Chen Feng-Li, Liu Xin-Li, Zhao Yue, Li Gang, Gao Bo-Hong, Wang Xin-Yi
State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Dalton Trans. 2024 Oct 29;53(42):17233-17243. doi: 10.1039/d4dt01954g.
A new substituted Hqnal ligand, Hqnal-5-Br, and four resulting Fe complexes [Fe(qnal-5-Br)]A·sol (A = NO, sol = CHOH 1; A = ClO, sol = CHOH 2; A = OTf, sol = 2CHOH·HO 3; and A = NTf, sol = CHCl4; Hqnal-5-Br = -(5-bromo-8-quinolinyl)-2-hydroxynaphthaldimine), have been synthesized and characterized. All four complexes, despite having different anions, adopt similar 1D [Fe(qnal-5-Br)] cation chains linked by orthogonal π⋯π interactions. These chains are further connected to form 2D and 3D structures by other supramolecular interactions. Complexes 1-3 all exhibit abrupt spin crossover behaviors, with the transition temperatures being 230, 189, and 185 K, respectively, while complex 4 is in a high-spin state. The influence of solvents on spin crossover properties was assessed magnetic measurements on the desolvated samples. Following desolvation, while complexes 1 and 2 show slight variations in their transition temperatures, complexes 3 and 4 undergo significant changes in their magnetic profiles. Desolvation in complex 3 leads to either a HS state or a very incomplete hysteretic transition with a low transition temperature for different sample batches. In contrast, the gradual desolvation in complex 4 leads to diminished solvent residues and progressive transition from a stable HS state to an SCO-active state.
