Affiliation:
1. Graduate School of Pharmaceutical Sciences The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
2. RIKEN Center for Sustainable Resource Science (CSRS) 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
3. RIKEN Center for Emergent Matter Science (CEMS) 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
4. Research Initiative for Supra-Materials (RISM) Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
Abstract
AbstractAlthough second near‐infrared (NIR‐II, 1000–1500 nm) light has attracted considerable attention, especially for life sciences applications, the development of organic dyes with NIR‐II absorption remains a formidable challenge. Herein we report the design, synthesis, and electronic properties of 20π‐electron antiaromatic benziphthalocyanines (BPcs) that exhibit intense absorption bands in the NIR region. The strong, low‐energy absorption of the antiaromatic BPcs is attributed to electric‐dipole‐allowed HOMO‐LUMO transitions with narrow band gaps, enabled by the reduced structural symmetry of BPc compared with regular porphyrins and phthalocyanines. The combination of peripheral substituents and a central metal decreases the HOMO‐LUMO energy gaps, leading to the extension of the absorption bands into the NIR‐II region (reaching 1100 nm) under reductive conditions.
Funder
Japan Society for the Promotion of Science
Japan Science and Technology Agency
Nagase Science Technology Foundation
Naito Foundation
Uehara Memorial Foundation