Tandem templating strategies facilitate the assembly of calix[8]arene-supported Ln18 clusters.

Calix[n]arenes offer ideal chemical functionality through the polyphenolic lower rim to construct nano-sized coordination clusters with lanthanide (Ln) metal ions (e.g., NdIII10, GdIII8). However, the number of metal centers they can accommodate is still limited compared to that achievable with smaller ligands (e.g., GdIII140, GdIII104). Here, we exploit a combination of the "anion template strategy" and "templating ligands" to synthesise three highly symmetric (D3h, trigonal planar) LnIII18 (Ln = La, Nd, and Gd) systems, representing the largest calix[n]arene-based coordination clusters yet. The LnIII18 fragment is templated by a chloride anion located at the center of the cluster, wherefrom twelve µ3-OH- ligands bind 'internally' to the eighteen LnIII ions. 'Externally' the metallic skeleton is connected by p-tert-butylcalix[8]arene, oxo, chloro and carbonate ligands. The crystal packing in the lattice reveals large cylindrical channels of ∼26 Å in diameter, whose pore volume corresponds to ∼50% of the unit cell volume (using a 1.2 Å spherical probe radius). Magnetic measurements reveal the predominance of weak antiferromagnetic exchange in the Gd analog. Heat capacity data of GdIII18 reveal a high magnetic entropy with -ΔSm = 23.7 J K-1 kg-1, indicating potential for engineering magnetic refrigerant materials with calix[8]arenes.

A bis-calix[4]arene-supported [CuII16] cage.

Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with Cu(NO3)2·3H2O and N-methyldiethanolamine (Me-deaH2) in a basic dmf/MeOH mixture affords [CuII16(L)2(Me-dea)4(µ4-NO3)2(µ-OH)4(dmf)3.5(MeOH)0.5(H2O)2](H6L)·16dmf·4H2O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu12], in which the four capping metal ions are the CuII ions housed in the calix[4]arene polyphenolic pockets. The [CuII8] square prism is held together "internally" by a combination of hydroxide and nitrate anions, with the N-methyldiethanolamine co-ligands forming dimeric [CuII2] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H6L2- ligand per [Cu16] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting.

Engineered MOF-Enzyme Nanocomposites for Tumor Microenvironment-Activated Photodynamic Therapy with Self-Luminescence and Oxygen Self-Supply.

Photodynamic therapy (PDT) is a promising strategy for cancer treatment. However, its efficiency is hindered by three key parameters, namely, limited penetration depth of external light, tumor hypoxia, and self-aggregation of photosensitizers. Herein, we fabricated a novel "all-in-one" chemiluminescence-PDT nanosystem through the integration of an oxygen-supplying protein (hemoglobin, Hb) and a luminescent donor (luminol, Lum) in hierarchically engineered mesoporous porphyrinic metal-organic framework (MOF) nanoparticles. Mechanistically, the in situ chemiluminescence of Lum is activated by the high concentration of H2O2 in 4T1 cancer cells and further catalyzed by Hb and then absorbed by the porphyrin ligands in MOF nanoparticles through chemiluminescence resonance energy transfer. The excited porphyrins then sensitize oxygen supplied by Hb to produce sufficient reactive oxygen species that kill cancer cells. The MOF-based nanocomposite demonstrates excellent anticancer activity both in vitro and in vivo, with eventually a 68.1% tumor inhibition rate after intravenous injections without external light irradiation. This self-illuminating, oxygen-self-supplying nanosystem integrates all essential components of PDT into one simple nanoplatform, demonstrating great potential for the selective phototherapy of deep-seated cancer.

One-Pot Fabrication of Hollow Porphyrinic MOF Nanoparticles with Ultrahigh Drug Loading toward Controlled Delivery and Synergistic Cancer Therapy.

Hollow nanostructures have attracted significant research interest in drug delivery systems due to their high capacities for drug loading and unique physicochemical properties, showing great potential in specific biomedical applications. Herein, hollow porphyrinic metal-organic framework (H-PMOF) nanoparticles with a mesoporous spherical shell have been fabricated via a facile self-sacrificial ZIF-8 nanoparticle template strategy. The H-PMOF nanoplatform not only demonstrates a greatly enhanced photodynamic therapy efficacy compared with nonhollow porphyrinic MOF nanoparticles but also can be used as a superior drug carrier to co-load doxorubicin (DOX) and indocyanine green (ICG) with an ultrahigh drug-loading capacity of 635%. Furthermore, cancer cell membrane camouflage of the (DOX and ICG)@H-PMOF composite nanoparticles affords a biomimetic nanoplatform, that is, (DOX and ICG)@H-PMOF@mem (DIHPm for short), with an outstanding homologous tumor-targeting and immune-escaping ability. Interestingly, DIHPm shows both pH-controlled and near-infrared laser-triggered DOX release. Both in vitro and in vivo studies of DIHPm demonstrate an excellent imaging-guided synergistic photodynamic/photothermal/chemotherapy anticancer activity with negligible systemic toxicity. The development of the high-performance H-PMOF nanoplatform provides new insights into the design of MOF-based multifunctional nanomedicines for combination cancer therapy and precise theranostics.

Synthesis and characterization of iron(II) and ruthenium(II) hydrido hydrazine complexes.

Treatment of trans-[MHCl(dmpe)(2)] (M = Fe, Ru) with hydrazine afforded the hydrido hydrazine complexes cis- and trans-[MH(N(2)H(4))(dmpe)(2)](+) which have been characterized by NMR spectroscopy ((1)H, (31)P, and (15)N). Both cis and trans isomers of the Fe complex and the trans isomer of the Ru complex were characterized by X-ray crystallography. Reactions with acid and base afforded a range of N(2)H(x) complexes, including several unstable hydrido hydrazido complexes.

