Two new isomeric complexes containing a well-resolved 1D water morph and (6, 3)-connected framework through hydrogen bonding interactions

Two new isomeric complexes, namely {[Cu(fum)(tpy)] · 5H₂O}_n (1) and [Cu₂(fum)₂(tpy)₂] · 4H₂O (2), have been synthesized simultaneously from the reaction of Cu(fum) with tpy (where fum = fumarate, tpy = 2,2′:6′,2″-terpyridine) under mild condition. The crystal structures of complexes were determined by X-ray single-crystal diffraction. Complex 1 stabilizes in an unusual 1D water tape notated T4(2)10(2), which is directed by two chiral helical water chains; binuclear complex 2 represents a complicated (6, 3)-connected framework via supramolecular interactions. Additionally, complex 1 exhibits weak ferromagnetic behavior.     

Synthesis,structures and properties of cobalt(II) and copper(I) complexes of 2,6-diamino-3-[(2-carboxymethyl)phenylazo]-pyridine

The reaction of methyl anthranilate, sodium nitrite, and 2,6-diamino-pyridine affords a new compound, 2,6-diamino-3-[(2-carboxymethyl) phenylazo]-pyridine (L), which has been characterized with X-ray crystallography and NMR spectrum. The reaction of L and CoCl₂? 6H₂O or Cu(ClO₄)₂? 6H₂O gives a dinuclear cobalt(II) complex [Co₂L₂Cl₃]Cl (1), and a copper(I) complex [CuL₂]ClO₄ (2),respectively. They are characterized by X-ray crystallography, X-ray photoelectron spectroscopy, NMR spectra, magnetic measurement and emission spectra. Magnetic behavior of 1 denotes the occurrence of intramolecular antiferromagnetic interactions (J = ? 141.8 cm^? 1). Complex 2 exhibits photoluminescence at 557 nm.     

A highly selective and sensitive Schiff-base based turn-on optical sensor for Cu2 + in aqueous medium and acetonitrile

A simple “turn-on” fluorescence chemosensor L (E)-2-((4-(diphenylamino)benzylide-ne)amino)phenol has been synthesized, which displays a rapid, highly sensitive and selective detection for Cu^2 + ions amongst other metal ions. The association constant for L-Cu^2 + complex determine from Benesi–Hildbrand plot was found as 1.96 × 10⁷ M^− 1 and 5.43 × 10⁷ M^− 1 with the detection limit of 1.8 × 10^− 7 M and 8.5 × 10^− 7 M in CH₃CN and CH₃CN/H₂O (v/v = 4/6, pH = 7.4) HEPES buffer, respectively. Potential application of L for Cu^2 + detection in real water samples was also investigated.     

Synthesis,crystal structure and magnetic properties of a dinuclear dysprosium single-molecule magnet

To seek novel dysprosium based single-molecule magnets, a dinuclear dysprosium complex, namely [Dy₂(L)₂(DBM)₂(DMF)₂]·2DMF (1) was successfully obtained by employing tridentate Schiff base ligand (where H₂L = 2-hydroxy-N′’-(2-hydroxy-3-methoxybenzylidene) benzohydrazide), HDBM = dibenzoylmethane, DMF = dimethylformamide). Single-crystal X-ray structural analysis reveals that the key feature of 1 is neutral dinuclear complex, in which two Dy(III) ions with eight-coordinated environment are bridged by two phenoxido oxygen atoms from two Schiff base ligands. Interestingly, complex 1 could be regarded as the structurally related derivatives to our previous reported complex of [Dy₂(L)₂(DBM)₂(DMF)₂] (1a) but adding two guest DMF solvents. More importantly, the energy barrier to magnetic relaxation of 1 is slightly higher, with a value of 33 K, when compared to the corresponding complex 1a of 24 K, which provides a good example towards regulating magnetization dynamics in dinuclear dysprosium (III) single-molecule magnets by guest solvent molecules.     

