Hybrid conjugated organic oligomers consisting of oligodiacetylene and thiophene units: synthesis and optical properties.

Novel and highly soluble hybrid conjugated organic oligomers consisting of oligodiacetylene and thiophene units have been synthesized in high purity through iterative and divergent approaches based on a sequence of Sonogashira reactions. The series of thiophene-containing oligodiacetylenes (ThODAs) and homocoupled ThODAs (HThODAs) show--both in solution and in the solid state--a strong optical absorption, which is progressively red shifted with increasing chain length. The linear correlation of the absorption maximum (lambda(A)(max)) with the inverse of conjugation length (CL = number of double and triple bonds) shows that the effective conjugation length of this system is extended up to at least CL = 20.

Radical cations of all-trans oligodiacetylenes: optical absorption and reactivity toward nucleophiles.

High yields of the radical cations of oligodiacetylenes have been prepared by photoinduced electron transfer using a positively charged cosensitizer and by pulse radiolysis. The absorption maxima of the oligodiacetylene (ODA) radical cations show a bathochromic shift to the infrared region and a large increase of their lifetimes with chain elongation. Their reactivity toward nucleophiles decreases for longer ODAs, illustrating clearly the stabilizing effect of charge delocalization along the oligomeric chain.

Synthesis and optoelectronic properties of nanometer-sized and highly soluble homocoupled oligodiacetylenes.

A new series of pure, nanometer-sized and highly-soluble homocoupled oligodiacetylenes (HODA) consisting of two symmetrical oligodiacetylene units was synthesized with high yield and on a multi-milligram scale under mild, catalytic Sonogashira conditions. The lambda(max) and the epsilon(max) of absorption for these HODAs show an increase with the chain elongation. The lambda(max) converges to 450 nm for the longest members of the series at micromolar concentration and to 462 nm for thin drop-casted films.

Synthesis and optical properties of all-trans-oligodiacetylenes.

A new series of pure and highly soluble oligodiacetylenes (ODAs) was synthesized in high yield and on a multi-milligram scale by a sequence of Sonogashira reactions with a strongly reduced level of homocoupling. The lambda max and epsilon max of these ODAs show an increase with both chain elongation and solvent polarity. A plot of lambda max absorption versus 1/CL (CL=conjugation length) was shown to be linear.