Reactions of Cu(II), Cd(II), and Ni(II) with a new tetradentate ligand N1,N3-bis(1-(1H-benzimidazol-2-yl)ethylidene)propane-1,3-diamine (H2bbepd) afforded four mononuclear pincer-like complexes of [Cu(H2bbepd)(ClO4)]·CH3OH·ClO4 (1), [Cd(H2bbepd)(CH3OH)(ClO4)]·CH3OH·ClO4 (2), [Ni(H2bbepd)(H2O)2]·2ClO4 (3), and [Ni(H2bbepd)(NO3)2] (4), respectively. The labile small coordinated components (anions or solvent molecules) on the apical coordination site of metal ions in complexes 1–4 display three different modes, which can be substituted by 4,4′-bipyridine (bpy) to obtain four new multinuclear complexes of [Cu2(H2bbepd)2(bpy)]2·4ClO4 (5), [Cd4(H2bbepd)4(bpy)3(ClO4)2]·6ClO4·(bpy)·2CH3OH·6H2O (6), {[Ni(H2bbepd)(bpy)]·2ClO4·CH3OH}n (7), and {[Ni (H2bbepd)(bpy)]·2NO3·CH3OH·H2O}n (8), respectively. Complex 5 is a binuclear dumbbell-like molecule, complex 6 is a rare example of discrete linear tetranuclear molecule, while complexes 7 and 8 are one-dimensional chains formed by an alternate arrangement of bpy molecules and mononuclear subunits. The differences in complexes 5–8 are largely dependent on the structure of the mononuclear precusors of complexes 1–4. All eight complexes are assembled into higher dimensional supramolecular frameworks by diverse nonconvalent interactions including unusual anion···π interactions between perchlorate and five-membered benzimidazole rings.

In order to explore the supramolecular solid-state structural and packing transformations and the property tuning as a function of reaction time, a tripodal triBZ-ntb (4,4′,4′′-(2,2′,2′′-nitrilotris(methylene)tris(1H-benzo[d]imidazole-2,1-diyl)tris(methylene))tribenzonitrile) ligand was self-assembled with cadmium chloride by applying a hydrothermal method for differing reaction times. Three coordination structures were obtained, namely, [Cd(triBZ-ntb)Cl]2(CdCl4)·2H2O·2DMF (Cd5), [Cd(triBZ-ntb)Cl2]·3H2O (Cd10), and [Cd(triBZ-ntb)Cl]2(CdCl4)·2H2O (Cd20), and characterized by IR, EA, single crystal and powder X-ray diffraction methods. Cd5 and Cd20 have identical coordination monomers, [Cd(triBZ-ntb)Cl]+ and (CdCl4)2− counter anions, with a total metal-to-ligand ratio of 3:2, but with slightly different packing states. Meanwhile, the intermediate compound Cd10 is composed of only a neutral coordination unit [Cd(triBZ-ntb)Cl2], with a metal-to-ligand ratio of 1:1, by the additional coordination of one Cl− to the Cd(II) metal center. During the structural transformation process, the formation of (CdCl4)2− counter anions in Cd5 and Cd20 serves as an auxiliary “cabinet” for the storage of surplus Cd2+ metal ions. Theoretical study reveals the relative energy changes in the transformation processes. Furthermore, the switchable structures and packing states in these complexes result in tunable luminescent properties.

Correction for ‘Semidirected versus holodirected coordination and single-component white light luminescence in Pb(II) complexes’ by Ling Chen et al., New J. Chem., 2015, 39, 5287–5292.

2-Methyl-8-hydroxyquinoline (HMq) and the tripodal ligands 4,4′,4′′-(2,2′,2′′-nitrilotris (methylene)tris(1H-benzo[d]imidazole-2,1-diyl)tris(methylene))tribenzonitrile (triBZ-NTB) and 4,4′,4′′-(2,2′,2′′-nitrilotris(methylene)tris(1H-benzo[d]imidazole-2,1-diyl)tris(methylene))tribenzoic acid (H3triCB-NTB) were used individually to assemble a hetero-nuclear, a tetra-nuclear and two mono-nuclear Pb(II) complexes. The Pb(II) coordination centers in two of these complexes were observed to display semidirected coordination with the ligands and counter anions (small solvent molecules), whereas the other two complexes showed holodirected coordination, together leading to varied coordination geometries. The combination of ligand-to-metal charge-transfer (LMCT) and metal-centered (MC) emissions in the semidirected Pb(II) complexes resulted in single-component white light luminescence.

•Solvent-mediated structural transition between (4,4)-net and CdI2-net•Thermodynamically favored conversion by recrystallization process.•A mixture can be converted into pure substance in this way.The coordination of a rigid triangular ligand 2,4,6-tris[4-(1H-imidazole-1-yl)phenyl]-1,3,5-triazine (TIPT) with Cd(II) ions afforded two compounds with structural motifs of a CdI2-type and a (4,4) network for anions OTf− (CF3SO3−) and OTs− (p-CH3C6H5SO3−), respectively, between which structural transition can be induced by anion exchange via solvent-mediated recrystallization process. Using this method, a pure substance can be obtained from a mixture under the excess of certain kind of anions.Structural transition between (4,4)-net and CdI2-net can be induced by anion exchange via solvent-mediated recrystallization process in Cd(II) complexes.

Four non-interpenetrating 3D Ag(I) coordination polymers have been obtained from the reactions of a tripodal ligand, benzene-1,3,5-triyl triisonicotinate (BTTP4), with AgBF4, AgSbF6, AgCF3CO2 and AgCF3SO3. In all complexes, large hexagonal rings with dimensions of 16 × 19 Å (atom-to-atom separation) are formed, which share edges to fabricate the 2D honeycomb network. Parallel stacking of these honeycomb networks in an offset way sustained mainly by π–π interactions results in 2D → 3D non-interpenetrating dimension increase, affording 1D tubular ‘channels’ hosting free solvent molecules and/or counterions in the lattice. The pore size and shape are found to be influenced by the effects of counter anion, ligand conformation and π–π interactions, providing potential microporous frameworks.

•NH⋯N and NH⋯O hydrogen-bonding recognition•Self-assembly•Dumbbell-shape coordinated building block•Tripodal•Tunable by the length of spacersThree hydrogen-bonding frameworks based on NH⋯N and NH⋯O Hbond linkages have been synthesized and structurally characterized by using ntb (tris(2-benzimidazoylmethyl)amine) to react with two Cd(II) salts in the presence of dysfunctional bridging spacers of NaN3, 4'4-bipy and H2tpa (terephthalic acid) respectively. The building blocks of three complexes exhibit dumbbell-shape which stacks each other in the lattice leading to three 3D hydrogen-bonding frameworks with diversiform topology net of distorted NaCl net, (4,4) layer and 424 · 64 net.Three hydrogen-bonding frameworks have been synthesized via assembly of dumbbell-shape building units which were tunable by the length of spacers. The inerrant NH⋯N and N-H⋯O hydrogen-bonding recognition between ntb and the counter anions is responsible for the assembly of dumbbell-shape coordinated building block.