A series of layered alkylammonium–chromium phosphates, formulated as [CnH2n+1NH3]Cr(OH)PO4 (n=2–6), has been synthesized under hydrothermal conditions. The interlayer spacing, increasing linearly with the increase of alkyl-chain length from 13.61 Å (n=2) to 21.20 Å (n=6), is occupied by a double sheet of packed amine molecules with a tilt angle of ca. 51° respect to the inorganic sheet. The powders are constituted by circular plates (diameter=0.5–3 µm, thickness=~50 nm) with central holes when n=4–6, stacked in axial direction showing worm-like morphologies. The presence of holes, and some corrugated and zig-zag fashions observed on the edge of thin circular plates are the most probable ways for the reduction of the steric tensions between organic and inorganic portions in these hybrid materials. The thermal and thermo-oxidative stability of selected compounds have been studied, including the determination of activation energy data for the decomposition processes.

Financial support from Spanish Ministerio de Economía y Competitividad (MAT2010-15094, MAT2013-40950-R, Factoría de Cristalización – Consolider Ingenio 2010, and Técnicos de Infraestructuras Científico-Tecnológicas Grant PTA2011-4903-I to ZA) and FEDER founding is acknowledged.

Peer Reviewed