Linearly condensed polythiophenes: characteristic molecular aggregation of thieno[2″,3″:4′,5′]thieno[2′,3′-d]thieno[3,2-b]thiophene crystals revealed by ultraviolet photoelectron spectroscopy

Abstract

Linearly-condensed polythiophenes (4 and 5) have been prepared and their characteristic aggregation behaviour as hydrogen-poor n: compounds in the solid state has been investigated in comparison with those of the lower homologues (2 and 3); the photoelectron spectra of the series 2-5 were measured in the solid state as well as in the gas phase. For 4 the difference in the ionization energies for the gaseous (adiabatic; 7.22 eV) and solid (threshold; 4.86 eV) states is significant, giving rise to a large polarization energy (2.36 eV), which is larger than the calculated value (1.83 eV) based on the packing density and molecular polarizability. This has been interpreted in terms of the intermolecular orbital interactions in the solid state of 4. Such an interaction has not been observed in the lower homologues (2 and 3).The discovery of an organic superconductor under ambient pressure from bis(ethy1enedithio)tetrathiafulvalene complexes (BEDT-TTF),13 ' has demonstrated that an enhancement in the spatial arrangements of intermolecular interactions is important in stabilizing the metallic states and, further, in designing organic superconductors.' Four sulfur atoms in the BEDT-TTF molecule, when introduced into the TTF skeleton, reinforce the interaction between quasi-one-dimensional stacks of BEDT-TTF molecules in the crystal through their side-byside packing arrangements.Against this background, we have investigated the linearlycondensed polythiophene 1. This polymer molecule bears essentially no hydrogen atoms in the molecular periphery, and is therefore expected to interact efficiently intermolecularly through S ---S contacts. Polycondensed thiophene itself has not yet been obtained. In contrast, lower homologues of a series of linearly-condensed thiophenes, i.e. thieno [3,2-b] thiophene(2) and thieno[3,2-b]thieno[2',3'-d]thiophene(3), which are regarded as the prototype of linearly-condensed polythiophenes, are already known. We have also prepared two higher homologues of this series; thieno [2",3": 4',5']thieno[2',3'-d]thieno[3,2-b]thiophene (4) and dithieno[2,3-d : 2',3'-d']thieno-[3,2-b: 4,5-br]dithiophene (9, which are isoelectronic with 1 2 3 4 5 Paper 2/00173J

Synthesis, Characterization, and Field‐Effect Transistor Performance of Thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene Derivatives

“…A solution of lithiated 8 in diethyl ether was added to a vigorously stirred suspension of anhydrous CuCl 2 in diethyl ether, affording the product TTA in yields of 20-35%. [28,29] However, if the process was attempted in the reverse order, no desired product was observed. TTA was then converted to the corresponding dibrominated TTA by 2 equiv of N-bromosuccinimide (NBS) in CHCl 3 to give 2,6-dibromo-thieno [3,2-b]thieno[2 0 ,3 0 :4,5] thieno[2,3-d]thiophene (2BrTTA) in 71% yield.…”

“…b]thieno[2(,3 00 :4,5]thieno[2,3-d]thiophene (TTA)[29]: To a stirred solution of sulfide 8 (812 mg, 3.2 mmol) in diethyl ether (100 mL) was added a 2.5 M solution of Bu n Li in hexane (3.0 mL, 7.5 mmol) under a nitrogen atmosphere at À10 8C. The mixture was stirred for 2 h and then added to a vigorously stirred suspension of anhydrous CuCl 2 (0.95 g, 7.1 mmol) in diethyl ether (30 mL).…”

First‐Principles Investigation of the Electronic and Conducting Properties of Oligothienoacenes and their Derivatives

“…The various types of charge-hopping pathways in the crystal structure of compound 7, [35] are shown in Figure 1 c. By symmetry, pathway 4 was the same as pathway 1, pathways 3, 5, and 6 were the same as pathway 2, pathways 8, 11, and 12 were the same as pathway 7, and pathways 10, 13, and 14 were the same as pathway 9. We calculated the electronic couplings for all four types of dimer configurations (Table 4).…”

Theoretical investigations of the structures and electronic spectra of 2-dicyanovinyldithieno[2,3-b:3′,2′-d]thiophene (DCST) and 2-dicyanovinyldithieno[3,2-b:2′,3′-d]thiophene (DCTT)

“…In the past several decades, a-oligothiophenes, in which thiophene rings are connected with CAC single bonds at a-positions, have been extensively investigated, due to the fact that the carbon-sulfur oligomers are planar or quasi-linear with conjugated p-systems [8][9][10][11][12][13][14][15][16][17]. However, homologous b-oligothiophenes, in which thiophene rings are connected with CAC single bonds at b-positions, have attracted little attention, except for the planar macro-cyclic trimer [18][19][20].…”