Synthesis of poly[6-(2,6-bis(1′-methylbenzimidazolyl)pyridin-4-yloxy)hexyl acrylate] (PBIP) and magnetic property of its neodymium complex (PBIP-Nd<Superscript>3+</Superscript>)

Homopolymer (PBIP) containing 2,6-bis(1′-methylbenzimidazolyl)pyridine (MeBIP) ligands in the side chain was synthesized by RAFT polymerization and its kinetics was studied. Polymeric complex PBIP-Nd³⁺ was prepared by chelating PBIP with lanthanide ion Nd³⁺. The homopolymers and PBIP-Nd³⁺ complex were investigated by NMR, FTIR, GPC and TGA. The optical property of PBIP-Nd³⁺ complex was characterized by UV-Vis spectroscopy. The magnetic property of PBIP-Nd³⁺ complex was measured as a function of temperature (5 K to 300 K) and as a function of field (?3.98 × 10⁶ A/m to 3.98 × 10⁶ A/m). These results indicated that PBIP-Nd³⁺ complex is paramagnetic.     

A novel selective fluorescent chemosensor for Fe 3+ ions based on phthalonitrile dimer: synthesis,analysis, and theoretical studies

Phenyl-4,4-di(3,6-dibutoxyphthalonitrile) ( 3 ) was synthesized by the reaction of 1,4-phenylenebisboronic acid ( 1 ) and 4-bromo-3,6-dibutoxyphthalonitrile ( 2 ), using Suzuki cross-coupling reaction. The newly synthesized compound ( 3 ) was characterized by FT-IR, MALDI-MS, ESI-MS, ¹ H-NMR, ¹³ C-NMR, and ¹³ C-DEPT-135-NMR. The fluorescence property of phenyl-4,4-di(3,6-dibutoxyphthalonitrile) ( 3 ) towards various metal ions was investigated by fluorescence spectroscopy, and it was observed thatthe compound ( 3 ) displayed a significantly ‘turn-off’ response to Fe ³⁺ , which was referred to 1:2 complex formation between ligand ( 3 ) and Fe ³⁺ . The compound was also studied via density functional theory calculations revealing the interaction mechanism of the molecule with Fe ³⁺ ions.     

In situ analysis for spontaneous reduction of Eu<Superscript>3+</Superscript> in LiCl pyroprocessing media at 923 K

The spontaneous reduction of Eu³⁺ to Eu²⁺ was examined when EuCl₃ was added into a pyroprocessing media of LiCl molten salt at 923 K. The amount of Eu²⁺ was calculated by measuring the total charge consumed to oxidize Eu²⁺ ions to Eu³⁺ ions. The concentration ratio of Eu²⁺ to Eu³⁺ was estimated to be about 0.40 in the media. In addition, it is confirmed that the reduction of Eu³⁺ to Eu²⁺ is caused by the oxidation power of Cl⁻ to Cl₂. The coexistence of Eu³⁺ and Eu²⁺ in the LiCl molten salt system was examined by UV–Visible and luminescence spectroscopy. The molar absorptivities of Eu³⁺ and Eu²⁺, calculated from UV–Visible absorption spectra, were 423 and 1954 M⁻¹ cm⁻¹, respectively.     

Effcient Near-Infrared Quantum Cutting in Tm3+/Yb3 Codoped LiYF4 Single Crystals for Solar Photovoltaic

Downconversion (DC) with emission of two near-infrared photons about 1000 nm for each blue photon absorbed was obtained in thulium (Tm³⁺) and ytterbium (Yb³ ) codoped yt-trium lithium fluoride (LiYF₄) single crystals grown by an improved Bridgman method. The luminescent properties of the crystals were measured through photoluminescence excitation, emission spectra and decay curves. Luminescence between 960 and 1050 nm from Yb³ : ²F_5/2→²F_7/2 transition, which was originated from the DC from Tm³ ions to Yb³ ions, was observed under the excitation of blue photon at 465 nm. Moreover, the energy transfer processes were studied based on the Inokuti-Hirayama model, and the results indicated that the energy transfer from Tm³ to Yb³ was an electric dipole-dipole interaction. The max-imum quantum cutting effciency approached up to 167.5% in LiYF₄ single crystal codoped with 0.49mol% Tm³ and 5.99mol% Yb³ . Application of this crystal has prospects for increasing the energy e ciency of crystalline Si solar cells by photon doubling of the high energy part of the solar spectrum     

