Effect of Lumophore and Plasticiser Concentration on The Heterogeneity of Oxygen Quenching in Thin Film Oxygen Sensors

Kinetic heterogeneity of the luminescence decay and oxygen quenching of Pt and Pd octaethylporphyrin/ethyl cellulose (OEP/EC) thin film oxygen sensors has been investigated with respect to (a) concentration of lumophore and (b) addition of plasticiser. The source of kinetic heterogeneity shown by PtOEP films under N₂ is a monomer–dimer equilibrium in which the dimer luminescence decays with k = 0.0527×10⁶ s⁻¹ and the monomer luminescence with k = 0.0101×10⁶ s⁻¹ and K _D = 790 (±20) mol dm⁻³. For PdOEP/EC films there is no detectable aggregation and luminescence decays under N₂ show good fits to single exponential curve fits at all concentrations studied. The addition of either tripbutyl phosphate or dimethylphthalate as plasticiser does not decrease kinetic heterogeneity for oxygen quenching of luminescence in the films.     

Microwave-assisted synthesis of (tris-acetylacetonato)(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)terbium(III) complex with outstanding high green luminescence

Microwave-assisted synthesis method enabled the preparation of the (tris-acetylacetonate)(2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinate) terbium(III) (Tb(acac)₃(dmdpphen)) complex with outstanding high green luminescence. This method is appropriate for green chemistry and energy-saving processes. The Tb(acac)₃(dmdpphen) complex has good thermal stability. Emission peaks are assigned to the f-f transitions of the Tb³⁺. The Tb(acac)₃(dmdpphen) complex is expected to be used in functional materials of electronic products.     

Optical oxygen sensing materials based on trinuclear starburst ruthenium(II) complexes assembled in mesoporous silica

The preparation and oxygen sensing properties of optical materials based on two trinuclear starburst ruthenium(II) complexes: [Ru₃(bpy)₆(TMMB)]⁶⁺ (1) and [Ru₃(phen)₆(TMMB)]⁶⁺ (2) (bpy=2,2′-bpyridine, phen=1,10-phenathroline, TMMB=1,3,5-tris[2-(2′-pyridyl)benzimidazoyl]methylbenzene) assembled in two mesoporous silicate (MS) are described in this paper. The luminescence of Ru complexes/silicate assemble materials can be quenched by molecular oxygen with good sensitivity (I₀/I₁>5 for 2/MS and I₀/I₁>3 for 1/MS), indicating that trinuclear starburst Ru(II) complexes/MS systems are sensitive to oxygen molecules.     

基于荧光猝灭原理的光纤溶解氧传感器研制

采用锁相放大技术研制了基于荧光猝灭原理的光纤溶解氧传感器,并组装了其测试系统。该系统采用高亮度蓝色LED作为光源,光电倍增管作为探测器,光栅光谱仪作为分光仪器,并使用SR830锁相放大器来检测荧光与激发光之间的相移。测定了相移差与调制信号频率、占空比之间的关系。实验结果表明,频率为60kHz、占空比为10%的矩形调制信号能使传感器的检测精度达到最大,对光纤溶解氧传感器的进一步研究具有参考意义。     

Blue LED Excitable Temperature Sensors Based on a New Europium(III) Chelate

A new europium(III) chelate is synthesized and characterized. The wavelength of sensitization of Eu³⁺ luminescence is shifted further into visible so that efficient excitation with 425, 435 and 450-nm LEDs becomes possible. Photophysical properties and temperature dependence of luminescence are investigated in toluene solution and various polymer matrixes. The sensor materials are also characterized in terms of cross-sensitivity to oxygen and photostability. The sensor material based on the europium complex immobilized into poly(vinylidene chloride-co-acrylonitrile) shows negligible cross-sensitivity to oxygen and is particularly attractive for applications at physiological conditions. Other materials can be applied for sensing and imaging purposes at room temperatures. The new materials can also be used for compensating optical (oxygen, CO₂ etc.) sensors for temperature effects.     

