title: Cu2{[18]ane-N6} complexes: structures, magnetism, and phosphate monoester binding.
abstract: A novel Cu(II)2 complex of the [18]ane-N6 macrocycle ([18]ane-N6 = 1,4,7,10,13,16-hexaazacyclooctadecane) was prepared from the reaction between [18]ane-N6 and Cu(II) salts such as Cu(NO3)2 and Cu(OAc)2. A structural study of the complex derived from Cu(OAc)2 (1) revealed a Cu(II)2 core encircled by a [18]ane-N6 ligand and two mu-O-OAc ligands. The facile replacement of mu-O-OAc by a phosphate monoester [PO3(OR)2-] yielded a number of bis(phosphate monoester)dicopper complexes with ROPO3(2-) as hydrogen phosphate (HPO4(2-), 3a), phenyl phosphate [PO3(OPh)2-, 3b], glycerol 2-phosphate [PO3(OCH(CH2OH)2)2-, 3c], alpha-d-gluocose phosphate [PO3(C6H11O6)2-, 3d], and dl-alpha-glycerol phosphate [PO3(OCH2CHOHCH2OH)2-, 3e]. Structural studies of compounds 3a-d confirmed both the retention of the Cu2{[18]ane-N6} core and a mu-O-PO3(OR) coordination mode. Displacement of acetate by a phosphate monoester in an aqueous solution was accompanied by a significant change in the visible absorption, which enables the establishment of relative association constants of PO3(OR)2- on the order of 10(4) in the unbuffered solution and 10(3) in the buffered solution (HEPES). Measurement of the magnetic susceptibility of compound 3a over the temperature range of 5-300 K and subsequent modeling revealed a weak antiferromagnetic coupling (J = -1.1 cm(-1)) between two Cu(II) centers.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33124, USA.
authors.forename: Julia E
authors.initials: JE
authors.lastname: Barker
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Gordon T
authors.initials: GT
authors.lastname: Yee
authors.forename: Wei-Zhong
authors.initials: WZ
authors.lastname: Chen
authors.forename: Guangbin
authors.initials: G
authors.lastname: Wang
authors.forename: Vilma M
authors.initials: VM
authors.lastname: Rivera
authors.forename: Tong
authors.initials: T
authors.lastname: Ren
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004952:Esters / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008280:Magnetics; D008958:Models, Molecular; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D017186:Titrimetry
chemical_list: D004952:Esters; D007477:Ions; D010710:Phosphates; D002244:Carbon; D003300:Copper; D009584:Nitrogen