1H NMR Shift of Single Molecular Water and Its Ligand Interactions in Organic Solvents

Loose H-bonded water named as “free water” or “confined water” plays an important role in “on water catalysis”, or on properties of lignocellulose-based composites, as well as protein-ligand binding (lock and key inhibition) and protein mediated multivalent weak cooperative interactions like carbohydrate-protein complexes in biological systems. To quantify the number of banded hydrogen bonds for single molecular water is challenging. In order to identify the “free water” via 1H NMR, a theoretical value of chemical shift of single molecular water with zero bonding is rationally set here. Water ligand interactions with common organic solvents were investigated systematically. The role of water ligand interactions in “on water” catalysis is elucidated.