Predicting Emission in Substituted N‐Alkyl Carbazoles to Create New Mechanoluminescent Molecules

• Published in: ChemistrySelect (Weinheim) 2023-09, Vol.8 (34), p.n/a
• Main Authors: Malme, Justin T., Jabadul, Shajib, Hoy, Erik P.
• Format: Article
• Language: English
• Subjects: Carbazoles; Density Functional Theory; Mechanoluminescence; Organic Crystals
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202300508

Mechanoluminescence (ML) is the emission of light caused by mechanical stresses on solid, usually crystalline substances. Recently, it has been observed that a specific class of organic crystals, N‐alkyl carbazoles, have both low melting points and high proclivity for self‐assembly, making them easily renewable for long‐term device applications. To develop new carbazole‐based ML materials for device applications, it is necessary to be able to tune their emission to desirable wavelengths. In this study, we computationally investigated using chemical substituents with electron‐withdrawing/donating character to tune the emission wavelength of N‐alkyl carbazoles. We find that strongly electron‐withdrawing substituent groups can be used as one controlling factor for tuning emission wavelengths for N‐alkyl carbazoles. This finding provides materials scientists with a new family of derivatives for designing effective organic materials with desirable ML emission properties. Unsubstituted N‐alkyl carbazoles have been experimentally demonstrated to exhibit renewable mechanoluminescence. This computational study examines the effectiveness of using electron‐donating or withdrawing substituents for tuning the expected emission energies of N‐alkyl carbazoles.