The key Cl− ligand for metal‐to‐ligand charge transfer in mononuclear terpyridine ruthenium(II) and binuclear ruthenium(II) tetrapyridylpyrazine complexes

Electronic structures of binuclear ruthenium complexes [Ru₂(terpy)₂(tppz)]⁴⁺ ( 1A ) and [Ru₂Cl₂(L)₂(tppz)]²⁺ {L = bpy ( 2A ), phen ( 3A ), and dpphen ( 4A )} were studied by density functional theory calculations. Abbreviations of the ligands (Ls) are bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline, dpphen = 4,7‐diphenyl‐1,10‐phenanthroline, terpy = 2,2′:6′,2″‐terpyridine, and tppz = tetrakis(2‐pyridyl)pyrazine. Their mononuclear reference complexes [Ru(terpy)₂]²⁺ ( 1B ) and [RuClL(terpy)]⁺ {L = bpy ( 2B ), phen ( 3B ), and dpphen ( 4B )} were also examined. Geometries of these mononuclear and binuclear Ru(II) complexes were fully optimized. Their geometric parameters are in good agreement with the experimental data. The binuclear complexes were characterized by electrospray ionization mass spectrometry, UV–Vis spectroscopy, and cyclic voltammograms. Hexafluorophosphate salts of binuclear ruthenium complexes of 3A and 4A were newly prepared. The crystal structure of binuclear complex 1A (PF₆)₄ was also determined. Orbital interactions were analyzed to characterize the metal‐to‐ligand charge‐transfer (MLCT) states in these complexes. The Cl^? ligand works to raise the orbital energy of the metal lone pair, which leads to the low MLCT state. Copyright © 2011 John Wiley & Sons, Ltd.     

Potential-modulated electrochemiluminescence of a tris(2,2′-bipyridine)ruthenium(II) / lidocaine system under 430 kHz ultrasound irradiation

The electrochemiluminescence (ECL) of tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)₃²⁺) in the presence of lidocaine was investigated under ultrasound (US) irradiation. The sonoelectrochemical experiments are conducted by indirect irradiation of ultrasound with a piezoelectric transducer operating at 430 kHz. In a supporting electrolyte at pH 11, the Ru(bpy)₃²⁺/lidocaine system gave weak ECL peaks around +1.2 V and +1.45 V, respectively. The ECL signal at +1.2 V was attributed to redox reactions of the oxidative intermediates of Ru(bpy)₃²⁺ and lidocaine, while the signal at +1.45 V was assumed to be caused by an advanced oxidation process due to the generation of hydroxyl radicals (OH) at the electrode surface. In this study, the potential modulation approach is employed in the study of ECL process upon US irradiations because it can suppress the noise components from sonoluminescence effectly and improve the resolution of ECL-potential profiles. It is found ECL signals were greatly enhanced upon US irradiation at the output power of 30 W, however, the relative intensity of ECL signal at +1.2 V was larger than that obtained with a rotating disk electrode even though the mass transport effect is equilvalent. The experiment results suggest that the chemical effect (i.e., generation of OH) by 430 kHz US becomes remarkable in the electrochemical process. Detailed ECL reaction routes under US are proposed in this study.     

Sonochemical syntheses of binuclear lead(II)-azido supramolecule with ligand 3,4,7,8-tetramethyl-1,10-phenanthroline as precursor for preparation of lead(II) oxide nanoparticles

The new neutral binuclear lead(II) azido coordination compound, [Pb₂(tmph)₂(μ-N₃)₂(CH₃COO)₂] (1) [tmph = 3,4,7,8-tetramethyl-1,10-phenanthroline], has been synthesized by a sonochemical method. Single crystal X-ray structure shows that the overall structure of 1 is binuclear unit. Complex 1 has a bridging azido pathway, end-to-end bridging azides between a pair of lead(II) centers. This is further extended into a one-dimensional (1D) and three-dimensional (3D) supramolecular structure by Pb⋯C and π–π weak directional intermolecular interactions. The coordination number of lead(II) ions is seven, PbN₄O₃, with two N-donor atoms from tmph ligands and three O-donors from acetate anions and two N-donors from two azide anions. It has a “stereo-chemically active” electron lone pair, and the coordination sphere is hemidirected. The PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The morphology and size of the prepared PbO samples were further observed using scanning electron microscopy (SEM).     

