Xiao-Yan Li

Syntheses, crystal structures and catalytic activities of two solvent-induced homotrinuclear Co(II) complexes with a naphthalenediol-based bis(Salamo)-type tetraoxime ligand

Two homotrinuclear Co(II) complexes, [Co3(L)(OAc)2(CH3OH)2] 2CHCl3 (1) and [Co3(L)(OAc)2(H2O)2] (2) based on a naphthalenediol-based acyclic bis(Salamo)-type tetraoxime ligand were synthesized. 1 and 2 were influenced by the coordinated methanol and water molecules, respectively, and their X-ray crystal structures revealed that they have similar molecular structures. Two terminal Co(II) ions, located at the N2O2 coordination spheres of the Salamo moieties, are both in distorted trigonal-bipyramidal geometries, while the third Co(II) ion in the central O4 cavity shows an octahedral geometry with two solvent molecules placed in the apical sites. Different solvent molecules lead to different supramolecular structures. The catecholase activities of 1 and 2 were examined using 3,5-di-tert-butylcatechol (3,5-DTBC) in acetonitrile solution under completely aerobic conditions. The catalytic reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers (Kcat) of 14.72 h−1 and 26.39 h−1 for 1 and 2, respectively.

Tri- and hexanuclear heterometallic Ni(II)–M(II) (M = Ca, Sr and Ba) bis(salamo)-type complexes: synthesis, structure and fluorescence properties

Three heterometallic Ni(II)–M(II) (M = Ca, Sr and Ba) complexes, two discrete heterotrinuclear complexes [Ni2(L)Ca(OAc)2(CH3OH)2]·2C2H5OH·2CHCl3 (1) and [Ni2(L)Sr(OAc)2(CH3OH)2]·2CH3OH·2CH2Cl2 (2) and a discrete heterohexanuclear dimer [Ni2(L)Ba(OAc)2(CH3OH)2(H2O)]2·2CH3OH (3), were synthesized with a naphthalenediol-based acyclic bis(salamo)-type ligand (H4L), and characterized by elemental analyses, IR, UV-vis spectra, fluorescence spectra and X-ray crystallography. The heterometallic complexes were acquired by the reaction of H4L with 2 equiv. of Ni(OAc)2·4H2O and 1 equiv. of M(OAc)2 (M = Ca, Sr and Ba). The crystal structures of complexes 1–3 have been determined by single-crystal X-ray diffractions. Owing to the different nature of the N2O2 and O6 sites of the ligand H4L, the introduction of two different metal(II) atoms to the site-selective moiety, leads to the two Ni(II) atoms occupied both the N2O2 sites, an alkaline earth metal atom occupied the O6 site of the ligand (L)4− unit, respectively. Furthermore, the fluorescence properties have been discussed.

Fluorescence properties of heterotrinuclear Zn(II)–M(II) (M = Ca, Sr and Ba) bis(salamo)-type complexes

A series of hetero-trinuclear Zn(II) complexes, [Zn2Ca(L)(OAc)2]·CHCl3 (1), [Zn2Sr(L)(OAc)2] (2) and [Zn2Ba(L)(OAc)2] (3) with a bis(salamo)-type tetraoxime ligand H4L were synthesized and characterized by elemental analyses, IR, UV-vis spectra etc. Spectral titrations and X-ray crystallography clearly show that the stoichiometry of the heterotrinuclear complexes are all 1u2006:u20062:u20061 (ligand/Zn(II)/M(II)). The different natures of the N2O2 and O6 sites of the ligand H4L lead to the site-selective introduction of two different kinds of metal(II) atoms. All the Zn(II) atoms are penta-coordinated with distorted square pyramidal geometries. The coordination numbers of Ca(II), Sr(II) and Ba(II) atoms in the O6 environment are all 8, and they have slightly distorted square antiprism geometries. Furthermore, ion competitive experiments show that the coordinating capability in the central O6 site is in the order of Ca(II) > Sr(II) > Ba(II).

A Reversible Bis(Salamo)-Based Fluorescence Sensor for Selective Detection of Cd2+ in Water-Containing Systems and Food Samples

A novel, simple, highly selective, and sensitive fluorescence chemosensor for detecting Cd2+ that was constructed from a bis(salamo)-type compound (H4L) with two N2O2 chelating moieties as ionophore was successfully developed. Sensor H4L could show fluorescence turn-on response rapidly and significant selectivity to Cd2+ over many other metallic ions (Cu2+, Ba2+, Ca2+, K+, Cr3+, Mn2+, Sr2+, Co2+, Na+, Li+, Ni2+, Ag+, and Zn2+), and a clear change in color from colorless to yellow that can be very easily observed via the naked eyes in the existence of Cd2+, while other metallic ions do not induce such a change. Interestingly, its fluorescent intensity was increased sharply with the increased concentration of Cd2+. The detection limit of sensor H4L towards Cd2+ was down to 8.61 × 10−7 M.

