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An unexpected dominance of the coordination affinity of the sulfate anion over those of two organic chelating ligands, (1-methyl-1H-benzo[d]imidazol-2-yl)methanol (Hmbm) and pyridin-2-ylmethanamine (pma), was observed during the study of the solvothermal assembly of [Co11(mbm)6(pma)2(SO4)8(H2O)6(CH3OH)6]·5CH3OH (1), from CoSO4·7H2O at 100 °C in methanol. ESI-MS of solutions at different periods of the assembly reveal a hierarchical sequence, [Co1] → [Co2] → [Co3] → [Co4] → [Co5] → [Co9], where the lower nuclearity species are richer in Co2+ and SO42− before the inclusion of more mbm ligands at the last step. Its crystal structure consists of an almost symmetrical wheel of nine cobalt atoms, [Co9(mbm)6(SO4)8(H2O)6] in edge-sharing octahedral coordination arranged in triangles with two peripheral dangling [Co(pma)(CH3OH)3]. The sulfate ions exhibit three different coordination modes, two in μ6-, two in μ3- and four as μ2-bridging. Its thermal, optical and magnetic properties are also reported. [ABSTRACT FROM AUTHOR]

Analyses of the structural information of molecular fragments from the mass spectra of the solid-state products and their reaction solutions allow for the understanding of their formation and of their diverse properties. The reaction of CuCl2 and (1-methyl-1H-benzo[d]imidazole-2-yl)methanol (HL) led only to crystals containing molecular dimers of [Cu2(L)2Cl2] (Cu2). The CuII–CuII distance and Cu–OR–Cu angle in the structure are 3.044 Å and 104.8°, respectively. The magnetic susceptibility (3–400 K) is characterized by a very strong intradimer antiferromagnetic interaction of J = −465 and interdimer zj = −0.83 cm−1. But mass spectrometry of a dissolved single crystal in different source energies identifies both its fragmentation and oligomerization to [Cu II3 ] and [Cu II4 ]. DFT calculations give the relative stabilization energies of the fragments observed in ESI-MS to provide a formation process. [ABSTRACT FROM AUTHOR]

The conjugation of bridging bis(diphenylphosphine oxide) alkane or arene ligands was found to control the structural dimensionality and the emission color of complexes from reactions with SmIII(hfac)3(H2O)2 (hfac− = hexafluoroacetylacetonato) while retaining the Sm…Sm distances. Bis(diphenylphosphine oxide)-1,4-butane (L1) affords a one-dimensional (1D) ribbon {Sm(hfac)3(L1)}∞ (1) that emits red color, while bis(diphenyl-phosphinoyl)-1,4-benzene (L2) results in a two-dimensional (2D) network {Sm(hfac)2(CF3COO)(L2)3}∞ (2) and near-white emission, but bis(diphenyl-phosphinoyl)-9,10-anthracene (L3) forms a zero-dimensional (0D) cyclic structure {Sm(hfac)3(L3)}2 (3) with strong π…π interactions that emit green color. Noticeably, the conjugation change is accompanied by a configurational change of coordination from trans for 1 and 2 to cis for 3. The color change is associated with the superposition of ligand and Sm based electronic band energies and their intensities. Such white light emission by a single compound having contributions from different building components is quite rare. [ABSTRACT FROM AUTHOR]

The newly synthesized ionic triple salt Ru–Er, {[RuII(bpy)2(dbim)][ErIII(hfac)4][CF3COO]·H2O} (bpy = 2,2′-bipyridine; hfac− = hexafluoroacetylacetonate; dbim = 2,2′-dibenzimidazole) exhibits near-infrared (NIR) emission at 1535 nm by intermolecular Ru → Er (d → f) energy transfer across supramolecular interactions when pumped within the Ru(ii) 3MLCT band. It is the first such observation for a transition metal–lanthanide ionic pair. [ABSTRACT FROM AUTHOR]

