Theoretical study on the structures, electronic properties, and aromaticity of thia[4]circulenes

Abstract

The structures, electronic properties, and aromaticity of a series of thia[4]circulenes are predicted using quantum chemical calculations. All the thia[4]circulenes studied adopt bowl-shaped geometries which become deeper when the number...

Aromaticity in the Electronic Ground and Lowest Triplet States of Molecules with Fused Thiophene Rings

“…The most stable of these sulflowers is thought to be (C 2 S) 8 10 which has been shown to have the lowest energy per repeat unit [23,24] . Computational studies of more strained sulflowers with 4, 5, 11 and 12 condensed thiophene rings have been carried out by other authors [24,25] . Dianions and dications of (C 2 S) 8 and other hetero[8]circulenes are thought to have increased stability due to the establishment of a 4 n +2 Hückel‐aromatic π system involving the ‘inner’ C 8 ring [26] .…”

Linear π-conjugated polycyclic compounds consisting of four-, five-, and six-membered rings: benzo[1′′,2′′:3,4;4′′,5′′:3′,4′]bis(cyclobuta[1,2-c]thiophene)

“…BBCT will show moderate global aromaticity; the two fused 4MRs will attenuate the aromaticity of the central benzene ring and the fused thiophene ring at the 3,4-bond (c-type) with low electron density because its inherent diene character will attenuate the antiaromatic character of the 4MRs. 27,31–35 Finally, BBCT has a unique structural feature, i.e. , the linear annulation of 5-, 4-, 6-, 4-, and 5-membered rings.…”

“…BBCT will show moderate global aromaticity; the two fused 4MRs will attenuate the aromaticity of the central benzene ring and the fused thiophene ring at the 3,4-bond (c-type) with low electron density because its inherent diene character will attenuate the antiaromatic character of the 4MRs. 27,[31][32][33][34][35] Finally, BBCT has a unique structural feature, i.e., the linear annulation of 5-, 4-, 6-, 4-, and 5-membered rings. [36][37][38][39][40][41][42][43] In this context, we herein report the synthesis, electronic properties, crystal structures, and aromaticity of BBCT and its methylated compound BBCT-Me and compare them with the properties and structure of [3]phenylene as a reference compound, 10 for future potential application of these molecules as p-type semiconducting materials.…”

Aromaticity enhancement of cyclopentadiene in piperidine derivatives: a DFT study on combination of the anomeric effect and Schleyer hyperconjugative aromaticity

“…2,3 Nowadays, the aromaticity theory has developed and structural, topological, electronic, magnetic, and energetic indices have been used to evaluate aromaticity/antiaromaticity. 4–7…”

“…2,3 Nowadays, the aromaticity theory has developed and structural, topological, electronic, magnetic, and energetic indices have been used to evaluate aromaticity/antiaromaticity. [4][5][6][7] The effective role of the aromaticity theory is undeniable and it is considered as one of the basic theories in chemistry. 8 Aromaticity cannot be directly measured quantitatively.…”