Sonochemical Synthesis of a New Lead(II) Coordination Polymer with 2-Quinoline Carboxylate Ligand: A Precursor for the P
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Sonochemical Synthesis of a New Lead(II) Coordination Polymer with 2-Quinoline Carboxylate Ligand: A Precursor for the Preparation of Nano-structured Lead(II) Oxide Akram Panjehpour • Ali Morsali
Received: 20 November 2011 / Accepted: 5 March 2012 / Published online: 10 April 2012 Ó Springer Science+Business Media, LLC 2012
Abstract Crystalline and nano-structure of a new Pb(II) coordination polymer, [Pb(NO2)(2-quc)]n (1), {Hquc = 2-quinoline carboxylic acid} is synthesized via heat gradient and sonochemical methods, respectively. The newly synthesized structures are characterized by scanning electron microscopy (SEM), X- ray powder diffraction (XRD), IR and 1HNMR spectroscopies, elemental analyses and single crystal X-ray diffraction is used to understand the exact structure of the crystalline 1. Thermal stability of nano and bulk samples of compound 1 are studied and compared through thermal gravimetric and differential thermal analyses. PbO nanoparticles are then produced by calcination of the nano-structure of compound 1 at 600 °C. The obtained PbO is characterized by XRD and SEM analyses. Keywords Nano-structure Coordination polymer Lead(II) PbO Crystal structure
1 Introduction Design and synthesis of metal coordination polymers are of great interest due to the special properties of these compounds and their potential applications in host–guest chemistry, sorption [1, 2], electrical conductivity, luminescence [3], catalysis and molecular wires and magnets A. Panjehpour Department of Chemistry, Payame Noor University, Tehran, Islamic Republic of Iran A. Morsali (&) Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P. O. Box 14155-4838, Tehran, Islamic Republic of Iran e-mail: [email protected]; [email protected]
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[4]. Such unique properties are rarely evidenced in mononuclear compounds [5–21]. Among the wide variety of metal coordination polymers, lead coordination polymers and polynuclear complexes have attracted much attention due to their interesting structural features as a consequence of the large radius, adoption of different coordination numbers, and occurrence of stereo-chemically active lone pairs of electron [22]. The possible stereo-chemical activity of the lone pair of Pb(II) compounds has been discussed by Shimoni-Livny et al. [23], based on a thorough review of crystal data available in the Cambridge Structural Database (CSD). They classified lead coordination as holodirected, in which Pb–ligand bonds are directed through the surface of encompassing sphere, and hemidirected, referring to those with Pb–ligand bonds directed only to a part of the coordination sphere leaving a gap in the distribution of bonds to the ligand. From synthetic point of view, several different approaches have been proposed for preparation of coordination polymers such as: (1) slow diffusion of reactants into a polymeric matrix, (2) diffusion from gas phase, (3) evaporation of solvent at ambient or under reduced temperature, (4) precipitation or recrystallisation from a mixture
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