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A new biomimetic model complex of the active site of acireductone dioxygenase (ARD) was synthesized and crystallographically characterized ([Ni(II)(N-(ethyl-N′Me 2)(Py)(2-t-ButPhOH))(OTf)]- 1). 1 displays carbon–carbon oxidative cleavage activity in the presence of O2 towards the substrate 2-hydroxyacetophenone. This reactivity was monitored via UV-Visible and NMR spectroscopy. We postulate that the reactivity of 1 with O2 leads to the formation of a putative Ni(III)-superoxo transient species resulting from the direct activation of O2via the nickel center during the oxidative reaction. This proposed intermediate and reaction mechanism were studied in detail using DFT calculations. 1 and its substrate bound derivatives display reactivity toward mild outer sphere oxidants, suggesting ease of access to high valent Ni coordination complexes, consistent with our calculations. If confirmed, the direct activation of O2 at a nickel center could have implications for the mechanism of action of ARD and other nickel-based dioxygenases and their respective non-traditional, enzymatic moonlighting functions, as well as contribute to a general understanding of direct oxidation of nickel(II) coordination complexes by O2. [ABSTRACT FROM AUTHOR]

The reaction between Th(IV) dipyriamethyrin dichloride and sodium cyclopentadienyl (Cp) results in the formation of a cyclopentadienyl capped thorium dipyriamethyrin complex, which to our knowledge represents the first expanded porphyrin f-element Cp complex. [ABSTRACT FROM AUTHOR]

A heteroleptic copper(I) bis(phenanthroline) complex with aldehyde groups at the 4,7 positions of the phenanthroline ligand was synthesized. The complex is responsive to alcohol, resulting in a distinct colour change caused by the facile reaction of the aldehyde group with alcohol, forming a hemiacetal product. The aldehyde species can be regenerated after heating the intermediate at 80 °C for 10 minutes, demonstrating the reusability of the complex for alcohol detection. This work presents a new strategy for applying transition metal complexes in small molecule sensing by installing functional groups in the secondary coordination sphere which reversibly react with analytes. [ABSTRACT FROM AUTHOR]

Palladium metallates containing 4-oxo-4H-chromene-3-carbaldehyde derived ONS donor Schiff bases were synthesized and their efficacy was tested in the direct amination of diosgenin – a phyto steroid. Based on the pharmacological importance of diosgenin, the obtained derivatives were exposed to study their effect on breast cancer cells where they significantly reduced the growth of cancer cells and left non-malignant breast epithelial cells unaffected. Among the derivatives, D3, D4 and D6 showed a better anti-proliferative effect and further analysis revealed that the D3, D4 and D6 derivatives markedly promoted cell cycle arrest and apoptosis by attenuation of the AKT1 signalling pathway. [ABSTRACT FROM AUTHOR]

A post-synthetic strategy is reported that allows for functionalisation of Au(I)–bis NHCs via carbonate formation. The scope of this methodology was explored using both aromatic and aliphatic alcohols. As a demonstration of potential utility, the fluorescent Au(I)–bis NHC conjugate 5 was prepared; it was found to have enhanced stability when formulated with bovine serum albumin, localise within the mitochondria of A549 cells and do so without compromising the high cytotoxicity seen for the parent Au(I)–bis NHC system. [ABSTRACT FROM AUTHOR]

New Rh (1) and Ir (2) complexes of an N-heterocyclic carbene (NHC) featuring a terthiophene backbone were synthesized. Single crystal X-ray diffraction studies of 1 and 2 at 100 K and 298 K respectively, revealed two enantiotropic polymorphic phases with similar lattice parameters for each compound. The transition temperature between two crystalline forms for each compound was determined by measuring the percentage of reflections with a different space group ranging from 100 K to 298 K. Both 1 and 2 were also found to catalyze the hydrogen transfer reaction. The conducting metallopolymers poly-1 and poly-2 were synthesized from oxidative electropolymerization of 1 and 2, respectively, in CH2Cl2 electrolyte solution on indium tin oxide-(ITO) coated glass. The electrochromic properties of synthesized conducting metallopolymers were studied by UV-vis-NIR spectroelectrochemistry. [ABSTRACT FROM AUTHOR]

