Structure Elucidation of Pharmaceutically Relevant Compounds Within Pyrene-Based Frameworks

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Single-crystal X-ray diffraction (SCXRD) is crucial for molecular structure determination but faces challenges with small molecules and APIs that resist crystallization.
• Coformers are often required to obtain quality crystals, and some compounds may be unstable under standard crystallization conditions.

Purpose of the Study:

• To introduce a novel guanidinium-organosulfonate (GS) framework, tetrakis(guanidinium) pyrenetetrasulfonate (G4PYR), for encapsulating challenging small molecules and APIs.
• To demonstrate the utility of G4PYR in forming well-ordered hydrogen-bonded structures suitable for X-ray diffraction analysis.
• To establish a workflow for investigating host-guest complex formation using powder X-ray diffraction and high-throughput experimentation.

Main Methods:

• Synthesis and characterization of the tetrakis(guanidinium) pyrenetetrasulfonate (G4PYR) framework.
• Encapsulation studies with various small molecules and active pharmaceutical ingredients (APIs).
• Structural analysis using single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD).
• High-throughput experimentation for host-guest complex investigation.

Main Results:

• G4PYR framework successfully encapsulates a range of functionalized small molecules (e.g., benzaldehyde, benzamide) and biologically relevant compounds (e.g., lidocaine, ropinirole, uracil, thymine, adenosine, thymidine).
• The G4PYR framework forms well-ordered hydrogen-bonding networks with predictable pyrene-pyrene distances.
• Demonstrated suitability for targeting arene-based APIs with pendant groups.
• Developed and validated a workflow for host-guest complex formation studies.

Conclusions:

• Tetrakis(guanidinium) pyrenetetrasulfonate (G4PYR) provides a robust platform for the structural determination of small molecules and APIs that are difficult to crystallize.
• The G4PYR framework offers a promising strategy for coformer-free crystal engineering and structural analysis.
• The presented workflow enables efficient investigation of host-guest complex formation, advancing drug discovery and materials science.