title: Hydrated phosphorus oxyacids alone and adsorbed on nanosilica.
abstract: Low-temperature (1)Н NMR spectroscopy was used to study states of water bound to phosphoric and phosphonic acids (phosporus oxyacids, POA) alone or adsorbed onto nanosilica OX-50 (specific surface area S(BET)=52 m(2)/g) or A-300 (S(BET)=297 m(2)/g). Concentrated solutions or weakly hydrated solid POA or dried silica/POA powders placed in CCl(4) medium are characterized by different temperature dependences of the chemical shift of the proton resonance (δ(H)) because of partial dissociation of PO-H bonds strongly affected by water amounts and temperature. NMR cryoporometry results show that both small water clusters and nanodomains are present at the interfaces of hydrated solid POA and silica/POA powders. Quantum chemical calculations of the (1)H NMR spectra demonstrate the influence of POA/water cluster structure and dissociation of the PO-H bonds on the δ(H) values.
authors.affiliation: Chuiko Institute of Surface Chemistry, General Naumov Street 17, 03164 Kyiv, Ukraine. vlad_gunko@ukr.net
authors.forename: V M
authors.initials: VM
authors.lastname: Gun'ko
authors.forename: L P
authors.initials: LP
authors.lastname: Morozova
authors.forename: A A
authors.initials: AA
authors.lastname: Turova
authors.forename: A V
authors.initials: AV
authors.lastname: Turov
authors.forename: V E
authors.initials: VE
authors.lastname: Gaishun
authors.forename: V M
authors.initials: VM
authors.lastname: Bogatyrev
authors.forename: V V
authors.initials: VV
authors.lastname: Turov