TY - JOUR
T1 - π-Expansion-Directed Modulation of Spin–Fluorescence Coupling in Spin-Crossover Hofmann-Type Frameworks
AU - Chen, Hong Tai
AU - Hu, Jie Sheng
AU - Chen, Yu Xiao
AU - Ren, Jin Qing
AU - Yu, Meng
AU - Tao, Jun
N1 - Publisher Copyright:
© 2026 American Chemical Society
PY - 2026/1/19
Y1 - 2026/1/19
N2 - The coupling between spin crossover (SCO) and luminescence provides a direct, noninvasive optical readout of spin-state switching, which is pivotal for the development of advanced molecular sensors, memory devices, and opto-spintronic applications. Herein, we report two two-dimensional Hofmann-type coordination polymers, i.e., {Fe2(PYNA)4[Ag(CN)2]4} (1) and {Fe3(PYAN)6[Ag(CN)2]6}·o-DCB (2, o-DCB = ortho-dichlorobenzene), based on two extended π-conjugated ligands, 4-(2-naphthalenyl)pyridine (PYNA) and 4-(2-anthracenyl)pyridine (PYAN), respectively. Divergent SCO behaviors were observed for the two compounds, as confirmed by temperature-dependent magnetic susceptibility measurements, structural analyses, and differential scanning calorimetry measurements. In addition, light-induced excited spin-state trapping effects were found in the two SCO compounds, and bidirectional photoswitching of spin states can be realized reversibly. Crucially, a comparative variable-temperature fluorescence (FL) study highlights a π-expansion-driven contrast: SCO-FL coupling is operative in 1 but absent in 2. Theoretical calculations directly account for the distinct energy transfer pathways in 1 and 2, rationalizing their contrasting outcomes in achieving SCO-FL coupling. This study provides important support for the precise modulation of the spin-optical coupling properties through ligand engineering.
AB - The coupling between spin crossover (SCO) and luminescence provides a direct, noninvasive optical readout of spin-state switching, which is pivotal for the development of advanced molecular sensors, memory devices, and opto-spintronic applications. Herein, we report two two-dimensional Hofmann-type coordination polymers, i.e., {Fe2(PYNA)4[Ag(CN)2]4} (1) and {Fe3(PYAN)6[Ag(CN)2]6}·o-DCB (2, o-DCB = ortho-dichlorobenzene), based on two extended π-conjugated ligands, 4-(2-naphthalenyl)pyridine (PYNA) and 4-(2-anthracenyl)pyridine (PYAN), respectively. Divergent SCO behaviors were observed for the two compounds, as confirmed by temperature-dependent magnetic susceptibility measurements, structural analyses, and differential scanning calorimetry measurements. In addition, light-induced excited spin-state trapping effects were found in the two SCO compounds, and bidirectional photoswitching of spin states can be realized reversibly. Crucially, a comparative variable-temperature fluorescence (FL) study highlights a π-expansion-driven contrast: SCO-FL coupling is operative in 1 but absent in 2. Theoretical calculations directly account for the distinct energy transfer pathways in 1 and 2, rationalizing their contrasting outcomes in achieving SCO-FL coupling. This study provides important support for the precise modulation of the spin-optical coupling properties through ligand engineering.
UR - https://www.scopus.com/pages/publications/105027626598
U2 - 10.1021/acs.inorgchem.5c05053
DO - 10.1021/acs.inorgchem.5c05053
M3 - Article
C2 - 41498422
AN - SCOPUS:105027626598
SN - 0020-1669
VL - 65
SP - 1528
EP - 1537
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 2
ER -