An unusual mechanism for HOMO-LUMO gap narrowing in a minimal near-IR dye generated by the deprotonation of bis(dicyanomethylene)indan

作者：Fujisawa Jun ichi^*

来源：Chemical Physics Letters, 2014, 608: 355-359.

DOI：10.1016/j.cplett.2014.06.012

A minimal near-IR (NIR) dye with the lower molecular-weight than 250 is produced by the deprotonation of 1,3-bis(dicyanomethylene) indan. Despite the small pi-conjugation system, the anionic dye shows light absorption and fluorescence in the red to near infra-red region. This Letter reports on the unusual mechanism for HOMO-LUMO gap narrowing for the NIR dye. Density functional theory (DFT) analyses show the molecular-orbital transition from the LUMO+1 to HOMO by the deprotonation, which significantly reduces the HOMO-LUMO gap. Time-dependent DFT and group-theory analyses well explain the electronic-excitation properties. This is a new mechanism for reducing a HOMO-LUMO gap without extending pi-conjugation systems.

• 出版日期2014-7-21