1-D, 2-D and 3-D coordination polymers assembled from polynuclear Co II units based on the isophthalate(-2) ligand Eun Young Kim a , Young Joo Song a , Hyo Geun Koo a , Ju Hoon Lee a , Hyun Min Park a , Cheal Kim a,⇑ , Tae-Hwan Kwon b , Seong Huh b , Sung-Jin Kim c,⇑ , Youngmee Kim c a Department of Fine Chemistry, and Eco-Product and Materials Education Center, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea b Department of Chemistry and Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yongin 449-791, Republic of Korea c Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Republic of Korea article info Article history: Received 11 August 2010 Accepted 9 September 2010 Available online 22 September 2010 Keywords: Isophthalic acid Polynuclear Co II units Coordination polymers Co II complexes Gas sorption abstract Three polymeric complexes containing polynuclear Co II units, [Co 2 (Cbtp) 2 (ip) 2 ](1), [N(CH 3 ) 4 ] 2 [Co 3 (ip) 4 ] (2), and [{Co 7 (ip) 5 (l-OH) 4 }(l-bpp) 2 ]Á2(H 2 O) (3), have been prepared by solvothermal synthesis. Iso- phthalic acid (H 2 ip) has been used for the construction of polynuclear Co II units, and three auxiliary ligands, namely Cbtp, quinazoline, and bpp, have also been employed to change nuclearity of Co II unit and the dimensionality of polymeric Co II compounds: 1-D structure containing dinuclear Co II units with Cbtp, 2-D structure containing trinuclear Co II units without quinazoline, and 3-D structure containing heptanuclear Co II units with bpp. The gas sorption study of 3 revealed a relative high uptake of CO 2 over N 2 because of small dimension of channels. The thermal stabilities and magnetic properties of these com- plexes were also examined. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The synthesis and use of multinucleating ligands has become a common strategy for the preparation of polynuclear coordination complexes with new and sophisticated structures and functions [1–3]. The investigation of the properties ensuing from such archi- tectures has found relevance in areas as diverse as bioinorganic chemistry [4], molecular magnetism [5,6], molecular electronics [7] or materials chemistry [8]. Carboxylate-including ligands [9–15] such as phthalate, biphenyldicarboxylate, benzenetricarb- oxylate, and adamatanedicarboxylate can be used as multinucleat- ing ligands to make multi-dimensional coordination polymers containing polynuclear units. These kinds of ligands have the po- tential capacity to bridge metal centers to form polymeric struc- tures, and the wide range of stable complexes are due to (a) the various coordination modes for the carboxylate ion, bridging modes (g 1 :g 1 :l 2 ), (g 2 :l 2 ) or (g 1 :g 2 :l 3 ), and chelating mode (g 1 :g 1 ), (b) the stable coordination geometries of Co II ions, such as tetrahedral, trigonal bipyramidal, or octahedral, and (c) the presence of a num- ber of coordinated water or hydroxide ligands [16,17]. Paramagnetic Co II is a good candidate for the construction of multinuclear coordination polymers with carboxylate or dicarbox- ylate ligands. The study of metal carboxylate complexes has been an interesting topic due to their structures and magnetism, and these properties are based on the carboxylates which can bridge the metal centers to create diverse magnetic interactions. Several examples of polynuclear Co II clusters have been reported, and their magnetic properties were systematically investigated [17–40]. In this paper, isophthalic acid (H 2 ip) has been chosen for the construction of polynuclear Co II –carboxylate complexes, and auxiliary ligands, such as Cbtp (Cbtp = 2,6-bis((1H-1,2,4-triazol-1- yl)methyl)pyridine), quinazoline, and bpp (1,3-bis(4-pyridyl)pro- pane), have been employed to this system to form 1-D, 2-D, and 3-D coordination polymers containing polynuclear Co II units. Three polymeric complexes containing polynuclear Co II cluster units, [Co 2 (Cbtp) 2 (ip) 2 ] (1), [N(CH 3 ) 4 ] 2 [Co 3 (ip) 4 ] (2), and [{Co 7 (ip) 5 - (l-OH) 4 }(l-bpp) 2 ]Á2(H 2 O) (3) have been prepared, and their properties including the magnetic susceptibility and the gas sorption ability have been studied. In addition, the thermal stabilities of these complexes were also investigated. 2. Experimental 2.1. Materials 2,6-Bis(bromomethyl)pyridine, sodium-1,2,4-triazolide, qui- nazoline, 4,4 0 -trimethylene-dipyridine, isophthalic acid, ammo- nium hydroxide, methanol, ethanol, DMF, methylene chloride, Co(NO 3 ) 2 Á6H 2 O, Co(OAc) 2 Á4H 2 O, were purchased from Aldrich and 0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2010.09.013 ⇑ Corresponding authors. Tel.: +82 2 970 6693; fax: +82 2 973 9149 (C. Kim); tel.: +82 2 3277 3589; fax: +82 2 3277 2384 (S.-J. Kim). E-mail addresses: chealkim@snut.ac.kr (C. Kim), sjkim@ewha.ac.kr (S.-J. Kim). Polyhedron 29 (2010) 3335–3341 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly