12 research outputs found
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Quinoidal Azaacenes: 99 % Diradical Character
Quinoidal azaacenes with almost pure diradical character (y=0.95 to y=0.99) were synthesized. All compounds exhibit paramagnetic behavior investigated by EPR and NMR spectroscopy, and SQUID measurements, revealing thermally populated triplet states with an extremely low-energy gap ΔEST′ of 0.58 to 1.0 kcal mol−1. The species are persistent in solution (half-life≈14–21 h) and in the solid state they are stable for weeks
Dimerization of a reactive azaacene diradical: synthesis of a covalent azaacene cage
Abstract
Two series of regioisomeric dicyanomethylene substituted dithienodiazatetracenes with formal para- or ortho-quinodimethane subunits were synthesized and characterized. Whereas the para-isomers (p-n, diradical index y0=0.01) are stable and isolable, the ortho-isomer (y0=0.98) dimerizes into a covalent azaacene cage. Four elongated σ-CC bonds are formed and the former triisopropylsilyl(TIPS) -ethynylene groups transformed into cumulene units. The azaacene cage dimer (o-1)2 was characterized by X-ray single crystal structure analysis and temperature-dependent infrared (IR), electron paramagnetic resonance (EPR, solid-state), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV/Vis) spectroscopies (solution) indicating reformation of o-1
Utilizing Diels Alder click chemistry to functionalize the organic organic interface of semiconducting polymers
Para-connected cyclophenylenes and hemispherical polyarenes: Building blocks for single-walled carbon nanotubes?
Synthesis, Characterization and Photoluminescence of Dimeric and Polymeric Metallaynes of Group 10–12 Metals Containing Conjugation-breaking Diphenylmethane Unit
Modeling of alkynes: synthesis and theoretical properties
In this paper we present the synthesis and simulation of alkynes derivatives. Semiempirical calculations were carried out for the ground and first excited states, including the spectroscopic properties of the absorption and emission (fluorescence and phosphorescence) spectra by INDO/S-CI and DNdM-INDO/S-CI methods with geometries fully optimized by PM3/CI. The fact that the theoretical spectra are in accord with the experimental absorption spectra gives us a new possible approach on how structure modifications could affect the non-linear optical properties of alkynes