Hydrogen Bonded Metal Complex Research Articles

IrIII as a strategy for preorganisation in H-bonded motifs

ABSTRACT We report how four sets of thiourea-based heterodimers interact, and how incorporation of a metal centre imparts reduced degrees of rotational freedom. Through single-crystal X-ray diffraction, 1H NMR, and UV-vis analysis, the interactions of these systems are dissected and presented. These motifs are considered to be stable and desirable for supramolecular hydrogen-bonded functional materials. Interpretation of the structural design of thiourea-based ligand and its incorporation into metal complexes can contribute to the understanding of preorganised self-assembly and open new pathways in design of novel soft materials. This work also contributes to the unexplored library of hydrogen-bonded metal complexes based on iridium. As such we examined the photoluminescence of the system of general formula [Ir(C^N)2(N^S)] and the effect of hydrogen bonding on the emission properties when combined with different n-heteroacenes.

Fine Tuning and Specific Binding Sites with a Porous Hydrogen-Bonded Metal-Complex Framework for Gas Selective Separations.

Research on hydrogen-bonded organic frameworks (HOFs) has been developed for quite a long time; however, those with both established permanent porosities and functional properties are extremely rare due to weak hydrogen-bonding interactions among molecular organic linkers, which are much more fragile and difficult to stabilize. Herein, through judiciously combining the superiority of both the moderately stable coordination bonds in metal-organic frameworks and hydrogen bonds, we have realized a microporous hydrogen-bonded metal-complex or metallotecton framework HOF-21, which not only shows permanent porosity, but also exhibits highly selective separation performance of C2H2/C2H4 at room temperature. The outstanding separation performance can be ascribed to sieving effect confined by the fine-tuning pores and the superimposed hydrogen-bonding interaction between C2H2 and SiF62- on both ends as validated by both modeling and neutron powder diffraction experiments. More importantly, the collapsed HOF-21 can be restored by simply immersing it into water or salt solution. To the best of our knowledge, such extraordinary water stability and restorability of HOF-21 were observed for the first time in HOFs, underlying the bright perspective of such new HOF materials for their industrial usage.

Crystal structure, catecholase activity and ESI-MS of a mixed valence cobalt(III)–cobalt(II) complex derived from a macrocyclic ligand: Identification/proposition of hydrogen bonded metal complex⋯solvent aggregates in ESI-MS

This paper presents the synthesis, crystal structure, catechol oxidase activity and electrospray ionization mass spectra (ESI-MS positive) of a mixed-valence CoIIICoII compound [CoIIICoIIL(N3)3]· 0.5CH3CN·0.27H2O (1) derived from the Robson type tetraiminodiphenolate macrocyclic ligand H2L, which is the [2+2] condensation product of 2,6-diformyl-4-methylphenol and 2,2-dimethyl-1,3-diaminopropane. Compound 1 crystallizes in the monoclinic P21/n space group. The structure consists of two independent units of diphenoxo-bridged CoIIICoII moieties where the CoIII center is hexacoordinated (distorted octahedral) having O(phenoxo)2N(imine)2N(azide)2 environment, while CoII center is pentacoordinated (distorted square pyramidal) having O(phenoxo)2N(imine)2N(azide) environment. Catechol oxidase activity of 1 has been investigated using 3,5-di-tert-butylcatechol (3,5-DTBCH2) as the substrate, revealing that it is an active catalyst with Kcat value 114.24h–1. Electrospray ionization mass spectra (ESI-MS positive) of 1 and 1+3,5-DTBCH2 in acetonitrile have been recorded. No complex⋯substrate aggregate in the spectrum of 1+3,5-DTBCH2 has been identified. However, interestingly, two hydrogen bonded metal complex⋯solvent aggregates [{CoII(LH2)(N3)}⋯(CH3CN)]+ and [{CoIII(LH2)(N3)2}⋯(CH3CN)]+ have been identified in the spectrum of 1. Catecholase activity has also been studied with pyrocatechol and tetrachlorocatechol (TCCH2) as substrates. While no activity has been found with TCCH2, weak activity has been observed with pyrocatechol.

Hollow Nanospheres and Flowers of CuS from Self-Assembled Cu(II) Coordination Polymer and Hydrogen-Bonded Complexes of N-(2-Hydroxybenzyl)-l-serine

Utilization of a novel two-dimensional coordination polymer generated from a trinuclear building block [Cu3(HSser)3(H2O)2]·2H2O (1) as a precursor in the synthesis of copper sulfide serendipitously resulted in CuS nanospheres with hollow interiors. The formation of CuS nanocrystals with the three-dimensional hierarchical flower-like morphology from the hydrogen-bonded metal complex [Cu(H2Sser)2]·H2O (2) as a precursor may be understood from the spatial arrangement of the metal atom and the organic ligand in the crystal lattice plays a major role in determining the shape of the nanomaterials. Detailed investigation on the effect of experimental conditions and the packing patterns of the complexes in the crystal lattice reveals the formation mechanism of the morphologically different CuS. The electrochemical behavior of these nanosized CuS meso-assemblies as a cathode material for lithium ion batteries reveals that the reaction proceeds through an insertion and deinsertion mechanism and the CuS with a hollow interior is more efficient and has good cyclability compared to that with a flower-like morphology.

Hydrogen-Bonded Metal-Complex Sulfonate (MCS) Inclusion Compounds: Effect of the Guest Molecule on the Host Framework

Soft molecular host frameworks made of the hydrogen-bonded metal complex (MC) Co(NH3)(6)3+ and 4,4'-biphenyldisulfonate (BPDS) include different guest molecules to form inclusion compounds of the type (MC)2(BPDS)3.n(guest). Structurally characterized were six compounds with guest molecules of DMSO, DMF, piperidine, acetone, acetonitrile, and THF. The metal-complex sulfonate frameworks in all of them are of the pillared layer type where the layers are constructed of extensively hydrogen-bonded metal-complex cations and sulfonate (S) anions (and some hydrogen-bonded water) while the organic residues of the 4,4'-biphenyldisulfonate serve as pillars. The hydrogen-bonded MCS layers and the orientations of the pillars adjust and rearrange in order to generate cavities that would accommodate different guest molecules. The steric, electronic, and hydrogen-bonding needs of the guest molecules mold the soft framework into different structures. These MCS host-guest frameworks are very close structural analogues of the well-studied guanidinium sulfonate (GS) networks and mimic their flexibility and overall durability.

Construction of Porous Solids from Hydrogen-Bonded Metal Complexes of 1,3,5-Benzenetricarboxylic Acid

The reaction of M(II) acetate hydrate (M = Co, Ni, and Zn) with 1,3,5-benzenetricarboxylic (BTC) acid yields a material formulated as M3(BTC)2·12H2O. These compounds are isostructural as revealed by their XRPD patterns and a single crystal structure analysis performed on the cobalt containing solid [monoclinic, space group C2, a = 17.482 (6) A, b = 12.963 (5) A, c = 6.559 (2) A, β = 112.04°, V = 1377.8 (8) A, Z = 4]. This solid is composed of zigzag chains of tetra-aqua cobalt(II) benzenetricarboxylate that are hydrogen-bonded to yield a tightly held 3-D network. Upon liberating 11 water ligands per formula unit a porous solid results, M3(BTC)2·H2O, which was found to reversibly and repeatedly bind water without destruction of the framework. The proposed 1-D channels of the monohydrate have a pore diameter of 4 × 5 A, which is typical of those observed in zeolites and molecular sieves. The successful inclusion of ammonia into the porous solid was demonstrated. Larger molecules and others without a reactiv...