What Defines a Crystal Structure? Effects of Chalcogen Atoms in 3,7‐Bis(methylchalcogeno)benzo[1,2‐b:4,5‐b′]dichalcogenophene‐Based Organic Semiconductors^†

Abstract

To understand the effects of chalcogen atoms on the crystal structure of the series of 3,7-bis(methylchalcogeno)benzo[1,2-b:4,5-b′+dichalcogenophene-based organic semiconductors, three benzodifuran derivatives (1-3) and dimethoxy derivatives of benzodithiophene and benzodiselenophene (4 and 7) were newly synthesized to complete the "3 × 3 matrix" of the oxygen-, sulfur-, and selenium-derivatives (1-9). The crystal structures of 1-9 were classified into four classes, sandwich pitched -stack (1), dimeric (2 and 3), pitched -stack (4, 5, 7, 8, 9), and brickwork structure (6 and 9). The causes for the different crystal structures depending on the chalcogen atoms were investigated by the theoretical calculations, indicating that the chalcogen atoms in the core and substituents primarily affected the packing structures. Although the crystal growth in the vapor phase afforded different polymorphs, the relationship between the crystal structure and the carrier transport property was carefully investigated. With these comprehensive evaluations, we conclude that; i) methylchalcogenolation is a powerful tool to alter the packing structure, ii) each methylchalcogeno group has its features that largely influence the intermolecular interaction and electronic structure in the solid state, and iii) organic semiconductors being crystallizable into appropriate pitched -stack structures are promising as high-performance active materials for FET applications.

Methylthiolation of Acenes: Change of Crystal Structure from Herringbone to Rubrene-like Pitched π-Stacking Structure

“… a Calculated on the basis of the crystal structures measured at 300 K. b From ref . c From ref . d See the Supporting Information. …”

“…Under these circumstances, we coincidentally observed that β-methylthiolated benzo[1,2-b:4,5-b′]dithiophene (β-MT-BDT, Figure 1) crystallized into a pitched π-stacking structure in 2017. 15 This discovery was followed by the synthesis of a series of β-MT-BDT-related molecules, e.g., its oxygen and selenium analogues (β-MX-BDX, Figure 1) 16,17 and π-extended derivatives, 18 and their crystal structures were elucidated by single-crystal X-ray analysis. We found that β-methylchalcogenolation is a reliable and general molecular design strategy for realizing acenedichalcogenophene derivatives with pitched πstacking structures.…”

Supramolecular architectures featuring Se⋯N secondary-bonding interactions in crystals of selenium-rich molecules: a comparison with their congeners

“…Se⋯N chalcogen bond formation, an effect which is magnified in the molecular packing by the observation that Se⋯N chalcogen bonds increase the aromaticity of rings within their molecules which then enhances their likelihood of forming π⋯π interactions with consequent impact upon charge transport and magnetic properties. 102,165,166…”

“…Se⋯N chalcogen bond formation, an effect which is magnified in the molecular packing by the observation that Se⋯N chalcogen bonds increase the aromaticity of rings within their molecules which then enhances their likelihood of forming π⋯π interactions with consequent impact upon charge transport and magnetic properties. 102,165,166 The attention now turns to seeking correlations between the Ch⋯N separation and/or Y-Ch⋯N with Ch = Se on the one hand, and Ch = Te or S on the other. Geometric data in support of this analysis are presented in Table 8.…”

Theoretical study of the tuning role of β-methylthio or β-methylselenyl on the charge-transport properties of acenedithiophenes derivatives

“…9 In recent years, there have been comparative studies of sulfur and selenium atoms, which are located in the same main family, with the former being of almost continuous interest. [27][28][29] Because selenium's position in the periodic table of elements indicates that it has a greater mass and volume than sulfur, then whether the introduction of selenium atoms would bring about a more outstanding performance in terms of changing the molecular stacking and maintaining the stability of the devices made of its molecules in practical applications is not clear. Recently, anti-b-MS-BDT was synthesized experimentally, and it was reported to have the characteristics of 2D brickwork p-stacking, 30 which would be conducive to charge transport.…”