Thermolysis Synthesis of Pure Phase Nano-Sized Cobalt(II) Oxide from Novel Cobalt(II)-Pyrazole Discrete Nano Coordination Compound Younes Hanifehpour 1 • Behzad Soltani 2 • Babak Mirtamizdoust 3 • Bamin Khomami 4 • Sang Woo Joo 1 Received: 11 October 2015 / Accepted: 4 January 2016 Ó Springer Science+Business Media New York 2016 Abstract Nano-structures of a new discrete coordination compound of divalent cobalt with the pyrazol (pzH) con- taining the terminal isothiocyanate anions, [Co(pzH) 2 (NCS) 2 ](1), with discrete molecular architecture in solid state was synthesized by a sonochemical method. The new nanostructure was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, IR, and elemental analysis. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The discrete mole- cules interact with each other through labile interactions creating a 3D supramolecular framework. The CoO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. Keywords Co-3D supramolecular framework Á Nano coordination compounds Á Isothiocyanate Á CoO nanoparticles 1 Introduction Design and synthesis of discrete coordination compound have attracted extensive interest for their great application potential for separation, recognition, catalysis, and sensor technologies [1]. In the past decade, the rational design and syntheses of novel coordination supramolecular compounds have made considerable progress in the field of crystal engineering and supramolecular chemistry [2, 3]. Coordination bonding, electrostatic interactions and versatile hydrogen bonding, p–p stacking have been com- monly recognized in constructing extended networks [4]. The creation of new molecules is a main goal of chemistry, and of great contribution to human well-being and pros- perity. Molecules are architectures of atoms, while crystal engineering of crystalline solids deals with targeted struc- tures built from molecules. Discrete molecular architecture (DMA) involves the synthesis of discrete, supramolecular entities that exist both in solid state and the solution [5, 6]. One of the more prevalent and effective design strategies is directional-bonding approach. In this building block-based methodology, complementary subunits are reacted in the appropriate ratio to give a final aggregate whose size and structure are dictated by the molecular information stored within the precursors themselves [7, 8]. Heterocyclic nitrogen ligands such as pyrazole-based compounds are known for their interesting coordination chemistry as co- ligands, often giving di- or polynuclear complexes [9]. Some examples of such compounds are [Cu(l-Cl)(2- & Younes Hanifehpour younes.hanifehpour@gmail.com; y_hanifehpour@yu.ac.kr & Babak Mirtamizdoust Babakm.tamizdoust@gmail.com & Sang Woo Joo swjoo1@gmail.com 1 School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea 2 Department of Chemistry, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran 3 Department of Chemistry, Faculty of Science, University of Qom, PO Box 37185-359, Qom, Iran 4 Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA 123 J Inorg Organomet Polym DOI 10.1007/s10904-016-0326-6