Herein, quasi-square planar CuII(Hmbm)Cl2 (CBC, Hmbm = (1-methyl-1H-benzo[d]imidazol-2-yl)methanol) was arranged in a pseudo orthogonal way to form Cl-bridged chains, and further π…π interactions resulted in distorted hexagonal layers. DFT calculations reveal a bond strength order of Cu–Cl ＞ Cu–O/N > Cu…Cl. ESI-MS data reveal several small fragments from CBC, but oligomeric [CuII2], [CuII3], and [CuII4] for non-zero in-source energies; MS data indicates the occurrence of several chemical processes, viz. splitting of the ligand, oligomerization, and redox reaction of alcohol to aldehyde and CuII to CuI. Gibbs free energies for the fragments were estimated using DFT. The magnetic susceptibility was modeled with the ferromagnetic coupling J(Cu–Cl2a…Cu) = +0.99(30) cm−1 and J′(π…π) = +0.35(16) cm−1 and g = 2.38(2). HF-EPR determined the anisotropic g-values, gx = 2.24, gy = 2.16, and gz = 2.09, and a hyperfine constant of Az = 450 G. DFT calculations from crystal structure data reveal a J(Cu–Cl2a…Cu) of +3.6 at 296 K and +4.1 cm−1 at 90 K that dominates the magnetic properties, whereas J′(π…π) = 0.04 cm−1 is negligibly small. [ABSTRACT FROM AUTHOR]

The research on metal–organic frameworks (MOFs) has been developing at an extraordinary pace in its two decades of existence, as judged by the exponential growth of novel structures and the constant expansion of its applicability and research scope. A major part of the research and its success are due to the vital role of the concept of mixed organic ligands in the design, tuning and functions. This perspective, therefore, reviews the recent advances in MOFs based on this concept, which is generally based on employing a small polydentate ligand (here labelled as “nodal ligand”) to form either clusters, rods or layers, which are then connected by a second ditopic linker ligand to form the framework. The structures of the materials can be grouped into the following three categories: layer-spacer (usually known as pillared-layer), rod-spacer, and cluster-spacer based MOFs. Depending on the size and geometry of the spacer ligands, interpenetrations of frameworks are occasionally found. These MOFs show a wide range of properties such as (a) crystal-to-crystal transformations upon solvent modifications, post-synthetic metal exchange or ligand reactions, (b) gas sorption, solvent selectivity and purification, (c) specific catalysis, (d) optical properties including colour change, luminescence, non-linear optic, (e) short- and long range magnetic ordering, metamagnetism and reversible ground-state modifications and (f) drug and iodine carriers with controlled release. In the following, we will highlight the importance of the above concept in the design, tuning, and functions of a selection of existing MOFs having mixed organic ligands and their associated structures and properties. The results obtained so far using this concept look very promising for fine-tuning the pore size and shape for selective adsorption and specificity in catalytic reactions, which appears to be one way to propel the advances in the application and commercialization of MOFs. [ABSTRACT FROM AUTHOR]

Three new polynuclear complexes, [Co7(bm)12]·(ClO4)2·13H2O (1), [Co4(bm)4Cl4(C3H7OH)4] (2), and [Co4(bm)4(μ-HCO2)2(μ2-HCO2)2(C3H7OH)2] (3) (Hbm = (1H-Benzimidazol)-methanol), have been synthesized and characterized by elemental analysis, IR, powder X-ray diffraction and X-ray single-crystal diffraction. Compound 1features a centrosymmetric wheel-like heptanuclear Co(ii) cluster. Compound 2having a I41/aspace group exhibits a tetranuclear Co(ii) cluster with a cubane topology in which the central Co(ii) ion and oxygen atoms from bm occupy the alternate vertices of the cube. However, compound 3has a tetranuclear Co(ii) cluster with a C2/cspace group different from that of compound 2. These results show that the geometries and sizes of the corresponding anions as well as their coordinating and hydrogen-bonding properties are essential in determining the final structures of the assemblies. Magnetic properties of 1–3in the 2–300 K have also been discussed. The {Co7} (1) and {Co4} (2) cores display dominant ferromagnetic interactions while the {Co4} (3) core displays dominant anti-ferromagnetic interactions. [ABSTRACT FROM AUTHOR]

The solvothermal reaction of In(iii) and 1,2,4,5-benzeneteracarboxylic acid with the presence of piperazine leads to the generation of a novel 3D chiral porous coordination polymer with PtS topological net. Interestingly, the resulting crystals were not a racemic mixture but enantiomeric excess, which was confirmed by the measurement of optical rotation of bulk samples using solid vibrational circular dichroism (VCD) spectra and the solid circular dichroism (CD) spectra based on large crystals from one crystallization. High-pressure CO2and CH4adsorption measurement at 298 K reveals that activated 1can absorb 45.8 cm3(STP)/g CO2at 22 atm and 22.5 cm3(STP)/g CH4at 25 atm. [ABSTRACT FROM AUTHOR]