN) solvent within the naphthanoimidazolate-built cavity.
• Identified C-H...pi interactions as the primary binding force in the crystalline state.

Conclusions:

• The studied metallo-macrocycles exhibit predictable self-assembly and a defined conformation.
• The naphthanoimidazolate cavity effectively encapsulates solvent molecules.
• C-H...pi interactions play a crucial role in stabilizing guest binding within the macrocycle.
• This work provides insights into the design of host molecules for specific guest recognition.