Asymmetric Salamo-type Ligand Research Articles

Deep insights into novel hexa-coordinated phenoxy-bridged trinuclear Ni(II) asymmetric salamo-like complexes affected by different types of combined solvents

By changing different types of combined solvents, two novel trinuclear Ni(II) complexes, [Ni3(L)2(NO3)2(MeOH)2] (1) and [Ni3(L)2(NO3)2]2 (2) were constructed from an asymmetric salamo-type ligand H2L and Ni(NO3)2·6H2O, respectively. The specific coordination modes of the two complexes have been clearly confirmed by X-ray single-crystal data. The results manifested that the complexes 1 and 2 possess similar coordination structures with solvent methanol molecules involved in coordination in complex 1, however, no coordinated solvent molecule appears in complex 2. The ligand (L)2− units were shown to be involved in coordination with Ni(II) atoms by analysis of infrared and UV–vis absorption spectroscopy. DFT and Hirshfeld surfaces analyses were performed on the complexes. Fluorescent strengths of both complexes were markedly lower compared to the ligand H2L and decreased gradually with increasing concentration of Ni(II) ions, which indicated the charge transfer from H2L to Ni(II) ions involved in the coordination.

AN NOVEL ANTIBACTERIAL ACTIVE [CuII–GdIII] COMPLEX CONSTRUCTED FROM AN ASYMMETRIC SALAMO-BASED LIGAND: SYNTHESIS AND STRUCTURAL CHARACTERIZATION

In the present study, we describe a reaction of Cu(OAc)2·H2O and Gd(NO3)3·6H2O with equimolar amounts of the asymmetric salamo-type ligand 6-methoxy-6′-ethoxy-2,2′-[ethylenedioxybis(azinomethyl)]diphenol (H2L) generated by Schiff base condensation of 2-[O-(1-ethyloxyamide)]oxime-3-methoxy-phenol with 3-ethoxysalicylaldehyde to obtain a novel 3d–4f hetero-polynuclear complex [{Cu(L)Gd(NO3)3}2] [Cu(L)Gd(NO3)3]2. The complex is fully characterized by X-ray diffraction (XRD), elemental analyses, FTIR and UV-Vis spectra. The phase purity is clearly confirmed by powder XRD. In the [CuII–GdIII] complex, the coordination environments of CuII ions are different, but the apical coordination atoms to the GdIII ions are nearly identical. The antibacterial and fluorescent properties of the H2L ligand and the [CuII–GdIII] complex are also investigated. Supramolecular interactions are studied in detail.

A novel antibacterial active [CuII—GdIII] complex constructed from an asymmetric salamo-based ligand: synthesis and structural characterization

In the present study, we describe a reaction of Cu(OAc)2·H2O and Gd(NO3)3·6H2O with equimolar amounts of the asymmetric salamo-type ligand 6-methoxy-6'-ethoxy-2,2'-[ethylenedioxybis(azinomethyl)]diphenol (H2L) generated by Schiff base condensation of 2-[O-(1-ethyloxyamide)]oxime-3-methoxy-phenol with 3-ethoxysalicylaldehyde to obtain a novel 3d—4f hetero-polynuclear complex [{Cu(L)Gd(NO3)3}2][Cu(L)Gd(NO3)3]2. The complex is fully characterized by X-ray diffraction (XRD), elemental analyses, FTIR and UV-Vis spectra. The phase purity is clearly confirmed by powder XRD. In the [CuII—GdIII] complex, the coordination environments of CuII ions are different, but the apical coordination atoms to the GdIII ions are nearly identical. The antibacterial and fluorescent properties of the H2L ligand and the [CuII—GdIII] complex are also investigated. Supramolecular interactions are studied in detail.

An Unprecedented Trinuclear Nickel(II) Complex Assembled from an Asymmetric Salamo-Type Ligand

An unprecedented trinuclear Ni(II) complex assembled from an asymmetric Salamo-type ligand 6-ethoxy- 4′,6′-dichloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol (H2L) is synthesized. The Ni(II) complex with the general formula [Ni3(L)2(μ3-OAc)2]·3CH3CN is characterized by IR, UV-vis, and fluorescence spectra and the single crystal X-ray analysis. All the Ni(II) atoms are hexacoordinated with slightly distorted octahedral symmetries. Interestingly, each Ni(II) atom is not located on the N2O2 cavity of the asymmetric Salamo-type (L)2– unit, and two μ3-OAc ions adopt an uncommon μ3-η2:η1 binding mode connecting the Ni1, Ni2, and Ni3 atoms. Furthermore, the crystallizing acetonitrile molecules successfully assemble into an infinite 2D network by hydrogen bonding and C–H···π interactions.

