Lv, Zhong PengSrivastava, DivyaConley, KevinRuoko, Tero PetriXu, HongyiLightowler, MollyHong, XiaodanCui, XiaoqiHuang, ZhehaoYang, TaiminWang, Hai YingKarttunen, Antti J.Bergström, Lennart2025-05-302025-05-30WOS:001190394100001ORCID:/0000-0002-8271-3906/work/184762082http://www.scopus.com/inward/record.url?scp=85188532707&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733754783The charge-transfer (CT) interactions between organic compounds are reflected in the (opto)electronic properties. Determining and visualizing crystal structures of CT complexes are essential for the design of functional materials with desirable properties. Complexes of pyranine (PYR), methyl viologen (MV), and their derivatives are the most studied water-based CT complexes. Nevertheless, very few crystal structures of CT complexes have been reported so far. In this study, the structures of two PYRs-MVs CT crystals and a map of the noncovalent interactions using 3D electron diffraction (3DED) are reported. Physical properties, e.g., band structure, conductivity, and electronic spectra of the CT complexes and their crystals are investigated and compared with a range of methods, including solid and liquid state spectroscopies and highly accurate quantum chemical calculations based on density functional theory (DFT). The combination of 3DED, spectroscopy, and DFT calculation can provide important insight into the structure-property relationship of crystalline CT materials, especially for submicrometer-sized crystals.This work was supported by the Academy of Finland (Z.‐P.L. No. 330214; T.‐P. R. No. 340103; Center of Excellence Program in Life‐inspired Hybrid Materials, LIBER No. 346107 and 346108; Flagship Competence Center for Materials Bioeconomy, FinnCERES No. 318890 and 318891), EU H2020 Marie Skłodowska‐Curie grant (T.‐P. R. No. 101022777; T.Y. No. 101146059), National Natural Science Foundation of China (H.‐Y.W. No. 21801127), The Swedish Research Council (H.X. No. 2017–05333; L.B. No. 2019‐05624), The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (T.Y. No. 2022–02778), The Royal Swedish Academy (T.Y. No. CH2022‐0015 and PH2022‐0021), The Science for Life Laboratory through the technique development grant (MicroED@SciLifeLab). The authors thank Dr. X. Bai for his assistance in the electric property test of the crystals. The authors acknowledge the Finnish IT Center for Science (CSC) for computational resources.10en© 2024 The Authors.3D electron diffractioncharge-transfercrystaldensity functional theorynoncovalent interaction2024-03-2510.1002/smtd.20230122985188532707