Molecular structures and vibrational frequencies for cis-[PdCl2(tmen)] and cis-[Pd(N3)2(tmen)]: A DFT study

Theoretical molecular structures of the complexes cis-[PdCl₂(tmen)] and cis-[Pd(N₃)₂(tmen)] (tmen = N,N,N′,N′-tetramethylethylenediamine) were investigated using B3LYP/DFT method. The calculated molecular parameters, bond distances and angles, revealed a square-planar geometry around the metallic center for both compounds with the azide being linear. The theoretical infrared spectra of C₁ symmetry (electronic state ¹A) of the compounds are in agreement with the experimental data.     

Two 1D [CuxIx]-based coordination polymers of tetraphosphine ligands

Diffusion reactions of CuI with N,N,N′,N′-tetra(diphenylphosphanylmethyl)ethylene diamine) (dppeda) and 1,4-N,N,N′,N′-tetra(diphenylphosphanylmethyl)benzene diamine (dpppda) in MeCN/toluene in a zigzag glass tube or solvothermal reactions of CuI and dppeda or dpppda in MeCN produced two [Cu_xI_x]-based coordination polymers, [Cu₂I₂(dppeda)]·2MeCN (1·2MeCN) and [Cu₄I₄(dpppda)]·MeCN (2·MeCN), respectively. Both compounds were characterized by elemental analysis, IR spectroscopy, ¹H and ³¹P{¹H} NMR, ESI-MS and thermogravimetric analysis, and their structures were determined by single crystal X-ray diffraction. In 1, [Cu₂I₂] cores are interconnected by dppeda ligands in a μ-η²:η² end-to-end mode to form a 1D chain, while in 2 stair-like [Cu₄I₄] cores are linked by dpppda ligands in a unique Z-shaped μ-η²:η² side-by-side mode to produce the other kind of 1D chain.     

DNA binding of mixed-metal supramolecular Ru, Pt complexes

The mixed-metal supramolecular complexes [(tpy)Ru(PEt₂Ph)(dpp)PtCl₂](PF₆)₂ and [(tpy)Ru(PEt₂Ph)(bpm)PtCl₂](PF₆)₂ are of interest in that they couple light absorbing ruthenium centers to a reactive metal site through a communicative bridge (tpy=2,2^′:6^′,2^′′-terpyridine, BPM=2,2^′-bipyrimidine and DPP=2,3-bis(2-pyridyl)pyrazine). These systems have been studied and shown to avidly bind to DNA, greatly reducing its mobility through an agarose gel.     

Design and construction of two new polymers featuring macrocyclic subunits based on a rigid clamp-like ligand

Reaction of a rigid conjugated clamp-like ligand N,N′-bis(pyridin-3-yl)-2,6-pyridinedicarboxamide (bppdca) with ZnSO₄·7H₂O or CoSO₄·7H₂O resulted in the formation of two new polymers, namely, {[Zn₂(bppdca)(SO₄)₂(DMF)₂]·(DMF)}_n (1) and {[Co(bppdca)(SO₄)(CH₃OH)(DMF)]·H₂O}_n (2). Both 1 and 2 feature one-dimensional double-chain structures with macrocyclic subunits, and the chains further self-assemble into a higher-dimensional framework via the hydrogen-bonding and π–π stacking interactions. Fluorescence studies show that the free ligand displays a strong fluorescence emission in solid state at room temperature, but in 1 and 2, the complexation of the ligand with metal ions and weak intermolecular interactions make the fluorescence emission partial quenching.     

Novel Hg and Mn supramolecular complexes with a versatile building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiolate involving in situ ligand formation

Reaction of potassium N′-(pyridine-4-carbonyl)-hydrazinecarbodithioate ([K⁺(H₂L)⁻]) with Hg^II or Mn^II inorganic salt in the presence of 1,10-phenanthroline (phen) or 4,4′-bipyridine (bipy), yields complexes [Hg(pyt)₂(phen)] (1) and {[Mn(pyt)₂(H₂O)₂]·(bipy)·(H₂O)₂}_n (2), in which the pyt ligand (Hpyt = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol) is obtained by in situ ligand formation from the acyclic precursor [K⁺(H₂L)⁻]. Single crystal X-ray diffraction suggests that the pyt anionic ligands in 1 and 2 behave as thiolate and thione isomers, respectively, and display S- and μ-N_pyridyl, N_oxadiazole-binding fashions. Complex 1 shows a 1-D fishbone-like supramolecular array via strong aromatic stacking interactions between the discrete mononuclear coordination motifs, whereas 2 has a 2-D layered host coordination framework with the inclusion of bipy and water guests in the cavities.     

