Tuning the NIR Absorption Properties of 1,3,4,6,9b‐Pentaazaphenalene Derivatives Through the Spatially Separated Frontier Molecular Orbitals

• Published in: European journal of organic chemistry Vol. 2020; no. 7; pp. 777 - 783
• Main Authors: Watanabe, Hiroyuki, Ochi, Junki, Tanaka, Kazuo, Chujo, Yoshiki
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 21.02.2020; Wiley Subscription Services, Inc
• Subjects: Absorption; Azaphenalene; Chemistry; Chemistry, Organic; Derivatives; Electrons; Energy levels; Fused‐ring systems; Heterocycles; Molecular orbitals; Near infrared; Physical Sciences; Science & Technology; Heterocycles; POLYMERS; Azaphenalene; SOLAR-CELLS; FLUOROPHORES; PERFORMANCE; AZULENE; PHOTOPHYSICAL PROPERTIES; TERAZULENE; Fused-ring systems; Near infrared
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201901569

Strategical modulation of energy levels of molecular electronic orbitals and resulting near‐infrared (NIR) absorption properties of 2,5,7,9‐tetrasubstituted 1,3,4,6,9b‐pentaazaphenalene (5AP) derivatives are reported. Recent reports on NIR‐absorbing materials mainly rely on donor–acceptor electronic interactions or macrocyclic π‐conjugated systems. We achieved the narrow HOMO–LUMO gap based on spatially separated frontier molecular orbitals (FMOs) of 5APs. The FMOs of 5APs enabled us to selectively tune either their HOMO or LUMO by choosing the position of the substituent. Judicious modification of substituents on a 1,3,4,6,9b‐pentaazaphenalene scaffold resulted in NIR absorption materials. The spatially separated frontier molecular orbitals enabled independent tuning of their energy levels toward NIR absorption properties.