New open-framework phosphate and phosphite compounds of gallium

New group IIIA metal phosphate-oxalates containing dimethylammonium cations with proton conductivity

Three new group IIIA metal phosphate-oxalate (MPO) compounds, namely [(CH3)2NH2]2[M2(HPO4)2(H2PO4)2(C2O4)] (M = Al (1), Ga (2)) and [(CH3)2NH2]2[In2(HPO4)2(H2PO4)2(C2O4)]·H2O (3), have been synthesized. Their crystal structures feature an anionic layer with the sql topology net. In particular, 1 displays a proton conductivity (σ) of 9.09 × 10-3 S cm-1 at 85 °C and under 98% relative humidity, which is the highest among MPOs. This study not only endows the main group metal-based MPO family with new members, but also contributes to further understanding of the structure-directing roles of amines and provides a feasible idea for improving the proton conductivity of MPOs.

Synthesis of Micro- and Nanoparticles in Sub- and Supercritical Water: From the Laboratory to Larger Scales

The use of micro- and nanoparticles is gaining more and more importance because of their wide range of uses and benefits based on their unique mechanical, physical, electrical, optical, electronic, and magnetic properties. In recent decades, supercritical fluid technologies have strongly emerged as an effective alternative to other numerous particle generation processes, mainly thanks to the peculiar properties exhibited by supercritical fluids. Carbon dioxide and water have so far been two of the most commonly used fluids for particle generation, the former being the fluid par excellence in this field, mainly, because it offers the possibility of precipitating thermolabile particles. Nevertheless, the use of high-pressure and -temperature water opens an innovative and very interesting field of study, especially with regards to the precipitation of particles that could hardly be precipitated when CO2 is used, such as metal particles with a considerable value in the market. This review describes an innovative method to obtain micro- and nanoparticles: hydrothermal synthesis by means of near and supercritical water. It also describes the differences between this method and other conventional procedures, the most currently active research centers, the types of particles synthesized, the techniques to evaluate the products obtained, the main operating parameters, the types of reactors, and amongst them, the most significant and the most frequently used, the scaling-up studies under progress, and the milestones to be reached in the coming years.

High proton conductivity behavior in a 2D metal sulfite constructed from a histidine ligand

In the presence of the amino acid histidine, an inorganic–organic hybrid metal sulfite, Zn₂(SO₃)₂(C₆N₃O₂H₉)₂·H₂O (1), has been prepared under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 shows a 2D layer framework built up from a classical second building unit (S4R), and bridged histidine molecule. Notably, it is the first report of a metal sulfite in the presence of an amino acid molecule. A 1D H-bonding array can be constructed by the H-bonding interaction between histidine molecules and sulfite groups. Moreover, a new function of metal sulfite for proton conduction was investigated by alternating-current impedance analysis. The results demonstrate that compound 1 shows a high proton conductivity of approximately 10⁻³ S cm⁻¹ at 348 K and 98% relative humidity.

In the presence of the amino acid histidine, an inorganic–organic hybrid metal sulfite (compound 1), has been prepared under hydrothermal conditions. Compound 1 shows a high proton conductivity of, approximately 10⁻³ S cm⁻¹ at 348 K and 98% RH.

Concise template syntheses of gallium phosphates driven by in situ direct alkylation of aliphatic and aromatic precursors by methanol

In situ template design and generation strategy is applied to synthesize microporous materials. We report five new organically templated gallium phosphates with different structures varying from 1D chain to 2D layer and 3D framework.

Role of 4,4′-bipyridine versus longer spacers 4,4′-azobipyridine, 1,2-bis(4-pyridyl)ethylene, and 1,2-bis(pyridin-3-ylmethylene)hydrazine in the formation of thermally labile metallophosphate coordination polymers

Uncoordinated N-donors spacers in the title compounds facilitate interesting orthogonal H-bonding, leading to the formation of 3-D polymeric networks.