N-(Diethylaminothiocarbonyl)ferrocenecarbimidoyl chloride, a versatile reagent

N, N-Diethiyl-N′-ferrocenoylthiourea reacts with thiophosgene to form N- (diethylaminothiocarbonyl) ferrocenecarbimidoyl chloride, which yields N-(diethylaminothiocarbonyl)-N′-(aryl/alkyl)ferrocenecarbamidines when reacted with primary amines via nucleophilic substitution. The reaction of bis(N,N-diethyl-N′-ferrocenoylthioureato)nickel(II) with phosgene gives 2,6-bis(diethylamino)-4-ferrocenium-1,3,5-thiadiazinium-tetrachloroniccolat(II). The X-ray structure determination of N-(diethylaminothiocarbonyl)benzimidoyl chloride is presented.     

A novel infinite 1D covalent chain of end-to-end thiocyanato bridged heptacoordinated cadmium(II)Schiff base: π…π interaction and weak C–H…S hydrogen bonded supramolecule

A new Schiff base, N,N′-(bis(pyridin-2-yl)formylidene)ethane-1,2-diamine (bpfd) is prepared and used to synthesize a novel end-to-end thiocyanato bridged infinite 1D polymeric heptacoordinated cadmium(II) chain [Cd(bpfd)(μ_1,3-NCS)(NCS)]_n (1) which forms a 3D supramolecule through weak C–H…S hydrogen bonding and π…π interaction.     

Towards Rational Synthesis of Microporous Aluminophosphate AlPO4-21 by Hydrothermal Combinatorial Approach

We present a strategy toward the rational synthesis of microporous materials by combination of computational and combinatorial approach. In terms of nonbonding interaction energies of host–guest calculated by the molecular dynamics simulations using Cerius²package, the templating abilities of various organic amines in the formation of microporous aluminophosphate AlPO₄-21 have been evaluated. Through rational selection of the predicted suitable templates, such as ethanolamine, trimethylamine and N, N, N′, N′-tetramethylenediamine, AlPO₄-21 has been successfully synthesized by hydrothermal combinatorial approaches in the reaction system 1.0Al(ⁱOPr)₃-xH₃PO₄-yR-255.0H₂O (R amines). The as-synthesized products are characterized by automated X-ray powder diffraction, ICP, TG, and single-crystal X-ray diffraction analyses. Their framework structures belong to zeotype AWO, which possesses eight-membered ring channels along [001] direction.     

Synthesis of Organosoluble and Optically Active Poly(ester-imide)s by Direct Polycondensation with Tosyl Chloride in Pyridine and Dimethylformamide

Summary 4,4′-Oxydiphthalic anhydride (1) was reacted with L-methionine (2) in acetic acid and the resulting N,N′-(4,4′-oxydiphthaloyl)-bis-L-methionine diacid (4) was obtained in high yield. The direct polycondensation reaction of this diacid with several aromatic diols such as bisphenol A (5a), phenolphthalein (5b), 1,4-dihydroxyanthraquinone (5c), 4,4′-dihydroxydiphenyl sulfide (5d), 2,6-dihydroxytoluene (5e), 4,4′-dihydroxydiphenyl sulfone (5f) and 2,4′-dihydroxyacetophenone (5g) was carried out in a system of tosyl chloride (TsCl), pyridine (Py) and N,N-dimethylformamide (DMF). The reactions with TsCl were significantly promoted by controlling alcoholysis with diols in the presence of the catalytic amounts of DMF to give a series of optically active poly(ester-imide)s (PEI)s with good yield and moderate inherent viscosity ranging 0.21–0.71 dL/g. The polycondensation reactions were significantly affected by the amounts of DMF, molar concentration of monomers, TsCl and pyridine, aging time, addition time of diols, temperature and the reaction time. All of the above polymers were fully characterized by ¹H-NMR, FT-IR, elemental analysis and specific rotation. Some structural characterization and physical properties of these new optically active PEIs are reported.     

