Supramolecular assemblies of two piperazine metal-organic bismuth(III) derivatives: a new precursor for the preparation of bismuth(III) oxide bromide nano-structures

Abstract

Two BiBr₃ supramolecular complexes, [Bi(2-bpmp)Br_2.06Cl_0.94] (1) and [Bi(4-H₂bpmp)Br_4.29Cl_0.71]·H₂O (2) {2-bpmp = N,N′-bis(2-pyridylmethyl)piperazine and 4-bpmp = N,N′-bis(4-pyridylmethyl)piperazine}, were prepared by reaction of bismuth(III) chloride and potassium bromide with two nitrogen donor ligands under thermal gradient conditions using the branched tube method. Compounds 1 and 2 were structurally characterized by single-crystal X-ray diffraction. In monomeric 1, bismuth is coordinated by two pyridyl and piperazine nitrogens of 2-bpmp, and by three halides. Compound 2 is also monomeric but is bonded to only one pyridyl nitrogen. In both compounds, extensive hydrogen-bonding interactions lead to supramolecular networks; in 2, the hydrogen bonds are augmented by π–π stacking interactions. Thermal stabilities of both compounds were studied by thermal gravimetric and differential thermal analyses. Thermal decomposition of nanosized 1 and 2 in air produced BiOBr nanoparticles.

Keywords:

• Bismuth(III)
• N,N′-Bis(2-pyridylmethyl)piperazine
• N,N′-Bis(4-pyridylmethyl)piperazine
• Supramolecular complexes
• Nanoparticles

Acknowledgments

This work is funded by the grant World Class University Grant No. R32-2008-000-20082-0 of the National Research Foundation of Korea. The authors also thank Tabiat Modares and Payame Noor Universities for all the supports provided.