Deceleration of Proton Exchange between Monosaccharides and Water by Metallocryptand and Related Compounds

Area of Science:

• Supramolecular Chemistry
• Biophysical Chemistry
• Materials Science

Background:

• Proton exchange dynamics are crucial for biological processes.
• Understanding molecular interactions with water is key in glycobiology.
• Metallocryptands offer unique structural and electronic properties.

Purpose of the Study:

• To investigate the effect of a tris(salen) nickel(II) metallocryptand (LNi3) on proton exchange rates.
• To explore the potential of LNi3 as a modulator of proton transfer reactions.
• To understand the role of the salen framework in influencing hydrogen-bonding networks.

Main Methods:

• Synthesis and characterization of the tris(salen) nickel(II) metallocryptand (LNi3).
• Kinetic studies measuring proton exchange rates between monosaccharides (glucose, mannose, fructose, galactose) and water.
• Comparative studies using a mononuclear analogue (LmNi) and a metal-free analogue (H6L).

Main Results:

• LNi3 dramatically decelerated proton exchange rates by up to 74-fold at 0.025 equiv.
• Deceleration effects were observed for various monosaccharides and methanol.
• Comparative studies indicated the salen framework's role in reorganizing hydrogen-bonding networks.

Conclusions:

• Salen-based molecules represent a novel class of proton exchange modulators.
• LNi3 demonstrates significant control over proton exchange under nonphysiological conditions.
• These findings provide a basis for studying hydration and controlling dynamic processes in glycobiology.