A family of calix[4]arene-supported [Mn(III)2Mn(II)2] clusters.

In the cone conformation calix[4]arenes possess lower-rim polyphenolic pockets that are ideal for the complexation of various transition-metal centres. Reaction of these molecules with manganese salts in the presence of an appropriate base (and in some cases co-ligand) results in the formation of a family of calixarene-supported [Mn(III)(2)Mn(II)(2)] clusters that behave as single-molecule magnets (SMMs). Variation in the alkyl groups present at the upper-rim of the cone allows for the expression of a degree of control over the self-assembly of these SMM building blocks, whilst retaining the general magnetic properties. The presence of various different ligands around the periphery of the magnetic core has some effect over the extended self-assembly of these SMMs.

Flexible metal-organic supramolecular isomers for gas separation.

Three interpenetrated metal-organic supramolecular isomers were synthesised using a flexible tetrahedral organic linker and Zn(2) clusters that sorb CO(2) preferably over N(2), H(2) and methane at room temperature.

Iron(0) and ruthenium(0) complexes of dinitrogen.

The synthesis of a series of iron and ruthenium complexes with the new ligand PP(i)(3) (1) P(CH(2)CH(2)P(i)Pr(2))(3) is described. The iron(0) and ruthenium(0) dinitrogen complexes Fe(N(2))(PP(i)(3)) (4) and Ru(N(2))(PP(i)(3)) (5) were synthesized by treatment of the iron(II) and ruthenium(II) cationic species [FeCl(PP(i)(3))](+) (2) and [RuCl(PP(i)(3))](+) (3) with potassium graphite under a nitrogen atmosphere. The cationic dinitrogen species [Fe(N(2))H(PP(i)(3))](+) (6) and [Ru(N(2))H(PP(i)(3))](+) (7) were prepared by treatment of 4 and 5, respectively, with 1 equiv of a weak organic acid. Complexes 2.[BPh(4)], 3.[BPh(4)], 4, 5, and 6.[BF(4)] were characterized by X-ray crystallography. The structural characterization of 5 is the first report for a ruthenium(0) dinitrogen complex.

Interpenetrated nano-capsule networks based on the alkali metal assisted assembly of p-carboxylatocalix[4]arene-O-methyl ether.

Reaction of p-carboxylatocalix[4]arene-O-methyl ether with either rubidium or caesium hydroxide results in the formation of interpenetrated nano-capsule networks with the calixarene in the 1,3-alternate conformation.

Gas-induced transformation and expansion of a non-porous organic solid.

Organic solids composed by weak van der Waals forces are attracting considerable attention owing to their potential applications in gas storage, separation and sensor applications. Herein we report a gas-induced transformation that remarkably converts the high-density guest-free form of a well-known organic host (p-tert-butylcalix[4]arene) to a low-density form and vice versa, a process that would be expected to involve surmounting a considerable energy barrier. This transformation occurs despite the fact that the high-density form is devoid of channels or pores. Gas molecules seem to diffuse through the non-porous solid into small lattice voids, and initiate the transition to the low-density kinetic form with approximately 10% expansion of the crystalline organic lattice, which corresponds to absorption of CO2 and N2O (refs 4,5). This suggests the possibility of a more general phenomenon that can be exploited to find more porous materials from non-porous organic and metal-organic frameworks that possess void space large enough to accommodate the gas molecules.

Calix[5]arene: a versatile sublimate that displays gas sorption properties.

Varied temperature sublimation of calix[5]arene results in the formation of two distinctly different crystal structures or polymorphs alpha and beta, the latter of which is based on both 'self-included' and 'back-to-back' helical arrangements of the molecule, while also being active towards CO2 sorption at room temperature and 1 atmosphere pressure.

Frustrated organic solids display unexpected gas sorption.

Between nonsorptive solvate and desolvate forms of p-tert-butylcalix[5]arene lies a frustrated crystalline region in which there is rapid sorption of gases. From sorption studies, we conclude that the frustrated form is porous and that the intermediate form represents a new type of material that was previously unrecognized by traditional gas sorption trends or ideals for other active systems.

Lanthanide crown ether complexes of p-sulfonatocalix[5]arene.

Two types of arrays are formed in water involving aza-crown ethers, p-sulfonatocalix[5]arene and europium(III) ions. One is a co-ordination polymer connecting calixarenes, sodium ions and lanthanide ions based on "ferris wheel" moieties incorporating aza-18-crown-6 and sodium ions. The second structure is a host-guest arrangement with di-protonated diaza-18-crown-6 in the cavity of the calixarenes as part of secondary coordination spheres of aquated europium(iii) ions.

Controlling the conformation and interplay of p-sulfonatocalix[6]arene as lanthanide crown ether complexes.

Control over the conformational flexibility of p-sulfonatocalix[6]arene in the solid state is possible in the presence of varied stoichiometric amounts of [18]crown-6 and selected lanthanide(III) chlorides. Complexes 1 and 2 have the calixarene in the elusive up-up double cone conformation, whilst complex 3 has the calixarene in the centrosymmetric up-down double partial cone conformation, whereby it acts as a divergent receptor. Complex 1 has a double molecular capsule arrangement which is composed of two p-sulfonatocalix[6]arenes shrouding two [18]crown-6 molecules, also with both coordinated and homoleptic aquated lanthanide ions around the hydrophilic sulfonate rims of the calixarenes. Complex 2 has a ferris wheel arrangement with one lanthanide metal centre coordinated to a sulfonate group and another coordinated to the crown ether whilst tethered to a sulfonate group of the calixarene. Complex 3 forms from a solution with large excess of [18]crown-6, and possesses a crown ether molecule in each of the partial cones and has homoleptic aquated lanthanide ions involved in a complicated hydrogen-bonding regime within the extended structure.