Photooxidation of N,N-bis(3,5-di-tert.-butylsalicylidene)-1,2-diamino hexane-manganese(III) chloride (Jacobsen catalyst) in chloroform

Mn^III(J-salen)Cl (Jacobsen catalyst) with J-salen=N,N^′-bis(3,5-di-tert.-butylsalicylidene)-1,2-diaminocyclohexane dianion in CHCl₃ is photooxidized by the solvent to a Mn^IV(J-salen) complex, presumably Mn^IV(J-salen)Cl₂, with φ=0.002 at λ_irr=333 nm.     

Ditopic, flexible hydrazone-based building blocks with pendant 2,2′:6′,2′′-terpyridine metal-binding domains

The synthesis and characterization of three new bis(2,2′:6′,2′-terpyridine) (tpy) ligands containing different hydrazone spacers between the metal-binding domains are described. Treatment of 1,4-benzenedicarbaldehyde bis(2,2′:6′,2′′-terpyridin-4′-ylhydrazone) (1) with [(tpy)RuCl₃] in the presence of N-ethylmorpholine results in the formation of [(tpy)Ru(μ-1)Ru(tpy)]⁴⁺. Single crystal X-ray diffraction data for [(tpy)Ru(μ-1)Ru(tpy)][PF₆]₄·8MeCN confirm the ability of the hydrazone-based ligand to bridge two ruthenium(II) centres, providing proof-of-principle for the application of this class of flexible ligand in the design of coordination polymers.     

A two-dimensional metal-organic framework composed of paddle-wheel cobalt clusters with permanent porosity

A cobalt(II)-organic framework, [Co₂(TPEC)(DMA)₂]·(DMA)₃ (1) (H₂TPEC = 1,1,2,2-tetra(4-(4-carboxyl-phenyl)benzenyl)ethene; DMA = N,N′’-dimethylacetamide), was synthesized and characterized by single crystal diffraction analysis. The structure shows a two-dimensional (2D) sheet composed of paddle-wheel Co₂(COO)₄ clusters linking TPEC ligands. The permanent porosity was established for the activated phase and gas sorption isotherms acquired.     

Switching on the photochemical reactivity in heterodimetallic Os–Ru bipyridyl complexes containing a bis(bidentate) phosphine

For the first time the excited states of the RuP₂N₄ moiety belonging to a new heterodimetallic Os^II–Ru^II bipyridyl complex are successfully designed in order to introduce photochemical reactivity. This dramatic effect is achieved via the use of the sterically demanding bis(bidentate) phosphine cis, trans, cis-1,2,3,4-tetrakis(diphenylphosphino)cyclobutane (dppcb). Thus, the temperature dependence of the luminescence lifetimes ranging from 77 to 298 K for the novel homodimetallic species meso-(ΔΛ/ΛΔ)-[Os₂(dppcb)(bpy)₄](PF₆)₄ (1) and rac-(ΔΔ/ΛΛ)-[Os₂(dppcb)(bpy)₄](PF₆)₄ (2) clearly indicates that the d–d state responsible for photochemistry is not populated. By contrast, the analogous temperature dependence for the new heterodimetallic species ΔΛ/ΛΔ-[Os(bpy)₂(dppcb)Ru(bpy)₂](PF₆)₄ (3) and ΔΔ/ΛΛ-[Os(bpy)₂(dppcb)Ru(bpy)₂](PF₆)₄ (4) unequivocally shows that as a consequence of the population of the d–d state the photochemical reactivity is switched on. Since single crystal X-ray structure analyses are a major clue to the understanding of photophysical and photochemical properties, also the X-ray structures of 1–3 are given.     

