Ji Wen, Zou Ya, Guo Lu, Niu Weiwei, Jiao Tianyu, Phan Hoa, Wu Jishan, Li Guangwu
Center of Single-Molecule Sciences, Institute of Modern Optics, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, China.
Yunnan Key Laboratory of Electromagnetic Materials and Devices, School of Materials and Energy, School of Engineering, Yunnan University, Kunming, 650091, China.
Angew Chem Int Ed Engl. 2025 Sep 22;64(39):e202512663. doi: 10.1002/anie.202512663. Epub 2025 Aug 8.
This study presents the successful synthesis of a series of stable iminium diradical(oid)s. CNR1OTf, CNR2OTf, and CNR3OTf can be readily prepared by treating their corresponding methoxy precursors with triflate acid. Remarkably, they all display excellent stability under light and ambient conditions. CNR1 exhibits a closed shell electronic feature, whereas CNR2 features an open shell singlet ground state. CNR3OTf possess triplet ground electronic state, as evidenced by ESR and superconducting quantum interference device (SQUID) measurements. Through meticulous fitting of the SQUID data, a singlet-triplet energy gaps (∆E) of +1.04 kcal mol along with intermolecular antiferromagnetic interactions (θ) of -28 K were obtained. In comparison to CNR1, both the open shell CNR2 and CNR3 display distinctively red shifted long wavelength absorption bands that extend up to approximately 2400 nm. Such long wavelength absorption characteristics are quite scarce among organic materials. This research offers a novel approach for the design and synthesis of iminium diradical(oid)s, which feature tunable ground states and exhibit intense absorption in the second near infrared (NIR-II) region, opening up new possibilities in the field of organic materials research.
