First perphenylated carbo-oligoacetylenes: an extension of the polytriacetylene family.

The first examples of a novel family of sp-carbon-rich n-π-conjugated oligomers/polymers, namely carbo-mers of polyacetylene, also referred to as "1,4-PTA" isomers of the classical polytriacetylenes (1,2-PTAs), are described in the perphenylated series. The two first representatives proved to be stable in solution, and exhibit a zig-zag arrangement in the crystal state. The third member of the family, isolated in SnCl(2) matrix, proved to be stable in the solid state and was characterized by MALDI-TOF MS, (1)H NMR, CPMAS (13)C NMR, and absorption spectroscopy. An explanation for its reactivity in solution is proposed. The chromophoric properties in the visible region are shown to vary significantly and consistently along the series.