Phosphorus or nitrogen - the first phosphatriptycene in coordination polymer chemistry

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Development of heteroditopic ligands is crucial for constructing complex metal-organic architectures.
• Triptycene-based ligands offer unique structural rigidity and defined spatial arrangements.
• Understanding metal-ligand interactions based on hard-soft acid-base (HSAB) principles is key in coordination chemistry.

Purpose of the Study:

• To synthesize and characterize TRIP-Py, the first heteroditopic ligand with a phoshatriptycene scaffold.
• To investigate the selective coordination behavior of TRIP-Py towards various metal cations.
• To explore the formation of discrete complexes and coordination polymers using TRIP-Py as a linker.

Main Methods:

• Synthesis of the TRIP-Py ligand.
• Single-crystal X-ray diffraction for structural analysis of coordination compounds.
• Spectroscopic methods (e.g., NMR) for characterization and coordination studies.
• Exploration of metal-ligand interactions using HSAB theory.

Main Results:

• TRIP-Py selectively coordinates metal ions (Zn^II, Pt^II, Hg^II, Au^I, Cd^II) based on their HSAB character, with N-donors binding harder cations and P-donors binding softer ones.
• TRIP-Py acts as a ditopic linker to form a trinuclear mixed-metal complex with Zn^II and Au^I.
• Coordination with Cd^II results in a monometallic polymer, highlighting Cd^II's preference for the N-donor.
• Formation of 1D and 2D heterobimetallic polymers with Zn^II and Hg^II, some featuring solvent-accessible voids.
• The rigidity of TRIP-Py facilitates crystallization, enabling the study of 14 crystalline solids.

Conclusions:

• TRIP-Py is a versatile heteroditopic ligand capable of selective metal ion binding and the construction of diverse coordination architectures.
• The phoshatriptycene scaffold imparts structural rigidity and facilitates crystallographic studies.
• The P-donor site serves as a valuable NMR probe for coordination studies.
• TRIP-Py offers a platform for designing novel metal-organic materials with potential applications in catalysis and sensing.