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Porphyrin-based imine gels assembled from small molecular precursors have been developed as a novel type of catalysts in hydrogen production from water splitting. The gels offer chemical variety and hierarchically porous structures and are susceptible to modification via porphyrin metal centres. The Pd gel shows cathodic electrocatalytic activity to produce H2 when coated on FTO electrodes. The gels are stable and active for visible-light driven hydrogen production in the presence of a sacrificial electron donor and a cocatalyst. Impregnation of the Pd metal centre greatly enhances the H2 evolution rate. The Pd gel enables efficient photocatalytic H2 evolution via photoinjection of electrons from the light-harvesting gel network into the Pt nanoparticles. When illuminated with visible light, the Pt-doped PdTAPP–TFPT gel produces hydrogen from aqueous sodium ascorbate solution without significant degradation during four runs (1.0744 × 105μmol g−1 for 120 h totally). Interestingly the wet gels show remarkably higher H2 production efficiency than their dried counterparts. [ABSTRACT FROM AUTHOR]

A series of (metallo)porphyrin imine gels have been synthesized based on imine chemistry. The resulting aerogels have sponge-like porous networked structures consisting of interconnected nanoparticles with hierarchical porosity. The aerogels have high specific surface areas (up to 719 m2 g−1) and large pore volumes (up to 2.60 cm3 g−1). The effect of metal ions on the uptake of gases in these aerogels was investigated. The impregnation of various metal ions (Pd(ii), Ni(ii), Mn(iii), Fe(iii) and Sn(iv)) enhances the uptake capacity of various gases (e.g., CO2) despite their higher densities. Among the metal ions, Pd(ii) is the best to increase the adsorption capacity and the isosteric heat of CO2 adsorption. The Pd-tapp–A4 aerogel exhibits CO2 volumetric uptake (1.62 mmol g−1, 7.13 wt% at 298 K, 1 bar) with a high isosteric heat of adsorption (40.0 kJ mol−1). The gels also show potential applications in catalysis because of their unique hierarchical porosity and the availability of metal centers. In combination with microfluidic technology, a catalytic gel capillary reactor has been assembled with the Pd-tapp–A4 gel supported on the inner surface of a functionalized capillary. [ABSTRACT FROM AUTHOR]

A series of novel aerogels have been obtained based on imine chemistry. The aerogels were prepared by polycondensation of various bridging aldehydes and amines via a sol–gel process. The imine aerogels of tetrakis-(4-aminophenyl)methane (A1) consist of three-dimensional networks of interconnected nanometer-sized particles with hierarchically porous structures. The porosity of the areogels is tuneable by the choice of precursors, precursor concentration and reaction solvent. The aerogels exhibit BET surface areas up to 1021 m2 g−1 (A1-biformyl aerogel A1B1-0.030), as measured by N2 adsorption at 77 K. The A1B1-0.030 aerogel possesses a CO2 uptake of 1.5 mmol g−1 at 298 K and 1.0 bar with an isosteric heat of 38.1 kJ mol−1 and displays high CO2/N2 selectivity up to 70.9, which is derived from the ideal adsorbed solution theory. The A1B1-0.030 aerogel also shows a good capacity to uptake aromatic toluene molecules from an aqueous solution. Moreover, the hierarchically porous structure endows the A1B1-0.030 aerogel with good performance in enrichment of large molecules (polycyclic aromatic hydrocarbons PAHs and organochlorine pesticides OCPs) as the coating adsorbent in solid-phase microextraction (SPME) fibres. [ABSTRACT FROM AUTHOR]

Metal-organic skeleton based gel electrolytes are prepared for the first time for high efficiency quasi-solid-state DSSCs. The gel electrolytes feature in their sponge-like porous matrix of a metal-organic gel (MOG) assembled by coordination of Al3+ and 1,3,5-benzenetricarboxylate (H3BTC), which can provide an excellent ability to accommodate electrolyte ingredients, thus largely preserving the properties of the liquid electrolyte. Meanwhile, the MOG electrolyte can well penetrate into the photoanode film to ensure a good interfacial contact. The effects of the concentration of active species in the MOG electrolyte on the photoelectrical performances are investigated. On increasing the concentration, Jsc of gel-state cells improves gradually due to the enhanced I-/I3- redox couple content, while Voc undergoes an increase first but decreases subsequently. The synergistic function of cations (such as Al3+, Li+, etc.) and tert-butylpyridine (TBP), which can induce a conductive band (CB) shift of the TiO2 photoanode and affect the electron recombination, may contribute to the variation of Voc. By optimizing the composition of the gel electrolyte, a high conversion efficiency of over 8.60% can be obtained, which is a little lower than that of a liquid-state cell (9.13%). This research study will open up a new way to fabricate quasi-solid-state DSSCs with high efficiency. [ABSTRACT FROM AUTHOR]

Modification of Fe-tricarboxylate based metal–organic gels yielded tert-butyl substituted or phosphine-functionalised gels in alcohols or DMF, which were prepared from 5-tert-butylisophthalic acid and 5-diphenylphosphanylisophthalic acid, respectively. Owing to their permeability, such phosphine-functionalised metal–organic gels can act as a new type of functionalisable porous scaffold. The phosphorus-containing gel was subsequently functionalised with Pd(ii) by immersion in a solution of Pd(COD)Cl2(COD = 1,5-cyclooctadiene). The subsequently functionalised Pd(ii)-immobilised gel and its xerogel/aerogel showed high activity in the catalysis of Suzuki C–C coupling comparable to unsupported complexes. The gel/xerogels could be reused under ambient atmosphere. [ABSTRACT FROM AUTHOR]

A novel dynamic covalent gel has been prepared via the imine bond formation reaction of tetraamine building blocks with luminescent tetraphenylethene tetraaldehyde units. The gel shows high hierarchical porosity (SBET = 512 m(2) g(-1)) and remarkable aggregation-induced emission enhancement, which has been demonstrated to be a selective sensor.

Self-diffusion and structural properties of ammonia, methylamine and trimethylamine have been studied by molecular dynamics simulation in the temperature range between the melting pressure curve and 700 K at pressures up to 400 MPa. The calculation results agree well with the experiment, which suggests that one can use the simulation method as a powerful tool to obtain self-diffusion coefficients over wide range of temperatures and pressures, under which it is rather difficult for experiments. The local structures of such fluids are investigated by calculating radial distribution functions (RDFs), the numbers of hydrogen bonds and coordination numbers. The correlation between self-diffusion and structural properties, and the influence of temperature and pressure on them are discussed. The simulation results demonstrate that the temperature effects are more pronounced than the pressure effects on self-diffusion and structural properties, and the effect of hydrogen bonding on the translational dynamics in any of these systems is a minor factor, while it is mainly affected by the close packing of amine molecules.