From Monomers to π-Stacks. A Comprehensive Study of the Structure and Properties of Monomeric, π-Dimerized, and π-Stacked Forms of the Cation Radical of 3‘,4‘-Dibutyl-2,5‘‘-diphenyl-2,2‘:5‘,2‘‘-terthiophene

Citations Over TimeTop 1% of 1997 papers

Abstract

3‘,4‘-Dibutyl-5,5‘‘-diphenyl-2,2‘:5‘,2‘‘-terthiophene (Bu2Ph2Tth) can be readily converted to the stable cation radical [Bu2Ph2Tth]+. The hexafluorophosphate salts of the cation radical ([Bu2Ph2Tth]PF6) are synthesized in millimolar quantities by either chemical or constant current electrochemical oxidation; the latter method gave X-ray quality single crystals. X-ray powder diffraction studies indicate the materials from both syntheses have the same structure. The crystal structure of [Bu2Ph2Tth]PF6 was determined and is temperature dependent. At 293 K, [Bu2Ph2Tth]PF6 crystallizes in the C2/c space group while at 106 K it belongs to the P21/n space group and exhibits a superlattice structure where the c axis is approximately double that at 293 K. Both structures consist of columnar “slipped π-stacks” of [Bu2Ph2Tth]+ cations and channels of PF6- anions. At 293 K, the cations stack with a regular interplanar contact distance of 3.47 Å; at 106 K, the contact distances alternate regularly such that each cation has interplanar contact distances of 3.36(5) and 3.42(5) Å with the two neighboring cations in the π-stack. The crystal structure of Bu2Ph2Tth was also determined, and comparisons are made to the structure of [Bu2Ph2Tth]PF6. Several physical techniques (UV−vis−NIR−IR absorption, spectroelectrochemistry, ESR, conductivity) were used to investigate the electronic structure of the cation radical in solution, embedded in a thin film polymer network and as a pure solid sample. The measured physical properties correlate with the crystal structures of [Bu2Ph2Tth]PF6 and indicate that the material has a band-like electronic structure characteristic of a semiconductor.

Related Papers

• → A crystallographic study of 2-hydroxyacetophenone N(4)-cyclohexyl thiosemicarbazone(2006)24 cited
• → Synthesis and crystal structure of methylammonium dicitratoborate(2009)10 cited
• → Synthesis and crystal structure of 2-benzoyl-4-methyl phenyl benzoate(2005)8 cited
• → Synthesis and Crystal Structure Analysis of 3,5,5,7-Tetraacetylnonane-2,8-Dione(2011)2 cited
• → Homoallylic coupling in 1,4-dihydronaphthalenes. Part 2. Crystal structure of cis-2a,5-dihydro-5-acenaphthoic acid(1977)2 cited