Protonation sites in methyl nitrate and the formation of transient CH4NO3 radicals. A neutralization—reionization mass spectrometric and computational study

Protonation sites in methyl nitrate (1) were evaluated computationally at the Gaussian 2(MP2) level of ab initio theory. The methoxy oxygen was the most basic site that had a calculated proton affinity of PA = 728–738 kJ mol⁻¹ depending on the optimization method used to calculate the equilibrium geometry of the CH₃O(H)-NO₂⁺ ion (2⁺). Protonation at the terminal oxygen atoms in methyl nitrate was less exothermic; the calculated proton affinities were 725, 722, and 712 kJ mol⁻¹ for the formation of the syn-syn, anti-syn, and syn-anti ion rotamers 3a⁺, 3b⁺, and 3c⁺, respectively. Ion 2⁺ was prepared by an ion-molecule reaction of NO₂⁺ with methanol and used to generate the transient CH₃O(H)-NO₂^. radical (2) by femtosecond collisional electron transfer. Exothermic protonation of 1 produced a mixture of 3a⁺–3c⁺ with 2⁺ that was used to generate transient radicals 3a–3c. Radical 2 was found to be unbound and dissociated without barrier to methanol and NO₂. Radicals 3a–3c were calculated to be weakly bound. When formed by vertical neutralization, 3a–3c dissociated completely on the 4.2 μs time scale of the experiment. The main dissociations of 3a–3c were formations of CH₃O^. + HONO and CH₃ONO + OH^.. The gas-phase chemistry of radicals 3a–3c and their dissociation products, as studied by neutralization—reionization mass spectrometry, was dominated by Franck—Condon effects on collisional neutralization and reionization. The adiabatic ionization energies of 3a–3c were calculated as 7.54, 7.57, and 7.66 eV, respectively.     

Luminescent properties of SrBPO5:Dy3+ and effect of Co-doping with Tm3+

A series of phosphors SrBPO₅:Dy³⁺ and SrBPO₅:Dy³⁺,Tm³⁺ was synthesized by traditional solid-state high-temperature method and was characterized by X-ray diffraction (XRD) and fluorescence spectrophotometry. For SrBPO₅:Dy³⁺ material, the f-f transitions of Dy³⁺ ions were assigned and discussed, and the optimal doping concentration of Dy³⁺ was found. As a result of co-doping SrBPO₅:Dy³⁺ with Tm³⁺, the phosphors SrBPO₅:Dy³⁺,Tm³⁺ can be effectively excited by 360 nm ultraviolet (UV), and exhibit color-tunable emission from blue to yellowish-white region with different doping concentration. The present study can pave the way for the creation of efficient UV phosphors using Dy³⁺,Tm³⁺ co-doped systems for near-UV InGaN-based light emitting diodes (LEDs).     

Iron(III)‐Selective Chelation‐Enhanced Fluorescence Sensing for In Vivo Imaging Applications

A “turn‐on” pattern Fe³⁺‐selective fluorescent sensor was synthesized and characterized that showed high fluorescence discrimination of Fe³⁺ over Fe²⁺ and other tested ions. With a 62‐fold fluorescence enhancement towards Fe³⁺, the probe was employed to detect Fe³⁺ in vivo in HeLa cells and Caenorhabditis elegans, and it was also successfully used to elucidate Fe³⁺ enrichment and exchange infected by innexin3 (Inx3) in hemichannel‐closed Sf9 cells.     

