Synthesis of [F]xenon difluoride as a radiolabeling reagent from [F]fluoride ion in a micro-reactor and at production scale

[¹⁸F]Xenon difluoride ([¹⁸F]XeF₂), was produced by treating xenon difluoride with cyclotron-produced [¹⁸F]fluoride ion to provide a potentially useful agent for labeling novel radiotracers with fluorine-18 (t_1/2 = 109.7 min) for imaging applications with positron emission tomography. Firstly, the effects of various reaction parameters, for example, vessel material, solvent, cation and base on this process were studied at room temperature. Glass vials facilitated the reaction more readily than polypropylene vials. The reaction was less efficient in acetonitrile than in dichloromethane. Cs⁺ or K⁺ with or without the cryptand, K 2.2.2, was acceptable as counter cation. The production of [¹⁸F]XeF₂ was retarded by K₂CO₃, suggesting that generation of hydrogen fluoride in the reaction milieu promoted the incorporation of fluorine-18 into xenon difluoride. Secondly, the effect of temperature was studied using a microfluidic platform in which [¹⁸F]XeF₂ was produced in acetonitrile at elevated temperature (≥85 °C) over 94 s. These results enabled us to develop a method for obtaining [¹⁸F]XeF₂ on a production scale (up to 25 mCi) through reaction of [¹⁸F]fluoride ion with xenon difluoride in acetonitrile at 90 °C for 10 min. [¹⁸F]XeF₂ was separated from the reaction mixture by distillation at 110 °C. Furthermore, [¹⁸F]XeF₂ was shown to be reactive towards substrates, such as 1-((trimethylsilyl)oxy)cyclohexene and fluorene.     

Be and P NMR analyses on Be complexation with cyclo-tri-μ-imidotriphosphate anions in aqueous solution

Microscopic information on the complexation of Be²⁺ with cyclo-tri-μ-imidotriphosphate anions in aqueous solution has been gained by both ⁹Be and ³¹P NMR techniques at −2.3 °C. Separate NMR signals corresponding to free and complexed species have been observed in both spectra. Based on an empirical additivity rule, i.e., proportionality observed between the ⁹Be NMR chemical shift values and the number of coordinating atoms of ligand molecules, the ⁹Be NMR spectra have been deconvoluted. By precise equilibrium analyses, the formation of [BeX(H₂O)₃]⁺ and [BeX₂(H₂O)₂]⁰ (X = non-bridging oxygen donor as a coordination atom in the phosphate groups) has been verified, and the formation of complexes coordinating with the nitrogen atoms of the cyclic framework in the ligand molecule has been excluded. Instead, the formation of one-to-one (ML) complexes, one-to-two (ML₂), together with two-to-one (M₂L) complexes (L = cP₃O₆(NH)₃) has been disclosed, the stability constants of which have been evaluated as log K_ML = 3.87 ± 0.03 (mol dm⁻³)⁻¹, log K_ML2 = 2.43 ± 0.03 (mol dm⁻³)⁻² and log K_M2L = 1.30 ± 0.02 (mol dm⁻³)⁻², respectively. ³¹P NMR spectra measured concurrently have verified the formation of the complexes estimated by the ⁹Be NMR measurement. Intrinsic ³¹P NMR chemical shift values of the phosphorus atoms belonging to ligand molecules complexed with Be²⁺, together with the ³¹P-³¹P spin-spin coupling constants have been determined.     

Diphenyllead(IV) thiosemicarbazonates and pyrazolonates: Synthesis and characterization

Cyclization of thiosemicarbazones derived from β-keto esters and β-keto amides (HTSC) in the presence of diphenyllead(IV) acetate was explored in methanol solution at room temperature and under reflux. All β-keto ester TSCs underwent cyclization to give the corresponding pyrazolone (HL), which, except in one case, deprotonated and coordinated the PbPh₂²⁺ moiety to form homoleptic [PbPh₂(L)₂] or heteroleptic [PbPh₂(OAc)(L)] derivatives. Cyclization did not occur with β-keto amide TSCs and only [PbPh₂(TSC)₂] or [PbPh₂(OAc)(TSC)] thiosemicarbazonates were isolated. The complexes were characterized by IR spectroscopy in the solid state and by ¹H, ¹³C and ²⁰⁷Pb NMR spectroscopy in DMSO–d₆ solution, in which they evolve and decompose with time. Additionally, crystals of p-acetoacetanisidide thiosemicarbazone (HTSC¹⁰), [PbPh₂(OAc)(L⁵)] · MeOH (HL⁵ = 2,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazolone-1-carbothioamide), [PbPh₂Cl(L²)] (HL² = 2,5-dihydro-5-oxo-3-phenyl-1H-pyrazolone-1-carbothioamide), [PbPh₂(OAc)(TSC⁸)] · 2MeOH (HTSC⁸ = acetoacetanilide thiosemicarbazone), [PbPh₂(OAc)(TSC¹⁰)] · H₂O and [PbPh₂(OAc)(TSC¹¹)] · 0.75MeOH (HTSC¹¹ = o-acetoacetotoluidide) were studied by X-ray crystallography. The complexes, monomers or dimers with almost linear C–Pb–C moieties, are compared with the corresponding derivatives of Pb(II).     

