title: Supramolecular dioxygen receptors composed of an anionic water-soluble porphinatoiron(II) and cyclodextrin dimers.
abstract: Three types of per-O-methylated β-cyclodextrin dimers, Im2CD, Im3NHCD and Py3NHCD, were prepared as globin models. Im2CD was synthesized by the condensation reaction of mono(2(A)-amino)-per-O-methylated β-cyclodextrin with 3-(1H-imidazol-1-yl)pentanedioic acid. Im3NHCD and Py3NHCD were obtained through the S(N)2 reactions of mono(2(A),3(A)-epoxy)-per-O-methylated β-cyclodextrin with 3-(1H-imidazol-1-yl)pentane-1,5-diamine and 3,5-bis(aminomethyl)pyridine, respectively. These cyclodextrin dimers formed 1:1 supramolecular inclusion complexes of tetrakis(4-sulfonatophenyl)porphinatoiron(II) (Fe(II)TPPS) in aqueous solution. The supramolecular complexes bound dioxygen (O(2)), with the O(2) affinity of the Fe(II)TPPS/Im3NHCD complex (P(1/2)(O2) = 1.5 ± 0.1 Torr) being much higher than those of the Fe(II)TPPS/Im2CD (36 ± 2 Torr) and Fe(II)TPPS/Py3NHCD complexes (70 ± 5 Torr). On the basis of the results of the present study and previous results, it is concluded that the imidazole axial ligand at the linker attached at the 3- and 3'-positions of the cyclodextrin units causes higher O(2) affinity as compared with the imidazole ligand at the 2- and 2'-positions and the pyridine ligand at the 2,2'- or 3,3'-positions. The electron donating ability and orientation of the axial ligand may control the O(2) affinity of a supramolecular receptor.
authors: Department of Molecular Chemistry and Biochemistry, Doshisha University, Tatara, Kyotanabe, Kyoto 610-0321, Japan. kkano@mail.doshisha.ac.jp
authors: Koji
authors: K
authors: Kano
authors: Syoichi
authors: S
authors: Chimoto
authors: Mariko
authors: M
authors: Tamaki
authors: Yoshiki
authors: Y
authors: Itoh
authors: Hiroaki
authors: H
authors: Kitagishi
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D003505:Cyclodextrins / Q000737:chemistry*; D019281:Dimerization; D006420:Hemeproteins / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D008024:Ligands; D008665:Metalloporphyrins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*
chemical_list: C466420:5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron(III) chloride; D056831:Coordination Complexes; D003505:Cyclodextrins; D006420:Hemeproteins; D007093:Imidazoles; D008024:Ligands; D008665:Metalloporphyrins; D011725:Pyridines; D014867:Water; C029899:imidazole; C023666:pyridine; D010100:Oxygen