title: Anion binding by metallo-receptors of 5,5'-dicarbamate-2,2'-bipyridine ligands.
abstract: Three 5,5'-dicarbamate-2,2'-bipyridine ligands (L = L(1)-L(3)) bearing ethyl, isopropyl or tert-butyl terminals, respectively, on the carbamate substituents were synthesized. Reaction of the ligands L with the transition metal ions M = Fe(2+), Cu(2+), Zn(2+) or Ru(2+) gave the complexes ML(n)X(2)·xG (1-12, n = 1-3; X = Cl, NO(3), ClO(4), BF(4), PF(6), ½SO(4); G = Et(2)O, DMSO, CH(3)OH, H(2)O), of which [Fe(L(2))(3) ⊃ SO(4)]·8.5H(2)O (2), [Fe(L(1))(3) ⊃ (BF(4))(2)]·2CH(3)OH (7), [Fe(L(2))(3) ⊃ (Et(2)O)(2)](BF(4))(2)·2CH(3)OH (8), [ZnCl(2)(L(1))][ZnCl(2)(L(1))(DMSO)]·2DMSO (9), [Zn(L(1))(3) ⊃ (NO(3))(2)]·2H(2)O (10), [Zn(L(2))(3) ⊃ (ClO(4))(Et(2)O)]ClO(4)·Et(2)O·2CH(3)OH·1.5H(2)O (11), and [Cu(L(1))(2)(DMSO)](ClO(4))(2)·2DMSO (12) were elucidated by single-crystal X-ray crystallography. In the complexes ML(n)X(2)·xG the metal ion is coordinated by n = 1, 2 or 3 chelating bipyridine moieties (with other anionic or solvent ligands for n = 1 and 2) depending on the transition metal and reaction conditions. Interestingly, the carbamate functionalities are involved in hydrogen bonding with various guests (anions or solvents), especially in the tris(chelate) complexes which feature the well-organized C(3)-clefts for effective guest inclusion. Moreover, the anion binding behavior of the pre-organized tris(chelate) complexes was investigated in solution by fluorescence titration using the emissive [RuL(3)](2+) moiety as a probe. The results show that fluorescent recognition of anion in solution can be achieved by the Ru(II) complexes which exhibit good selectivities for SO(4)(2-).
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, 710069, China. wubiao@nwu.edu.cn
authors.forename: Biao
authors.initials: B
authors.lastname: Wu
authors.forename: Jin
authors.initials: J
authors.lastname: Yang
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Huang
authors.forename: Shaoguang
authors.initials: S
authors.lastname: Li
authors.forename: Chuandong
authors.initials: C
authors.lastname: Jia
authors.forename: Xiao-Juan
authors.initials: XJ
authors.lastname: Yang
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.forename: Christoph
authors.initials: C
authors.lastname: Janiak
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D000838:Anions / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation
chemical_list: C560955:5,5'-dicarbamate-2,2'-bipyridine; D000838:Anions; D002219:Carbamates; D056831:Coordination Complexes; D008024:Ligands; D015082:2,2'-Dipyridyl