Rhodamine 6G-Labeled Pyridyl Aroylhydrazone Fe(II) Complex Exhibiting Synergetic Spin Crossover and Fluorescence

• Published in: Journal of the American Chemical Society Vol. 140; no. 30; pp. 9426 - 9433
• Main Authors: Yuan, Juan, Wu, Shu-Qi, Liu, Mei-Jiao, Sato, Osamu, Kou, Hui-Zhong
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.08.2018; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Physical Sciences; Science & Technology; ROOM-TEMPERATURE; CHEMOSENSOR; MOLECULAR CALCULATIONS; APPROXIMATION; BEHAVIOR; GUEST; STATE; NANOCOMPOSITE; THERMAL HYSTERESIS; GAUSSIAN-BASIS SETS
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.8b00103

Here, we use a pyridinecarbaldehyde rhodamine 6G hydrazone ligand (L) to synthesize an Fe­(II) complex 1 for the search of new fluorescent-spin crossover (SCO) materials. Single-crystal structural determinations suggest that the Fe­(II) ion is chelated by two ring-opened ligands (L-o) to form a FeN4O2 coordination environment, and intermolecular π---π contacts of the xanthene groups connect the adjacent molecules to form a supramolecular one-dimensional chain. Magnetic susceptibility measurements on complex 1 show that three-step SCO takes place in the temperature range of 120–350 K, and its desolvated form 1-d exhibits SCO around room temperature (T c↑ = 343 K and T c↓ = 303 K) with a wide hysteresis loop of 40 K. Moreover, complex 1-d displays light-induced excited spin-state trapping phenomenon. Intriguingly, the fluorescence intensity of the maximum emission at 560 nm for complex 1-d displays discontinuous variation in the range of 250–400 K, indicative of the occurrence of synergetic fluorescence and SCO.