Reactions of Fe(II) precursors with the tetradentate ligand S,S'-bis(2-pyridylmethyl)-1,2-thioethane (bpte) and monodentate NCE(-) coligands afforded mononuclear complexes [Fe(bpte)(NCE)2] (1, E = S; 2, E = Se; 3, E = BH3) that exhibit temperature-induced spin crossover (SCO). As the ligand field strength increases from NCS(-) to NCSe(-) to NCBH3(-), the SCO shifts to higher temperatures. Complex 1 exhibits only a partial (15%) conversion from the high-spin (HS) to the low-spin (LS) state, with an onset around 100 K. Complex 3 exhibits a complete SCO with T1/2 = 243 K. While the γ-2 polymorph also shows the complete SCO with T1/2 = 192 K, the α-2 polymorph exhibits a two-step SCO with the first step leading to a 50% HS → LS conversion with T1/2 = 120 K and the second step proceeding incompletely in the 80-50 K range. The amount of residual HS fraction of α-2 that remains below 60 K depends on the cooling rate. Fast flash-cooling allows trapping of as much as 45% of the HS fraction, while slow cooling leads to a 14% residual HS fraction. The slowly cooled sample of α-2 was subjected to irradiation in the magnetometer cavity resulting in a light-induced excited spin state trapping (LIESST) effect. As demonstrated by Mössbauer spectroscopy, an HS fraction of up to 85% could be achieved by irradiation at 4.2 K.

The X-ray crystallographic characterization and solid state photoluminescence (PL) study of three new tetranuclear copper(I) clusters, [Cu4(O2CR)4], R = (3-F)C6H4 (1), (2,3,4-F)3C6H2 (2), and CF3/C6F5 (3), revealed a dependence of PL on the structural type.

Biomass feedstocks contain inorganic compounds generally classified as ash. The ash consists of compounds of potassium, calcium, magnesium, silicon, phosphorus. and other elements. These elements have been reported to influence both the pyrolysis reactions as well as the destabilization of the pyrolysis oils during storage. The inorganic elements have also been reported to deposit on catalyst surfaces during in situ catalytic pyrolysis leading to the eventual deactivation of acidic catalysts such as zeolites. The deposition of inorganic elements and their effects on formulated red mud (FRM) catalyst during in situ catalytic pyrolysis of pinyon juniper wood was investigated. The inorganic elements were measured for the fresh, coked, and regenerated catalysts. The BET specific surface area of the FRM catalyst decreased from 76 m2/g for the fresh catalyst to 53 m2/g for the stable regenerated catalyst. After three regenerations, the BET specific surface area stabilized at 53 m2/g and remained constant after all other regenerations. Potassium, calcium, magnesium, and phosphorus were deposited on the catalyst. Potassium deposition was linear with the number of regenerations while magnesium and calcium depositions were initially rapid but leveled-off after three regenerations of the catalyst. Phosphorus deposition was almost linear, but the data were more scattered compared to that of potassium. The potassium deposition was attributed to physical phenomenon whereas calcium and magnesium depositions were more akin to chemical reactions related to the loss of BET surface area of the catalyst. The deposition of these elements on the surface of the catalyst did not deactivate it. After each catalyst regeneration, the oil yield was not significantly affected and the oil oxygen content and viscosity decreased slightly. This clearly showed that formulated red mud is a robust catalyst suitable for in situ catalytic fast pyrolysis of biomass.

The first example of a reversible [Cu(4)] <--> [Cu(6)] interconversion for polynuclear copper(I) complexes under controlled experimental settings is reported. It illustrates the key role of specific crystal growth conditions for accessing the target cluster nuclearity that consequently determines physical properties of the resulting solid state products. Thus, when copper(I) benzoate crystallizes from a 1,2-dichlorobenzene solution at room temperature, it forms [Cu(4)]-core based crystalline material, [Cu(4)(O(2)CC(6)H(5))(4)] (1). In contrast, crystal growth by deposition from the gas phase at elevated temperatures results in the exclusive formation of [Cu(6)(O(2)CC(6)H(5))(6)] (2). Complexes 1 and 2 have been isolated in pure form, fully characterized, and reversibly interconverted into each other. The effect of a core structure on the spectroscopic properties of 1 and 2, such as IR, Raman, and photoluminescence, has been investigated. Additionally, a combination of X-ray powder and single crystal diffraction methods has been used to discover the temperature induced phase transition in the hexanuclear copper(I) system. Two modifications of 2 exhibiting slightly different solid state packing of the [Cu(6)(O(2)CC(6)H(5))(6)] units have been identified at room and low temperature. Moreover, reversible single-crystal-to-single-crystal transitions between these polymorphic forms have been confirmed. The important role of weak intermolecular interactions between polynuclear copper(I) units in the solid state has also been revealed and discussed.

Volatile copper(I) benzoates with variable degrees of fluorination are used for p-doping of organic hole-transport layers in single-carrier devices, charge-generation layers, and in organic light-emitting diodes. The charge-transport abilities of the doped materials correlate with the degree and position of the fluorination on the aromatic ring of the carboxylate groups.