Redox Isomerism of α-Ferrocenylcarbenium Ions

The formation of α-ferrocenylcarbenium ions FcC⁺H₂ (λ_max 600 nm) and FcC⁺HCH₃ (λ_max 730 nm) and their redox isomerism at the protonation of ferrocenylmethanol and vinylferrocene was proved using the method of electronic spectroscopy. The effect on the process of the solvent and acid nature as well as of hydrogen peroxide additives is discussed.     

A Novel Fluorescent Probe for Lead Ions

A new fluorescent probe for lead ions, p-nitrophenyl 3H-phenoxazin-3-one-7-yl phosphoric acid (NPPA), has been synthesized by linking resorufLn (serving as a fluorophore and electron acceptor) to p-nitrophenol (serving as a fluorescence quencher and electron donor) through phosphodiester bonds. When NPPA was irradiated with light, intramolecular fluorescence self-quenching took place due to the PET (photoinduced electron transfer) from the donor to the acceptor. However, upon addition of Pb^Ⅱ, the phosphate ester bonds in the probe were cleaved and the fluorophore was released, accompanying the retrievement of fluorescence.     

How Hot are Your Ions Really? A Threshold Collision-Induced Dissociation Study of Substituted Benzylpyridinium “Thermometer” Ions

The first absolute experimental bond dissociation energies (BDEs) for the main heterolytic bond cleavages of four benzylpyridinium “thermometer” ions are measured using threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. In this experiment, substituted benzylpyridinium ions are introduced into the apparatus using an electrospray ionization source, thermalized, and collided with Xe at varied kinetic energies to determine absolute cross-sections for these reactions. Various effects are accounted for, including kinetic shifts, multiple collisions, and internal and kinetic energy distributions. These experimentally measured 0 K BDEs are compared with computationally predicted values at the B3LYP-GD3BJ, M06-GD3, and MP2(full) levels of theory with a 6-311+G(2d,2p) basis set using vibrational frequencies and geometries determined at the B3LYP/6-311+G(d,p) level. Additional dissociation pathways are observed for nitrobenzylpyridinium experimentally and investigated using these same levels of theory. Experimental BDEs are also compared against values in the literature at the AM1, HF, B3LYP, B3P86, and CCSD(T) levels of theory. Of the calculated values obtained in this work, the MP2(full) level of theory with counterpoise corrections best reproduces the experimental results, as do the similar literature CCSD(T) values. Lastly, the survival yield method is used to determine the characteristic temperature (T_char) of the electrospray source prior to the thermalization region and to confirm efficient thermalization.

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The Hydrolysis of Hydroxamic Acid Complexants in the Presence of Non-Oxidizing Metal Ions 2: Neptunium (IV) Ions

Hydroxamic acids are salt free, organic compounds with affinities for cations such as Fe³⁺, Np⁴⁺ and Pu⁴⁺, and have been identified as suitable reagents for the control of Pu and Np in advanced nuclear fuel reprocessing. The results of a UV-visible, near-IR spectrophotometric study of the 1:1 and 2:1 complexes formed between formo- and aceto-hydroxamic acids (FHA, AHA) and Np(IV) ions are interpreted using speciation diagrams for the identification of the species present at different pH and ligand to metal ratios. A kinetic model that describes the instability of the complex due to hydrolysis of the hydroxamate moiety, previously developed for the Fe(III)-AHA complexes (Andrieux et al. in J. Solution Chem. 36:1201–1217, [2007]), is tested here against experimental Np(IV)-FHA data. Consequently, the complexation constant for formation of the 1:1 Np(IV)-FHA complex in nitric acid is estimated at K ₁=2715 and indications are that complexation protects the ligand against hydrolysis at 0.1>pH>−0.1.     

Naphthalimide as Highly Selective Fluorescent Sensor for Ag^＋ Ions

The naphthalimide derivative. NA1 was synthesized, which consists of a bis（2-（ethylthio）ethyl）amine group binding cations and naphthalimide unit as chromogenic and fluorogenic signaling subunit. Absorption and emission spectra and the effect of polarity of solvents and pH values were studied. The photo-induced electron transfer （PET） occurred from the donor of bis（2-（ethylthio）ethyl）amine group to the naphthalimide fluorophore. The present study demonstrates that NA1 is a viable candidate as a fluorescent receptor for a new Ag^＋ ion sensor. This silver ion chemosensor can discriminate Ag^＋ ion well among heavy metal ions by an enhancement of the fluorescence intensity in ethanol-water （1 ： 9, V ： V）. And NA1 is also a pH-sensor because the fluorescence of the compound varies with the pH values.     