Supramolecular chemosensor for selective detection of iron in aqueous medium

We have successfully developed a ‘turn-on’ colorimetric chemosensor for Fe³⁺ based on 1,10-phenanthroline. An amide derivative of 1,10-phenanthroline 4 was developed for the selective recognition of Fe³⁺ over Co²⁺, Cr³⁺, Cu²⁺, Mn²⁺, Ni²⁺, Ag⁺ and Zn²⁺ and could measure Fe³⁺ concentration in the range of 15–210 μM by UV–vis spectroscopy. Moreover, the addition of Fe³⁺ to a colourless solution of 4 turned its colour to light pink, indicating that 4 is capable of detecting Fe³⁺ by the naked eye. Compound 4 exhibits a major absorption band centred at 268 which shifted to 278 nm after addition of Fe³⁺, and a shoulder band around 514 nm was also observed. The complexation of Fe³⁺ with 4 was analysed at a different pH and favourable binding was observed at pH 6.2.     

Preparation of Silver Nanoparticles Reduced by Formamidinesulfinic Acid and Its Application in Colorimetric Sensor

A rapid one-step preparation approach of silver nanoparticles (AgNPs) was reported by employing formamidinesulfinic acid as reducing agent and soluble starch as stabilizing agent. The formation of AgNPs was further confirmed by using UV–Vis absorption spectroscopy, X-ray diffraction spectroscopy and transmission electron microscopy techniques. The resultant AgNPs could be directly used for the colorimetric reaction with metal ions. The results showed that Al³⁺, Cr³⁺, Fe³⁺ and Hg²⁺ ions could induce the color change of AgNPs from yellow to pink (Al³⁺), orange (Cr³⁺) and colorless (Fe³⁺ and Hg²⁺), respectively, which can be observed by the naked eye. Based on these, a sensitive colorimetric sensor for Al³⁺, Fe³⁺, Cr³⁺ and Hg²⁺ ions detection was developed.     

2-羟基-1-萘甲醛缩-2-萘甲酰腙对Zn2+的选择性识别

设计合成了识别Zn²⁺的荧光传感分子--2-羟基-1-萘甲醛缩-2-萘甲酰腙(3)。 通过红外光谱、核磁共振谱和质谱测试技术表征了其结构。 利用其光谱性质研究了该物质对几种过渡金属离子的识别性质,初步探讨了其结合模式。 结果表明,在乙腈介质中,受体分子3表现出对Zn²⁺良好的选择性,Zn²⁺的加入导致受体分子3的吸收光谱在435 nm处出现1新峰,其吸光度逐渐增强,同时于239、302、330、342和387 nm处观察到5个清晰的等吸收点;在516 nm处荧光增强101倍,而其它过渡金属只引起受体分子]3的荧光略微增强。 Job法实验揭示受体分子3与Zn²⁺的结合比为1∶1。     

LiBa0.95-yBO3:0.05Tb3+,yBi3+荧光粉的制备及荧光性质

以硼酸和碳酸盐为原料,用高温固相法制备了可被（近）紫外光（369、254 nm）有效激发的Tb³⁺单掺杂LiBa_1-xBO₃：xTb³⁺（物质的量分数x=0.02、0.03、0.04、0.05、0.06、0.07）及Bi³⁺和Tb³⁺共掺杂LiBa_0.95-yBO₃：0.05Tb³⁺,yBi³⁺（物质的量分数y=0.02、0.03、0.04、0.05、0.06、0.07）的2个系列荧光粉,产物的结构和形貌分别用粉末X射线衍射（PXRD）和扫描电子显微镜进行表征。PXRD测定结果表明2个系列的产物均为纯相LiBaBO₃。通过对第一系列产物荧光光谱的测定,筛选出发光强度最好的产物,据此确定铽离子的最佳掺杂量;在此基础上制备出铋离子掺杂量不同的第二系列荧光粉。荧光光谱测定的实验结果表明,Tb³⁺/Bi³⁺共掺杂的荧光粉的发光强度好于Tb³⁺单掺杂的荧光粉,这说明Bi³⁺对Tb³⁺有敏化作用;而且随着Bi³⁺掺杂量的增加,产物的荧光强度表现出先增加后减小的趋势,当Bi³⁺的掺杂量y=0.03时,产物的荧光强度达到最大。Bi³⁺和Tb³⁺之间存在偶极-四极相互作用而进行能量传递。系列荧光粉的CIE坐标显示其发光颜色在一定程度上呈现出由绿色光到白光的渐变趋势。     