Construction of a new Cu2+ coated wire ion selective electrode based on 2-((2-(2-(2-(2-hydroxy-5-methoxybenzylidene amino)phenyl)disufanyl)phenylimino)methyl)-4-methoxyphenol Schiff base

In this article a new coated platinum Cu²⁺ ion selective electrode based on 2-((2-(2-(2-(2-hydroxy-5-methoxybenzylideneamino)phenyl)disufanyl)phenylimino) methyl)-4-methoxyphenol Schiff base (L₁) as a new ionophore is described. This sensor has a wide linear range of concentration (1.2 × 10⁻⁷-1.0 × 10⁻¹ mol L⁻¹) and a low detection limit of 9.8 × 10⁻⁸ mol L⁻¹of Cu(NO₃)₂. It has a Nernstian response with slope of 29.54 ± 1.62 mV decade⁻¹ and it is applicable in the pH range of 4.0-6.0 without any divergence in potentioal. The coated electrode has a short response time of approximately 9 s and is stable at least for 3.5 months. The electrode shows a good selectivity for Cu²⁺ ion toward a wide variety of metal ions. The proposed sensor was successfully applied for the determination of Cu²⁺ ion in different real and environmental samples and as indicator electrode for potentiometric titration of Cu²⁺ ion with EDTA.     

Structure and redox behavior of Ru(II)-diene complexes

A series of Ru(acac)₂(η⁴-diene) complexes containing cis- and trans-diene coordination have been investigated by cyclic voltammetry to correlate structural bonding and conformation patterns of diene ligands with redox behaviors. The solid-state structure of Ru(acac)₂(2,3-dimethyl-1,3-butadiene) has been determined by single crystal X-ray diffraction methods. Ru(acac)₂(2,3-dimethyl-1,3-butadiene) crystallizes in the monoclinic space group C2/c with a = 12.368(2) Å, b = 17.0600(2) Å, c = 16.0110(2) Å, β = 98.4405(10)° and V = 3341.38(10) ų for Z = 8. A structural comparison between several Ru-trans-η⁴-diene complexes and Ru-η⁴-1,3-cyclohexadiene revealed no difference in the Ru-C(diene) bond distances. However, through cyclic voltammetry experiments these species demonstrated different redox behavior, as function of the coordinated diene ligand.     

Electrochemical behavior of hexafluoroniobate, heptafluorotungstate, and oxotetrafluorovanadate anions in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide room temperature ionic liquid

Electrochemical behavior of hexafluoroniobate (Nb(V)F₆⁻), heptafluorotungstate (W(VI)F₇⁻), and oxotetrafluorovanadate (V(V)OF₄⁻) anions has been investigated in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPyrTFSA) ionic liquid at 298 K by means of cyclic voltammetry and chronoamperometry. Cyclic voltammograms at a Pt electrode showed that Nb(V)F₆⁻ anion is reduced to Nb(IV)F₆²⁻ by a one-electron reversible reaction. Electrochemical reductions of W(VI)F₇⁻ and V(V)OF₄⁻ anions at a Pt electrode are quasi-reversible and irreversible reactions, respectively, according to cyclic voltammetry. The diffusion coefficients of Nb(V)F₆⁻, W(VI)F₇⁻ and V(V)OF₄⁻ determined by chronoamperometry are 1.34 × 10⁻⁷, 7.45 × 10⁻⁸ and 2.49 × 10⁻⁷ cm² s⁻¹, respectively. The Stokes radii of Nb(V)F₆⁻, W(VI)F₇⁻, and V(V)OF₄⁻ in BMPyrTFSA have been calculated to be 0.23, 0.38, and 0.12 nm, from the diffusion coefficients and viscosities obtained.     

