Comparison of 1,4-distyrylfluorene and 1,4-distyrylbenzene analogues: synthesis, structure, electrochemistry and photophysics.

A series of nine 1,4-distyrylfluorene derivatives (2) functionalized with substituents of variable electrondonating or -accepting capabilities was synthesised. The photophysical properties of the molecules were investigated, including UV/vis absorption, photoluminescence emission, and fluorescence quantum yields. Photophysical properties of chromophores 2 were found to exhibit significant solvatochromic effects, especially in the Stokes shift and photoluminescence maxima. The electrochemical properties of series 2 were also assessed by cyclic voltammetry and differential pulse voltammetry. Results of photophysical and electrochemical analyses were further supported by DFT calculations (B3LYP/6-31G*) and single crystal X-ray diffraction on select molecules. The contributions of intermolecular π-stacking and hydrogen bonding to crystal packing are discussed. A series of nine 1,4-distyrylphenylene derivatives (3) were also synthesised and similarly characterized for comparison to photophysical and solvatochromic effects observed in series 2. Properties of similarly-substituted molecules in series 2 and 3 were compared to one another in order to assess the influence of the 1,4-fluorenylene unit.

Naphthoxaphospholes as examples of fluorescent phospha-acenes.

Seven new fluorescent 2-R-naphtho[2,3-d]oxaphospholes (R-NOPs) (4a­g; R = tBu (a), Ad (b), C(6)H(5) (c), 4-MeC(6)H(4) (d), 4-ClC(6)H(4) (e), 4-BrC(6)H(4) (f ), 4-MeOC(6)H(4) (g)), have been synthesized by cyclocondensation reactions of benzimidoyl chlorides with 3-phosphino-2-naphthol (3). The compounds were characterized by multinuclear NMR, UV-vis, and fluorescence spectroscopy. Compounds 4a­d and 4g were characterized by cyclic voltammetry experiments. The solid state structures of compounds 4b and 4d were also determined by single-crystal X-ray diffraction experiments.

Photochemically-induced dioxygenase-type CO-release reactivity of group 12 metal flavonolate complexes.

Exposure of 3-hydroxyflavonolate complexes of the group 12 metals to UV light under aerobic conditions results in oxidative carbon-carbon bond cleavage and CO release. This reactivity is novel in that it occurs under mild reaction conditions and suggests that light-induced CO-release reactivity involving metal flavonolate species may be possible in biological systems.