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Abstract: Herein, we report that a new flexible coordination network, NiL2 (L=4‐(4‐pyridyl)‐biphenyl‐4‐carboxylic acid), with diamondoid topology switches between non‐porous (closed) and several porous (open) phases at specific CO2 and CH4 pressures. These phases are manifested by multi‐step low‐pressure isotherms for CO2 or a single‐step high‐pressure isotherm for CH4. The potential methane working capacity of NiL2 approaches that of compressed natural gas but at much lower pressures. The guest‐induced phase transitions of NiL2 were studied by single‐crystal XRD, in situ variable pressure powder XRD, synchrotron powder XRD, pressure‐gradient differential scanning calorimetry (P‐DSC), and molecular modeling. The detailed structural information provides insight into the extreme flexibility of NiL2. Specifically, the extended linker ligand, L, undergoes ligand contortion and interactions between interpenetrated networks or sorbate–sorbent interactions enable the observed switching. [ABSTRACT FROM AUTHOR]

The aromatic core in dipyridyl linker ligands is found to impact the mode of 2-fold interpenetration in hybrid ultramicroporous materials formed by pillared square grid networks. An analysis of the crystal structures suggests that linker conformation and weak interactions between the linkers in adjacent networks might explain this phenomenon. [ABSTRACT FROM AUTHOR]

The article discusses a study on the self-assembly of complex structures including a [2]catenane ([2]), trefoil knot (TK), and Solomon Link from a simple pair of ligands, diamino-2,2'-bipyridine (DAB), and diformylpyridine (DFP). It says that the insertion of methylene groups between the phenoxy and bipyridyl units of the diaminopyridine ligand of the molecular Borromean rings (BRs) have been anticipated to maintain the stacking interactions. Moreover, the DAB ligand is discussed.

The heteroscorpionate ligands [HB(taz)2(pzR)]−(pzR= pz, pzMe2, pzPh) and [HB(taz)(pz)2]−, synthesised from the appropriate potassium hydrotris(pyrazolyl)borate salt and 4-ethyl-3-methyl-5-thioxo-1,2,4-triazole (Htaz), react with [{Rh(cod)(μ-Cl)}2] to give [Rh(cod)Tx] {Tx= HB(taz)2(pz), HB(taz)2(pzMe2), HB(taz)2(pzPh), HB(taz)(pz)2}; the heteroscorpionate rhodaboratrane [Rh{B(taz)2(pzMe2)}{HB(taz)2(pzMe2)}] is the only isolable product from the reaction of [{Rh(nbd)(μ-Cl)}2] with K[HB(taz)2(pzMe2)]. Carbonylation of the cod complexes gave a mixture of [Rh(CO)2Tx] and [(RhTx)2(μ-CO)3] which reacts with PR3to give [Rh(CO)(PR3)Tx] (R = Cy, NMe2, Ph, OPh). In the solid state the complexes are square planar with the particular structure dependent on the steric and/or electronic properties of the scorpionate and ancillary ligands. The complex [Rh(cod){HB(taz)(pz)2}] has the heteroscorpionate κ2[N2]-coordinated to rhodium with the B–H bond directed away from the rhodium square plane while [Rh(cod){HB(taz)2(pzMe2)}] is κ2[SN]-coordinated, with the B–H bond directed towards the metal. The complexes [Rh(CO)(PPh3){HB(taz)2(pz)}] and [Rh(CO)(PPh3){HB(taz)2(pzMe2)}] are also κ2[SN]-coordinated but with the pyrazolyl ring cisto PPh3; in the former the B–H bond is directed towards rhodium while in the latter the ring is pseudo-parallel to the rhodium square plane, as also found for [Rh(CO)2{HB(taz)2(pzMe2)}]. The analogues [Rh(CO)(PR3){HB(taz)2(pzMe2)}] (R = Cy, NMe2) have the phosphines transto the pyrazolyl ring. Uniquely, [Rh(CO)(PPh3){HB(taz)2(pzPh)}] is κ2[S2]-coordinated. A qualitative mechanism is given for the rapid ring-exchange, and hence isomerisation, observed in solution. [ABSTRACT FROM AUTHOR]