Copper coordination polymers from cavitand ligands: hierarchical spaces from cage and capsule motifs, and other topologies

Brønsted acid- and Ni(II)-catalyzed C-H oxidation/rearrangement of cyclotriveratrylenes (CTVs) to cyclic and acyclic quinones as potential anti-cancer agents

This paper describes a simple and practical protocol for the direct synthesis of acyclic and cyclic quinone derivatives via an acid-promoted nickel(II)-catalyzed inner rim C-H oxidation of cyclotriveratrylene (CTV) and its analogues. The cyclic quinone derivatives resulted from trimethoxy-cyclotriveratrylene (TCTV) through C-C bond formation via intramolecular ipso substitution followed by subsequent anionic rearrangement containing stereo-vicinal quaternary centers. The DFT calculations strongly support the experimental findings and reveal the role of Brønsted acids in the C-H bond activation of CTV. All the newly synthesized compounds were screened for their in vitro anti-cancer activity using colorimetric SRB assay analysis. Among them, compounds 3a, 3d, 3h, 4a, 4b, 4c and 4e exhibited moderate anticancer activity against A549, HCT-116, PC-3, MDA-MB-231, HEK-293 and SW620 human cancer cell lines.

A classical [V10O28]6- anion templated high-nuclearity silver thiolate cluster

Polyoxovanadates (POVs) as templates are still scarcely observed in silver clusters. Herein, the largest known POV-based silver cluster (Ag50) was synthesized, which is a core-shell conformation composed of the in situ generated classical [V₁₀O₂₈]^6- core and Ag₅₀ shell, constrained by the S- and O-donor ligands with a specific distribution. Such {V₁₀O₂₈@Ag₅₀} structure displays geometric inheritance from the D_2h symmetric decavanadate to the silver skeleton. The solution behavior, solid-state stability and photoelectric properties are discussed in detail. This work provides enlightenment for the further construction of POV-templated high-nuclearity silver clusters.

A class of organic cages featuring twin cavities

A variety of organic cages with different geometries have been developed during the last decade, most of them exhibiting a single cavity. In contrast, the number of organic cages featuring a pair of cavities remains scarce. These structures may pave the way towards novel porous materials with emergent properties and functions.We herein report on rational design of a three-dimensional hexaformyl precursor 1, which exhibits two types of conformers, i.e. Conformer-1 and -2, with different cleft positions and sizes. Aided by molecular dynamics simulations, we select two triamino conformation capturers (denoted CC). Small-sized CC-1 selectively capture Conformer-1 by matching its cleft size, while the large-sized CC-2 is able to match and capture both conformers. This strategy allows the formation of three compounds with twin cavities, which we coin diphane. The self-assembly of diphane units results in superstructures with tunable proton conductivity, which reaches up to 1.37×10^-5 S cm^-1.

The preparation of nanocages with unprecedented architectures may lead to new functions. Here the authors report the self-assembly of organic cages featuring twin cavities; the geometry and pocket size determine the molecular packing and the proton conductivity performance.

Effect of pyridyl donors from organic ligands versus metalloligands on material design

This review illustrates designs and structures of various coordination frameworks constructed using assorted organic ligands and metalloligands offering pyridyl donors to evaluate the impact of flexibility versus rigidity on material design.

Coordination polymers with embedded recognition sites: lessons from cyclotriveratrylene-type ligands

Coordination polymers with molecular recognition sites are assembled using cyclotriveratrylene ligands. Many show differential guest-spaces with host and lattice sites available, however common host–guest and self-inclusion motifs can block sites.

A CTV Analogue: Arene-Persubstituted Cyclotrixylohydroquinoylene and Its Derivatives

A crown-shaped cyclotriveratrylene (CTV) analogue with persubstituted arene units-namely, cyclotrixylohydroquinoylene (CTX)-was synthesized from tetrasubstituted o-xylohydroquinone. Importantly, a series of CTX derivatives were prepared by introducing second bridged methylene, phenylphosphine oxide, and dimethylsilyl at the middle rim, referred to as CTX[CH₂], CTX[P(O)Ph], and CTX[SiMe₂], respectively, with the completely locked crown conformation, leading to the formation of unique C₃-symmetric Chinese censer-shaped pocket structures. In addition, the water-soluble CTX[CH₂] derivative (WCTX[CH₂]) was synthesized from CTX[CH₂] by simple oxidation reaction with the modification at the upper rim, and its host-guest interaction with methyl viologen in water was investigated.

