Cytotoxic O-bridged inert titanium(IV) complexes of phenylenediamine-bis(phenolato) ligands

Binuclear O-bridged titanium(IV) complexes of phenylenediamine-bis(phenolato) ligands were obtained from the corresponding ligands and Ti(OiPr)₄ and analyzed by ¹H, ¹³C and diffusion NMR. The comparative hydrolytic stability in 1:9 D₂O/DMSO-d₆ was assessed by ¹H NMR, and the complexes featured t_1/2 values of above 100 h. The cytotoxic activity of the binuclear complexes was measured toward human colon HT-29 cancer cell line by the MTT assay. Although as expected most complexes exhibited mild or no cytotoxic activity, one leading complex demonstrated marked activity with IC₅₀ value of 77 ± 40 μM.     

Two octamolybdate-based coordination polymers with high photocatalytic activities under visible light irradiation

Two coordination polymers based on octamolybdate and 2-aminopyrazine, namely, [Cu^I₂(HL)₂(L)(β-[Mo₈O₂₆])]·3H₂O (1) and [(H₂L)₂(β-[Mo₈O₂₆])]·4H₂O (2) (L = 2-aminopyrazine), have been synthesized hydrothermally. The structures of the compounds were determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra, elemental analyses, powder X-ray diffraction analyses and thermogravimetric analyses. Compound 1 displays a double chain structure, which is extended by the intermolecular NH ⋯ O hydrogen-bonding interactions to generate a 3D supramolecular architecture. Compound 2 exhibits a discrete structure, which is connected by the intermolecular OH ⋯ O hydrogen-bonding interactions to yield a 3D supramolecular architecture. Compounds 1 and 2 display small band gaps of 1.89 and 1.66 eV, respectively. Moreover, compounds 1 and 2 exhibit high photocatalytic activities for degradation of methylene blue under visible light irradiation.     

A 3D Cu(II) coordination polymer constructed from BIBP (BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene) ligand with semiconductive property

Hydrothermal reaction of Cu(NO₃)₂·3H₂O with BIBP and H₂hfipbb at 105 °C yielded a novel 3D Cu(II) coordination polymer, {[Cu₂(BIBP)_0.5(hfipbb)₂(CH₃CN)]·5H₂O}_n (1) [BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene, H₂hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)]. Compound 1 displays a 3D 2-fold interpenetrating framework with {4⁴.6⁶} sqp topology, containing interesting ⋯LRLR⋯ double helical chains. The compound 1 was characterized by IR spectra, elemental analysis, thermal analysis and single crystal X-ray diffraction. In addition, solid-state UV–vis spectra experiment shows that compound 1 exhibits semiconductive property with a band gap of 2.46 eV.     

Assembly of one 2D layer and two 3D pillared-layer structures derived from metal ions and 5-(pyridin-4-yl)isophthalic acid with or without pillars

Three new coordination polymers, [Mn(L)(H₂O)₂]₂·5H₂O (1), [Cu(L)(4,4′-bipy)]₂·H₂O (2) and [Pb(L)(4,4′-bipy)_0.5] (3) (H₂L = 5-(pyridin-4-yl)isophthalic acid; 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized by IR, thermogravimetric analysis, X-ray powder diffraction and X-ray single crystal diffraction. Complex 1 shows a 2D layer structure which stacks with the other ones to form 1D channels to hold 1D water chains. Complex 2 displays a 3D + 3D → 3D polycatenation network. 3 shows a unique 2D + 2D → 3D polycatenation net in which each Pb center has a hemidirected coordination geometry due to the existence of “inert pair effect”. The thermal and luminescent properties of 1–3 were also examined.     

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.     