Enhanced ultraviolet up-conversion emissions of Tm/Yb codoped YF3 nanocrystals

Tm³⁺/Yb³⁺ codoped rod-like YF₃ nanocrystals were synthesized through a facile hydrothermal method. After annealing in an argon atmosphere, the nanocrystals emitted bright blue and intense ultraviolet (UV) light under a 980-nm continuous wave diode laser excitation. Up-conversion emissions centered at ∼291 nm (¹I₆ → ³H₆), ∼347 nm (¹I₆ → ³F₄), ∼362 nm (¹D₂ → ³H₆), ∼452 nm (¹D₂ → ³F₄), ∼476 nm (¹G₄ → ³H₆), ∼642 nm (¹G₄ → ³F₄), and ∼805 nm (³H₄ → ³H₆) were recorded using a fluorescence spectrophotometer. Especially, enhanced UV emissions were studied by changing Yb³⁺/Tm³⁺ doping concentrations, the annealing temperatures, and the excitation power densities. A possible mechanism, energy transfer-cross relaxation-energy transfer (ET-CR-ET), was proposed based on a simple rate-equation model to elucidate the process of the enhanced UV emissions.     

Structure and spectroscopy of diorganotin(IV) complexes derived from N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide

Three new diorganotin(IV) complexes of the general formula R₂Sn[3-(OMe)-2-OC₆H₃CHN-NC(O)Ph] (R = Ph, Ia; R = Me, Ib; R = n-Bu, Ic) have been synthesised from the corresponding diorganotin(IV) dichlorides and the ligand, N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide in methanol at room temperature in the presence of trimethylamine. All the complexes have been characterized by elemental analysis, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra, and their structures have been confirmed by single crystal X-ray diffraction analysis of one representative compound Ia. Complex Ia crystallises in the orthorhombic system, space group Pna2₁ with a = 12.424(5), b = 9.911(5), c = 18.872(5) Å; Z = 4. The ligand N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (H₂L) coordinates to the metal centre in the enolate form via the phenolic O, imino N and enolic O atoms. In Ia, the central tin atom adopts a distorted trigonal bipyramidal coordination geometry with the oxygen atoms in axial positions, while the imino nitrogen atom of the Schiff base and the two phenyl groups occupy the equatorial sites. The δ(¹¹⁹Sn) values for the complexes Ia, Ib and Ic are −327.3, −151.7 and −187.2 ppm, respectively, thus indicating penta-coordinated Sn centres in solution.     

Effect of aldehyde and methoxy substituents on nucleophilic aromatic substitution by [F]fluoride

For a series of benzaldehydes only with a leaving group or with both a leaving group and a single methoxy substituent ¹⁸F-fluorination via nucleophilic aromatic substitution (S_NAr) was studied in DMF and Me₂SO. In general, the radiochemical yields were clearly higher in DMF than in Me₂SO. In the fluorodehalogenation reaction (leaving group: halogen = Br, Cl), extremely low radiochemical yields were observed in Me₂SO (<1%). By monitoring labeling reactions using HPLC, oxidation of the aldehyde function of the precursor was detected. Especially, 2-bromobenzaldehyde was oxidized fastest in Me₂SO (within 3 min reaction time, 90% of the precursor was consumed; radiochemical yield = 1.0 ± 0.5%); however, in DMF oxidation was always kept at a low level during the entire reaction (<5% of the precursor was oxidized; radiochemical yield = 73.0 ± 0.2%). In DMF, nitrobenzaldehydes with a methoxy substituent (methoxy group in meta-position to the nitro group) were labeled with good radiochemical yields (4-methoxy-2-nitrobenzaldehyde: 87 ± 3%; 2-methoxy-4-nitrobenzaldehyde: 83 ± 3%; 2-methoxy-6-nitrobenzaldehyde: 79 ± 4%) comparable to the non-substituted nitrobenzaldehydes (2-nitrobenzaldehyde: 84 ± 3%; 4-nitrobenzaldehyde: 81 ± 5%). Moreover, for structurally similar compounds, radiochemical yields showed a good correlation with ¹³C-NMR ppm values of the aromatic carbon atom bearing the leaving group.     

