Abstract
Two new Co(II) complexes, [{Co(L)}2{Co(Pic)2(CH3OH)2}] (1) and [{CoL(μ-OAc)}2Co] (2), where H2L = 2,2′-[Ethylenedioxybis(nitrilomethylidyne)]dinaphthol, were designed, synthesized and characterized by elemental analysis, FT-IR spectra, UV-Vis spectra, and X-ray crystallography. Complex 1 consists of two [CoL] and one [Co(Pic)2(CH3OH)2] (Pic = picrate) units and in the [CoL] unit, the Co(II) atom is tetra-coordinated with a slightly distorted square-planar geometry. In the [Co(Pic)2(CH3OH)2] unit, the Co(II) atom is hexa-coordinated with a slightly distorted octahedral geometry. Meanwhile in complex 2, two acetate ions coordinate to three Co(II) atoms through Co-O-C-O-Co bridges and four μ-naphthoxo oxygen atoms from two [CoL] units also coordinated to the central Co(II) atom. Thus, complex 2 has two distorted square pyramidal coordination geometries around the terminal Co(II) atom and an octahedral geometry around the central Co(II) atom. The supramolecular structures of complex 1 is a 3D-network supramolecular structure linked by C-H···O hydrogen bonds and π···π stacking interaction, but complex 2 possesses a self-assembled 2D-layer supramolecular structure linked by C-H···π and π···π stacking interactions. The structure determinations show that the coordination anions are important factors influencing the crystalline array.
Highlights
IntroductionSalen-type compounds or their derivatives have received much attention because of their versatile architectures and topologies tuned by metal ions and organic ligands [1,2,3,4,5], and due to their properties for potential applications in various areas, such as catalysis [6], bioscience [7,8,9,10], host-guest chemistry [11,12,13,14], electrochemistry [15,16], magnetism [17,18,19,20,21], optical properties [22,23,24,25,26,27,28], and molecular recognition [22,23,29,30]
There are many important factors, such as the metal ions, ligands, counter anions or coordination anions, temperatures, pH values, and solvents [38,39,40,41,42,43,44,45], which always have a major influence on the Crystals 2017, 7, 247; doi:10.3390/cryst7080247
With Co(Pic)2 ·6H2 O and Co(OAc)2 ·4H2 O in methanol solution, respectively, but the big structural differences in 1 and 2 suggest that the coordination anions affect the ultimate structures of the assemblies: when the Pic− is involved in the coordination with Co(II) atoms, the mononuclear
Summary
Salen-type compounds or their derivatives have received much attention because of their versatile architectures and topologies tuned by metal ions and organic ligands [1,2,3,4,5], and due to their properties for potential applications in various areas, such as catalysis [6], bioscience [7,8,9,10], host-guest chemistry [11,12,13,14], electrochemistry [15,16], magnetism [17,18,19,20,21], optical properties [22,23,24,25,26,27,28], and molecular recognition [22,23,29,30]. More and more research programs have focused on the syntheses of Salamo-type complexes by the structural motifs of substituent groups in recent years [31,32,33], because the Salamo compounds are more stable than the Salen compounds [34]. Among the groups that can be coordinated with metal ions, coordinated apart from with ligands, coordination anion isthe one of the direct andisobvious factors. Apart from ligands, coordination anion one of the direct and to further study theIninfluencing factors onthe complex structures incomplex the process of constructing obvious factors. Order to further study influencing factors on structures in the processmetal complexes with themetal. Salamo ligands,with we designed synthesized a Salamo ligands H2aLSalamo (Scheme 1). Of constructing complexes the Salamoand ligands, we designed and synthesized ligands.
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