Three d10 coordination polymers based on rigid ligands with flexible functional groups: Syntheses,structures and luminescence

Three coordination polymers, namely, {[Zn(L)(BPY)]·DMF·H₂O}_n (1), {[Zn(L)(TPY)]·0.5H₂BDC·H₂O}_n (2), {[Cd(L)(H₂O)₂]·DMF}_n (3), have been synthesized based on a rigid linear carboxylate ligand (H₂L = 2′,5′-dimethoxy-[1,1′:4′,1″-terphenyl]-4,4″-dicarboxylic acid) and different lengths of pyridine ligands (TPY = 4,3′:5′,4″-terpyridine; BPY = 4,4′-bipyridine). These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. Complex 1 is a 6-connected 3-fold interpenetrating pcu net with point symbol {4¹² ∙ 6³}, 2 and 3 can be simplified as 4-connected sql nets with point symbol {4⁴ ∙ 6²}. In addition, their photoluminescent properties are also investigated in detail.     

Novel 3-dimensional sixfold interpenetrating diamondoid networks of copper(I) coordination polymers of polypyridyl ligands – Syntheses,characterization and crystal structures

Two new coordination polymers [Cu(L¹)₂]_n(ClO₄)_n·2nH₂O (1), [Cu(L²)₂]_n(ClO₄)_n·2nH₂O (2) of polydentate imine/pyridyl ligands, L¹ and L² with Cu(I) ion have been synthesized and characterized by single crystal X-ray diffraction studies, elemental analyses, IR′ UV–vis and NMR spectroscopy. They represent 3-dimensional, sixfold interpenetrating diamondoid network structures having large pores of dimension, 35 × 21 Å² in 1 and 38 × 19 Å² in 2, respectively.     

One mononuclear single-molecule magnet derived from Dy(III) and dmbpy (dmbpy = 4,4′-dimethyl-2,2′-dipyridyl)

Three β–diketonate mononuclear Ln-based compounds, formulated as [Tb^III(hfac)₃(dmbpy)](1), [Dy^III(hfac)₃(dmbpy)](2) and [Er^III(hfac)₃(dmbpy)](3) (hfac = hexafluoroacetylacetone, dmbpy = 4,4′-dimethyl-2,2′-dipyridyl) have been synthesized and structurally characterized by single crystal X-ray diffraction. Structure characterization reveals that complexes 1, 2 and 3 are isomorphous. Shape measurement shows the coordination geometry of complex 2 is trigonal dodecahedron (D_2d). Magnetic property study indicates complex 2 shows SIM behavior with observed frequency-dependent signals at low temperature.     

Two novel grid networks based on Keggin-type polyoxometalate clusters assembled through weak Cu⋯O interactions

Two novel grid networks based on Keggin-type polyoxoanion, formulated [Cu(2,2′-bipy)₂](HPMo₁₂O₄₀) · H₂O (1) and [Cu(2,2′-bipy)₂](HPW₁₂O₄₀) · H₂O (2) have been synthesized hydrothermally and characterized by elemental analyses, IR, EPR and X-ray single crystal diffraction. 1 is a 2D grid network built by the interconnection of bisupporting polyoxoanion clusters assembled through weak Cu⋯O interactions. The EPR spectrum of 1 indicates that its unpaired electrons are placed in d_x²−y² orbital of the ground state of Cu(II). Compound 2 is isostructural with compound 1.     

One-dimensional nanoporous M2L2 rhombohedral molecular square with strong blue fluorescent emission

The hydrothermal reactions of Zn(ClO₄)₂ · 6H₂O and Cd(ClO₄)₂ · 6H₂O with the ligand N,N^′-bis(pyridylcarbonyl)-4,4^′-diaminodiphenyl ether (L) afford two one-dimensional (1D) coordination polymers, ([CdL(ClO₄)₂ · (H₂O)₂] · 2H₂O) (1) and [ZnL(ClO₄)₂ · (H₂O)₂] · 2H₂O, (2) having a nanoporous M₂L₂ rhombohedral molecular square with an approximately accessible cavity of 12.9 × 12.9 (1) and 12.7 × 12.7 (2) Å without any interpenetrations. Both 1 and 2 are isostructural and display very strong blue fluorescent emission in the solid state at room temperature.     