Co-existence of heterometallic Zn2Er and ZnEr arrayed chromophores for the sensitization of near-infrared (NIR) luminescence

With the Zn-Schiff-base [ZnL(Py)] from the simple Salen-type Schiff-base ligand H₂L (H₂L = N,N′-bis(salicylidene)ethylene-1,2-diamine) as the precursor, two co-crystallized heterometallic (Zn₂Ln and ZnLn array) complexes [Zn₂Ln(L)₂(Py)₂(NO₃)₂]·[ZnLn(L)(Py)(NO₃)₃(H₂O)]·NO₃·mMeOH·nS (Ln = Er(1), S = CH₃CN, m = 2, n = 1 or Gd(2), S = H₂O, m = 1, n = 3) were obtained by the further reaction with Ln(NO₃)₃·6H₂O, respectively. The result of their photophysical properties shows the intramolecular effective energy transfer has been demonstrated in the Zn₂Er and ZnEr arrayed complex 1, and the co-existence of different chromophores should be a potentially new way to the fine-tuning properties of NIR luminescence from Er³⁺ ions.     

Hetero-trinuclear near-infrared (NIR) luminescent ZnLn2 (Ln = Nd,Yb or Er) complexes based on monomer ZnL Schiff-base precursor and o-vanillin

With the monomer [Zn(L¹)(H₂O)] (1) complex in situ formed by the deprotonated hexadentate Salen-type Schiff-base ligand H₂L¹ (H₂L¹ = N,N′-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine) and Zn(NO₃)₂ as the precursor, series of the hetero-trinuclear ZnLn₂ complexes [ZnLn₂(L¹)₂(L²)(NO₃)₂Cl] (Ln = Nd, 2; Ln = Yb, 3; Ln = Er, 4 or Ln = Gd, 5) were obtained from the further reaction with LnCl₃ (Ln = Nd, Yb Er or Gd) and the second o-vanillin (HL²) ligand, respectively. The photophysical properties of complexes 2–4 showed that the characteristic near-infrared (NIR) luminescence of Ln^3 + ions with two emission centers and emissive lifetimes in microsecond ranges, was sensitized from the excited state (both ¹LC and ³LC) of mixed H₂L¹–HL² ligands.     

Two helical one-dimensional copper(II) coordination polymers based on N-(2-hydroxylbenzyl)glycine and N-(2-hydroxylbenzyl)-l-alanine: Syntheses,crystal structures and magnetic studies

Two new helical Cu(II) coordination polymers, [Cu(2,2′-bpy)(Hsgly)]Cl · 2H₂O(H₂sgly = N-(2-hydroxylbenzyl)glycine) (1) and [Cu(2,2′-bpy)(Hsala)](NO₃) · 2H₂O(H₂sala = N-(2-hydroxylbenzyl)-l-alanine) (2) were synthesized. Single crystal X-ray diffraction analysis indicated that both complexes showed helical chains arrangement of Cu(II) centers bridged by carboxyl groups. The magnetic measurements showed complex 1 exhibited ferromagnetic interaction while there was no interaction between the Cu(II) centers in complex 2.     

Synthesis,crystal structures and properties of two Pd(II) and Pt(II) complexes involving 3,5-diphenylpyrazole and NO2 donor ligands

A pyrazolate bridged binuclear Pd(II) complex [Pd₂(μ-dppz)₂(Hida)₂] · CH₃OH · 2H₂O (1) (dppz = 3,5-diphenylpyrazolate) with monoprotonated iminodiacetate (Hida) and a mononuclear Pt(II) complex containing Hdppz and 2,6-pyridinedicarboxylate (2,6-dipic) [Pt(Hdppz)(2,6-dipic)] · CH₃OH (2) have been synthesized and characterized by elemental analysis, ¹H NMR, ESI-MS and single crystal X-ray diffraction studies. The molecular packing for 1 shows a 2D network while that for 2 constitutes a left-handed 1D helix. Moderate luminescence property and antimicrobial activity against Bacillus subtilis have been noted for both.     

