A pair of coordination polymers of composition (NBu)[M(fan)] (fan = fluoranilate; M = Fe and Zn) were synthesized and structurally characterized. In each case the compound consists of a pair of interpenetrating three-dimensional, (10,3)-a networks in which metal centers are linked by chelating/bridging fluoranilate ligands. Tetrabutylammonium cations are located in the spaces between the two networks. Despite the structural similarity, significant differences exist between (NBu)[Fe(fan)] and (NBu)[Zn(fan)] with respect to the oxidation states of the metal centers and ligands. For (NBu)[Fe(fan)] the structure determination as well as Mössbauer spectroscopy indicate the oxidation state for the Fe is close to +3, which contrasts with the +2 state for the Zn analogue. The differences between the two compounds extends to the ligands, with the Zn network involving only fluoranilate dianions, whereas the average oxidation state for the fluoranilate in the Fe network lies somewhere between -2 and -3. Magnetic studies on the Fe compound indicate short-range ordering. Electrochemical and spectro-electrochemical investigations indicate that the fluoranilate ligand is redox-active in both complexes; a reduced form of (NBu)[Fe(fan)] was generated by chemical reduction. Conductivity measurements indicate that (NBu)[Fe(fan)] is a semiconductor, which is attributed to the mixed valency of the fluoranilate ligands.
Oxygen is a critical gas for medical and industrial settings. Much of today's global oxygen supply is via inefficient technologies such as cryogenic distillation, membranes or zeolites. Metal–organic frameworks (MOFs) promise a superior alternative for oxygen separation, as their fundamental chemistry can in principle be tailored for reversible and selective oxygen capture. We evaluate the characteristics for reversible and selective uptake of oxygen by MOFs, focussing on redox‐active sites. Key characteristics for separation can also be seen in MOFs for oxygen storage roles. Engineering solutions to release adsorbed oxygen from the MOFs are discussed including Temperature Swing Adsorption (TSA), Pressure Swing Adsorption (PSA) and the highly efficient Magnetic Induction Swing Adsorption (MISA). We conclude with the applications and outlooks for oxygen capture, storage and release, and the likely impacts the next generation of MOFs will have on industry and the broader community.
The structures and optical band gaps of twelve radical anionic 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 7,7,8,8-tetracyano-2,3,4,5-tetrafluoroquinodimethane (F 4 TCNQ) based charge-transfer complexes are reported. The compounds described have been categorised into three general types based upon solidstate arrangements of the donor and acceptor molecules. Crystallographic, EPR and IR spectroscopic investigations indicated that both TCNQ and F 4 TCNQ in each of the compounds described exist in the radical monoanion form. Visible-NIR absorption measurements indicate optical band gaps in the range of 0.79 to 1.08 eV. Whilst the packing arrangements in CT complexes are known to affect the band gap, in the cases considered here no clear relationship between the packing arrangement and the optical band gap is apparent. The results suggest that in the absence of mixed valency the packing arrangement does not impact significantly upon the magnitude of the optical band gap.
Occupational therapy practitioners are familiar with most principles of family-centered practice. However, implementation of those principles differs significantly across practice settings.
The elucidation of mechanisms to modulate the properties of multifunctional electroactive, conductive, and magnetic porous materials is desirable to aid their future application. The synthesis and characterization of a two-dimensional (2D) mixedvalence metal−tetraoxolene coordination polymer containing a redoxactive dication, (PhenQ)[Fe 2 (Clan) 10]-phenanthrolindiium), are reported. The PhenQ 2+ cation in 1 introduces additional accessible framework redox states and effectively directs the localization of ligand valence states. Static and dynamic magnetic susceptibility measurements demonstrated that the dimethylformamide (DMF) solvate, 1b, undergoes spontaneous magnetization below T c = 31 K, with variable-temperature electrical conductivity measurements revealing that 1b is a modest semiconductor with a conductivity of σ 295K = 4.9 × 10 −4 S cm −1 (E a = 0.249(2) eV). In concert, these results demonstrate that introducing noncovalent interactions between anionic metal−tetraoxolene frameworks and redox-active cations is an effective method to alter the electronic structure and properties of these porous frameworks. Moreover, they forecast the synthesis of new anionic metal−tetraoxolene compounds with diverse electronic and magnetic properties using this hitherto unused strategy.
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