Preparation of electrochemical sensor for lead(II) based on molecularly imprinted film

A high selective voltammetric sensor for Pb²⁺ was introduced. The feasibility of utilizing strong interactions between Schiff bases and metal ion to prepare the molecularly imprinted polymers (MIPs) electrochemical sensor for Pb²⁺ in aqueous solutions was studied. Some parameters affecting sensor response were optimized and then a calibration curve was plotted. A dynamic linear range of 3.00 × 10⁻⁷ to 5.00 × 10⁻⁵ mol/L was obtained. The redox process of Pb²⁺ on the imprinted electrode is controlled by surface reaction. The stability and the life of imprinted membrane were improved by storing into diluted Pb²⁺ ion solution. The proposed method was applied to determination of Pb²⁺ in the Yellow River.     

Sonochemical synthesis of two new nano structure zinc(II) 1,10-phenanthroline coordination supramolecular compounds: New precursors to produce nano-sized zinc(II) oxide

Nanoparticles of two zinc(II) coordination supramolecule compounds (CSCs), [Zn(L)Cl2] (1) and [Zn(L)Br2] (2) L = 1,10-phen = 1,10-phenanthroline ligand, have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Zn⁺² ions are four coordinated. Topological analysis shows that the compound 1 and 2 are new topology for net: 1,3M4-1. Nanoparticles of zinc(II) oxide have been prepared by calcination of two different zinc(II) CPs at 500 °C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and IR spectroscopy.     

Oxygen (O6+) ion beam irradiation effects on etching parameter in lexan polymeric track detector

The polymer Lexan was irradiated to 80MeV O⁶⁺ ion beam using the 15UD pelletron at Inter University Accelerator Centre, New Delhi. The ion fluence ranging from 10¹¹ to 3 × 10¹² ions/cm² has been used to study the dose effects of irradiation on Lexan. By using the etching technique, it is observed that the bulk etch rate of the sample increases with increasing the ion influence, while the activation energy associated with it show a decreasing trend which can be explained on the basis of polymer degradation.      

Competition Between Energy Transfer Quenching and Chelation Enhanced Fluorescence in a Cu (II) Coordinated Conjugated Polymer System

An investigation of the mechanism of the fluorescence quenching by Cu²⁺ for a conjugated polymer system initially designed as a fluorescence “turn-on” chemosensor based on chelation enhanced fluorescence (CHEF) is described in this paper. Unlike all other metal cations tested, the polymer/Cu²⁺ hybrid system with a 1:1 ratio between the receptor and Cu²⁺ has only weak fluorescence with λ_max = 490 nm and a quantum yield of 0.004 in THF at room temperature. In solvent glasses at 77 K the fluorescence remained quenched suggesting that the quenching mechanism was due to energy transfer between the Cu²⁺ and the conjugated polymer backbone. The energy transfer quenching competes effectively with the electron transfer involved in the CHEF resulting in a more selective chemosensory system. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Syntheses,X‐ray crystal structures,and emission properties of protonated tripyridyltriazines and their ruthenium(II) complexes

A series of metal‐free compounds, ie, planar triprotonated triazine, triazineH₃Cl(PF₆)₂ ( 1 ), planar triprotonated triazineH₃Br(PF₆)₂ ( 2 ), and nonplanar monoprotonated triazineHPF₆ ( 3 ), were prepared. Abbreviations used are triazine = tri‐2‐pyridyltriazine. Ruthenium complexes [RuCl(bpy)(L)](PF₆), [RuCl(bpy)(L)](PF₆)₂, and [Ru(L)₂](PF₆)₂ were also prepared, where bpy is 2,2′‐bipyridine and L's are triazine ( 4 ) and monoprotonated triazine ( 5 ), respectively. Ruthenium complexes [Ru(triazine)₂](PF₆)₂ ( 6 ) were also prepared and crystallized. The X‐ray crystal structures of the 3 compounds 1 , 2 , and 3 and the complex 6 were determined. They were also characterized by electrospray ionization mass spectrometry, UV‐vis spectroscopy, and density functional theory calculations.     

