Synthesis and characterization of new barium methylphosphonates

Abstract

Eight new barium methylphosphonates were prepared and described. In dependence on pH, either barium hydrogen methylphosphonates or barium methylphosphonates can be formed. In the case of barium methylphosphonates, BaCHPO·3HO crystallizes from the solution at room temperature and BaCHPO·HO at a temperature above 65 °C. On heating, these hydrates form two anhydrous barium methylphosphonates (α-BaCHPO and β-BaCHPO) with the same composition but with a different structure. In a basic environment, barium hydrogen methylphosphonate monohydrate, Ba(CHPOH)·HO, transforms to BaCHPO·3HO through an intermediate with the formula Ba(CHPOH)(CHPO)·4HO. The reverse reaction, that is the reaction of BaCHPO·3HO with methylphosphonic acid, proceeds to the intermediate only and hydrogen methylphosphonate is not formed. Acidic Ba(CHPOH)·HO is able to interact with basic amines and form stable intercalates with them. Structures of β-BaCHPO (P2/c, a = 8.4501(6) Å, b = 7.2555(7) Å, c = 7.4604(8) Å, β = 99.837(8)°, Z = 4) and BaCHPO·HO (P2/c, a = 20.5077(5) Å, b = 7.2175(2) Å, c = 7.4909(3) Å, β = 95.522(3)°, Z = 8) were solved from powder X-ray diffraction data. Both compounds are layered, and the layers are formed of two sheets of Ba atoms connected through oxygen atoms of the phosphonate groups. The methyl groups point towards the interlayer space. In the case of BaCHPO·HO, the molecules of water are coordinated to the Ba atoms and are placed in the interlayer space among the methyl groups.

Strain-less Perovskite Film Engineered by Interfacial Molecule for Stable Perovskite Solar Cells

“…Fourier transform infrared (FTIR) was employed to investigate the interaction between SnO 2 and the functional materials. In Figure S1, the characteristic peaks of pure MPA and PEA are assigned, − where the P-CH 3 stretching vibration in MPA appears at 763.8 cm –1 and the P–O–C stretching vibration is observed at 764 cm –1 for PEA. The distinct peaks on the SnO 2 surface are not evident after post-treatment with MPA and PEA, possibly because of their insufficient quantity for detection.…”