Sonogashira Cross-Coupling as a Route to Tunable Hybrid Organic-Inorganic Rods with a Polyoxometalate Backbone.

A new diiodo-bifunctionalized Anderson-Evans polyoxometalate (TBA)3[MnMo6O18{(OCH2)3CNHCO(C6H4-p-I)}2] (1; TBA = [(C4H9)4N]+) was prepared and used as a new platform to generate tunable rigid-molecular rods (2a-2c) via Sonogashira cross-coupling. Single-crystal X-ray diffraction analysis of 1 and 2c reveals that they are type B Anderson-Evans structures with molecular lengths of 23 and 38 Å, respectively.

Highly Efficient Triplet Photosensitizers: A Systematic Approach to the Application of Ir(III) Complexes containing Extended Phenanthrolines.

A series of Ir(III) complexes, based on 1,10-phenanthroline featuring aryl acetylene chromophores, were prepared and investigated as triplet photosensitizers. The complexes were synthesized by Sonogashira cross-coupling reactions using a "chemistry-on-the-complex" method. The absorption properties and luminescence lifetimes were successfully tuned by controlling the number and type of light-harvesting group. Intense UV/Vis absorption was observed for the Ir(III) complexes with two light-harvesting groups at the 3- and 8-positions of the phenanthroline. The asymmetric Ir(III) complex (with a triphenylamine (TPA) and a pyrene moiety attached) exhibited the longest lifetime. Red emission was observed for all the complexes in deaerated solutions at room temperature. Their emission at low temperature (77 K) and nanosecond time-resolved transient difference absorption spectra revealed the origin of their triplet excited states. The singlet-oxygen ((1) O2 ) sensitization and triplet-triplet annihilation (TTA)-based upconversion were explored. Highly efficient TTA upconversion (ΦUC =28.1 %) and (1) O2 sensitization (ΦΔ =97.0 %) were achieved for the asymmetric Ir(III) complex, which showed intense absorption in the visible region (λabs =482 nm, ϵ=50900 m(-1) cm(-1) ) and had a long-lived triplet excited state (53.3 µs at RT).

Methoxy functionalisation: exerting synthetic control of the supramolecular and electronic structure of nitrogen-doped nanographenes.

We describe a series of functionalized N-containing heterosuperbenzenes, created with a view to investigating the strategic role of methoxy substituents in (i) promoting cyclodehydrogenation and (ii) tuning the electronic properties and (iii) the supramolecular order in the resultant fused products.

Intriguing Diels-Alder products: chiral centres with an added twist.

Two chiral fluoranthene-based polyaromatics were isolated from a Diels-Alder cycloaddition between two molecules of 7,9-diphenylcyclopenta[a]acenapthylene-8-one. The two highly coloured, novel compounds were characterized by a combination of spectroscopic techniques and single crystal X-ray diffraction. Structural differences between the unexpected products included the nature of their conjugated fluoranthene portions and the position, strain and handedness of their chiral centres.

The synthesis and characterisation of novel ferrocenyl polyphenylenes.

This work describes the synthesis and characterisation of a new series of polyphenylenes with up to four ferrocenyl moieties. The synthetic route involves the preparation of a number of novel precursors. Cyclopentadienones, generated from the two-fold Knoevenagel condensation of di-ferrocenyl propanones and diketones, are used in [2 + 4] Diels-Alder cycloadditions with appropriately substituted acetylenes. 13 is amongst the compounds isolated. It is the largest ferrocenyl-supported polyaromatic hydrocarbon (PAH) to date. Prepared via a Sonogashira cross-coupling reaction between ethynyl-Fc and iodo-HBC, it comprises a hexa-peri-hexabenzocoronene (HBC) core linked via acetylene to a ferrocenyl unit (Fc). The electrochemical and absorption properties of the ferrocenyl-polyphenylenes and the fully conjugated 13 are discussed. The NLO data for 13, determined by hyper Rayleigh scattering techniques, are compared to those of similar fulleryl-based compounds in the literature.

Substituted pyridazines as ligands in homoleptic (fac and mer) and heteroleptic Ru(II) complexes.

This article reports the preparation of a range of phenyl, pyridyl and pyrazinyl substituted pyridazines via the inverse electron demand [2 + 4] Diels-Alder reaction between 3,6-di(2-pyridyl)-1,2,4,5-tetrazines (bptz) and 3,6-di(2-pyrazinyl)-1,2,4,5-tetrazines (bpztz) and suitable dienophiles including acenaphthalene. The resulting polyaromatic compounds vary systematically in the number of aromatic substituents and the number and position of N-heteroatoms. For four of these compounds, the effect of the molecular changes on the solid-state structures were investigated using single crystal X-ray crystallography. The pyridazines were used as bidentate ligands in {M(II)(bipy)(2)} and tris(homoleptic) complexes (M = Fe, Ru). The optical and electrochemical properties of these complexes reflect the electron accepting character of the new ligands. The facial and meridional isomers of the tris complexes could be separated by column chromatography (on silica), thus allowing a spectral comparison of their absorption and emission properties. The solid-state structures of several of the metal complexes are discussed, including that of the facial isomer of the tris Ru(II) complex of 3,6-bis(2-pyridyl)-4,5-bis(4-pyridyl)pyridazine--a potential preformed geometric motif for the predirected construction of supramolecular assemblies.