Ab initio conformational study of 2,2′:5′,2″-terthiophene

Synthesis of organometallic Ru(II) and Fe(II) complexes containing fused rings hemi-helical ligands as chromophores. Evaluation of non-linear optical properties by HRS

“…Yet, extended conjugated chain in systems based on thiophene rings, is expected to present an improved planarity since the torsion angle between rings can become quite small. In accordance, ab initio calculations [18] suggests that for terthiophene, although the gas-phase structure is not planar, the conformational inter-conversion energy is very low and sensitive to the chemical environment. Also a 0022-328X/$ -see front matter Ó 2008 Elsevier B.V. All rights reserved.…”

Compromise between conjugation length and charge-transfer in nonlinear optical η5-monocyclopentadienyliron(II) complexes with substituted oligo-thiophene nitrile ligands: Synthesis, electrochemical studies and first hyperpolarizabilities

“…For oligo-thiophene derived ligands, however, an improved planarity can be expected from the limited sterical hindrance as compared to oligo-phenyls. Although an ab initio calculation by Ciofalo and La Manna [17] suggest that even for terthiophene the gas-phase structure is not planar, they found a very low energy barrier for conformational inter-conversion and as a result the geometry is very sensitive to the chemical environment. This is further illustrated by a semi-empirical calculation by Porter et al [18], which indicates that the structure of bithiophene becomes planar in aqueous solution.…”

Towards first-principles based modeling of poly-3-alkylthiophenes: The nature of interactions in 2,2′-bithiophene dimer

“…It should be noted, however, that parallel structures are favoured in the case of the stacked P3AT chains. Computational studies of short oligotiophenes in vacuo show that the preferred configuration of monomer is the non-planar one [38]. However, the interchain p-p interactions between the flat conjugated polymer chains are stronger in comparison to the twisted one; in a result the former arrangement is preferable.…”