Luminescence-Based Oxygen Sensors: ReL(CO)3Cl and ReL(CO)3CN Complexes on Copolymer Supports

A new class of luminescent rhenium complexes has been tested as oxygen sensors based on luminescent quenching. ReL(CO)₃Cl and ReL(CO)₃CN (L = 2,2-bipyridine or 1,10-phenanthroline and substituted analogues) have several features that seem to indicate suitability as oxygen sensors. These include simple synthesis, long excited-state lifetimes, and high luminescence quantum yields. Intensity and lifetime oxygen quenching measurements were used to study the complexes in various polymer supports including homopolymers of PDMS (polydimethylsiloxane), a methacryloxy containing PDMS (Gp-163), and trimethylsilylmethylmethacrylate (T3642), and copolymers containing Gp-163 and T3642. In contrast to previous studies utilizing [Ru(4,7-diphenyl-1,10-phenanthroline)₃]²⁺ as an oxygen sensor, quenching of the Re complexes proved much more sensitive to the polymer support. With suitable supports, the rhenium chloro complexes demonstrated significant quenching; but the cyano complexes, in spite of being robust in solution, exhibited severe photochemical instability in polymers. The potential of this class of complexes as oxygen sensors and as molecular probes as well as the ramifications in the design of new and different types of sensors is discussed.     

Fluorescence enhancement of lanthanide(III) perchlorate by 1,10-phenanthroline in bis(benzoylmethyl) sulfoxide complexes and luminescence mechanism

Two novel ternary rare earth complexes LnL₅L′(ClO₄)₃2H₂O (Ln=Eu(III), Tb(III); L=bis(benzoylmethyl) sulfoxide, L′=phen) were synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC,¹H NMR and UV spectra. The fluorescence spectra illustrated that both the Eu(III) and Tb(III) ternary complexes displayed strong characteristic metal-centered fluorescence in solid state. After the introduction of the second ligand phen group, the relative emission intensities and fluorescence lifetimes of the ternary complex EuL₅L′(ClO₄)₃2H₂O (L=C₆H₅COCH₂SOCH₂COC₆H₅, L′=phen) enhanced more obviously than that of the binary complex EuL₅(ClO₄)₃3H₂O. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand phen could sensitize fluorescence intensities of Eu(III) ions, and the introduction of phen group was resulted in the enhancement of the fluorescence properties of the Eu(III) ternary rare earth complexes. The phosphorescence spectra are also discussed.     

两种钌配合物皮秒发光动力学过程研究

采用稳态发光光谱、瞬态发光动力学测量等手段,对两种钉配合物[Ru(bpy)3](ClO4)2和[Ru(bpy)2 HPIP](ClO4)2的发光性质进行了研究.稳态发光光谱表明[Ru(bpy)2 HPIP](ClO4)2发光明显偏弱;皮秒瞬态发光动力学测量显示[Ru(bpy)2 HPIP](ClO4)2的激发态弛豫过程...     

洁净和氧吸附的Cu(100)表面重构的理论研究

在密度泛函理论下,计算了清洁和吸附氧原子的Cu(100)表面的驰豫和优势吸附构型。结果表明,氧原子在金属表面采用四重穴位时,具有最大的结合能,顶位吸附时结合能最小,桥位吸附时结合能居间。这一计算结果与实验报道一致。各种密度泛函方法的比较后,发现采用mPW1PW91密度泛函和LanL2dz赝势基组,能够准确给出与实验相符的计算结果。平板模型计算的分态密度图显示,在吸附过程中出现d轨道向Fermi能级移动并越过Fermi能级,而O原子的p轨道能级远离Fermi能级,表明有电子从铜原子的d轨道转移到氧原子的2p轨道,簇模型和平板模型的布居分析显示表面氧带有约0.65～0.7 e的负电荷。研究表明,采用适当的基组和泛函方法,即使采用簇模型来模拟表面,也可以获得与实验比较吻合的计算结果。     

Anisotropic self-diffusion of fluorinated poly(methacrylate) in metal-organic frameworks assessed with molecular dynamics simulation

Utilizing the periodically structured metal–organic framework(MOF) as the reaction vessel is a promising technique to achieve the aligned polymer molecular chains, where the diffusion procedure of the polymer monomer inside MOF is one of the key mechanisms. To investigate the diffusion mechanism of fluorinated polymer monomers in MOFs, in this paper the molecular dynamics simulations combined with the density functional theory and the Monte Carlo method are used and the all-atom models of TFMA(trifluoroethyl methacrylate) monomer and two types of MOFs, [Zn_2(BDC)_2(TED)]n and[Zn_2(BPDC)_2(TED)]n, are established. The diffusion behaviors of TFMA monomer in these two MOFs are simulated and the main influencing factors are analyzed. The obtained results are as follows. First, the electrostatic interactions between TFMA monomers and MOFs cause the monomers to concentrate in the MOF channel, which slows down the monomer diffusion. Second, the anisotropic shape of the one-dimensional MOF channel leads to different diffusion speeds of monomers in different directions. Third, MOF with a larger pore diameter due to a longer organic ligand, [Zn_2(BPDC)_2(TED)]n in this paper, facilitates the diffusion of monomers in the MOF channel. Finally, as the number of monomers increases, the self-diffusion coefficient is reduced by the steric effect.     

