Partially metallated polymers of 2-vinylfluorene in tetrahydrofuran THF and THF-dimethoxyethane mixtures were studied by electronic absorption spectroscopy. Effects arising from interaction of the ion pairs within the polymer chain were clearly observed. Conversion of the contact ion pairs with lithium and sodium cations into the solvent-separated ion pairs is influenced by interactions between the solvent-separated ions pairs. The polymer carbanions with bulky K+ and Cs+ cations exhibited a shift of λ with increasing carbanion concentration, suggesting the formation of an extended polymer chain in solution.

Studies of Partially Metallated Poly(2-vinylfluorene)'s in Solution 1 - Ion Pair Structure and the Concentration Effects of Carbanion Salts Along the Polymer Chain

The ion pair structure of partially metallated poly(2-vinylfluorene) is studied by means of electronic absorption and fluorescence spectroscopy. The degree of metallation along the polymer chain influences the ion pair structure effectively. In the ground state the conversion of contact ion pairs into solvent-separated ion pairs along the polymer chain is depressed by electrostatic interaction between the ion pairs. The contact ion pairs with a bulky counter cation form aligned pendant fluorenide chromophores. In the excited state the steric effect of counter cation in the polymer chain hinders the rearrangement of the fluorenide chromophores after Franck-Condon transition and this effect is more remarkable with large counter cations. It is suggested that these polymer effects, electrostatic and steric effects, influence the conformation of the polymer chain. An intramolecular energy migration along the polymer chain is also studied.

Ion Pair Structure and Photochemistry of Partially Metallated Poly(2-Vinylfluorene) in Solution

The free ion of fluorenone radical anion (FlO) was formed even in tetrahydrofuran (THF) by the flash photolysis of the alkali-metal salts of the sulfonyl carbanion in the presence of neutral FlO and this was attributed to the ion pair structure of the sulfonyl carbanions.

Shin-Ichi Nishi

Papers

Formation of the free ion of fluorenone radical anion in tetrahydrofuran by the flash photolysis of the sulfonyl carbanions