An Unexpected Salamo-Type Copper(II) Complex: Synthesis, Crystal Structure, Thermal Behavior, and Spectroscopic Analysis

A novel supramolecular Cu(ΙΙ) complex [Cu2(L2)2] (H2L2 = 4-bromosalicylaldehyde O-(2-hydroxyethyl)oxime) is synthesized through the complexation of Cu(OAc)2·H2O with an asymmetric salamo-type ligand 4-bromo-6′-hydroxy-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H3L1) and is structurally characterized by single crystal X-ray diffraction. The X-ray crystal structure of the Cu(ΙΙ) complex reveals it to crystallize in the triclinic system, space group $$P\overline1$$ , in which each Cu(II) atom is in a distorted square pyramidal geometry. The whole Cu(ΙΙ) complex consists of a series of [Cu2(L2)2] units, forming an infinite 1D chain supramolecular structure. Meanwhile, the Cu(II) complex exhibits emission with the maximum emission wavelength λmax = 431 nm when excited at λex = 367 nm.

An unprecedented trinuclear nickel(II) complex assembled from an asymmetric Salamo-type ligand

An unprecedented trinuclear nickel(II) complex assembled from an asymmetric Salamo-type ligand

Salamo-type trinuclear and tetranuclear cobalt(II) complexes based on a new asymmetry Salamo-type ligand: syntheses, crystal structures, and fluorescence properties

Two multinuclear Co(II) complexes, [{Co(L)(i-PrOH)}2Co(H2O)]∙2CH3CN (1) and [{Co(L)(μ-OAc)Co(MeOH)2}2]∙2CH3COCH3 (2), have been synthesized with a new asymmetric Salamo-type ligand (H3L = 6-hydroxy-6′-ethoxy-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol). The Co(II) complexes were obtained by different solvents, and the structures are completely different. In the Co(II) complex 1, the ratio of the ligand H3L to Co(II) atom is 2 : 3 and the Co(II) ions are all five-coordinate with trigonal bipyramidal geometries. In the Co(II) complex 2, the ratio of the ligand H3L to Co(II) atom is 2 : 4. Two central Co(II) ions are six coordinate with distorted octahedral geometries and two terminal Co(II) ions are five coordinate with distorted trigonal bipyramidal geometries. Self-assembling of an infinite 1-D supramolecular chain is formed by C–H⋯π interactions in 1. Interestingly, an infinite 2-D-layer plane structure is formed by the self-assembling array of 2 linked by C–H⋯π interactions. 1 and 2 exhibit blue emissions with the maximum emission wavelengths λmax = 403 and 395 nm when excited at 330 nm.

Four new nickel(II) complexes based on an asymmetric Salamo-type ligand: Synthesis, structure, solvent effect and electrochemical property

Four new solvent-induced Ni(II) complexes with chemical formulae {[NiL(MeOH)(μ-OAc)]2Ni}·2MeOH (1), {[NiL(EtOH)(μ-OAc)]2Ni} (2), {[NiL(i-PrOH)(μ-OAc)]2Ni} (3) and {[NiL(DMF)(μ-OAc)]2Ni}·2DMF·0.44H2O (4), where H2L=5-methoxy-4′-chloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol, have been synthesized and characterized by elemental analyses, 1H NMR, FT–IR, UV–Vis spectra and X-ray crystallography. X-ray crystallographic analyses of the Ni(II) complexes reveal that they crystallize in the triclinic system, space group P1¯, and consists of three Ni(II) ions, two deprotonated L2− units, two μ-acetato ligands and two coordinated solvent molecules. In each of the Ni(II) complexes, the Ni(II) ions are hexa-coordinated with a slightly distorted octahedral coordination geometries. Although the molecule structures of the Ni(II) complexes are similar each other, obtained in different solvents, the supramolecular structures are entirely different. The complexes 1 and 3 possess a self-assembled infinite 2D and 1D supramolecular structures via the intermolecular hydrogen bonds, respectively. But the Ni(II) complexes 2 and 4 are formed 0D structures by intramolecular hydrogen bonds. Cyclic voltammetry is used to characterize electrochemical property of the Ni(II) complex 1.

