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A 3D ten-connected self-penetrating network based on the pentacobalt(II) clusters, [Co5(1,4-ndc)4(OH)2(1,3-bix)2]n (1) (1,4-H2ndc = 1,4-naphthalenedicarboxylic acid; 1,3-bix = 1,3-bis(imidazol-1-ylmethyl)benzene), is synthesized and characterized. Topological analysis indicates that it has ile-364345362 network. The magnetic data reveals the dominant antiferromagnetic interactions between the Co(II) cations.

Article history:Received 20 April 2012Accepted 17 May 2012Available online 24 May 2012Keywords:SolvothermalLanthanideCrystal structureLuminescence Twoisostructurallanthanidecomplexes,[Ln 2 (INO) 4 (NO 3 ) 2 ] n ·2nDMF[Ln=Eu(1),Tb(2)](INO=isonicotinate-N-oxide;DMF=N,N-dimethylformamide),havebeensynthesizedunderthesolvothermalconditionandcharac-terized by single-crystal X-ray diffraction, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA)andelementalanalysis(EA).Inthesetwocomplexes,eachdinuclearLn(III)unitisconnectedwithsixneighboringdinuclear units, which finally constructs a three-dimensional (3D)framework.Along the crystallographic [0 0 1]direction,thereareone-dimensional(1D)tunnels,inwhichfreeDMFmoleculesresideasguests.Additionally,thephotoluminescent properties of 1 and 2 are also discussed.© 2012 Elsevier B.V. All rights reserved. In recent years, design and syntheses of metal-organic frame-works (MOFs) based on lanthanide ions have been under intenseinvestigation for their interesting topologies and various applicationssuch as gas separation and single-molecule magnets [1]. Especially,many lanthanide complexes offer the potential applications in medi-cal imaging, sensors and electro-optical devices since lanthanide ionshave narrow emissions in both visible and near-IR regions with rela-tively long luminescence lifetimes [2]. However, the direct excitationof the4f–4f transitionsis muchdifficult owingto theparity-forbiddentransitions in principle. To obtain efficient luminescent emission, thecommon method is the selection of suitable chromophores as anten-nas which can effectively transfer energy indirectly to the lanthanideions throughthe ligand-to-metal energy transfer (LMET) [3]. Aromat-ic carboxylic ligands, which usually have broad and strong absorptionbands in the UV region, have been proven to be good candidates asantennas or sensitizers [4]. Recently, we focus our interest on theconstruction lanthanide MOFs from carboxylic ligands. Herein wereport the syntheses, structures and photoluminescence of twolanthanide complexes.Complexes 1 and 2 were obtained via solvothermal syntheses [5]and single-crystal X-ray diffraction analyses of 1 and 2 confirmed thatthey are isostructural [6]. Therefore, in the following discussion thestructure of 1 is taken as the example to be described in detail. In theasymmetric unit of 1, there is one Eu(III) cation, two INO ligands, oneNO