Locking water molecules via ternary O-H?O intramolecular hydrogen bonds in perhydroxylated closo-dodecaborate

A multitude of applications related to perhydroxylated closo-dodecaborate B-12(OH)(12)2- in the condensed phase are inseparable from the fundamental mechanisms underlying the high water orientation selectivity based on the base B-12(OH)(12)2- . Herein, we directly compare the structural evolution of water clusters, ranging from monomer to hexamer, oriented by functional groups in the bases B(12)H(12)2-, B12H11OH2- andB(12)(OH)(12)2-- using multiple theoretical methods. A significant revelation is made regarding B-12(OH)(12)2- : each additional water molecule is locked into the intramolecular hydrogen bond B-O-H ternary ring in an embedded form. This new pattern of water cluster growth suggests that B-(H-O)MIDLINE HORIZONTAL ELLIPSISH-O interactions prevail over the competition from water-hydrogen bonds (OMIDLINE HORIZONTAL ELLIPSISH-O), distinguishing it from the behavior observed in B(12)H(12)2- and B-12(OH)(12)2- bases, in which competition arises from a mixed competing model involving dihydrogen bonds (B-HMIDLINE HORIZONTAL ELLIPSISH-O), conventional hydrogen bonds (B-(H-O)MIDLINE HORIZONTAL ELLIPSISH-O) and water hydrogen bonds (OMIDLINE HORIZONTAL ELLIPSISH-O). Through aqueous solvation and ab initio molecular dynamics analysis, we further demonstrate the largest water clusters in the first hydrated shell with exceptional thermodynamic stability around B-12(OH)(12)2- . These findings provide a solid scientific foundation for the design of boron cluster chemistry incorporating hydroxyl-group-modified borate salts with potential implications for various applications.

Automated summary

This study explores the structural evolution of perhydroxylated closo-dodecaborate B-12(OH)(12)2- in water environment and the mechanism of water cluster formation. It reveals that each additional water molecule is locked into the intramolecular hydrogen bond B-O-H ternary ring in an embedded form. Unlike other bases, the competition during the formation of water clusters in perhydroxylated closo-dodecaborate B-12(OH)(12)2- is mainly dominated by B-(H-O) interactions. Through analysis, it is found that the largest water clusters in the first hydrated shell exhibit exceptional thermodynamic stability. These findings have significant scientific implications for designing boron cluster chemistry incorporating hydroxyl-group-modified borate salts with potential applications.