Issue 35, 2024

Effects of mono- or di-fluoro-substitution on spin crossover behavior in a pair of Schiff base-like FeII-coordination polymers

Abstract

Spin crossover (SCO) has long been a hot topic in the field of molecular magnetism owing to its unique bistability character. Rational control of thermal hysteresis and transition temperature (T1/2) is crucial for their practical applications, which rely on precise manipulation of the substituents of SCO coordinating ligands and molecular packing interactions. In this study, we designed two different bridging ligands (2-FDPB: 4,4′-(2-fluoro-1,4-phenylene)dipyridine; 2,3-FDPB: 4,4′-(2,3-difluoro-1,4-phenylene)dipyridine) featuring one and two fluoro substitution on the central benzene ring and applied a Schiff base-like equatorial tetradentate ligand {diethyl(E,E)-2,2′-[4,5-difluoro-1,2-phenyl-bis(iminomethylidyne)]bis(3-oxobutanoate)-(2-)-N,N′,O3,O3′} (H2L) to coordinate with the FeII ion. Two FeII-coordination chain polymers [FeII(L)(2,3-FDPB)]·0.25CH2Cl2 (1) and [FeII(L)(2-FDPB)]·0.5CH3OH (2) were obtained. 1 crystallizes in the monoclinic P21/n space group with only one FeII center, while 2 crystallizes in the triclinic P[1 with combining macron] space group with two independent FeII centers. Unlike the identical 2D layer stacking in 1, 2 exhibited alternating stacking of the extending 2D layers and meshed chains. Magnetic measurements revealed the typical thermally induced spin crossover behavior (SCO): 1 exhibited a 41 K-wide thermal hysteresis with transition temperatures of T1/2↑ = 245 K and T1/2↓ = 204 K, while 2 showed a higher transition temperature (T1/2 = 330 K) with no thermal hysteresis. Magneto-structural correlation studies suggest that the electron-withdrawing effect present in the fluoro substituents does not have a significant impact on the SCO behaviors. Despite the fluoro substituents having a similar atomic radius of hydrogen atoms, variations in the number of these substituents can alter the crystallization behavior of these complexes, which in turn affects the solvents, molecular stacking patterns, and intermolecular interactions, ultimately influencing the SCO behaviors.

Graphical abstract: Effects of mono- or di-fluoro-substitution on spin crossover behavior in a pair of Schiff base-like FeII-coordination polymers

Supplementary files

Article information

Article type
Paper
Submitted
14 Apr 2024
Accepted
27 Jul 2024
First published
30 Jul 2024

Dalton Trans., 2024,53, 14692-14700

Effects of mono- or di-fluoro-substitution on spin crossover behavior in a pair of Schiff base-like FeII-coordination polymers

Y. Luo, R. Zhou, Z. Shao, D. Liu, H. Lu, M. Shang, L. Zhao, T. Liu and Y. Meng, Dalton Trans., 2024, 53, 14692 DOI: 10.1039/D4DT01103A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements