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A monomer-through-pentamer series of oligo(1,8-pyrenylene)s was synthesized using a two-step iterative synthetic strategy. The trimer, tetramer, and pentamer are mixtures of atropisomers that interconvert slowly at room temperature (as shown by variable-temperature NMR analysis). They are liquids well below room temperature, as indicated by POM, DSC and SWAXS analysis. These oligomers are highly fluorescent both in the liquid state and in dilute solution (λF,max = 444-457 nm, φF = 0.80) and an investigation of their photophysical properties demonstrated that delocalization plays a larger role in their excited states than it does in related pyrene-based oligomers.

Synthesis of dehydrobenzoannulenes (DBAs) with pyrene core from 1,8-diethynylpyrene and 1,3,6,8-tetraethynylpyrene as building blocks is reported. A sequence involving Sonogashira coupling, Corey- Fuchs reaction and oxidative coupling (Eglinton coupling) is used for the synthesis of pyrene-based dehydrobenzoannulenes. Due to the presence of pyrenechromophore these DBAs and their precursors are highly fluorescent and emit in the visible region, due to extended conjugation of the acetylenic units with the pyrene core. � Indian Academy of Sciences.

A concise, highly regioselective synthesis of 1,8-dibromo-4,5-dialkoxypyrenes has been developed and exploited in the synthesis of some 1,8-pyrenylene-ethynylene macrocycles. The (1)H NMR data and NICS calculations indicate that there is little or no macrocyclic ring current. Concentration-dependent UV-visible studies indicate no aggregation at low concentration, but 8b forms dimers with voids suitable for intercalation of small molecules in the solid state.

Synthesis of a pyrene octaaldehyde derivative and its aggregation through ?-? and C-H?O interactions in solution and in the solid state probed by fluorescence emission and other spectroscopic methods are reported. The effect of solvent, concentration, and temperature on the aggregation is investigated. � 2006 American Chemical Society.

The first synthesis of a pyrene-containing carbon nanoring, cyclo[12]paraphenylene[2]-2,7-pyrenylene ([12,2]CPPyr), is described. Through a sequence of stepwise macrocyclization using Pd and Ni catalysts followed by aromatization of L-shaped cyclohexane units afforded a [12,2]CPPyr in five steps from commercially available compounds. The UV-vis absorption and fluorescence spectra as well as TD-DFT calculations clarified the unique photophysical and electronic properties of the [12,2]CPPyr.

The synthesis of several 1,3,6,8-tetraethynylpyrene derivatives is reported. The effect of extended acetylenic conjugation on their absorption and fluorescence-emission properties is studied. Significant bathochromic shifts of both the absorption and fluorescence emission bands are observed. These derivatives emit fluorescence in the visible (400–550 nm) region. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

(Chemical Equation Presented) The first example of isolation and X-ray crystallographic structural characterization of two conformers arising from rotation along a diacetylenic bond is reported. In both the conformers extensive ?-? interactions are observed in the solid state. VT-NMR and fluorescence spectroscopic studies in solution suggest that the closed and open conformers are in equilibrium and that the closed conformer is the predominant species at room temperature. � 2008 American Chemical Society.

A concise, highly regioselective synthesis of 1,8-dibromo-4,5-dialkoxypyrenes has been developed and exploited in the synthesis of some 1,8-pyrenylene−ethynylene macrocycles. The 1H NMR data and NICS calculations indicate that there is little or no macrocyclic ring current. Concentration-dependent UV−visible studies indicate no aggregation at low concentration, but 8b forms dimers with voids suitable for intercalation of small molecules in the solid state.