Preparation of manganese-53

The nuclide⁵³Mn was produced by the following three nuclear reactions,⁵²Cr(d, n)⁵³Mn,⁵¹V(³He n)⁵³Mn and⁵⁰Cr(α, n), (α, p)⁵³Mn. Enriched⁵²Cr and⁵⁰Cr metal targets were prepared on copper plate holder by electrodeposition. The commercially available natural vanadium foil was used for the⁵¹V(³He, n)⁵³Mn reaction. Each target was bombarded in a cyclotron. Manganese was extracted and purified without using carrier from the bombarded targets by anion and cation exchanges and solvent extraction. The isotopic ratio⁵³Mn/⁵⁵Mn was measured by mass spectrometry and the amount of⁵⁵Mn was determined by neutron activation analysis. The activity of⁵³Mn obtained was 7 dpm by 750 millicoulombs in³He bombardment (E³He=20 MeV). The activity due to by-product⁵⁴Mn was about several thousands times higher than that of⁵³Mn in³He and deuteron bombardments, which were produced through⁵¹V(³He, γ)⁵⁴Mn and⁵³Cr(d, n)⁵⁴Mn. In alpha bombardment (E_α=15 MeV), the activity of⁵³Mn produced was 8 dpm by 95 millicoulombs. The activity ratio, dpm⁵⁴Mn/dpm⁵³Mn, was about 3, and this ratio was the best one among the results so far obtained.     

Laser photolysis of ozone in the presence of ammonia. Formation and decay of vibrationally excited NH2 radicals

NH₂ radicals were generated by laser pulsed photolysis of O₃ in the presence of NH₃ and their subsequent kinetics were monitored by LIF. The room-temperature rate constant for O(¹D)+NH₃ was measured to be (3.3±0.1)×10^−1u cm⁻³ molecule⁻¹ s⁻¹ by studying NH₂ accumulation profiles. The nascent energy distribution over NH₂ vibrational levels was studied and the fraction of NH₂ radicals generated in the ground vibrational state was found to be 0.42±0.08. Acceleration of the reaction NH₂+O₃ caused by vibrational excitation of NH₂ radicals was observed - the rate constants were (1.5±0.4)×10⁻¹² and (1.5±0.3)×10⁻¹³ cm⁻³ molecule⁻¹ s⁻¹, for vibrationally excited and non-excited NH₂, respectively. The reactive channel for removal of vibrationally excited NH₂ by ozone appears to be dominant.     

A tetraruthenium carbonyl cluster bearing indenyl-type ligand as the facial bonding mode

A tetraruthenium carbonyl cluster, (μ₃:η¹:η³:η⁵-3,4,5-trihydroacenaphthylenyl)Ru₄H(CO)₉ (3), was synthesized from (μ₃:η¹:η⁵-dihydroacenaphthylene)Ru₃H₂(CO)₁₂ (2) in chloroform. The molecular structure showed the trihydroacenaphthylenyl ligand to be a rare example of triply bridging nine electron donor ligands, being bound to three ruthenium atoms by the face-capping mode. One ruthenium atom was bonded by the π-cyclopentadienyl coordination mode, whereas the latter two were bound to four carbons in the six-membered ring by the η¹:η³-bonding mode.     

