Structural Diversity in Supramolecular Organization of Anionic Phosphate Monoesters: Role of Cations

Syntheses and structures of anionic arylphosphate monoesters [ArOP­(O)2(OH)]− (Ar = 2,6-CHPh2-4-R-C6H2; R = Me/Et/iPr/tBu) with different counter cations are reported. The counter cations were varied systematically: imidazolium cation, 2-methyl imidazolium cation, N-methyl imidazolium cation, N,N′-alkyl substituted imidazolium cation, 1,4-diazabicyclo[2.2.2]­octan-1-ium cation, 4,4′-bipyridinium dication, and magnesium­(II) dication. The objective was to examine if the supramolecular structure of anionic arylphosphate monoesters could be modulated by varying the cation. It was found that an eight-membered P2O4H2-hydrogen-bonded dimeric motif involving intermolecular H-bonding between the [P­(O)­(OH)] unit of the anionic phosphate monoester along with the counter cation is formed with 2-methyl imidazolium cation, N-methyl imidazolium cation, N,N′-alkyl substituted imidazolium cation, 1,4-diazabicyclo[2.2.2]­octan-1-ium cation, and magnesium­(II) dication; both discrete and polymeric H-bonded structures are observed. In the case of imidazolium cations and 1,4-diazabicyclo[2.2.2]­octan-1-ium cation, the formation of one-dimensional polymers (single lane/double lane) was observed. On the other hand, two types of phosphate motifs, intermolecular H-bonded dimer and an open-form, were observed in the case of 4,4′-bipyridinium dication.