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A series of three Mo2 dimers bridged by a meta-phenylene group has been studied in terms of electronic coupling (EC) and electron transfer (ET) in comparison with the para isomers. Optical analyses on the mixed-valence complexes indicate that by replacing a para-phenylene bridge with a meta one, the EC between the two Mo2 centers is dramatically weakened; consequently, the ET rates (ket ) are lowered by two to three orders of magnitude. In the para series, the EC parameters (Hab ) and ET rates (ket ) are greatly affected by O/S atomic alternation of the bridging ligand. However, for the meta analogues, similar EC and ET parameters are obtained, that is, Hab =300-400 cm-1 and ket ≈109 s-1 . These results suggest that through-σ-bond and/or through-space coupling channels become operative as the π conjugation is disabled. DFT calculations reveal that destructive quantum interference features seen for the meta series arise from the cancellation of two π-conjugated coupling pathways.

A direct analytical method based on spray-inlet microwave plasma torch tandem mass spectrometry was applied to simultaneously determine 4 phthalate esters (PAEs), namely, benzyl butyl phthalate, diethyl phthalate, dipentyl phthalate, and dodecyl phthalate with extremely high sensitivity in spirits without sample treatment. Among the 4 brands of spirit products, 3 kinds of PAE compounds were directly determined at very low concentrations from 1.30 to 114 ng·g-1 . Compared with other online and off-line methods, the spray-inlet microwave plasma torch tandem mass spectrometry technique is extremely simple, rapid, sensitive, and high efficient, providing an ideal screening tool for PAEs in spirits.

Magnetite is a very common mineral in various types of iron deposits and some sulfide deposits. Recent studies have focused on the use of trace elements in magnetite to discriminate ore types or trace ore-forming process. Germanium is a disperse element in the crust, but sometimes is not rare in magnetite. Germanium in magnetite can be determined by laser ablation ICP-MS due to its low detection limit (0.0X ppm). In this study, we summary the Ge data of magnetite from magmatic deposits, iron formations, skarn deposits, iron oxide copper-gold deposits, and igneous derived hydrothermal deposits. Magnetite from iron formations contains relatively high Ge (up to approximate to 250 ppm), whereas those from all other deposits mostly contains Ge less than 10 ppm, indicating that iron formations can be discriminated from other Fe deposits by Ge contents. Germanium in magmatic/hydrothermal magnetite is controlled by a few factors. Primary magma/fluid composition may be the major control of Ge in magnetite. Higher oxygen fugacity may be beneficial to Ge partition into magnetite. Sulfur fugacity and temperature may have little effect on Ge in magnetite. The enrichment mechanism of Ge in magnetite from iron formations remains unknown due to the complex ore genesis. Germanium along with other elements (Mn, Ni, Ga) and element ratios (Ge/Ga and Ge/Si raios) can distinguish different types of deposits, indicating that Ge can be used as a discriminate factor like Ti and V. Because of the availability of in situ analytical technique like laser ablation ICP-MS, in situ Ge/Si ratio of magnetite can serve as a geochemical tracer and may provide new constraints on the genesis of banded iron formations.

Two, symmetrical, mixed-valence (MV), complex cations-{[Mo2 (DAniF)3 ]2 (μ-oxamidate)}(+) (1(+) ) and {Mo2 (DAniF)3 ]2 (μ-dithiooxamidate)}(+) (2(+) ; DAniF=N,N'-di(p-anisyl)formamidinate)-are significantly differentiated in terms of electronic coupling between the two [Mo2 ] units. For 1(+) the intervalence (IV) charge-transfer band in the near-IR spectrum is truncated in half on the low-energy side as predicted for MV compounds at the Class II-III limit (2Hab /λ=1; for which Hab =electronic coupling matrix element and λ=reorganization energy). In contrast, the very strongly coupled analogue 2(+) , as indicated by 2Hab /λ=3.5 (> >1), exhibits a higher energy and more symmetrical IV band. As rare examples, this pair of MV species shows distinct optical behaviors for MV systems crossing the Class III region. Optical analysis and DFT calculations are carried out to elucidate the transformation from vibronic to electronic vertical transition.

Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) was used to determine the trace element concentrations of magnetite from the Heifengshan, Shuangfengshan, and Shaquanzi Fe(–Cu) deposits in the Eastern Tianshan Orogenic Belt. The magnetite from these deposits typically contains detectable Mg, Al, Ti, V, Cr, Mn, Co, Ni, Zn and Ga. The trace element contents in magnetite generally vary less than one order of magnitude. The subtle variations of trace element concentrations within a magnetite grain and between the magnetite grains in the same sample probably indicate local inhomogeneity of ore–forming fluids. The variations of Co in magnetite between samples are probably due to the mineral proportion of magnetite and pyrite. Factor analysis has discriminated three types of magnetite: Ni–Mn-V–Ti (Factor 1), Mg–Ai–Zn (Factor 2), and Ga–Co (Factor 3) magnetite. Magnetite from the Heifengshan and Shuangfengshan Fe deposits has similar normalized trace element spider patterns and cannot be discriminated according to these factors. However, magnetite from the Shaquanzi Fe–Cu deposit has affinity to Factor 2 with lower Mg and Al but higher Zn concentrations, indicating that the ore–forming fluids responsible for the Fe–Cu deposit are different from those for Fe deposits. Chemical composition of magnetite indicates that magnetite from these Fe(–Cu) deposits was formed by hydrothermal processes rather than magmatic differentiation. The formation of these Fe(–Cu) deposits may be related to felsic magmatism.

This account reviews our recent investigation on the electronic coupling and intramolecular electron transfer in D–B–A systems constructed by employing covalently bonded [Mo2] units as the electron donor (D) and acceptor (A) and phenylene groups as the bridges (B). In these complexes, the δ electrons are transferring from the donor to the acceptor and thus, exclusively responsible for the electrochemical and optical behaviors. The unique electronic structures for the donor and acceptor sites as well as the D–B–A molecules make them excellent experimental models for validating and refining the existing electronic coupling and electron transfer theories. By designed syntheses of the complex systems, the impact of coordinating atoms and length of bridging ligands and electronic property of the ancillary ligands on the donor–acceptor interaction have been examined by means of electrochemical, spectroscopic, magnetic techniques and theoretic calculations. The widely accepted Hush vibronic model and the latest CNS superexchange formalism have been employed to determine the electronic coupling matrix elements (H), which yield remarkably consistent results. By modulation of the structural variables, the electronic coupling interaction in the mixed-valence complexes varies from weakly to moderately strong coupling; the MV systems span a transition from Class II to the Class II/III borderline in terms of Robin-Day’s classification. On this basis, the intramolecular electron transfer kinetics has been studied under the Marcus–Hush semi-classical framework. The adiabatic electron transfer rate constants are determined in the range of 108–1012 s−1, depending on the nature of bridge. The results also offer new mechanistic insights into electron transfer theory, as both electron-hopping and hole-hopping pathways are confirmed to be effective for certain compounds.