The Power of Packing: Metallization of an Organic Semiconductor

Abstract

Benzoquino-bis-1,2,3-dithiazole 5 is a closed shell, antiaromatic 16π-electron zwitterion with a small HOMO-LUMO gap. Its crystal structure consists of planar ribbon-like molecular arrays packed into offset layers to generate a "brick-wall" motif with strong 2D interlayer electronic interactions. The spread of the valence and conduction bands, coupled with the narrow HOMO-LUMO gap, affords a small band gap semiconductor with σ = 1 × 10 S cm and E = 0.14 eV for transport within the brick-wall arrays. Closure of the band gap to form an all-organic molecular metal with σ > 10 S cm can be achieved by the application of pressure to 8 GPa.

Rational Construction of Highly Tunable Donor–Acceptor Materials Based on a Crystalline Host–Guest Platform

“…Thanks to the well‐developed design and synthesis technology, the characteristics of organic molecules could be well tuned, allowing for the design of various charge‐transfer systems. [1c,2] However, since the assembly of D and A species toward donor–acceptor system is complicated and usually affected by many factors, such as solvents or temperature, it is usually difficult to precisely predict and control the arrangement of these molecules in the long‐range order for the attainment of the required performance of complexes . Therefore, it is still a challenge for the controlled construction of organic charge‐transfer complexes featuring well‐illustrated principles of rational construction and modulated performance, and the regulation of D and A species arrangement could be a key factor.…”

Synthesis and Applications of 5‐Membered Chalcogen‐Nitrogen π‐Heterocycles with Three Heteroatoms

“…Very useful is double Herz cyclization allowing synthesis of benzo‐ and pyrido‐fused bis(1,2,3‐didiazoliums) (Scheme ) ,. Hybrid 1,2,3‐dithiazole / 1,2,3‐dithiazolium (Scheme ) and bipolar (Scheme ) derivatives were prepared in similar ways. Notably, the latter is a closed shell 16π‐electron, i. e. formally antiaromatic, compound.…”

“…1,2,3‐ and 2,1,3‐Thiaselenazolyls were synthesized by reduction of corresponding thiaselenazoliums (Scheme ), and 2,1,3‐thiaselenazolyls by thermolysis of 3,1,2,4‐benzothiaselenadiazines (Scheme ). Some derivatives were isolated and characterized by XRD ,,,,,,…”

“…Benzo‐ and azino‐fused 1,2,3‐dithiazolyls and their Se congeners (Scheme ) are promising building blocks in the design and synthesis of conductive (semiconductors and metals) and magnetic,,,–,,,, as well as optoelectronic, molecular materials.…”

“…With DFT calculations on benzo‐ and azino‐fused bis(1,2,3‐dithiazoles), it was shown that their ground state multiplicity can be effectively controlled by substitution, namely, electron‐acceptor substituents in the central ring stabilize bipolar singlet states, whereas electron‐donor substituents favor a triplet ground state . The band‐gap closure in these conductors to form an all‐organic molecular metal was produced by the employment of external pressure of 8 GPA . Overall, metallic state of 1,2,3‐dichalcogenazolyl‐based conductors is a subject of dimensionality, pressure and multiple orbital effects …”