Thiol-functionalized MCM-48： an Effective Absorbent of Mercury Ions

Water polluted by toxic metals remains an important environmental issue, and there hasrecently been a growing interest in the research of materials capable of removing toxicmetal ions from contaminated water. Mercury is one of the heavy metal ions that ha…     

“Anti-electrostatic” Halogen Bonding between Ions of Like Charge

Halogen bonding occurs between molecules featuring Lewis acidic halogen substituents and Lewis bases. It is often rationalized as a predominantly electrostatic interaction and thus interactions between ions of like charge (e. g., of anionic halogen bond donors with halides) seem counter-intuitive. Herein, we provide an overview on such complexes. First, theoretical studies are described and their findings are compared. Next, experimental evidences are presented in the form of crystal structure database analyses, recent examples of strong “anti-electrostatic” halogen bonding in crystals, and the observation of such interactions also in solution. We then compare these complexes to select examples of “counter-intuitive” adducts formed by other interactions, like hydrogen bonding. Finally, we comment on key differences between charge-transfer and electrostatic polarization.     

The Phenomenon of Mutual Media in Polypyrole with Electroactive Ions

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A Study of Metal Ions Packing Hydrated Layer of Inclusion Crystals

The inclusion crystal formed by the hexamethylenamine with p-nitrophenol has a layer type structure,and is divided or-ganic layer and inorganic layer,the latter has a width of 1.0136nm.Metal ions can enter hydrated layer of the crystal,the con-tents of the cations and water in the crystal are determined.The XRD analysis of the layer type structure of the crystal is also giv-en.     

Promoter Effects of Rare Earth Ions on Electrocatalytic Oxidation of Methanol

The promoter effects of rare earth ions on the electrocatalytic oxidation of methanol at the Pt electrode were studied using the cyclinc voltammetry and stable polarization techniques. It was found or the first time that Eu、Ho、Dy ions could accelerate the electrocatalytic oxidation of methanol at the Pt electrode,while Lu、Pr、Yb、Sm ions showed inhibitor effects.     

Liquid Extraction of Noble Metal Ions with an α-Amino Phosphonate

The extraction of Au(III), Pt(IV), and Pd(II) ions from aqueous hydrochloric acid solutions with solutions of bis(2-ethylhexyl) N-butyl-N-octylaminomethylphosphonate in chloroform and xylene was studied. The recovery of the noble metal ions is the most efficient at low acidities of the aqueous solution, with a high selectivity of separation from the concomitant Fe(III), Cu(II), Ni(II), and Co(II) ions.     

The Phenomenon of Mutual Media in Polypyrrole with Electroactive Ions

The dependence of the differential capacitance of polypyrrole doped with several typical dopants on potential is presented, which shows that the differential capacitance varies with the potential, the doped polypyrroles with electroactive ions give the largest capacitance near their formal potentials, which is attributed to the mutual media for electron transfer between polypyrrole and electroactive dopants. The existence of two conducting phases was observed in the complex capacitance plots. The electroactive anions act as an intra-conducting-phase medium for electron transfer, the electroactive cations act as an inter-conducting phase medium for electron transfer. The mutual media between polypyrrole and redox dopants lead to the increase of the discharging time.     

How Hot are Your Ions in TWAVE Ion Mobility Spectrometry?