Dimethylcyclam based fluoroionophore having Hg- and Cd-selective signaling behaviors

Diametrically disubstituted bis(anthrylmethyl) derivative of 1,8-dimethylcyclam exhibited pronounced Hg²⁺- and Cd²⁺-selective fluorogenic behaviors in aqueous acetonitrile solution. A distinctive OFF-ON type signaling was observed for Hg²⁺ and Cd²⁺ ions in aqueous acetonitrile (CH₃CN-H₂O = 90:10, v/v) solution, while a selective ON-OFF type switching behavior toward Hg²⁺ ions was observed in solution having higher water content (CH₃CN-H₂O = 50:50, v/v). The detection limit for the analysis of Hg²⁺ ions in 50% aqueous acetonitrile was found to be 3.8 × 10⁻⁶ M. The selective OR logic gate behavior of the prepared compound toward two toxic heavy metal ions of Hg²⁺ and Cd²⁺ ions in CH₃CN-H₂O (90:10, v/v) suggests the possibility as a new chemosensing device for the two important target metal ions.     

Synthesis and structural studies of phosphorus carbonyl manganacycles containing the tetraphenyldiselenoimidodiphosphinato ligand

The [Mn(CO)_4−x(L){Ph₂P(Se)NP(Se)Ph₂-κ²Se}] complexes, where x = 1 for L = PPh₃ and PMePh₂, and x = 2 for L = Ph₂PCH₂CH₂PPh₂ (diphos), were synthesized by two routes. The complexes were characterized by IR, mass spectrometry (FAB+), NMR (¹H, ¹³C, ³¹P, ⁷⁷Se) spectroscopy and/or single crystal X-ray diffraction. The X-ray diffraction analysis for [Mn(CO)₃PMePh₂{Ph₂P(Se)NP(Se)Ph₂-κ²Se}] showed that the unit cell contains two independent mononuclear molecules with different MnSePNPSe rings’ conformations.     

A new electrochemiluminescent detection system equipped with an electrically controlled heating cylindrical microelectrode

A new electrochemiluminescent (ECL) detection system equipped with an electrically controlled heating cylindrical microelectrode (HME) was developed in this paper. The cylindrical microelectrode made of platinum wire (25 μm in diameter, 6 mm in long) was used as the working electrode of the ECL detection system, the temperature of the electrode could be controlled electrically. The Ru(bpy)₃²⁺-ECL and Ru(bpy)₃²⁺-C₂O₄²⁻-ECL systems were used to evaluate this ECL detection system. The detection limit for oxalate was found to be 3.0 × 10⁻⁴ mol/L when T_e (temperature of the HME) was 22 °C, and found to be 3.0 × 10⁻⁶ mol/L at 80 °C, which indicates that the detection limit can be improved greatly at higher T_e, based on which, it is possible to establish a more sensitive method for measurement of ECL by using a heated microelectrode.     

Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe

EuPdGe was prepared from the elements by reaction in a sealed tantalum tube in a high-frequency furnace. Magnetic susceptibility measurements show Curie-Weiss behavior above 60 K with an experimental magnetic moment of 8.0(1)μ_B/Eu indicating divalent europium. At low external fields antiferromagnetic ordering is observed at T_N=8.5(5) K. Magnetization measurements indicate a metamagnetic transition at a critical field of 1.5(2) T and a saturation magnetization of 6.4(1)μ_B/Eu at 5 K and 5.5 T. EuPdGe is a metallic conductor with a room-temperature value of 5000±500 μΩ cm for the specific resistivity. ¹⁵¹Eu Mössbauer spectroscopic experiments show a single europium site with an isomer shift of δ=−9.7(1) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting with a hyperfine field of B=20.7(5) T is observed. Density functional calculations show the similarity of the electronic structures of EuPdGe and EuPtGe. T-Ge interactions (T=Pd, Pt) exist in both compounds. An ionic formula splitting Eu²⁺T⁰Ge²⁻ seems more appropriate than Eu²⁺T²⁺Ge⁴⁻ accounting for the bonding in both compounds. Geometry optimizations of EuTGe (T=Ni, Pt, Pd) show weak energy differences between the two structural types.     