Controlled partial decomposition of 2-selenonicotinic acid in the presence of Co2+ or Ni2+ resulted in the in situ formation of an unusual MOF based on triselenane ligands (RSeSeSeR) coordinated to M2+ centers as NSeN-pincers. Post-synthetic oxidation by treatment with aqueous H2O2 facilitates its solid-state conversion into a RSeO2− molecular coordination complex, which was tracked via powder X-ray diffraction studies and by single-crystal structural resolution of the final product. [ABSTRACT FROM AUTHOR]

β,β′-Phenylene bridged hexaphyrin[1.0.1.0.1.0] (naphthorosarin), an expanded porphyrin possessing C3v-symmetry, has been shown to possess unique electronic features. We now report a bimetallic Rh(I)-complex of naphthorosarin retaining 24 π-antiaromatic characteristics. The two Rh(I) cations reside on opposite sides of the macrocyclic π-system and are separated at a distance consistent with a possible Rh(I)–Rh(I) metallic bond interaction. [ABSTRACT FROM AUTHOR]

We report the synthesis of a novel hydroxyl-functionalised heteroleptic bis-NHC gold(I) complex that permits conjugation to various amines via carbamate bond formation. The resulting derivatives were studied in vitro using cell proliferation assays and fluorescent microscopic imaging of human cancer cell lines. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of the alkylidenyl-dibenzihexaphyrins bearing four indanedionyl groups at the meso-positions linked via four meso-exocyclic double bonds is reported. Treatment with trifluoroacetic acid at 50 °C leads to C(α)-protonation of the two indanedionyl groups resulting increased macrocyclic conjugation with dramatic red shifted absorption spectra. [ABSTRACT FROM AUTHOR]

We demonstrate that bisulfite can be used for reduction of a highly electrophilic anthraquinone derivative, N,N0-dimethyl-2,6-diaza- 9,10-anthraquinonediium (DAAQ), and subsequent autoxidation generates an equivalent of hydrogen peroxide. The mechanism for DAAQ reduction by bisulfite, DAAQ electrochemistry, and use of a simple test strip assay for H2O2, are described. [ABSTRACT FROM AUTHOR]

A set of self-assembled tri- and tetrapodal metal coordination cage structures (cage-1 and cage-2, respectively) constructed from the uranyl dication (UO22+) and a dibenzoic acid functionalised cis-calix[4]pyrrole (1) are described. The inherent photochemical reactivity of the uranyl dication mediates the transformation of cage-1 to cage-2via the activation of molecular oxygen. [ABSTRACT FROM AUTHOR]

The reaction between non-aqueous uranyl silylamide (UO2[N(SiMe3)2]2·2THF) under anaerobic conditions or uranyl acetate (UO2(OAc)2·2H2O) under standard laboratory conditions and dipyriamethryin affords a bench-stable uranyl complex. Competition studies as well as DFT calculations provide support for the observed selectivity for the uranyl cation over trivalent lanthanide and multiple transition metal precursors. [ABSTRACT FROM AUTHOR]

Three new tris(2-pyridylmethyl)amine-based ligands possessing phenylethynyl units have been prepared using Sonogashira couplings and substitution reactions. Copper(ii) complexes of those tetradentate ligands have also been synthesized. Solid-state structures of the six new compounds have been determined by single-crystal X-ray diffraction analyses. Examination of the molecular structures of the ligands revealed the expected triangular geometries with virtually undeformed carbon–carbon triple bonds. While the tertiary nitrogen of the free ligands seem to be prevented from participation in supramolecular non-covalent interactions by the pyridyl hydrogen at the 3-position, the pyridyl nitrogens play a crucial role in the packing mode of the crystal structure. The nitrogens form weak hydrogen bonds, varied in length between 2.32 and 2.66 Å, with the pyridyl hydrogen of its neighbouring molecule. The [N…H–C] contacts enforce one-dimensional columnar assemblies on ligands that organize into wall-like structures, which in turn assemble into three-dimensional structures through CH–π interactions. Structural analyses of Cu(ii) complexes of the ligands revealed propeller-like structures caused by steric crowding of three pyridine ligands. The copper complexes of the ligands having three phenylethynyl substituents showed a remarkably deformed carbon–carbon triple bond enforced by a steric effect of the three phenyl groups. Most significantly, a total of seventy non-covalent interactions, classified into twelve types of hydrogen-involving short contacts, were identified in this study. The phenylethynyl substituent participated in forty-two interactions as a hydrogen bond acceptor, and its role was more distinctive in the crystal structures of the Cu(ii) complexes. [ABSTRACT FROM AUTHOR]

