Halogen Bonding in Brominated BODIPY Crystals: a Crystallographic and Computational Study

Area of Science:

• Supramolecular Chemistry
• Crystal Engineering
• Organic Chemistry

Background:

• Halogen bonds (XBs) are crucial non-covalent interactions with applications in catalysis, liquid crystals, and crystal engineering.
• BODIPY dyes are versatile molecules with potential for functional material development.

Purpose of the Study:

• To analyze intermolecular interactions, specifically halogen bonds, in BODIPY derivatives with increasing bromination.
• To understand the role of halogen bonds in directing crystal packing and molecular assembly.

Main Methods:

• Computational analysis using Mercury for close contacts.
• Hirshfeld surface analysis for electron density partitioning.
• Quantum Theory of Atoms in Molecules (QT-AIM) for characterizing non-covalent interactions.

Main Results:

• Identified monocoordinated and bifurcated halogen bonds involving halide/halide interactions.
• Observed four-center cyclic nodes linked by halogen bonds in penta-brominated BODIPY.
• Demonstrated how increasing bromine atoms influences crystal packing and intermolecular interactions.

Conclusions:

• Halogen bonding plays a significant role in the crystal engineering of brominated BODIPYs.
• The identified cyclic motifs offer potential for designing novel supramolecular structures and self-assembled materials.