Luminescent iridium(iii)-boronic acid complexes for carbohydrate sensing

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Chemical Sensing

Background:

• Iridium(III) complexes are widely explored for their photophysical properties and potential applications in sensing.
• Boronic acids are known to reversibly bind with diols, making them suitable recognition units for saccharides.
• Developing selective and sensitive sensors for carbohydrates is crucial in various fields, including diagnostics and biochemical research.

Purpose of the Study:

• To synthesize and characterize a series of novel iridium(III) complexes functionalized with boronic acid groups.
• To evaluate the potential of these complexes as luminescent sensors for simple sugars like glucose and fructose.
• To investigate the influence of pH on the sensing performance and the interaction mechanism.

Main Methods:

• Multi-step synthesis of iridium(III) complexes incorporating pyridyl-triazole or pyridyl-oxadiazole ligands with boronic acid moieties.
• Characterization of ligands and complexes using techniques such as X-ray crystallography, NMR, and mass spectrometry.
• Photoluminescence titration studies and high-resolution mass spectrometry (HRMS) to assess carbohydrate binding and adduct formation.

Main Results:

• Four iridium(III) complexes of the type [Ir(ppy)2(L)]Cl were successfully synthesized and characterized.
• The complexes demonstrated the ability to form boronic acid cyclic esters with glucose and fructose.
• Enhanced adduct formation with fructose was observed at higher pH values, indicating pH-dependent sensing capabilities.

Conclusions:

• The synthesized iridium(III) complexes show promise as luminescent sensors for carbohydrates.
• The binding affinity and selectivity can be modulated by factors such as pH.
• Further studies could explore their application in more complex biological matrices or for detecting other saccharides.