"Chemistry-on-the-complex" synthetic methods have allowed the selective addition of 1-ethynylpyrene appendages to the 3-, 5-, 3,8- and 5,6-positions of Ir -coordinated 1,10-phenanthroline via Sonogashira cross-coupling. The resulting suite of complexes has given rise to the first rationalization of their absorption and emission properties as a function of the number and position of the pyrene moieties. Strong absorption in the visible region (e.g. 3,8-substituted Ir-3: λ =481 nm, ϵ=52 400 m cm ) and long-lived triplet excited states (e.g. 5-substituted Ir-2: τ =367.7 μs) were observed for the complexes in deaerated CH Cl . On testing the series as triplet sensitizers for triplet-triplet annihilation upconversion, those Ir complexes bearing pyrenyl appendages at the 3- and 3,8-positions (Ir-1, Ir-3) were found to give optimal upconversion quantum yields (30.2 % and 31.6 % respectively).

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.The dominance of inorganic semiconductors in the manufacture of optoelectronic devices and field effect transistors is gradually being undermined by the emergence of functional organic materials. [1][2][3] Although electron mobility remains a challenge, these represent lightweight, flexible alternatives that are more readily processed using solution-based methods. Within this arena, the opportunities proffered by the exceptional electronic and physical properties of graphene and its derivatives are undeniable. [4][5][6] As many aspects in the formation of large graphitic sheets are difficult to control, synthetic chemists have pioneered routes to nanographenes with impressive and varying dimensions, and an array of peripheral substituents. 7-10 Dependent on the latter are a range of material characteristics e.g. the nature of the p-p interactions, HOMO-LUMO gaps and film-forming capabilities. [11][12][13][14] The ability to manufacture graphene systems to such specificity is notably absent in exfoliation 15 /epitaxial growth 16 processes, and this makes the further development of bottom-up synthetic methodologies for the formation of next-generation and heteroatomcontaining graphenes all the more important. 10,17 Oxidative cyclodehydrogenation is a key step in the chemical formation of planarised ring systems. All-carbon systems cyclise rapidly, while heteroatom-containing polyphenylenes appear to adopt a more complex mechanism for ring closure, e.g. both partially and fully fused species tend to be generated in a single reaction. [18][19][20] Electron donating substituents both direct and promote CC bond formation under cyclodehydrogenation conditions. 21,22 Tuning the intramolecular properties of graphenes is one step in the search for technology-enabling materials. Also essential is the ability to exert some supramolecular control of structure. Disc-like molecules tend to aggregate in columnar p-p stacks which can be either enhanced or perturbed by peripheral units e.g. long chain alkyl substituted hexaperihexabenzocoronenes frequently exhibit liquid crystalline behaviour, 2 whereas their iodo-or tert-butyl-functionalised derivatives give rise to Bernal-stacked crystalline dimers. 23 This work reveals how the combination of heteroatom doping (as pioneered by Draper et al.), 17,24-26 with H-bonding peripheral substituents, can unlock some exciting new applications for nanographene materials by controlling the outcome of the synthetic process and the HOMO-LUMO gaps and intermolecular order of the end-products.The synthetic methods used to form the precursor polyphenylenes were modifications of published routes involving cyclopentadienones (generated via two-fold Knoevenagel condensations) and their subsequent [2+4] D...

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).