Syntheses,characterizations, and redox behaviors of new self-assembled metal complexes with bridging ligands incorporating chalcogen sites

Three new complexes, [Zn(dbsf)₂(dmf)₂] · 5.5dmf (dbsf = 4,4′-sulfonyldibenzoate) (1β), [Cu(tdsa)(phen)₂] · 1.5EtOH (tdsa = 5,5′-thiodisalicylate, phen = 1,10-phenanthroline) (2), and [Cu(sdp)(phen) · Cu(Hsdp)(phen)(CH₃COO)] · 3EtOH (sdp = 4,4′-sulfonyldiphenolate) (3) were prepared and structurally characterized. Complex 1β shows a one-dimensional coordination framework constructed from bridges between Zn(II) centers with two ligands. Complex 2 is a monomeric complex, which assembles by π–π interactions. Complex 3 shows a unique two-dimensional coordination framework that is constructed from two Cu(II) centers, sdp, and Hsdp. The redox properties of these three complexes were characterized by solid-state cyclic voltammetry. Complexes 1β and 3 show irreversible reduction waves because of the reduction of their sulfone sites. Complex 2 shows an irreversible oxidation wave because of oxidation of the sulfide site.     

An unusual emissive and colorimetric copper (II) detection by a selective probe based on a pseudo-crown cysteine dye: Solution and gas phase studies

An off-on-off emissive and colorimetric probe L, based on a Pseudo-Crown cysteine dye was designed for Copper (II). Compound L was studied in solution and in gas-phase (MALDI-MS) over alkaline, alkaline, earth-alkaline and transition metal ions (Li⁺, Na⁺, K⁺, Ca^2 +, Mg^2 +, Zn^2 +, Cu^2 +, Co^2 +, Ni^2 +, Pb^2 +, and Hg^2 +) in organic media. The recognition of Cu^2 + by L lead to red/dark red colored complexes, one emissive L₂Cu and another LCu, less emissive. In regards to fluorescent quantum yield in both cases an increase respective to L was visualized (2 fold for LCu and 7 fold for L₂Cu). The paramagnetic nature of both complexes was proved by the synthesis of both complex species, as well as, through ¹H NMR and FTIR. Compound L demonstrate to be able to detect and quantify the minimal amounts of 1.3 μM/3.3 μM of Cu^2 +.     

Synthesis,crystal structures and cytotoxic activity of mononuclear nickel(II) and dinuclear zinc(II) complexes with ligand derived from S-benzyldithiocarbazate

Ni(L)₂ (1) and Zn₂(μ-OL)₂(L)₂ (2), (HL = S-benzyl-β-N-(2-bromobenzylidene) dithiocarbazate), were synthesized and characterized by elemental analysis and X-ray single-crystal diffraction analysis. 1 is a mononuclear neutral nickel(II) complex and the center nickel atom is chelated by donors of N₂S₂ possessing a distorted tetrahedral configuration, while in 2, the adjacent two complex molecules are linked through two O atoms to form a dimer and the center zinc atom is five-coordinate in a distorted trigonal–bipyramidal geometry. The cytotoxic activity study indicated that 2 showed potent cytotoxic activity against the human liver hepatocellular carcinoma (HepG2) cancer cell lines, with IC₅₀ 2.4 ± 0.2 μg·mL^− 1, which is slightly weaker than 5-fluoroacil (5-FU) (0.89 ± 0.21 μg·mL^− 1) as reference. A gel electrophoresis assay demonstrated the ability of the complex to cleave the pBR322 plasmid DNA.     