A 3-dimensional networked molecular cage, NMC-1, has been synthesized. This macrocycle-based framework was prepared from a solvothermal reaction involving a flexible organic building block, calix[4]pyrrole dibenzoic acid (H2L), and Pr(NO3)3·6H2O. A unique feature of NMC-1 is that it retains free calix[4]pyrrole molecules in the framework pores. Treatment with a fluoride anion source serves to destroy the network and allows release of the organic guest. The net result is a ‘molecular ship’ in a ‘breakable bottle’. [ABSTRACT FROM AUTHOR]

We report the preparation and characterization of films of electroactive supramolecular polymers based on non-electroactive oligoalanines and electroactive oligoanilines. Fibroblasts adhered to and proliferated on the films, and the delivery of the clinically relevant anti-inflammatory drug dexamethasone phosphate could be enhanced upon the application of an electrical stimulus. [ABSTRACT FROM AUTHOR]

In this study, neutral mercury(ii) complexes of the composition [Hg(L1)(μ-Cl)2Hg3Cl6]n (1), [Hg(L1)(μ-Br)2HgBr2] (2), [Hg(L3)Br2] (2a), [Hg(L1)I2] (3), [Hg(L2)Cl2]·CH3OH (4) and [Hg(L2)(μ-Br)HgBr3]2 (5) (L1 = benzilbis((pyridin-2-yl)methylidenehydrazone); L2 = benzilbis((acetylpyridin-2-yl)methylidenehydrazone)) are described. Single-crystal X-ray crystallography showed that the molecular complexes can aggregate into larger entities depending upon the anion coordinated to the metal centre. Iodide gives discrete monomeric complexes, bromide generates a 1D coordination polymer formed through Hg–Br–Hg bridges and chloride gives rise to an inorganic–organic hybrid material. The significant differences in the reaction conditions indicate that the anions exert a substantial influence on the formation of the compounds – smaller anions show a larger potential for bridging metal ions and forming coordination polymers. A minute increase in the bulkiness of the ligand (two extra methyl substituents in L2) dramatically changes the coordination architectures, and leads to the formation of monomeric (chloride and iodide) and oligomeric (bromide) structures, rather than polymeric structures. The noncovalent C–H/π and π-hole interactions observed in the solid state architecture of some complexes have been rationalized by means of theoretical DFT calculations. [ABSTRACT FROM AUTHOR]

Photoexcitation of dichloromethane solutions of an uranyl macrocyclic complex with cyclo[1]furan[1]pyridine[4]-pyrrole (1) at the near-infrared (NIR) band (1177 nm) in the presence of electron donors and acceptors resulted in NIR-induced electron transfer without producing singlet oxygen via energy transfer. [ABSTRACT FROM AUTHOR]

A series of tetrakis(1H-pyrrole-2-carbaldehyde) receptors (2, 4, and 6) were synthesized in two steps from commercially available starting materials. The anion binding properties of these receptors can be tuned through electronic switching to stabilize a conformation displaying high affinity for the dihydrogenphosphate and pyrophosphate anions (as the tetrabutylammonium salts) in chloroform. [ABSTRACT FROM AUTHOR]

An o-phenylenevinylene-bridged tetrapyrrolic macrocycle (2) was synthesized by means of a Horner-Wadsworth-Emmons reaction between benzylbisphosphonate and SEM-protected diformylpyrrole, followed by deprotection of the SEM groups. This conformationally flexible tetrapyrrole can be considered as an expanded calix[4]pyrrole analogue, which acts as a receptor for the chloride and bromide anions in THF-d8, but undergoes deprotonation upon exposure to the fluoride anion. [ABSTRACT FROM AUTHOR]