A Highly Selective and Sensitive Fluorescent Chemosensor for Detection of Al3+ in Totally Aqueous Media

A fluorescent chemosensor ( 1 ) based on 2‐hydroxy‐1‐naphthaldehyde Schiff‐base was developed for the detection of Al³⁺ in 100% aqueous solution. Upon addition of Al³⁺, a significant fluorescence enhancement was observed, which was not affected by other metal ions including Na⁺, K⁺, Ca²⁺, Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cr³⁺, Ag⁺, Pb²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Fe²⁺ and Fe³⁺ under weak acid conditions. Moreover, the specific response to Al³⁺ was visible under natural light. The binding mode between 1 and Al³⁺ was clarified by ESI‐MS and ¹H NMR.     

The electrochemical stripping determination of bismuth in aqueous and nonaqueous media after its extraction

The cyclic voltammetry of bismuth in aqueous media and electrochemical stripping determination of bismuth in aqueous and nonaqueous media after its extraction using a rotating disc electrode of glassy carbon was studied. To raise the conductivity of the organic medium and for the preparation of a convenients medium for the determination of bismuth, an alcoholic (methanol) solution of NH₄SCN+HClO₄ was employed. In non-aqueous medium bismuth can be determined down to concentrations 10^?8M by anodic stripping voltammetry and to 5×10^?8M by anodic stripping chronopotentiometry. The selectivity of the determination of bismuth after its extraction was studied. Electrochemical determination of 10^?6M Bi³⁺ with error ±3–4% was not interfered with by these elements: Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, As³⁺ in the concentration 8×10^?3M, Fe³⁺, In³⁺, Sn²⁺ and Sn⁴⁺ (5× 10^?3M), Cu²⁺ (10^?3M), Sb³⁺ (1.5×10^?4M) and Hg²⁺ (2×10^?5M). The reproducibility of the electrochemical determination of bismuth according to the recommended procedure is very good.     

Study of the complexation chemistry and speciation of thallium for on-line preconcentration with immobilised quinolin-8-ol

The effects of various buffering reagents and pH conditions were investigated by flame atomic absorption spectrometry to optimise complexation of T1³⁺ with quinolin-8-ol (8-Q), immobilised on controlled-pore glass beads in a 5-cm column. As Tl³⁺ is a softer acid than the other trivalent cations of the Group III elements, the effects of the buffers are different from those observed previously for Al³⁺, Ga³⁺ and In³⁺. A mixed buffer of 0.1 mol l^–1 acetate and 0.1 mol l^–1 ammonium chloride at pH 10 proved most successful, although 0.1 mol l^–1 maleate was also satisfactory over a pH range of 4–10. As thallium normally exists as Tl⁺ in solution, an oxidation method was developed to convert the ions to Tl³⁺, which is more efficiently complexed by 8-Q. Addition of 1–10 l of bromine per 100 ml of sample was sufficient to oxidise Tl⁺ without heating. Excess bromine was removed by addition of phenol. With a flow-rate of 6 ml min^–1, the detection limit of Tl³⁺ is 3 ng ml^–1, for a 3-miri preconcentration time. The enrichment factor under these conditions is 55 and the characteristic concentration is 2 ng ml^–1. The major ions in sea water did not interfere with Tl³⁺ preconcentration and the tolerable limits of Fe³⁺, Cu²⁺ and Al³⁺ are high enough to permit analysis of river and sea waters. The method was applied successfully to the determination of thallium in potassium-enriched table salt. It was also shown that the concentrations of Tl⁺ and Tl³⁺ in a solution can be derived using the described procedure, allowing speciation of inorganic thallium.     

Radical Anions,Radical-Anion Salts,and Anionic Complexes of 2,1,3-Benzochalcogenadiazoles