Studies on interaction of Cr(III) polypyridyl complexes with DNA

Two chromium(III) complexes containing derivatives of 1,10-phenanthroline were synthesized and characterized using different spectroscopic methods. The interaction of the synthesized complexes with DNA was performed. From the absorption titration data, the binding constant for the complexes [Cr(imiphen)₂Cl₂]⁺ (1) and [Cr(furphen)₂Cl₂]⁺ (2) with DNA were found to be 5.69 ± 0.3 × 10⁴ M^− 1 for 1 and 3.7 ± 0.2 × 10⁴ M^− 1 for 2, respectively. The viscosity studies show that both the complexes bind to DNA in a partial intercalative mode. The results of competitive binding assay reveal that both complexes displace EB from DNA marginally. Gel electrophoresis data show that both the complexes 1 and 2 requires co-reagent to induce DNA cleavage but complex 2 exhibit better nuclease activity compared to complex 1. The results from this study describe the role of ligand structure in the binding and cleavage of DNA as furan based ligand exhibit better cleaving ability compared to imidazole moiety.     

A cobalt complex of a pentadentate aminopyridine ligand as an efficient catalyst for photocatalytic hydrogen generation

A linear pentadentate aminopyridine ligand 2,6-bis[(methyl(pyrid-2-ylmethyl)amino)-N-methyl]pyridine (Py^Mepam) has been prepared and characterized. This ligand readily coordinates with Co(II) or Zn(II) ions, and the resulting complexes of general formula [M(Py^Mepam)](BF₄)₂ (M = Co (1) and M = Zn (2)) have been thoroughly characterized and investigated for electro- and photocatalytic water reduction in acetonitrile. Electrochemical studies reveal that the complex 1 is active for electrocatalytic water reduction in acetonitrile. Under visible-light irradiation (λ > 400 nm), the complex 1 displays hydrogen evolution activity when in presence of [Ir(ppy)₂(bpy)]PF₆ as photosensitizer and triethylamine (TEA) as electron donor, whereas 2 shows negligible catalytic activity under the same conditions. Highest turnover numbers (TONs) of 290 for H₂ evolution are achieved from an optimized system containing 1 (0.1 mM), [Ir(ppy)₂(bpy)](PF₆) (0.5 mM), and 10 vol% TEA in CH₃CN-H₂O (1/1, v/v) mixed solvents at pH 10.     

Blue emission of a 2D non-interpenetrated zinc coordination polymer constructed through saturated fatty acid ligand

We report a new non-interpenetrated 2D zinc coordination polymer, [Zn(AA)(BPHY)]_n (1) (H₂AA = adipic acid, BPHY = 1,2-bis(4-pyridyl)hydrazine), which is a mixed ligand complex. The solid-state sample of 1 exhibits tunable blue emission excited by UV light with the wavelengths from 320 nm to 380 nm. The luminescent mechanism of 1 has been studied by theoretical calculation.     

New μ-oxo-bridged tetranuclear Cu(II) complex with Schiff-base ligand: Synthesis,crystal structure and magnetic properties

A new μ-oxo-bridged Cu(II) complex with cubane-like tetranuclear copper(II) complex, [Cu₄(L¹)₄] · 4H₂O (1) (H₂L¹ = 2-(3-methoxy-salicylidene-amino)-benzyl-alcohol), has been prepared, and structurally characterized by X-ray crystallography. Complex 1 crystallized in the monoclinic space group P₂₁/n and has a tetranuclear core of Cu₄O₄. The temperature dependence of magnetic susceptibility measurements shown that complex 1 exhibits a strong antiferromagnetic interaction with J = −103.4 cm⁻¹.     

PMMA-supported hybrid materials doped with highly near-infrared (NIR) luminescent neutral trikis-β-diketonate Yb3 + complex

Based on self-assembly of a trifluorinated and acylpyrazole-modified β-diketonate ligand HL ((Z)-3-methyl-1-phenyl-4-(2,2,2-trifluoro-1-hydroxyethylidene)-1H-pyrazol-5(4H)-one), LnCl₃⋅ 6H₂O (Ln = La, Yb or Gd) and 2,2′-bpy (2,2′-bipyridine), three trikis-β-diketonate complexes [Ln(L)₃(2,2′-bpy)] (Ln = La, 1; Ln = Yb, 2 or Ln = Gd, 3) were obtained, respectively. Further through physical doping, the series of PMMA-supported hybrid materials PMMA@[Ln(L)₃(2,2′-bpy)] with high thermal stability and good film-forming property are obtained. Especially for PMMA@2, the doping also causes the improved NIR luminescent property (Φ_em = 0.97%) in comparison to the individual Yb^3 +-β-diketonate complex 2 (Φ_em = 0.81%) even up to a concentration of 200:1.     