A heterotrimetallic Ni(II)–Dy(III) bis(salamo)-based complex: synthesis, structure and fluorescent property

Abstract A discrete heterotrinuclear complex [{Ni2LDy(OAc)3(CH3OH)}2]u2009·u20092CH3OHu2009·u20093CH2Cl2, with a naphthalenediol-based acyclic bis(salamo) ligand H4L, has been synthesized and structurally characterized using elemental analyses, IR, UV/Vis and fluorescence spectra and single crystal X-ray diffraction. The crystal structure shows two crystallographically independent but chemically identical molecules (molecules I and II). All the Ni(II) atoms are hexa-coordinated with slightly distorted octahedral geometries. The central Dy atoms are nona-coordinated with slightly distorted tricapped trigonal prism geometries. An infinite 3D supramolecular structure is formed via intermolecular hydrogen bonding and C–H…π interactions.

Luminescent and electrochemical properties of four novel butterfly-shaped hetero-pentanuclear [Zn 4 Ln] complexes constructed from a bis(salamo)-type ligand

Four novel butterfly-shaped hetero-pentanuclear 3d-4f complexes [Zn4(L)2Sm(H2O)4]3NO3·2EtOH (1) [Zn4(L)2Eu(NO3)2(MeOH)(EtOH)]NO3·H2O (2), [Zn4(L)2Gd(H2O)4]3NO3·MeOH·EtOH (3) and [Zn4(L)2Tb(NO3)(EtOH)(H2O)2]NO3·MeOH·EtOH (4) were synthesized by the reactions of a bis(salamo)-type tetraoxime ligand (H4L) with Zn(OAc)2·2H2O and Ln(NO3)3·6H2O (Lnu202f=u202fSm, Eu, Gd and Tb), respectively. The structures of complexes 1-4 were fully characterized by elemental analyses, FT-IR, UV-Vis spectroscopy and single crystal X-ray crystallography, and their luminescence properties were also discussed. In addition, cyclic voltammograms were used to characterize electrochemical properties of the Zn(II)-Ln(III) (Lnu202f=u202fSm, Eu, Gd and Tb) complexes.

Exploration and application of a highly sensitive bis(salamo)-based fluorescent sensor for B 4 O 7 2− in water-containing systems and living cells

A highly selective fluorescent sensor H4L based on a bis(salamo)-type compound with two N2O2 chelating moieties as ionophore was successfully developed. Sensor H4L was found to have excellent selectivity for B4O72− over many other anions (Br−, CI−, CN−, CO32−, HCO3−, H2PO4−, HSO4−, NO3−, OAc−, S2O3−, SCN−, SO42−, Hcy (homocysteine) and H2O2), and it exhibited an approximately 150-fold enhancement of the fluorescence response to B4O72− in Tris-HCl buffer (DMF/H2Ou2009=u20099:1, v/v, pHu2009=u20097) solutions. Significantly, its fluorescence intensity was enhanced in a linear fashion with increasing concentrations of B4O72−. The detection limit of sensor H4L towards B4O72− was 8.61u2009×u200910−7 M. The test strips could conveniently, efficiently and simply detect B4O72− ions in Tris-HCl buffer (DMF/H2Ou2009=u20099:1, v/v, pHu2009=u20097) solutions. Furthermore, sensor H4L showed excellent membrane permeability in living cells, and it was successfully used to monitor intracellular B4O72− by confocal luminescence imaging.

Dimethylsulfoxide-induced trinuclear Co(II) and Ni(II) salamo-type complexes: Syntheses, crystal structures and spectral properties

GRAPHICAL ABSTRACT ABSTRACT Two homotrinuclear Co(II) and Ni(II) complexes, [{CoL(OAc)(DMSO)}2Co]·2DMSO and [{NiL(OAc)(DMSO)}2Ni] have been synthesized by the reaction of 4,4′-dichloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol (H2L) with cobalt(II) and nickel(II) acetate tetrahydrate in the solution of DMSO, respectively, and characterized by elemental analyses, IR, UV–Vis spectra and X-ray crystallography. In the Co(II) complex, terminal Co2 and Co2#1 atoms located in the N2O2 sites, and are both hexa-coordinated with slightly distorted octahedral geometries. While the central Co1 atom is also hexa-coordinated by six oxygen atoms, four are phenoxy oxygen atoms from two (L)2− units, and two oxygen atoms from µ2-acetate ions, which has formed a octahedral geometry. In the Ni(II) complex, coordination environments of the Ni(II) atoms are similar to those of the Co(II) atoms. Infinite 1D supramolecular structure is formed via abundant intermolecular hydrogen bonding interactions in the Co(II) complex.

A supramolecular tetranuclear zinc(II) complex constructed from an asymmetrical Salamo-type ligand: synthesis, structure and fluorescence properties

Abstract The tetranuclear Zn(II) complex, [{ZnL(μ-OAc)Zn(CH3CH2CH2OH)}2], derived from an asymmetrical Salamo-type chelate ligand H3L (5-methoxy-6′-hydroxy-2,2′-[ethanedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and structurally characterized by elemental analysis, IR spectrum, X-ray crystallography, UV/Vis and fluorescence spectra. The structure is made up of four Zn(II) atoms, μ2-coordinated acetate ions and two coordinated n-propanol molecules, and forms an infinite one-dimensional supramolecular structure via intermolecular C–H···π interactions. The four Zn(II) atoms are penta-coordinated and show slightly distorted trigonal bipyramidal and tetragonal pyramidal symmetries.