Reversible morphological transition between nano-rods to micro-flowers through micro-hexagonal crystals in a sonochemical synthesis based on a polyoxovanadate compound

• Piperidinium salt of deca-vanadate cluster has been prepared.
• This has been characterized by single crystal X-ray crystallography.
• This compound is subjected to ultra-sonication to achieve nano-scale preparation.
• Morphological transitions between nano-rods and micro-crystals are shown.
• The morphological variations are studied by using TEM and FESEM microscopy.

We report ultra-sonication assisted morphological evolution in hexagonal macrocrystals of {V10O28} type polyoxometalate system [C5H11N]6[V10O28]·[CH3COOH]4·2H2O (1) as a function of sonication temperatures. Field emission scanning electron microscopy (FESEM) as well as transmission electron microscopy (TEM) studies reveal that at room temperature, sonication of macrocrystals results in the formation of spherical nanoparticles, that are transformed to nano-rods at the sonication temperature of 50 °C. The morphology is transformed from nano-rods to micro-flowers through hexagonal shaped microcrystals as the sonication temperature rose from 50 to 80 °C. It is observed that the hexagonal morphology of the original crystal is retained after a complete cycle (from 80 °C to complete evaporation of solvent) of morphological transitions. Compound 1 is unambiguously characterized by single crystal X-ray structure determination.

Single crystals of compound [C5H11N]6[V10O28]·4CH3COOH·2H2O (1) have been isolated by slow diffusion of piperidine into the sodium meta-vanadate solution, acidified with acetic acid. Compound 1 undergoes reversible morphological transitions between nano-rods and micro-sized hexagonal structures as a function of sonication temperatures.Figure optionsDownload as PowerPoint slide