A redox-switchable ligand, N,N′-dimethyldiaminocarbene[3]ferrocenophane (5), was synthesized and incorporated into a series of Ir- and Ru-based complexes. Electrochemical and spectroscopic analyses of (5)Ir(CO)2Cl (15) revealed that 5 displayed a Tolman electronic parameter value of 2050 cm−1 in the neutral state and 2061 cm−1 upon oxidation. Moreover, inspection of X-ray crystallography data recorded for (5)Ir(cis,cis-1,5-cyclooctadiene)Cl (13) revealed that 5 was sterically less bulky (%VBur = 28.4) than other known diaminocarbene[3]ferrocenophanes, which facilitated the synthesis of (5)(PPh3)Cl2Ru(3-phenylindenylid-1-ene) (18). Complex 18 exhibited quasi-reversible electrochemical processes at 0.79 and 0.98 V relative to SCE, which were assigned to the Fe and Ru centers in the complex, respectively, based on UV-vis and electron pair resonance spectroscopic measurements. Adding 2,3-dichloro-5,6-dicyanoquinone over the course of a ring-opening metathesis polymerization of cis,cis-1,5-cyclooctadiene catalyzed by 18 ([monomer]0/[18]0 = 2500) reduced the corresponding rate constant of the reaction by over an order of magnitude (pre-oxidation: kobs = 0.045 s−1; post-oxidation: kobs = 0.0012 s−1). Subsequent reduction of the oxidized species using decamethylferrocene restored catalytic activity (post-reduction: kobs = up to 0.016 s−1, depending on when the reductant was added). The difference in the polymerization rates was attributed to the relative donating ability of the redox-active ligand (i.e., strongly donating 5versus weakly donating 5+) which ultimately governed the activity displayed by the corresponding catalyst. [ABSTRACT FROM AUTHOR]

Using a tetrathiafulvalene functionalised calix[4]pyrrole (TTF-C[4]P; 1) and alkyl diester-linked bis-dinitrophenols (2-4), it was found that the solvent polarity and linker length have an effect on the molecular aggregation behaviour. 2D ¹H NOESY, DOSY NMR and UV-vis-NIR spectroscopic studies, as well as single crystal X-ray diffraction analyses support these conclusions. [ABSTRACT FROM AUTHOR]

Tetrathiafulvalenes (TTF)-annulated [28]hexaphyrin affords an electron rich flexible π-conjugated system whose limiting conformations can be controlled through choice of solvents. The conformation-dependent intramolecular charge transfer character, as well as electron reserve capability of the hexakis-TTF annulated hexaphyrin, was analyzed. [ABSTRACT FROM AUTHOR]

Two new expanded porphyrins, naphthorubyrin and naphthosapphyrin, were synthesized. The π-extended rubyrin was isolated and structurally characterized in its monoprotonated form. The sapphyrin congener undergoes pyrrole inversion as a function of the protonation state. These conformational effects are reflected in the spectroscopic features, including the excited singlet state lifetimes. [ABSTRACT FROM AUTHOR]

A three-dimensional extended, metal–organic rotaxane framework (MORF) that incorporates encircled “struts” has been synthesized through a one-pot self-assembly process involving a macrocyclic tetraimidazolium “molecular box”, naphthalene dicaboxylate dianion, and Zn(ii) cations. The present system represents progress towards controlling the features of three-dimensional metal–organic frameworks. [ABSTRACT FROM AUTHOR]

Lead(II)-texaphyrins and the first discrete binuclear l-oxo bismuth(III)-texaphyrin are reported. The latter was characterized via single crystal X-ray diffraction analysis. Cell proliferation assays using the A2780 ovarian cancer cell line were used to determine the cytotoxicity of the complexes. [ABSTRACT FROM AUTHOR]

The use of a pyrrole-strapped calix[4]pyrrole (1) permits the determination of chloride anion concentrations in mixed aqueous DMSO-d6-H2O environments via proton NMR spectroscopy. [ABSTRACT FROM AUTHOR]