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Two series of regioisomeric luminophores that contained a dithieno[2,3- a:3′,2′- c]phenazine (DTP) unit as an electron acceptor have been designed and synthesized. To investigate the effect of substitution pattern on the optoelectronic properties of these luminophores, electron donors ( N, N-dihexylaniline or N, N-dihexyl-4-vinylaniline) were incorporated at the 2,5-, 8,11-, and 9,10-positions of the DTP unit. We found that the optoelectronic properties of the regioisomeric luminophores were greatly affected by the substitution pattern: functionalization at the 8,11-positions of the DTP unit was superior to the other two substitution patterns in extending the effective π-conjugation and strengthening the intramolecular charge-transfer interactions. Moreover, the insertion of vinyl groups between the DTP and N, N-dihexylaniline units narrowed the energy band-gap for isomers 4 and 5. However, hypsochromically shifted absorption and photoluminescence maxima were observed for isomeric luminophore 6, in which electron donors were substituted at the 2,5-positions of the DTP unit. These results should facilitate greater understanding of the structure-property relationships in regioisomeric semiconductors and present a new way to design optoelectronic materials with effective substitution patterns. [ABSTRACT FROM AUTHOR]

A correction to the article "Charge Transfer Through Dithieno[2,3-a:3',2'-c]phenazine: Effect of Substitution Pattern on the Optoelectronic Properties of Regioisomeric Luminophores" is presented.

S- and Se-heteroarenes containing cyclopenta[b]thiopyran and/or cyclopenta[b]selenopyran moieties have been synthesized via PtCl2-catalyzed ring-expanding cycloaromatizations. Intervalence charge transfer bands can be observed for the three heteroarenes upon chemical oxidation, suggesting the electronic communication between S- and/or Se-fused aromatics. [ABSTRACT FROM AUTHOR]

Three symmetrical donor-acceptor-donor (D-A-D) luminophores ( C1, C2, and C3) with pyrazine derivatives as electron-withdrawing groups have been developed for multistimuli-responsive luminescence switching. For comparison, reference compounds R1 and R2 without the pyrazine moiety have also been synthesized. Intramolecular charge transfer (ICT) interactions can be found for all D-A-D luminophores owing to the electron-withdrawing properties of the two imine nitrogen atoms in the pyrazine ring and the electron-donating properties of the other two amine nitrogen atoms in the two triphenylamine units. Moreover, luminophores C1, C2, and C3 exhibit 'on-off-on' luminescence switching properties in mixtures of water/tetrahydrofuran with increasing water content, which is different from the 'on-off' switching for typical aggregation-caused quenching (ACQ) materials and 'off-on' switching for traditional aggregation-induced emission (AIE) materials. Additionally, upon grinding the pristine samples, luminophores C1, C2, and C3 display bathochromically shifted photoluminescence maxima that can be recovered by either solvent fuming or thermal annealing treatments. The piezofluorochromic (PFC) properties are more pronounced than those for reference compounds R1 and R2, which indicates that D-A molecules have the ability to amplify the PFC effect by tuning the ICT interactions upon tiny structural changes under pressure. Furthermore, the target luminophores demonstrate acid-responsive photoluminescence spectra that can be recovered in either basic or ambient environments. These results suggest that D-A complexes are potential candidates for multistimuli-responsive luminescence switching because their ICT profiles can be facilely tuned with tiny external stimuli. [ABSTRACT FROM AUTHOR]