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Abstract Co‐crystallization of the spin‐crossover (SCO) cationic complex, [Fe(1‐bpp)2]2+(1‐bpp=2,6‐bis(pyrazol‐1‐yl)pyridine) with fractionally charged organic anion TCNQδ−(0<δ<1) afforded hybrid materials [Fe(1‐bpp)2](TCNQ)3.5 ⋅ 3.5MeCN (1) and [Fe(1‐bpp)2](TCNQ)4 ⋅ 4DCE (2), where TCNQ=7,7,8,8‐tetracyanoquinodimethane, MeCN=acetonitrile, and DCE=1,2‐dichloroethane. Both materials exhibit semiconducting behavior, with the room‐temperature conductivity values of 1.1×10−4 S/cm and 1.7×10−3 S/cm, respectively. The magnetic behavior of both complexes exhibits strong dependence on the content of the interstitial solvent. Complex1undergoes a gradual temperature‐driven SCO, with the midpoint temperature ofT1/2=234 K. The partial solvent loss by1leads to the increase in theT1/2value while complete desolvation renders the material high‐spin (HS) in the entire studied temperature range. In the case of2, the solvated complex shows a gradual SCO withT1/2=166 K only when covered with a mother liquid, while the facile loss of interstitial solvent, even at room temperature, leads to the HS‐only behavior.
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Versatile Nickel(II) Scaffolds as Coordination‐Induced Spin‐State Switches for 19 F Magnetic Resonance‐Based Detection
Abstract 19F magnetic resonance (MR) based detection coupled with well‐designed inorganic systems shows promise in biological investigations. Two proof‐of‐concept inorganic probes that exploit a novel mechanism for19F MR sensing based on converting from low‐spin (S=0) to high‐spin (S=1) Ni2+are reported. Activation of diamagneticNiL1andNiL2by light or β‐galactosidase, respectively, converts them into paramagneticNiL0, which displays a single19F NMR peak shifted by >35 ppm with accelerated relaxation rates. This spin‐state switch is effective for sensing light or enzyme expression in live cells using19F MR spectroscopy and imaging that differentiate signals based on chemical shift and relaxation times. This general inorganic scaffold has potential for developing agents that can sense analytes ranging from ions to enzymes, opening up diverse possibilities for19F MR based biosensing.
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- Award ID(s):
- 1945401
- PAR ID:
- 10237012
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 59
- Issue:
- 50
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 22523-22530
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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