Advantages of the Ns group in the reactions of N-SO2R inosines with benzylamine and with NH3

The reactivity of N¹-alkylsulfonyl- and N¹-arylsulfonyl-2′,3′,5′-tri-O-acetylinosine with benzylamine and with ¹⁵NH₃, regarding the attack on C2, has been shown to be in the order CF₃SO₂ (Tf) > 2,4-(NO₂)₂C₆H₃SO₂ (DNs) ? 4-NO₂C₆H₄SO₂ (pNs) ≈ C₆F₅SO₂ (PFBs) > 2-NO₂C₆H₄SO₂ (Ns) ? CH₃SO₂ (Ms) > 4-CH₃C₆H₄SO₂ (Ts) > 2,4,6-(CH₃)₃C₆H₂SO₂ (Mts). In spite of its intermediate reactivity, the Ns group is the most appropriate, since in this case the formation of by-products is minimised during the ring-opening and ring-closing steps of the process. Another advantage of the Ns group is thus disclosed.     

Biomimetic sensor based on MnMn complex as manganese peroxidase mimetic for determination of rutin

A novel biomimetic sensor for rutin determination based on a dinuclear complex [Mn^IIIMn^II(Ldtb)(μ-OAc)₂]BPh₄ containing an unsymmetrical dinucleating ligand, 2-[N,N-bis(2-pyridylmethyl)-aminomethyl]-6-[N-(3,5-di-tert-butyl-2-oxidoben-zyl)-N-(2-pyridylamino)aminomethyl]-4-methylphenol (H₂Ldtb), as a manganese peroxidase mimetic was developed. Several parameters were investigated to evaluate the performance of the biomimetic sensor obtained after the incorporation of the dinuclear complex in a carbon paste. The best performance was obtained in 75:15:10% (w/w/w) of the graphite powder:Nujol:Mn^IIIMn^II complex, 0.1 mol L⁻¹ phosphate buffer solution (pH 6.0) and 4.0 × 10⁻⁵ mol L⁻¹ hydrogen peroxide. The response of the sensor towards rutin concentration was linear using square wave voltammetry in the range of 9.99 × 10⁻⁷ to 6.54 × 10⁻⁵ mol L⁻¹ (r = 0.9998) with a detection limit of 1.75 × 10⁻⁷ mol L⁻¹. The recovery study performed with pharmaceuticals ranged from 96.6% to 103.2% and the relative standard deviation was 1.85% for a solution containing 1.0 × 10⁻³ mol L⁻¹ rutin (n = 6). The lifetime of this biomimetic sensor was 200 days (at least 750 determinations). The results obtained for rutin in pharmaceuticals using the biomimetic sensor and those obtained with the official method are in agreement at the 95% confidence level.     

N,N-polymethylene-bisadenine complexes with d metal ions

The reaction of N⁹,N^9′-(tri or tetramethylene)-bisadenines (Ade₂C_x; x = 3 or 4) in HCl 2 M at 50 °C with MCl₂ · 2H₂O [M = Zn(II), Cd(II)] yields outer sphere compounds like the previously described [(H-Ade)₂C₃][ZnCl₄] · H₂O (3) and [(H-Ade)₂C₃]₂[Cd₂Cl₈(H₂O)₂] · 4H₂O (4) for Ade₂C₃ and the new {[(H-Ade)₂C₄][Cd₂Cl₆(H₂O)₂] · 2H₂O}_n (5) for Ade₂C₄. On the other hand, only in case of Zn(II) complexes by changing [HCl] to 0.1 M, the inner sphere compounds [H-(Ade)₂C₃(ZnCl₃)] (6) and [H-(Ade)₂C₄(ZnCl₃)] · 1.5H₂O (7) are obtained. X-ray diffraction study of compound 6, which represents the first inner sphere complex with a N⁹,N^9′-bisadenine, shows a zwitterionic form with one adenine ring protonated at N(1) while the other ring is coordinated via N(7) to a ZnCl₃ moiety as in other alkyl-adenine derivatives. In addition, with Ade₂C₄, is also possible to obtain another inner sphere complex: [(H-Ade)₂C₄(ZnCl₃)₂] · 3H₂O (8).     

Synthesis,spectroscopic and structural studies of 2,2,2-trifluoroethyl phosphorodiamidate complexes with tin(IV) chloride

The two octahedral complexes SnCl₄ · 2(O)P(NR₂)₂OCH₂CF₃ (R = Me (1) or Et (2)) have been prepared from SnCl₄ and the ligands (R₂N)₂P(O)OCH₂CF₃ in chloroform solution. Both adducts have been characterised by (³¹P and ¹¹⁹Sn) NMR, IR spectroscopy and elemental analysis. The NMR data show that the complexes exist as mixtures of cis and trans isomers in solution with the latter isomer being the predominant species. The structure of 1 has been determined by X-ray crystallography. Accordingly, the structure is centrosymmetric and the two ligands are bound trans to each other in the octahedral tin complex. DFT/B3LYP calculations show that trans configuration does indeed lead to the lowest energy species. Comparison of the structural, NMR and theoretical data of both complexes with those related to SnCl₄ · 2L (L = (Me₂N)₃P(O) and (Me₂N)₂P(O)F) further supports the important effects of the nature of the substituents in the ligand on the stereochemistry of the complex formed.     

