Dibenzo[b,f]arsepins possessing severely distorted cores compared to those of other heteropins were synthesized. These derivatives exhibited dual photoluminescence in the green-to-red region (500-700 nm) and the near-ultraviolet region (< 380 nm), whichcould be attributed to the planarization of the arsepin core in the lowest singlet excited (S 1 )s tate. The computational approach for the assessment of the aromatic indices revealed that the dibenzoarsepins studied show aromaticity (8p system) in the S 1 states in line with Bairdsrule.The lone pair electrons of the arsenic atoms play ac rucial role in the aromaticity in the S 1 states.

Dithienoarsoles, which were safely and easily prepared, showed various electronic states dependent on modification of the π-conjugated systems and reactions of the arsenic atoms. It has been demonstrated that dithienoarsole is a multi-mode-tunable luminophore.

RyotoI naba, [a] Ikuo Kawashima, [a] To shiki Fujii, [a] Ta kashiY umura, [b] HiroakiI moto,* [a, c] and Kensuke Naka* [a, c]

2,3,4,5-Tetraaryl-1-phenylarsoles were synthesized by utilizing safely generated diiodophenylarsine and zirconacyclopentadienes. The obtained peraryl arsoles showed aggregation-induced emission (AIE), where intense emission was observed in the solid states (quantum yields up to 0.61), whereas the corresponding solutions were very weakly emissive. The optical and electronic properties were examined by experimental and computational methods. It was elucidated that the aryl groups at the 2,5-positions affected the frontier orbitals and the aromaticity of the arsole core. On the other hand, those at the 1,3,5-positions were perpendicular to the luminophore and effective for a restriction of aggregation-caused quenching. Because the lone pair of the arsenic atom has a sufficient coordination ability due to the low aromaticity of the arsole moiety, a gold(I) chloride complex of 1,2,3,4,5-pentaphenylarsole was synthesized. The complex formation caused a blue shift of the emission from the bare ligand. Interestingly, the complex showed luminescent mechanochromism; grinding the crystals with a blue emission (λ =445 nm) gave amorphous samples with a greenish-blue emission (λ =496 nm).

Dibenzo[b,f]arsepins possessing severely distorted cores compared to those of other heteropins were synthesized. These derivatives exhibited dual photoluminescence in the green‐to‐red region (500–700 nm) and the near‐ultraviolet region (<380 nm), which could be attributed to the planarization of the arsepin core in the lowest singlet excited (S1) state. The computational approach for the assessment of the aromatic indices revealed that the dibenzoarsepins studied show aromaticity (8π system) in the S1 states in line with Baird's rule. The lone pair electrons of the arsenic atoms play a crucial role in the aromaticity in the S1 states.