Cu-tetracatechol metallopolymer catalyst for three component click reactions and β-borylation of α,β-unsaturated carbonyl compounds

Phenol-metal coordination polymers are used in applications such as catalysis, sensing and separation science. In addition, combining eco-friendly conditions with economical and handling advantages of the polymeric catalyst is of interest to the community. Here, we report a simple one pot synthesis of a tetracatechol based ligand and its coordination polymer with copper ions. The Cu polymer showed electrochemical potential with a band gap of 1.01 eV. The BET surface area of the metallopolymer was 91.19 m2 g-1 with 0.14 cm3 g-1 pore volume. The polymer catalyst was used in a one pot three component click reaction and in the borylation of unsaturated carbonyl compounds with a maximum 99% conversion in water and good turnover efficiency even after 4 repetitive catalysis cycles. The polymer catalyst offers several advantages such as high activity, easy handling, scalability, recyclability and cost effectiveness.

Cyclotriveratrylene-tethered trinuclear palladium(ii)-NHC complexes; reversal of site selectivity in Suzuki-Miyaura reactions

The trinuclear complexes [{PdI2(pyCl)}3(L1)] C1 and [{PdI2(pyCl)}3(L2)] C2, where pyCl = 3-chloropyridine, L1 = methyl(cyclotriguaiacylenyl)methylbenzimidazol-2-ylidene and L2 = benzyl(cyclotriguaiacylenyl)methylbenzimidazol-2-ylidene, each feature three palladium N-heterocyclic carbene (NHC) centres tethered onto a host-type cyclotriguaiacylene scaffold. Crystal structures of different solvates of complex C1 reveal different host-guest motifs including intra-cavity binding of dioxane guests concomitant with intramolecular halogen bonding interactions of C1. Mononuclear NHC analogues of C1 and C2, namely [PdI2(pyCl)(L3)] C3 and [PdI2(pyCl)(L4)] C4, where L3 = (3-chloropyridyl)-1-(2-methoxyphenyoxy)methyl-3-methylbenzimidazol-2-ylidene and L4 = (3-chloropyridyl)-1-(2-methoxyphenyoxy)methyl-3-benzylbenzimidazol-2-ylidene, were also synthesised and their crystal structures determined. Complexes C1-C4 are competent catalysts for Suzuki Miyaura cross-coupling, and interestingly exhibit a switch in the normal regioselectivity observed for reactions of 2,4-dibromopyridine with aryl boronic acids, usually C2-selective, yielding C4-arylated product preferentially over C2-arylated product.

Solvent-responsive cavitand lanthanum complex

A new, solvent responsive tetra-phosphonate cavitand lanthanum complex forms a dimer in acetonitrile, interconverts into a monomeric complex in acetone and is disassembled in methanol.

Variation of topologies and entanglements in metal–organic frameworks with mixed tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide and dicarboxylate ligands

Six metal–organic frameworks with variation of topologies and entanglements have been successfully synthesized with mixed tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide and dicarboxylate ligands.

2D networks of metallo-capsules and other coordination polymers from a hexapodal ligand

2D M₃L₂ coordination polymers (M = Re(i), Cu(ii), Co(ii), Ni(ii)) feature metal-linked M₆L₂-cages, and the Re(i) material absorbs iodine.

On rhenium(i)–silver(i) cyanide porous macrocyclic clusters

The first cyanide rhenium(i)–silver(i) clusters were synthesized in the course of simple one-pot high-yielding reactions.

A novel octa-nuclear 32-membered zirconocene macrocycle based on the aromatic selenite

A novel macrocyclic zirconocene(iv) aromatic selenite [(CpZr)₈L₁₆]·2(Cp₄Zr₂(μ-O)Cl₂) (complex 1) (Cp = cyclopentadienyl anion; L = 4-fluorobenzeneseleninic acid) was prepared by the reaction of bis(cyclopentadienyl)zirconium dichloride with 4-fluorobenzeneseleninic acid and characterized by elemental analysis, infrared spectroscopy, ¹H, ¹³C NMR spectroscopy, ESI-MS, XRD and X-ray diffraction.

A novel 2D infinite M3L2 cage-based Cd(ii) microporous coordination polymer with a tripodal carboxylic acid ligand and solvent-dependent luminescence properties

A novel M₃L₂ cage-based microporous coordination polymer has an obvious, surface-enhanced luminescence in the solvents CH₂Cl₂ and CHCl₃.

Two copper(i) cyanide coordination polymers modified by semi-rigid bis(benzimidazole) ligands: syntheses, crystal structures, and electrochemical and photocatalytic properties

Two Cu(i) cyanide complexes with semi-rigid bis(benzimidazole) ligands were synthesized and characterized. Both complexes manifest photocatalytic activities for the degradation of methylene blue.

Alkyl group-directed assembly of coordination polymers based on bis-(4-imidazol-1-yl-phenyl)-amine and their photocatalytic properties

Four new coordination polymers have been solvothermally synthesized to explore their diverse networks and photocatalytic properties.