Neutral iodotriazoles as scaffolds for stable halogen-bonded assemblies in solution

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Computational Chemistry

Background:

• Halogen bonding (XB) is a crucial non-covalent interaction in supramolecular chemistry.
• 1,4-diaryl-5-iodo-1,2,3-triazoles represent a novel class of potential halogen bond donors.
• Established XB donors like pentafluoroiodobenzene provide a benchmark for comparison.

Purpose of the Study:

• To investigate and quantify the halogen bond donor capabilities of neutral 1,4-diaryl-5-iodo-1,2,3-triazoles.
• To synthesize a bifunctional molecule incorporating both an XB donor (iodotriazole) and an XB acceptor (3-oxypyridine).
• To demonstrate the self-assembly of this molecule into dimers through halogen bonding.

Main Methods:

• Computational chemistry, specifically Density Functional Theory (DFT) calculations, was employed to model interactions.
• Experimental techniques including 1H and Diffusion Ordered Spectroscopy (DOSY) Nuclear Magnetic Resonance (NMR) were used for characterization.
• Nucleophilic Aromatic Substitution (SNAr) reactions were utilized for molecular assembly.

Main Results:

• The 1,4-diaryl-5-iodo-1,2,3-triazoles exhibit halogen bonding efficiency competitive with pentafluoroiodobenzene.
• A novel iodotriazole derivative functionalized with a 3-oxypyridine XB acceptor was successfully synthesized.
• Experimental evidence (1H and DOSY NMR) confirmed the formation of a dimer through two halogen bonds.

Conclusions:

• Neutral 1,4-diaryl-5-iodo-1,2,3-triazoles are effective halogen bond donors.
• The developed molecular scaffold enables self-assembly into stable halogen-bonded dimers.
• This work expands the toolkit of XB donors and provides a platform for designing novel supramolecular architectures.