Solvent-assisted monomeric molecular structure of the phosphate diester and the synthesis of menthol-based phosphate diesters

Phosphate diesters are well known to form intermolecular H-bonded dimeric structures in their solid-state. Recently, we reported 2,6-(CHPh)₂-4-iPr-phenyl substituted phosphate diester exists as H-bonded monomeric molecular structure along with water dimer in the solid-state. Herein we report 2,6-(CHPh)₂-4-iPr-phenyl substituted phosphate diester forms a monomeric molecular structure in the solid-state upon co-crystallization with dimethylformamide, DMF (Me₂NCHO). The -CHO group of DMF simultaneously acts as an H-bond acceptor to P-OH and an H-bond donor to P=O moieties. We also used the alcohols, ROH (R = Me, Et, iPr, and tBu), for crystallisation of 2,6-(CHPh)₂-4-iPr-phenyl substituted phosphate diester. In these instances, solvent-incorporated dimeric structures are found in the solid-state. We also report the syntheses and molecular structures of anionic phosphate diesters of 2,6-(CHPh)₂-4-iPr-phenyl substituted phosphate diester possessing various counter cations. Moreover, we also report the syntheses and molecular structures of phosphate diesters based on (−)-menthol, (+)-menthol and (+)/(−)-menthol. These exist as H-bonded dimers in the solid-state.

Graphic abstract

Herein we report 2,6-(CHPh)₂-4-iPr-phenyl substituted phosphate diester forms a monomeric molecular structure in the solid-state upon co-crystallization with dimethylformamide, DMF (Me₂NCHO). The -CHO group of DMF simultaneously acts as an H-bond acceptor to P-OH and an H-bond donor to P=O moieties.