Syntheses, Structures And Properties Of The Coordination Complexes Based On Iodine-containing Carboxylate Ligands

The overall goal of crystal engineering is the design and synthesis of crystalline materials with desired properties. One of the most important issues in this field is the design and control of molecular crystal packing. In recent times, an intense research effort is being devoted towards the development of halogen bonding. Considering that iodine atom can affect the assembly of supramolecular structures by forming halogen bonds and organic aromatic polycarboxylate ligands have the pluridentated and excellent coordinated ability, we combined the two to investigate halogen bonding in the constructing supramolecular architectures, and furnish different intriguing structures.In this paper, we considered it worthwhile to make use of the rigid ligand5-iodo-isophthalic acid (5-iipa), which possesses two carboxylate groups and one iodine atom. Here we report the synthesis and structure of seven divalent metal5-iipa coordination polymers that incorporate some selected N-containing auxiliary ligands:[Cu3(OH)2(5-iipa)2(phen)3(H2O)·4.5(H2O)]n (1)[Cu(5-iipa)(bpa)-2(H2O)]n (2),[Cu(5-iipa)(p-bix)]n (3), and [Cu(5-iipa)(bpp)-H2O]n (4),[Co2(5-iipa)2(bbi)2-3(C2H6O2)]n (5),[Co(5-iipa)(bbi)-DMF]n (6)(DMF=N,N’-dimethylformamide), and [Co2(5-iipa)2(bbi)2-2DMAc]n (7)(DMAc=N,N’-dimethylacetamide)(phen=1,10-phenanthroline, bpa=1,2-bis(4-pyridyl)ethane, p-bix=1,4-bis(imidazol-1-ylmethyl)-benzene, bbi=1,1′-(1,4-butanediyl)bis(imidazole), bpp=1,3-bi(4-pyridyl)propane). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-raydiffraction (PXRD), UV-vis absorption spectra, and thermogravimetric (TG) analyses. Compound1is a trinuclear complex, which extends to form a three-dimensional (3D) supramolecular structure through O…I, I…π andπ…π interactions. Moreover, I…π and O…I halogen bonding are found in the3D supramolecular structures of2and3, respectively. Compound4features a3D three-fold interpenetrating network with a (4,4)-connected (3.85)(32.83.9) topology. More interestingly, channels are detected in compounds5-7, which are mainly occupied by the free guest solvent molecules. Compound5exhibits an interesting three-fold parallel interpenetrated two-dimensional (2D)â†'three-dimensional (3D) network motifs based on I…I interactions. The adjacent2D parallel layers in compound6deviate from each other with the shift of9.72A along the b or-b axis. Compound7shows a double layer structure in which the bbi-Co waving-like ribbon is running along the c-axis.In order to gain insight into halogen…alogen interactions in extending coordination architectures, a new ligand3,5-diiodobenzoic acid (HL) has been synthesized. Herein, we report the preparation and characterization of a series of eight divalent metal coordination polymers, namely [Zn(L)2(p-bix)]n (8),[Zn3(L)6(bpp)]n,(9),[Cdi.5(L)3(bpp)]n (10),[Ni(L)2(bpe)-H2O]n (11),[Co(L)2(p-bix)]n (12),[Co1.5(L)3(bpy)0.5]n (13),[Mn3(L)6(bpe)]n (14) and [Mn3(L)6(bbi)]n (15).(bpe=1,2-bis(4-pyridyl)ethene, bpy=4,4’-bipyridine.) Single-crystal X-ray diffraction analyses on these complexes revealed that I…I interaction were found to be predominant in constructing the supramolecular architectures in all the complexes. The structures of compounds8-10and12exhibits an infinite metal-organic chain, and such chains are further united together to generate a three-dimensional (3D) supramolecular structure through inter-chain I…I interactions. Moreover, π…π interactions are found in the structure of10.8and12are isomorphous. Compound11features3D supramolecular architecture based on hydrogen bonding and I…I interactions. In isomorphous compounds13-15, two-dimensional (2D) metal-organic layer based on covalent bonding are expanded to a3D supramolecular structure based on I…I interactions.