Chiral Coordination Polymers with Amino Acids:

Characterization of Diastereomeric Equilibria of Pseudotetrahedral Bis[(R or S)-N-1-(Ar)Ethylsalicylaldiminato-κ2 N,O]zinc(II) with Λ/Δ-Chirality-At-Metal Induction

A family of bis[(R or S)-N-1-(Ar)ethylsalicylaldiminato-κ2 N,O]-Δ/Λ-zinc(II) {Ar=C6 H5 (ZnRL1 or ZnSL1 ), p-CH3 OC6 H4 (ZnRL2 or ZnSL2 ) and p-ClC6 H4 (ZnRL3 or ZnSL3 )} compounds was synthesized and investigated by multiple methods. They feature Λ/Δ-chirality-at-metal induction along the pseudo-C2 axis of the molecules. The chirality induction is quantitative in the solid state, explored by X-ray crystallography and powder X-ray diffraction (PXRD), where R or S-ligated complexes diastereoselectively yield Λ or Δ-configuration at the metal. On the other hand, Λ and Δ-diastereomers co-exist in solution. The Λ⇆Δ equilibrium is solvent- and temperature-dependent. Electronic circular dichroism (ECD) spectra confirm the existence of a diastereomeric excess of Λ-ZnRL1-3 or Δ-ZnSL1-3 in solution. DSC analysis reveals thermally induced irreversible phase transformation from a crystalline solid to an isotropic liquid phase. ECD spectra were reproduced by DFT geometry optimizations and time-dependent DFT (TD-DFT) calculations, providing ultimate proof of the dominant chirality atmetal in solution.

Syntheses, characterization and properties of three coordination polymers with interpenetrating structures comprising 4,4'-(1H-1,2,4-triazol-1-yl)methylene-bis(benzonic acid)

Three new coordination polymers (CPs), {[Pb(tmdb)](H₂O)} _n (1), {[Zn(tmdb)(bimb)_0.5]} _n (2) and {[Zn₃(tmdb)₃(bpmb)_1.5](H₂O)₆} _n (3) (H₂tmdb = 4,4'-(1H-1,2,4-triazol-1-yl)methylene-bis(benzonic acid), where bpmb = 1,4-bis(pyridin-4-ylmethoxy)benzene and bimb = 1,4-bis(imidazoly-1-yl)benzene), have been solvothermally or hydrothermally synthesized. Compound 1 is a 2D network with the point symbol (4·6·8)(4·6²) and compound 2 is a 4-fold interpenetrating 3D network with spiral chains. The topological type of 2 is dmc (topos&RCSR.ttd) with the point symbol (4·8²)(4·8⁵). Compound 3 is a 3-fold interpenetrating 3D network with the point symbol (6³)₂(8·6⁵)₂(10·6²)(8·10·6⁴). The electrochemiluminescence (ECL) behaviors of 2 and 3 were studied. The applications of CP 2 and 3 in detecting ions were explored, and the results show that they can be used as fluorescent probes to selectively detect and identify Fe³⁺ ions in water. In addition, the applications of CP 2 and 3 in the adsorption and separation of dyes were researched. Furthermore, the gas adsorption of 3 was studied.

Encapsulation of a Water Octamer Chain in a Chiral 2D Sheetlike Supramolecular Coordination Network Composed of Dinickel-Dicarboxylate Subunits

Four new chiral supramolecular coordination networks of Ni(II) of general formula [Ni₂(Hhissal)₂(dicarboxylate)(H₂O)₂]·nH₂O (where Hhissal = histidinesalicylate; dicarboxylate = adipate; n = 8 for 1, succinate; n = 4 for 2, maleate; n = 4 for 3, fumarate; and n = 6 for 4) are reported. On the basis of the single-crystal X-ray study, an unprecedented zig-zag chain structure of water octamer encapsulated in 1 has been identified. The supramolecular network of the dimetal subunits is formed through hydrogen bonding interactions between the amine N-H of Hhissal and the oxygen atom of the coordinated water molecule of one subunit with the uncoordinated oxygen atom and the coordinated oxygen atom of the carboxylate group of Hhissal of the next subunit, respectively. The strength of hydrogen bonding within this water cluster (the range of O···O distances is 2.702-2.760 Å) is similar to that found in ice. These networks are further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, polarimetry, UV-vis/diffuse reflectance and circular dichroism spectroscopy, and thermogravimetric analysis. A comparison of their properties indicates that these are isostructural with a variation of encapsulated water clusters.

Synthesis, Crystal Structures and Properties of Two-dimensional Complexes Constructed by Dicarboxylate and Bis(Imidazole) Co-ligands

The complexes {[Zn(1,3-bip)(3,5-pdc)]·2H2O}n and {[Cu(1,3-bip)(1,3-bdc)]·H2O}n, [1,3-bip=1,3-bis(imidazole)propane, 3,5-pdc=pyridine-3,5-dicarboxylic acid, 1,3-bdc=isophthalic acid], have been synthesised under hydrothermal conditions and structurally characterised. Their thermogravimetric and photoluminescence properties were also investigated.

Mixed-ligand hydroxocopper(ii)/pyridazine clusters embedded into 3D framework lattices

Three types of polynuclear Cu(ii) clusters rely on the compatibility of short-distance hydroxo-, carboxylato and pyridazine bridges and are applicable for the construction of 3D MOF structures.

Hierarchical importance of coordination and hydrogen bonds in the formation of homochiral 2D coordination polymers and 2D supramolecular assemblies

2D homochiral coordination polymers and their conversion to the corresponding homochiral 2D supramolecular assemblies using 4,4’-bipyridine as a bifunctional linker are reported.

Structural variability, topological analysis and photocatalytic properties of neoteric Cd(ii) coordination polymers based on semirigid bis(thiazolylbenzimidazole) and different types of carboxylic acid linkers

Six interesting architectures with different structural and topological motifs have been obtained. 3, 4 and 6 exhibit good photocatalytic activities for methylene blue degradation.