A pair of novel helical Zn(II) enantiomers constructed from l- and d-threonine Schiff bases: Synthesis,crystal structures and properties

Two novel homochiral helical Zn(II) coordination polymers, {[Zn₂(nap-l-thr)₂(H₂O)₂]·H₂O}_n (1) and {[Zn₂(nap-d-thr)₂(H₂O)₂]·H₂O}_n (2) (H₂nap-l-thr = N-(2-hydroxy-1-naphthylmethylidene)-l-threonine, H₂nap-d-thr = N-(2-hydroxy-1-naphthylmethylidene)-d-threonine) have been successfully synthesized and characterized by elemental analysis, IR, UV–visible and single-crystal X-ray diffraction. It is interesting to note that both complexes are a pair of enantiomers: 1 exhibits 1D right-handed helical chain of [Zn-COO⁻]_∞ and 2 is 1D left-handed helical chain of [Zn-COO⁻]_∞. There are various hydrogen bonds between the adjacent helical chains which result in a 2D homochiral supramolecular layer structure. Notably, under similar synthetic procedure by using the NO₃⁻, CH₃COO⁻, Cl⁻ salts of Zn^2 + ion as a starting reagent, and identical compounds were obtained. In addition, the chiral nature of complexes 1 and 2 are confirmed by the results of circular dichroism (CD) spectra measurements. Thermal stability and luminescence properties were also investigated.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

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.     

Rhodium(III) complexes of N-{2-(arylseleno/telluro)ethyl} morpholine: Synthesis,structure and applications as efficient catalyst for transfer hydrogenation reaction of ketones

N-{2-(Arylseleno/telluro)ethyl}morpholine (L1/L2) synthesized by reacting PhSe^?/ArTe^? (generated insitu) with (2-chloroethyl)morpholine hydrochloride, reacts with RhCl₃·3H₂O resulting in complexes [RhCl₂(L1/L2)₄][ClO₄] (1/2). ¹H, ¹³C{¹H} and ⁷⁷Se{¹H}/¹²⁵Te{¹H} NMR spectra of L1, L2, 1 and 2 were found characteristic. The single crystal structure of 2 has been solved. The L2 binds with Rh in 2 as a monodentate ligand. The geometry around Rh is distorted octahedral. The Rh–Te distances are in the range 2.6509(9)–2.6688(8) ?. Both the complexes efficiently catalyze transfer hydrogenation reaction of acetophenone (TON/TOF up to 9.9 × 10⁴/9.9 × 10³ h^? 1) and benzophenone (TON up to 9.8 × 10⁴ and TOF up to 9.8 × 10³ h^? 1).     

PNBE-supported metallopolymer-type hybrid materials through grafting of Ln3-benzimidazole-arrayed (Ln = Nd,Yb or Er) complex monomers with efficient NIR luminescence

Through the ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with each of the obtained allyl-containing complex monomers {[Ln₃(L)₄Cl₄(MeOH)₂]·Cl} (Ln = La, 1; Nd, 2; Yb, 3; Er, 4 or Gd, 5; HL = 4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol), a series of metallopolymers Poly({[Ln₃(L)₄Cl₄(MeOH)₂]·Cl}-co-NBE) were obtained, respectively. Especially for Poly(NBE-co-2) and Poly(NBE-co-3), covalently-bonded grafting endows significantly improved physical properties including efficient NIR luminescence (Φ_Nd^L = 0.58% and Φ_Yb^L = 0.88%) in solid state.     