Mechanisms of photocatalytic degradation of Victoria Blue R using nano-TiO2

The TiO₂-mediated photocatalysis process was used to successfully degrade dye pollutants. To better understand the mechanistic details of this TiO₂-assisted photodegradation of the Victoria Blue R (VBR) dye with UV irradiation, forty-four intermediates of the process were separated, identified and characterized by HPLC–PDA–ESI-MS (high performance liquid chromatography–photodiode array–electrospray ionization-mass spectrometry) technique in this study, and their evolution during the photocatalytic reaction is presented. The results indicated that the N-de-alkylation degradation of VBR dye took place in a stepwise manner to yield mono-, di-, tri-, tetra-, penta-, hexa-N-de-methylated and mono-N-de-ethylated VBR species, with N-hydroxyalkylated intermediates generated during the process. Moreover, the oxidative degradation yielded 4-diethylaminophenol, 4-diethylamino-4′-diethylaminobenzophenone, 4-(N,N-dimethylaminophenyl)-4′-(N′-ethylaminonaphthyl)ketone, 4-(N-ethylamino)naphthenol and their N-de-alkylated products. The reaction mechanisms of TiO₂/UV proposed in this study should be useful for future application of the technology to the degradation of dyes.     

Bimetallic nickel complexes of trimethyl phenyl linked salicylaldimine ligands: Synthesis, structure and their ethylene polymerization behaviors

Bimetallic salicylaldimine-nickel complexes, 2,4,6-Me₃-1,3-{[NCH–(3′-R-5′-Y-2′-O–C₆H₃)-κ²-N,O]Ni(Ph) (PPh₃)}₂ [R = tert-Bu, Y = Me, 1b; R = Ph, Y = H, 2b] were prepared and their catalytic behaviors of ethylene polymerization were investigated. The bimetallic complex 2b shows higher activities (2.9 × 10⁵ g PE mol⁻¹ Ni h⁻¹) for ethylene polymerization and affords polymer with high molecular weight (M_w = 1.41 × 10⁵) and broad molecular weight distribution (M_w/M_n = 6.1) than its mononuclear matrix, {[(2,6-Me₂C₆H₃)–NCH–(3′-Ph-2′-O–C₆H₃)-κ²-N,O]Ni(Ph)(PPh₃)} (3) (Activity = 5.5 × 10⁴ g PE mol⁻¹ Ni h⁻¹; M_w = 1.86 × 10⁴; M_w/M_n = 2.8).     

A New Metal–Organic ZnII Supramolecular Assembled via Hydrogen Bonds and N···N Interactions as a New Precursor for Preparation Zinc(II) Oxide Nanoparticles, Thermal, Spectroscopic and Structural Studies

A new 1D supramolecular involving two different ligands, {[Zn(GB)₂]·(μ-bpe)₃} _n (ClO₄)_2n ·nH₂O (GB = 2-guanidinobenzimidazole and bpe = 1,2-bis(4-pyridyl)ethylene, has been synthesised, characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy. The thermal stability of compound {[Zn(GB)₂]·(μ-bpe)₃} _n (ClO₄)_2n ·nH₂O was studied by thermal gravimetric and differential thermal analyses. The single crystal X-ray analysis shows that the complex is a one-dimensional polymer involving macrocycle rings as a result of non-covalent bridging bpe ligands via N–H···N and N···N interactions, N–H···bpe···bpe···H–N, with the basic repeating {[Zn(GB)₂](μ-bpe)₃}(ClO₄)₂·H₂O units and by connecting [Zn(GB)₂]²⁺ nodes. ZnO nanoparticles were obtained by calcination of compound {[Zn(GB)₂]·(μ-bpe)₃} _n (ClO₄)_2n ·nH₂O at 500 °C in air. The nanoparticles were characterized by X-ray diffraction and scanning electron microscopy.     