An Infinite 2D Supramolecular Cobalt(II) Complex Based on an Asymmetric Salamo-Type Ligand: Synthesis, Crystal Structure, and Spectral Properties

A new Co(ΙΙ) complex, [Co2(L)2]·CH3COCH3 based on an asymmetric Salamo-type ligand (H2L, 5-methoxy-4’,6’-dibromo-2,2’-[ethylenedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and characterized structurally by elemental analyses, IR, UV-Vis, and fluorescence spectra. The X-ray crystal structure shows the Co(II) ion is pentacoordinated with geometry of a distorted square-pyramidal symmetry. The Co(ΙΙ) complex consists of two Co(ΙΙ) ions, two deprotonated L2– units, and one noncoordinated acetone molecule. Each Co(ΙΙ) complex molecule links four other molecules into an infinite 2D supramolecular structure. Meanwhile, the Co(II) complex exhibits emission with the maximum emission wavelength λmax = 432 nm when excited at λex = 349 nm.

Novel multinuclear transition metal(II) complexes based on an asymmetric Salamo-type ligand: Syntheses, structure characterizations and fluorescent properties

Three multinuclear complexes, [{Cu(HL)(OAc)Cu}2]·CH3OH, [Zn(HL)(OAc)Zn(CH3CH2OH)] and [{Cd(HL)(OAc)Cd(CH3CH2OH)}2]·2CHCl3, have been synthesized with an asymmetric Salamo-type ligand H4L, and characterized by FT-IR, UV–vis spectra and X-ray crystallography. The Cu(II) complex contains two crystallographically independent but chemically identical dinuclear complexes (molecules 1 and 2). Meanwhile, self-assembled infinite 1D, 2D and 3D structures are formed by intermolecular hydrogen bonds and C–H⋯π interactions of neighboring complexes in the solid state. The Zn(II) complex also forms a novel dinuclear structure. And a self-assembled infinite 2D structure is formed by C–H⋯π interaction of neighboring complexes in the solid state. Otherwise, the Cd(II) complex forms an infinite 1D structure by C–H⋯π interaction of the neighboring complex molecules. In addition, the photophysical properties of the Cu(II), Zn(II) and Cd(II) complexes have also been discussed.

A 2D Supramolecular Copper(II) Complex With an Asymmetric Salamo-Type Ligand: Synthesis, Crystal Structure, and Fluorescent Property

A new Cu(II) complex with asymmetric Salamo-type ligand (H2L, 4-bromo-6′-ethoxy-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and characterized structurally. The X-ray crystal structure of the Cu(II) complex shows it to be a binuclear complex, in which each Cu(II) atom is in a distorted square-pyramidal geometry. The Cu(II) complex crystallizes in the monoclinic system, space group P21/c, with unit cell parameters a = 14.7109(1), b = 8.6254(7), c = 30.124(3) Å, β = 100.7400(1), and Z = 4. The Cu(II) complex consists of two Cu(II) atoms, and two L2– units, and each Cu(II) complex molecule links four other molecules into an infinite 2D-layer supramolecular structure. Meanwhile, the Cu(II) complex exhibits emission with the maximum emission wavelength λmax = 443 nm when excited at λex = 340 nm.

Synthesis, crystal structure and spectral properties of a supramolecular trinuclear nickel(II) complex with 5-methoxy-4′-bromo-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol

A novel trinuclear Ni(II) complex [{NiL(n-PrOH)(μ-OAc)}2Ni]·n-PrOH·H2O with an asymmetric Salamo-type ligand, 5-methoxy-4′-bromo-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L), has been synthesized and characterized by elemental analyses, IR, UV/Vis and fluorescence spectra and molar conductance measurement. The crystal structure of the Ni(II) complex has been determined by single-crystal X-ray diffraction. Two acetate groups coordinating to three Ni(II) ions through NiOCONi bridges and four μ-phenoxo oxygen atoms from two [NiL(n-PrOH)] units also coordinating to Ni(II) ions. In the Ni(II) complex, two n-propanol molecules are coordinated to the two terminal Ni(II) ions having slightly distorted octahedral coordination geometries and form a trinuclear structure, There are also one non-coordinated n-propanol and one non-coordinated water molecule. In the crystal structure, the Ni(II) complex is linked by intermolecular hydrogen bonds into an infinite 1D supramolecular chain-like structure.

Synthesis and Crystal Structure of Supramolecular Copper(II) Dimer with Asymmetric Salamo-Type Ligand

Synthesis and Crystal Structure of Supramolecular Copper(II) Dimer with Asymmetric Salamo-Type Ligand