Synthesis,luminescence, and structural characterization of Zn and Cd coordination polymers of flexible bis(imidazolyl) derivatives

Coordination polymers [Zn(imc)(L¹)] · H₂O, (1, imc = iminodiacetate, L¹ = bis(N-imidazolyl)methane) [Zn(hba)₂(L²)]₂ · EtOH · 3H₂O, (2, hba = p-hydroxybenzoate, L² = bis(N-benzimidazolyl)methane), [Cd(mal)(H₂O)(L³)](3, L³ = 1,4-bis(N-imidazolyl)butane, mal = maleate) have been prepared and structurally characterized. Complex 1 consists of hexa-coordinated central Zn ions and exhibits 2D network structure. The Zn atoms in 2 have tetrahedral coordination geometry, and are linked by bis(imidazolyl) ligands into 1D chain structure. The cadmium ions in 3 are hepta-coordinated with pentagonal bipyramidal geometry. Complex 3 displays 2D grid structure. The TGA showed that the coordination polymers are stable up to 200 °C. All the three complexes are emissive at room temperature in their solid state.     

Design,structure and magnetic properties of a novel one-dimensional Mn(II) coordination polymer constructed from 4-pyridyl-NH-1,2,3-triazole

A one-dimensional manganese(II) complex, [Mn(L₂)]_n (1, HL = 4-pyridyl-NH-1,2,3-triazole), has been hydrothermally synthesized at 120 °C. In the structure of 1, the Mn(II) ions are octahedral coordinated and further bridged by L⁻ ligands, forming a rigid 1D ribbon coordination chain. Varieties of supramolecular interactions, such as hydrogen bonds and CH ⋯ π interactions, play an important role on the stabilization of the structures. As revealed by magnetic measurement, complex 1 displays weak antiferromagnetic interaction with θ = –4.83 K, the best fit using Fisher's 1D Heisenberg model gives the intrachain magnetic coupling constant J = –0.21 cm^− 1 above 30 K due to the neighboring Mn(N–N)₂Mn rings twisted in the angle of almost 90°.     

Selective adenine/cytosine cations in one-dimensional coordination polymers of manganese (II) and copper (II) 2,3-pyridinedicarboxylates

One-dimensional coordination polymer {[1H,9H-ade]₂[MnL₂]?4H₂O}_n (1) and {[1H,3H-cyt]₂[CuL₂]?6H₂O}_n (2) (ade = adenine, cyt = cytosine, L = dianion of 2,3-pyridinedicarboxylic acid) are selectively synthesized and variable-temperature magnetic susceptibility measurements revealed weak antiferromagnetic interactions within the chains of 1 and 2 (J = ? 0.29 cm^? 1 for 1 and J = ?0.03 cm^? 1 for 2, according to the ? 2J_ijS_iS_j HDvV Hamiltonian formalism).     

Microporous solid based solely upon an intermolecular NH ⋯ O and NH ⋯ Cl hydrogen bond network

A novel porous solid of ruthenium(II, III) dimer complex, [Ru₂(p-O₂CC₆H₄NHCO^tBu)₄Cl], constructed by intermolecularly linking the hydrogen bonds of NH ⋯ O and NH ⋯ Cl was synthesized and the porous structure was crystallographically determined. The dried crystalline solid shows a high BET surface area determined by measuring the adsorption of nitrogen gas and water vapor.     

Structural characterization of a layered double salt Mn3(OH)2(SO4)2(H2O)2 · K2SO4

The title layered double salt Mn₃(OH)₂(SO₄)₂(H₂O)₂ · K₂SO₄ (1) was obtained from a simple hydrothermal reaction of CdSO₄ · 8/3H₂O, MnCl₂ · 4H₂O, α-aminopyridine (apy) and KI. X-ray analysis reveals that the two-dimensional (2-D) sheet of 1 is built up of the dimers of edge-sharing Mn(1) octahedral, extended by the apices of Mn(2) octahedral together with μ₃ and μ₄ SO₄ groups. With free K⁺ ion as guest species, the 2-D sheets are further self-assembled into a 3-D supramolecular network with 1-D channels through the Ow-H ⋯ O hydrogen-bonded interactions. The magnetic property of 1 was investigated, and a classical behavior is observed with an antiferromagnetic order below 12.5 K.