SYNERGISTIC EXTRACTION OF Eu(III) AND Am(III) BY THENOYLTRIFLUOROACETONE AND NEUTRAL DONOR EXTRACTANTS: (CARBAMOYLMETHYL)PHOSPHINE OXIDE AND 2,6-BIS((DIPHENYLPHOSPHINO)METHYL)PYRIDINE N,P, P-TRIOXIDE

ABSTRACT

Solvent extraction of Eu(III) and Am(III) from weakly acidic solutions with octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and 2,6-bis((diphenylphosphino)methyl)pyridine N, P, P-trioxide (NOPOPO) in 1,2-dichloroethane was studied on a comparative basis. NOPOPO was found to exhibit unusually high extractability for Eu(III) and Am(III), probably due to its trifunctional nature, sufficient steric flexibility and basicity of the functional groups. Both CMPO and NOPOPO demonstrated synergistic effects in extraction of Eu(III) and Am(III) when used in combination with thenoyltrifluoroacetone (HTTA). However, the stoichiometry of the extracted species with CMPO/HTTA and NOPOPO/HTTA was different under similar experimental conditions. The extractant dependencies of the synergistic extractions suggest that the extracted species are the adduct complexes, M(ClO₄)(TTA)₂(CMPO)₂ and M(ClO₄)₂(TTA)(NOPOPO)₂, respectively. It was also observed that CMPO and CMPO/HTTA in dichloroethane extracted Eu(III) and Am(III) equally well, with very similar extraction constants. However, NOPOPO and NOPOPO/HTTA in dichloroethane demonstrated a slight preference for Eu(III) over Am(III), with the extraction constants for Eu(III) more than one order of magnitude higher than that for Am(III).     

Self-assembly of a Co4III face-shared partial double cubane supported by alkoxo terminal and bridging ligands

The double μ₃-OMe supported tetrameric Co₄ complex [Co₄(μ₃-OMe)₂(μ-bemp)₂(N₃)₂(OH₂)₂](ClO₄)₂ · 4H₂O {1 · (ClO₄)₂ · 4H₂O} was isolated from the reaction of Co(ClO₄)₂ · 6H₂O with H₃bemp (where H₃bemp = 2,6-bis-[(2-hydroxy-ethylimino)-methyl]-4-methyl-phenol) and NaN₃ in presence of NEt₃ in aqueous methanol. The X-ray structure analysis reveals a cationic tetrameric arrangement consisting of a defective dicubane-like core with two missing vertexes. The four Co(III) ions are connected through in situ generated μ₃-OMe and central phenolate plus terminal ethanolate bridges of the ligand. Terminal aqua and azido coordinations finally fulfil the octahedral geometries around the Co^III ions within this Co₄ aggregate.     

Unusual iron-mediated C–N bond formation and synthesis of the Fe(III) complex of a polypyridine ligand with one carboxamide group

A high-spin iron(III) chloro complex [(PaPPy₃)Fe(Cl)](ClO₄) (1, where =N,N-bis(2-pyridylmethyl)amine-N-propyl-2-pyridine-2-carboxamide) has been synthesized via the “template effect” and structurally characterized. The template reaction leads to the formation of a new carbon–nitrogen bond from coupling of a primary alkyl chloride with a secondary amine.     

Reactivity studies of 2,3,5,6-Tetra(2-pyridyl) pyrazine (tppz) with first-row transition metal ions

Reactions of 2,3,5,6-tetra(2-pyridyl) pyrazine (tppz) with [ML₆][X]₂ (L = CH₃CN, H₂O;X = [BF₄]⁻, [ClO₄]⁻, [NO₃]⁻ [BArF]⁻(BArF - B[3,5-C₆H₃(CF₃)₂]₄) lead to the high-yield formation of mononuclear [M(tppz)₂]²⁺, (M = Mn^II, Fe^II, Co^II, and Ni^II) and dinuclear [Ni₂(tppz)(CH₃CN)₆]⁴⁺ species. The new compounds were fully characterized by X-ray crystallographic, spectroscopic, and magnetic susceptibility measurements. Surprisingly, the 2:1 M:tppz reactions did not lead to isolation of the dinuclear species except in the case of Ni(II). It was further noted that even in the case of the Ni reactions, the nuclearity of the product depends on the choice of anions and the reaction conditions. Magnetic measurements of the mononuclear species [Co(tppz)₂]²⁺ revealed thermally induced spin-crossover behavior from a high-spin S = 3/2 at higher temperatures to a low-spin S = 1/2 complex at lower temperatures. The dinuclear compound [Ni₂(tppz)(CH₃CN)₆]⁴⁺ exhibits a weak anti-ferromagnetic interaction through the bridging tppz ligand.