ABSTRACT
To establish a strategy for designing porous coordination polymers (PCPs) for ammonia capture, the first systematic study on the stability of PCPs against ammonia was conducted. Various types of PCPs were investigated by comparing their powder XRD patterns before and after treatment with ammonia. Among the PCPs tested, ZIF-8, MIL-53(Al), Al-BTB, MOF-76(M) (M=Y or Yb), MIL-101(Cr), and MOF-74(Mg) were stable up to 350 °C under an ammonia atmosphere at ambient pressure. The origin of the stability of PCPs is discussed from the viewpoint of their components, metal cations, and organic linkers. Furthermore, adsorption isotherm measurements show that the adsorptive behavior of PCPs is independent of their stability.
Subject(s)
Ammonia/chemistry , Polymers/chemistry , 2,2'-Dipyridyl/chemistry , Adsorption , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Copper/chemistry , Organometallic Compounds/chemistry , Oxygen/chemistry , Polymers/chemical synthesis , PorosityABSTRACT
The replacement of scarce and expensive platinum species poses a challenge in fuel-cell development. The design and synthesis of a novel type of Co(II) -N4 macrocyclic complex, [CoN4 ], based on the phenanthroline-indole macrocyclic ligand (PIM) is reported. This unique ligand allows the formation of mono- and dinuclear complexes with defined active sites that facilitate the direct four-electron reduction of oxygen. Electrochemical measurements revealed that the [CoN4 ]/C (20â wt %) catalysts have a high activity and long-term stability for the oxygen-reduction reaction (ORR) under alkaline conditions, similar to the Pt/C catalyst. These structurally well-defined complexes represent a nonprecious alternative to platinum species for future fuel-cell applications.
ABSTRACT
A new class of macrocyclic metal-N(4) complexes [MN(4)](n) (M = Co and Fe) were designed and synthesized based on a triangular ligand. Their unique triangular trinuclear structure provides a high density of active sites and facilitates the reduction of dioxygen via a four-electron pathway. Among them, a [CoN(4)](3)/C catalyst (20 wt %) exhibits high catalytic activity and long-time stability for the oxygen reduction reaction (ORR) in alkaline conditions, superior to the commercial Pt/C catalyst. Such structurally well-defined [MN(4)](n) complexes provide a platform for a new generation of nonprecious metal catalysts (NPMCs) for fuel cell applications.
ABSTRACT
A Ru complex-incorporated Ti-based MOF (Ti-MOF-Ru(tpy)2) has been synthesised by using a bis(4'-(4-carboxyphenyl)-terpyridine)Ru(ii) complex (Ru(tpy)2) as an organic linker. Ti-MOF-Ru(tpy)2 promotes photocatalytic hydrogen production from water containing a sacrificial electron donor under visible-light irradiation up to 620 nm.
ABSTRACT
A new lanthanoid porous coordination polymer, La-BTTc (BTTc = benzene-1,3,5-tris(2-thiophene-5-carboxylate)), was synthesized and structurally characterized to have densely aligned one-dimensional open metal sites, which were found to act as strong Lewis acid sites after the removal of the coordinated solvent.
ABSTRACT
Highly photoluminescent acceptor-donor-acceptor (A-D-A) and donor-acceptor (D-A) type compounds with a dithienosilole unit as the donor and perfluorotolyl or dimesitylboryl group(s) as the acceptor were prepared by the reaction of lithiated dithienosilole derivatives with perfluorotoluene or fluorodimesitylborane, respectively. The resulting A-D-A and D-A type compounds showed red-shifted UV absorption and PL bands compared to those of simple dithienosiloles having no acceptor units, reported previously, and were highly photoluminescent in the solid state as well as in solution. Solvatochromic behaviour that would arise from the intramolecular donor-acceptor interaction were observed for the D-A type compounds with respect to the UV absorption and PL spectra. In addition, it was found that bis(dimesitylboryl)dithienosilole and (dimesitylboryl)(methylthio)dithienosilole responded to coexisting fluoride anions, leading to clear UV absorption and PL spectral changes in solutions.