Construction and photoluminescence properties of two novel zinc(II) and cadmium(II) benzyl-tetrazole coordination polymers

Two new d¹⁰ coordination polymers, Zn(Beta)₂ (1) and Cd₂(Beta)₃Cl(H₂O) (2) (Hbeta = 5-benzyl-tetrazole) have been synthesized by the in situ [3 + 2] cycloaddition reaction of 5-benzylacetonitrile, sodium azide and MCl₂ [M = Zn (1); M = Cd (2)] under hydrothermal condition. Complex 1 is a coordination polymer comprised of numerous mildly undulated two-dimensional (2D) layers with a (4, 4) topological network; while complex 2 is a 3D coordination framework constructed from the interconnection of various helical chains through cadmium–chlorine bridges. Furthermore, the luminescence properties of two complexes have been investigated.     

Design,synthesis, crystal structure and photophysical studies of an emissive,terbium based sensor for zinc

The synthesis, crystal structure and photophysical studies of the probe complex Tb · L are described. Tb · L is a mononuclear complex with a 46-membered macrocyclic rings constructed by intermolecular hydrogen bond. The mononuclear complex Tb · L shows Laporte-forbidden ⁵D₄ → ⁷F_J f–f transitions and exhibits strong green luminescence emission bands in the solid state at ambient temperature which is characteristic of terbium ion. New selective luminescent lanthanide chemosensor for Zn(II) ion based on Tb · L is also described, suggesting host–guest complexation signaling transduction mechanism.     

Solvothermal syntheses,crystal structures and luminescent properties of two new aromatic dicarboxylate indium coordination polymers

Two new indium coordination polymers formulated as [In(BPDA)(phen)Cl]_n (1) and [In(BDC)(HBDC)·2DMF]_n (2) (H₂BPDA = 2,2′-biphenyldicarboxylic acid, C₁₄H₁₀O₄; phen = 1,10-phenanthroline, C₁₂H₈N₂; H₂BDC = 1,3-benzenedicarboxylic acid, C₈H₆O₄; DMF = N,N-dimethylformamide, C₃H₇NO) have been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, infrared (IR), thermal gravimetric analyses (TG) and luminescent studies. Molecular structural analyses reveal that complex 1 exhibits an indium-2,2′-biphenyldicarboxylate helical chained structure decorated with 1,10-phenanthroline, and complex 2 possesses a two-dimensional (2D) layered structure constructed by 1,3-benzenedicarboxylate ligands and InO₆ octahedra, which has a (4,4) topological structure. Blue-green emission at 480 nm (λ_ex = 340 nm) for 1, intense blue-green emission at 492 nm, green emission at 535 nm, and yellow-green emission at 576 nm (λ_ex = 340 nm) for 2 are observed in the solid state at room temperature.     

Ferromagnetic interactions in zinc(II) coordination complex containing nitronyl nitroxide radicals

A novel complex Zn(NIT2-py)₃(ClO₄)₂(NIT2-py = 2-(2′-pyridyl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl-3-oxide) (1) has been synthesized and characterized structurally and magnetically. The metal coordination sphere is fully occupied by three chelating nitroxide ligands, showing a distorted octahedral geometry. Temperature dependence of susceptibility measurements shows a weak ferromagnetic coupling between NIT2-py radicals with J = 2.13 cm⁻¹. The field dependence of the magnetization further confirms that the ground state of the compound S = 3/2 results from ferromagnetic interactions within the complex 1.