Photoinduced electron‐transfer reactions of tris(2,2′‐bipyridine)ruthenium(II)‐based carbonic anhydrase inhibitors tethering plural binding sites

Tris(2,2′‐bipyridine)ruthenium(II) complex‐based carbonic anhydrase (CA) inhibitors, [Ru(bpy)₂(bpydbs)]²⁺ {bpy = 2,2′‐bipyridine and bpydbs = 2,2′‐bipyridinyl‐4,4′‐dicarboxilic acid bis[(2‐{2‐[2‐(4‐sulfamoylbenzoylamino)ethoxy]ethoxy}ethyl)amide]} and [Ru(bpydbs)₃]²⁺, tethering plural benzenesulfonamide groups have been prepared. The CA catalytic activity was effectively suppressed by these synthetic [Ru(bpy)₂(bpydbs)]²⁺ and [Ru(bpydbs)₃]²⁺ inhibitors, and their dissociation constants at pH = 7.2 and at 25°C were determined to be K_I = 0.93 ± 0.02 μM and K_I = 0.24 ± 0.03 μM, respectively. Next, 2 photoinduced electron‐transfer (ET) systems comprising a Ru²⁺‐CA complex and an electron acceptor, such as chloropentaamminecobalt(III) ([CoCl(NH₃)₅]²⁺) or methylviologen (MV²⁺) were studied. In the presence of CA and a sacrificial electron acceptor, such as pentaamminechlorocobalt(III) complex, the photoexcited triplet state of ³([Ru(II)]²⁺)* was quenched through an intermolecular photoinduced ET mechanism. In case of the [Ru(bpydbs)₃]²⁺‐CA‐MV²⁺ system, the photoexcited triplet state of ³([Ru(bpydbs)₃]²⁺)* was quenched by sacrificial quencher through an intermolecular photoinduced ET mechanism, giving the oxidized [Ru(bpydbs)₃]³⁺. Then the following intramolecular ET from the amino acid residue, Tyr6, near the active site of CA proceeded. We observed a transient absorption around at 410 nm, arising from the formation of a Tyr^?+ in the [Ru(bpydbs)₃]²⁺‐CA‐MV²⁺ system. These artificial Ru(II)‐CA systems may clearly demonstrate both intermolecular and intramolecular photoinduced ET reactions of protein and could be one of the interesting models of the ET proteins. Their photophysical properties and the detailed ET mechanisms are discussed in order to clarify the multistep ET reactions.     

Structural and luminescence properties of [Ln(ODA)(phen)·4H2O] complexes (Ln=Sm and Dy, ODA=oxydiacetate, phen=1,10-phenanthroline)

Two novel complexes of Sm(III) and Dy(III) with mixed oxydiacetate (ODA) and 1,10-phenanthroline (phen) ligands were synthesized and their structure and luminescence properties were characterized. The complexes of [Ln(ODA)(phen)·4H₂O]Cl·5H₂O [Ln=Sm and Dy] crystallize in the monoclinic space group P2₁/n with Sm: a=12.3401(14) Å, b=16.821(2), c=12.6847(11) Å, β=107.939(10)°, V=2505.0(5) Å³, Z=4 and ρ=1.841 mg/m³, and with Dy: a=12.289(7) Å, b=16.805(6) Å, c=12.705(4) Å, β=108.144(18)°, V=2493.4(19) Å³, Z=4 and ρ=1.786 mg/m³. The complexes of [Sm(ODA)(phen)·4H₂O]⁺ and [Dy(ODA)(phen)·4H₂O]⁺ excited by UV light produce orange red and lightly white emissions, respectively, via the nonradiative energy transfer from phen to the metals. The quantum yield of the sensitized luminescence of [Dy(ODA)(phen)·4H₂O]⁺ (Q=19%) is much greater than that of [Sm(ODA)(phen)·4H₂O]⁺ (Q=1.4%). The luminescence decay times of the complexes were in a few microsecond range and independent of temperature.