Sokhrab B. Aliev

High Proton Conductivity and Spectroscopic Investigations of Metal–Organic Framework Materials Impregnated by Strong Acids

Strong toluenesulfonic and triflic acids were incorporated into a MIL-101 chromium(III) terephthalate coordination framework, producing hybrid proton-conducting solid electrolytes. These acid@MIL hybrid materials possess stable crystalline structures that do not deteriorate during multiple measurements or prolonged heating. Particularly, the triflic-containing compound demonstrates the highest 0.08 S cm(-1) proton conductivity at 15% relative humidity and a temperature of 60 °C, exceeding any of todays commercial materials for proton-exchange membranes. The structure of the proton-conducting media, as well as the long-range proton-transfer mechanics, was unveiled, in a certain respect, by Fourier transform infrared and (1)H NMR spectroscopy investigations. The acidic media presumably constitutes large separated droplets, coexisting in the MIL nanocages. One component of proton transfer appears to be related to the facile relay (Grotthuss) mechanism through extensive hydrogen-bonding interactions within such droplets. The second component occurs during continuous reorganization of the droplets, thus ensuring long-range proton transfer along the porous structure of the material.

Polyaniline-intercalated MIL-101: selective CO2 sorption and supercapacitor properties

A novel nanostructured hybrid material PANI@MIL-101(Cr) (PANI = polyaniline, MIL-101(Cr) – trichromium oxo-1,4-benzenedicarboxylate) was obtained by the intra-pore oxidative polymerization of guest aniline molecules within MIL-101. The compound was fully characterized using PXRD, TGA, FT-IR spectroscopy, XPS and SEM techniques. An introduction of PANI has dramatically increased the materials selectivity towards carbon dioxide over nitrogen with a CO2 uptake value of 2.26 mmol g−1 at 273 K (1.2 bar). Furthermore, cyclic voltammetry measurements revealed that PANI@MIL-101(Cr) is a supercapacitor with a relatively high specific capacitance value of 135 F g−1.

Electric-field-induced metastable state of electrical conductivity in polyaniline nanoparticles polymerized in nanopores of a MIL-101 dielectric matrix

Conducting polyaniline PANI has been obtained inside dielectric nanoporous coordination polymer MIL-101. The application of an electric field transforms both bulk PANI and nanocomposite PANI@MIL to a metastable high-conductive state. After a decrease in the applied electric field, PANI and PANI@MIL relax toward a state low-conductive stable by the law ln[σ(t)/σ(τ)] = −(t/τ)n, which is typical of disordered systems with the characteristic time τ of about six hours for PANI and with three times larger time for composite PANI@MIL. The temperature dependences of the electrical conductivity σ(T) of the samples in both high- and low-ohmic states are described by the fluctuation-induced conductivity model. Significant changes in relaxation processes and in the parameters of the fluctuation-induced tunneling conduction in nanocomposite PANI@MIL are due to a decrease in the sizes of polyaniline particles in the MIL-101 matrix to nanometers.

Materials with high proton conductivity above 200 °C based on a nanoporous metal–organic framework and non-aqueous ionic media

Correction for ‘Materials with high proton conductivity above 200 °C based on a nanoporous metal–organic framework and non-aqueous ionic media’ by Valentina G. Ponomareva et al., RSC Adv., 2017, 7, 403–407.

Synthesis of polypyrrole intercalated into channels of nanoporous metal-organic coordination polymer

A procedure has been developed for the intercalation of pyrrole into nanocavities of a metal-organic coordination polymer, chromium terephthalate MIL-101, and oxidative polymerization of pyrrole has been accomplished. The new composite nanomaterial thus obtained, polypyrrole@MIL-101, has been characterized by the data of elemental analysis, X-ray powder diffraction, thermal analysis, and scanning electron microscopy. Its specific surface area has been estimated at 1700 m2/g according to Brunauer-Emmett-Teller.

Synthesis and structure of the coordination polymer [Li5/3H1/3(H4chhc)]

The coordination polymer of the composition [Li5/3H1/3(H4chhc)] was synthesized by the reaction of lithium hydroxide monohydrate with 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H6chhc) at 100 °C in a 1,4-dioxane-methanol mixture. The structure of this compound was determined by X-ray crystallography and confirmed by IR spectroscopy, as well as by thermo-gravimetric and elemental analysis. The coordination polymer has a structure of a 3D metal-organic framework built from lithium cations and H4chhc2− anions.

Dilithium cyclohexanediacetate: A layered coordination polymer with non-valent hydrophobic contacts

By heating a solution of LiOH and 1,1′-cyclohexanediacetic acid (H2chda) coordination polymer [Li2(chda)] (1) having a layered nature is obtained and characterized.

Synthesis and crystal structure of the porous metal-organic coordination polymer [Zn4(Ndc)4(Oxdz)2] · 2H2O

New metal-organic coordination polymer [Zn4(Ndc)4(Oxdz)2] · 2H2O (H2Ndc = 2,6-naphthalenedicarboxylic acid, Oxdz = 1,3,4-oxadiazole) was prepared by heating a solution of zinc nitrate, naphthalenedicarboxylic acid, and 4-aminotriazole in DMF. Of particular interest is the in situ transformation of 4-aminotriazole into 1,3,4-oxadiazole. The structure and the composition of the obtained compounds were established by X-ray diffraction, IR spectroscopy, and elemental analysis. The metal-organic framework is electrically neutral and forms a channel structure with the pore diameter of 9 Å.

Crystal structure of layered metal-organic coordination polymers based on trinuclear zinc carboxylates: [Zn3(DMA)2(bpdc)3]·3DMA and [Zn3(im)2(bdc)3]·1.5H2O

New layered metal-organic coordination polymers [Zn3(bpdc)3(DMA)2]·3DMA (1) (H2bpdc = 4,4′-biphenyldicaboxylic acid, DMA = N,N′-dimethylacetamide) and [Zn3(bdc)3(im)2]·1.5H2O (2) (H2bdc = terephtalic acid, im = imidazole) are synthesized and characterized by X-ray crystallography.

Comparison of Current-Voltage Characteristics of Bulk Polyaniline and Nano Dimensional Polyaniline Particles in Nanoporous Dielectric Matrix of MIL-101

We investigated current-voltage (I-V) characteristics of bulk polyaniline and aniline polymerized inside nanopores of chromium terephthalate dielectric matrix MIL-101. The temperature dependence of electrical conductivity σ (T) of these materials are described by the fluctuation-induced tunneling model (FIT), which means that the main contribution to a net conductivity is caused by contacts between particles of the polyaniline. The comparison of I-V for these two types of materials shown that I-V characteristics of bulk polyaniline are described by the quasi-1D VRH model while for aniline polymerized inside nanopores of chromium terephthalate dielectric matrix MIL-101 by extended FIT model.