Effective temperatures of ions during traveling wave ion mobility spectrometry (TWIMS) analysis were measured using singly protonated leucine enkephalin dimer as a chemical thermometer by monitoring dissociation of the dimer into monomer, as well as the subsequent dissociation of monomer into a-, b-, and y-ions, as a function of instrumental parameters. At fixed helium cell and TWIMS cell gas flow rates, the extent of dissociation does not vary significantly with either the wave velocity or wave height, except at low (<500 m/s) wave velocities that are not commonly used. Increasing the flow rate of nitrogen gas into the TWIMS cell and decreasing the flow rate of helium gas into the helium cell resulted in greater dissociation. However, the mobility distributions of the fragment ions formed by dissociation of the dimer upon injection into the TWIMS cell are nearly indistinguishable from those of fragment ions formed in the collision cell prior to TWIMS analysis for all TWIMS experiments. These results indicate that heating and dissociation occur when ions are injected into the TWIMS cell, and that the effective temperature subsequently decreases to a point at which no further dissociation is observed during the TWIMS analysis. An upper limit to the effective ion temperature of 449 K during TWIMS analysis is obtained at a helium flow rate of 180 mL/min, TWIMS flow rate of 80 mL/min, and traveling wave height of 40 V, which is well below previously reported values. Effects of ion heating in TWIMS on gas-phase protein conformation are presented.     

MPS‐Modified Silica Nanoparticles Linked with Cd2+ Ions

Silica nanoparticles were linked by using 3‐mercaptopropyltrimethoxysilane (MPS) as a coupling agent and Cd²⁺ as bridging ions. The TEM micrographs showed approximately linear linkage between the silica nanoparticles rather than dense packing. The UV‐visible absorption spectra confirmed the formation of S‐Cd‐S bonds between the silica nanoparticles. The alternative films of MPS‐modified SiO₂ nanoparticles and Cd²⁺ ions were also prepared using the layer‐by‐layer self‐assembly technique and characterized by AFM.     

Flow-Injection Extraction–Photometric Trace Determination of Phosphate and Silicate Ions

As an extension of the method for extraction preconcentration in flow analysis including the extraction–chromatographic recovery of analytes and the chromatomembrane separation of the extract from the aqueous phase that was proposed previously, a procedure was developed for the flow-injection extraction–photometric trace determination of phosphate and silicate ions with the use of a 1% solution of tri-n-octylamine in chloroform as the extractant. Detection limits are 5 g/L for phosphate ions and 20 g/L for silicate ions.     

Thiourea Based Tweezer Anion Receptors for Selective Sensing of Fluoride Ions

Three 3,3＇-di（4-substituted-phenyl）-1,1＇-isophthaloylbis（thiourea） compounds were designed as novel neutral anion receptors, and synthesized by simple steps in good yields. The single crystal structure of receptor 1 shows that a solvent molecule was captured by the host molecule through intermolecular hydrogen bonding. Moreover, it was self-assembled as a supramolecular system for the presence of abundant inter- and intramolecular hydrogen bonding and π-π interactions between phenyl groups. Their application as anion receptors has been examined by UV-Vis and ^1H NMR spectroscopy, showing that they had a higher selectivity for fluoride than other halides. The host and guest formed a 1 ： 1 stoichiometry complex through hydrogen bonding interactions in the first step, then following a process of deprotonation in presence of an excess of F^- in the solvent of DMF.     

EPR Study on Mixed Valence States of Mo Ions in Molybdenum Nitride

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Characterizations and Catalytic Properties of Transition Metal Ions Incorporated in Mesoporous Materials

Mesoporous materials typified by MCM-41 possess well-ordered mesoporous channels with controllable pore sizes from 2-30 nm, and are expected as desirable materials for catalysis. However, silicious mesoporous materials generally do not have sufficient intrinsic catalytic activities. Thus many studies have focused on introducing catalytically active sites. It is expected that different synthetic methods would result in different coordination structures of metal cations introduced in MCM-41, a…     

Generation of α,β-Unsaturated Iminium Ions by Laser Flash Photolysis

Two at a time: α,β-Unsaturated iminium ions can be generated by laser flash photolysis of enaminophosphonium ions. The rate constants of their reactions with nucleophiles provide the first direct comparison of the electrophilicities of iminium ions derived from MacMillan's first- and second-generation catalysts.     

Transformation of Structure and Properties of Vesicles Induced by Transition Metal Ions

This paper proved that octodecyl propylenediamine could form vesicles in pure water and aqueous solution of CuCl2 or Cu（NO3）2. The structure and morphology of vesicles were different when the copper （Ⅱ） salt was added to the solution. The results showed that both the counterions and the ligands had strong influence on the configuration of coordinated structures and packing model in bilayer membrane of vesicles.