Merging antimicrobial and visible emission properties within 1,3,4-trisubstituted-1,2,3-triazolium salts

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Materials Science

Background:

• Bioactive molecules with visible light emission are valuable for bioimaging, chemosensing, and photodynamic therapy.
• 1,2,3-triazolium salts are a class of compounds with potential biological and photophysical applications.

Purpose of the Study:

• To synthesize and characterize 1,3,4-trisubstituted-1,2,3-triazolium salts with both antimicrobial and visible emission properties.
• To investigate the structure-activity relationships between incorporated aryl units and antimicrobial efficacy.
• To explore the photophysical properties, including emission color and Stokes shift, of the synthesized compounds.

Main Methods:

• Click chemistry approach for the synthesis of 1,2,3-triazolium salts.
• Incorporation of various hydrophobic aryl units (fluorenyl, naphthyl, anthracenyl, pyrenyl) at the N1 position.
• Antimicrobial activity testing against Gram-positive bacteria, Gram-negative bacteria, and yeast to determine minimum inhibitory concentration (MIC) values.
• Spectroscopic analysis to characterize visible emission properties and Stokes shifts.
• X-ray diffraction (XRD) analysis to confirm regioselective benzylation and intermolecular interactions.

Main Results:

• Synthesized 1,3,4-trisubstituted-1,2,3-triazolium bromide salts with visible emission and antimicrobial properties.
• Incorporation of aryl units resulted in large Stokes shifts (>100 nm) compared to triazole precursors.
• Increasing size of hydrophobic aryl units affected MIC values, but bioactivity could be preserved through substituent variation.
• Achieved blue, green, and yellow emission with low MIC values (e.g., 0.4 μM against Gram-positive bacteria).
• XRD confirmed regioselective N3 benzylation and dimeric intermolecular π-stacking.

Conclusions:

• 1,3,4-trisubstituted-1,2,3-triazolium salts represent a promising class of molecules with dual antimicrobial and visible emission functionalities.
• The photophysical and antimicrobial properties can be tuned by modifying the N1-aryl substituents and other positions on the triazolium ring.
• These compounds hold potential for applications in bioimaging, sensing, and antimicrobial therapies.