There is an increasing amount of interest in metal–organic frameworks (MOFs) for a variety of applications, from gas sensing and separations to electronics and catalysis. However, the mechanisms by which they crystallize remain poorly understood. Herein, an important new insight into MOF formation is reported. It is shown that, prior to network assembly, crystallization intermediates in the canonical ZIF‐8 system exist in a dynamic pre‐equilibrium, which depends on the reactant concentrations and the progress of reaction. Concentration can, therefore, be used as a synthetic handle to directly control particle size, with potential implications for industrial scale‐up and gas sorption applications. These findings enable the rationalization of apparent contradictions between previous studies of ZIF‐8 and opens up new opportunities for the control of crystallization in network solids more generally.

Me), have been synthesized and fully characterized by multi-nuclear NMR spectroscopy, elemental analysis, and single crystal X-ray diffraction studies. These complexes were immobilized on an insoluble polymethylaluminoxane (sMAO), MAO-modified silica (ssMAO) and a MAO-modified layered double hydroxide (LDH-MAO). The effect of substitution around the Cp ligand was examined in relation to their performance (activity, M w , PDI, morphology) for ethylene polymerization measured both in solution and in slurry phase. Maximum solution-phase activities of 3585 kg/mol.h.bar were recorded at modest [Zr]:[Al] ratios of 1:250. These were compared to the activities recorded using the equivalent solid supported complexes, we observed that sMAO was a superior support material with average increases in activity of 5.3 and 2.3 times relative to ssMAO and LDH-MAO respectively. Most striking was the observation that slurry-phase ethylene polymerization activities using equivalent pro-catalysts supported on sMAO showed enhanced performance compared to the solution phase up to a maximum of 4486 kg/mol.h.bar.

Versatility in metal substitution is one of the key aspects of metal-organic framework (MOF) chemistry, allowing properties to be tuned in a rational way. As a result, it important to understand why MOF syntheses involving different metals arrive at or fail to produce the same topological outcome. Frequently, conditions are tuned by trial-and-error to make MOFs with different metal species. We ask: is it possible to adjust synthetic conditions in a systematic way in order to design routes to desired phases? We have used in situ X-ray powder diffraction to study the solvothermal formation of isostructural M (bdc) dabco (M=Zn, Co, Ni) pillared-paddlewheel MOFs in real time. The metal ion strongly influences both kinetics and intermediates observed, leading in some cases to multiphase reaction profiles of unprecedented complexity. The standard models used for MOF crystallization break down in these cases; we show that a simple kinetic model describes the data and provides important chemical insights on phase selection.

A series heterodinuclear catalysts, operating without co‐catalyst, show good performances for the ring opening copolymerization (ROCOP) of cyclohexene oxide and carbon dioxide. The complexes feature a macrocyclic ligand designed to coordinate metals such as Zn(II), Mg(II) or Co(III), in a Schiff base ‘pocket’, and Na(I) in a modified crown‐ether binding ‘pocket’. The 11 new catalysts are used to explore the influences of the metal combinations and ligand backbones over catalytic activity and selectivity. The highest performance catalyst features the Co(III)Na(I) combination, [N,N′‐bis(3,3’‐triethylene glycol salicylidene)‐1,2‐ethylenediamino cobalt(III) di(acetate)]sodium (7), and it shows both excellent activity and selectivity at 1 bar carbon dioxide pressure (TOF=1590 h−1, >99 % polymer selectivity, 1 : 10: 4000, 100 °C), as well as high activity at higher carbon dioxide pressure (TOF=4343 h−1, 20 bar, 1 : 10 : 25000). Its rate law shows a first order dependence on both catalyst and cyclohexene oxide concentrations and a zeroth order for carbon dioxide pressure, over the range 10–40 bar. These new catalysts eliminate any need for ionic or Lewis base co‐catalyst and instead exploit the coordination of earth‐abundant and inexpensive Na(I) adjacent to a second metal to deliver efficient catalysis. They highlight the potential for well‐designed ancillary ligands and inexpensive Group 1 metals to deliver high performance heterodinuclear catalysts for carbon dioxide copolymerizations and, in future, these catalysts may also show promise in other alternating copolymerization and carbon dioxide utilizations.

The theoretical d.c. current-voltage characteristics of a `collisionless' alkali plasma diode are derived. It is assumed that electrons and ions are created only at the two incandescent plane electrodes, the latter being at the same temperature. The electrons and ions are assumed to leave the electrodes with half-Maxwellian distributions of velocities. Some ions are trapped in the potential well between the electrodes. It is found that the potential distribution is associated with a double sheath in front of the negative electrode, a plasma region of constant potential and an electron sheath at the positive electrode. The theoretical (I, V) characteristics are compared with experimental results obtained with a caesium plasma. At low applied voltages good agreement is obtained between theory and experiment; at higher voltages (where oscillations occur) the d.c. current falls to a lower value. Possible mechanisms for this drop are described.