By means of cyclic voltammetry (CV) and DFT calculations, it was found that the electron-acceptor ability of 2,1,3-benzochalcogenadiazoles 1 – 3 (chalcogen: S, Se, and Te, respectively) increases with increasing atomic number of the chalcogen. This trend is nontrivial, since it contradicts the electronegativity and atomic electron affinity of the chalcogens. In contrast to radical anions (RAs) [ 1 ]^.− and [ 2 ]^.−, RA [ 3 ]^.− was not detected by EPR spectroscopy under CV conditions. Chemical reduction of 1 – 3 was performed and new thermally stable RA salts [K(THF)]⁺[ 2 ]^.− ( 8 ) and [K(18-crown-6)]⁺[ 2 ]^.− ( 9 ) were isolated in addition to known salt [K(THF)]⁺[ 1 ]^.− ( 7 ). On contact with air, RAs [ 1 ]^.− and [ 2 ]^.− underwent fast decomposition in solution with the formation of anions [ECN]⁻, which were isolated in the form of salts [K(18-crown-6)]⁺[ECN]⁻ ( 10 , E=S; 11 , E=Se). In the case of 3 , RA [ 3 ]^.− was detected by EPR spectroscopy as the first representative of tellurium–nitrogen π-heterocyclic RAs but not isolated. Instead, salt [K(18-crown-6)]⁺₂[ 3 -Te₂]²⁻ ( 12 ) featuring a new anionic complex with coordinate Te−Te bond was obtained. On contact with air, salt 12 transformed into salt [K(18-crown-6)]⁺₂[ 3 -Te₄- 3 ]²⁻ ( 13 ) containing an anionic complex with two coordinate Te−Te bonds. The structures of 8 – 13 were confirmed by XRD, and the nature of the Te−Te coordinate bond in [ 3 -Te₂]²⁻ and [ 3 -Te₄- 3 ]²⁻ was studied by DFT calculations and QTAIM analysis.     

Fluorescence enhancement by gadolinium of the europium or samarium-dibenzoylmethane-diethylamine system

A fluorescence enhancement produced by adding Gd³⁺, Y³⁺, Tb³⁺, La³⁺ or Lu³⁺ to europium or samarium-dibenzoylmethane-diethylamine was observed. Gd³⁺ enhanced the fluorescence intensity by 2–3 orders of magnitude compared with the system without Gd³⁺. The new system was used for the simultaneous determination of traces of Sm³⁺ and Eu³⁺ in the ranges 1.0 × 10^?9?8.0 × 10^?8 M and 1.0 × 10^?11?4.0 × 10^?9 M, respectively, and the detection limits were 5 × 10^?13 M for Sm³⁺ and 8 × 10^?14 M for Eu³⁺. The luminescence mechanism of the system is discussed.     

Mechanistic Insight into Energy-Transfer Dynamics and Color Tunability of Na4CaSi3O9:Tb3+,Eu3+ for Warm White LEDs

In this work, a latent energy-transfer process in traditional Eu³⁺,Tb³⁺-doped phosphors is proposed and a new class of Eu³⁺,Tb³⁺-doped Na₄CaSi₃O₉ (NCSO) phosphors is presented which is enabled by luminescence decay dynamics that optimize the electron-transfer energy process. Relative to other Eu³⁺,Tb³⁺-doped phosphors, the as-synthesized Eu³⁺,Tb³⁺-doped NCSO phosphors show improved large-scale tunable emission color from green to red upon UV excitation, controlled by the Tb³⁺/Eu³⁺ doping ratio. Detailed spectroscopic measurements in the vacuum ultraviolet (VUV)/UV/Vis region were used to determine the Eu³⁺–O²⁻ charge-transfer energy, 4f–5d transition energies, and the energies of 4f excited multiplets of Eu³⁺ and Tb³⁺ with different 4f^N electronic configurations. The Tb³⁺→Eu³⁺ energy-transfer pathway in the co-doped sample was systematically investigated, by employing luminescence decay dynamics analysis to elucidate the relevant energy-transfer mechanism in combination with the appropriate model simulation. To demonstrate their application potential, a prototype white-light-emitting diode (WLED) device was successfully fabricated by using the yellow luminescence NCSO:0.03Tb³⁺, 0.05Eu³⁺ phosphor with high thermal stability and a BaMgAl₁₀O₁₇:Eu²⁺ phosphor in combination with a near-UV chip. These findings open up a new avenue to realize and develop multifunctional high-performance phosphors by manipulating the energy-transfer process for practical applications.