Chemiluminescence determination of citrate and pyruvate and their mixtures by the stopped-flow mixing technique

A novel kinetic chemiluminescent method using the stopped-flow mixing technique has been investigated for the rapid and sensitive determination of citrate and pyruvate. The method is based on a tris(2,2′-bipyridiyl)ruthenium(III) (Ru(bpy)₃³⁺) chemiluminescence (CL) reaction. Ru(bpy)₃³⁺ was generated in the mixing chamber by oxidising tris(2,2′-bipyridyl)ruthenium(II) with cerium(IV). After selecting the best operating parameters, calibration graphs were obtained over the concentration ranges 0.38-38 μg ml⁻¹ and 8.7-1300 ng ml⁻¹ for citrate and pyruvate, respectively. The limits of detection were 0.1 μg ml⁻¹ for citrate and 0.3 ng ml⁻¹ for pyruvate. Based on the differential rate of the chemiluminescent reaction corresponding to citrate and pyruvate, a very simple kinetic procedure was developed for the simultaneous determination of both compounds. Mixtures of citrate and pyruvate in ratios between 15:1 and 1.5:1 were satisfactorily resolved. The proposed method was successfully applied to the determination of citrate in pharmaceutical formulations, pyruvate in animal blood serum and both compounds in human urine.     

Synthesis and H NMR spectroscopic properties of substituted (η-tetraarylcyclobutadiene)(η-cyclopentadienyl)cobalt metallocenes

The reaction of diarylacetylenes with CoCl(PPh₃)₃ and sodium cyclopentadienylide or sodium carbomethoxycyclopentadienylide gave (η⁴-tetra-arylcyclobutadiene)(η⁵-cyclopentadienyl)cobalt and (η⁴-tetra-arylcyclobutadiene)(η⁵-carbomethoxycyclopentadienyl)cobalt, respectively, where aryl = para-XC₆H₄ (X = CF₃, F, MeO). The reaction was unsuccessful for the synthesis of (η⁴-tetra(para-methoxyphenyl)cyclobutadiene)(η⁵-cyclopentadienyl)cobalt, which was synthesised instead from dicarbonyl(η⁵-cyclopentadienyl)cobalt. In all of the examples starting with CoCl(PPh₃)₃ an intermediate (η⁵-cyclopentadienyl)- or (η⁵-carbomethoxycyclopentadienyl)(triphenylphosphine)-2,3,4,5-tetraarylcobaltacyclopentadiene complex was isolated, and two examples were characterised by X-ray crystallography. Heating the (η⁵-cyclopentadienyl)- or (η⁵-carbomethoxycyclopentadienyl)(triphenylphosphine)-2,3,4,5-tetraarylcobaltacyclopentadiene complexes resulted in clean conversion to the corresponding metallocenes. The influence of the para-aryl substituents on the ¹H NMR of the cyclopentadienyl moiety is tabulated, together with the influence of a range of R substituents in (η⁴-tetraphenylcyclobutadiene)(η⁵-RC₅H₄)cobalt (R = CO₂Me, CH₂OH, Me, CHO, CCH, CO₂H, CN, CONHR¹, 2-oxazolinyl, NH₂, NHAc, HgCl, Br, I, SiMe₃, SnMe₃, Ph).     

Photoluminescence of new red phosphor SrZnO2:Eu

SrZnO₂:Eu³⁺ has been synthesized by solid-state reaction and its photoluminescence in ultraviolet (UV)-vacuum ultraviolet (VUV) range was investigated. The broad bands around 254 nm are assigned to CT band of Eu³⁺-O²⁻. With the increasing of Eu³⁺ concentration, Eu³⁺ could occupy different sites, which leads to the broadening of CT band. A sharp band is observed in the region of 110-130 nm, which is related to the host absorption. The phosphors emit red luminescence centered at about 616 nm due to Eu³⁺⁵D₀→⁷F₂ both under 254 and 147 nm, but none of Eu²⁺ blue emission can be observed.