Chiral Resolution of Spin-Crossover Active Iron(II) [2x2] Grid Complexes

Nithin Suryadevara, Ansgar Pausch, Eufemio Moreno-Pineda, Asato Mizuno, Jochen Bürck, Ananya Baksi, Tim Hochdörffer, Ivan Šalitroš, Anne S. Ulrich, Manfred M. Kappes, Volker Schünemann, Wim Klopper, Mario Ruben

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Chiral magnetic materials are proposed for applications in second-order non-linear optics, magneto-chiral dichroism, among others. Recently, we have reported a set of tetra-nuclear Fe(II) grid complex conformers with general formula C/S-[Fe4L4]8+ (L: 2,6-bis(6-(pyrazol-1-yl)pyridin-2-yl)-1,5-dihydrobenzo[1,2-d : 4,5-d′]diimidazole). In the grid complexes, isomerism emerges from tautomerism and conformational isomerism of the ligand L, and the S-type grid complex is chiral, which originates from different non-centrosymmetric spatial organization of the trans type ligand around the Fe(II) center. However, the selective preparation of an enantiomerically pure grid complex in a controlled manner is difficult due to spontaneous self-assembly. To achieve the pre-synthesis programmable resolution of Fe(II) grid complexes, we designed and synthesized two novel intrinsically chiral ligands by appending chiral moieties to the parent ligand. The complexation of these chiral ligands with Fe(II) salt resulted in the formation of enantiomerically pure Fe(II) grid complexes, as unambiguously elucidated by CD and XRD studies. The enantiomeric complexes exhibited similar gradual and half-complete thermal and photo-induced SCO characteristics. The good agreement between the experimentally obtained and calculated CD spectra further supports the enantiomeric purity of the complexes and even the magnetic studies. The chiral resolution of Fe(II)- [2×2] grid complexes reported in this study, for the first time, might enable the fabrication of magneto-chiral molecular devices.
Original languageEnglish
Pages (from-to)15171-15179
JournalChemistry - A European Journal
Volume27
Issue number61
DOIs
Publication statusPublished - 2 Nov 2021
Externally publishedYes

Funding

This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) through CRC/TRR 88, “Cooperative Effects in Homo- and Hetero-Metallic Complexes (3MET)”. We thank the Karlsruhe Nano Micro Facility (KNMF, www.kit.edu/knmf) for providing access to the instruments at their laboratories. I.Š. acknowledges the financial support from Slovak grant agencies (APVV-19-0087, APVV-18-0197, APVV-18-0016, VEGA 1/0125/18), from institutional sources of the Department of Inorganic Chemistry, Palacký University Olomouc, Czech Republic and from Ministry of Education, Youth and Sports of the Czech Republic under the project CEITEC 2020 (LQ1601) are acknowledged for the financial support. EMP thanks the Panamanian National Systems of Investigators (SNI, SENACYT) for support. We thank Dr. Christoph Zippel and Prof. Stefan Bräse from IOC, KIT for helping us with Chiral HPLC and Polarimeter for our studies. Open Access funding enabled and organized by Projekt DEAL. This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) through CRC/TRR 88, “Cooperative Effects in Homo‐ and Hetero‐Metallic Complexes (3MET)”. We thank the Karlsruhe Nano Micro Facility (KNMF, www.kit.edu/knmf ) for providing access to the instruments at their laboratories. I.Š. acknowledges the financial support from Slovak grant agencies (APVV‐19‐0087, APVV‐18‐0197, APVV‐18‐0016, VEGA 1/0125/18), from institutional sources of the Department of Inorganic Chemistry, Palacký University Olomouc, Czech Republic and from Ministry of Education, Youth and Sports of the Czech Republic under the project CEITEC 2020 (LQ1601) are acknowledged for the financial support. EMP thanks the Panamanian National Systems of Investigators (SNI, SENACYT) for support. We thank Dr. Christoph Zippel and Prof. Stefan Bräse from IOC, KIT for helping us with Chiral HPLC and Polarimeter for our studies. Open access funding enabled and organized by Projekt DEAL.

FundersFunder number
Department of Inorganic Chemistry
Karlsruhe Institute of Technology
Deutsche ForschungsgemeinschaftAPVV‐18‐0197, VEGA 1/0125/18, APVV‐18‐0016, APVV‐19‐0087, CRC/TRR 88
Ministerstvo Školství, Mládeže a TělovýchovyLQ1601
Univerzita Palackého v Olomouci
Secretaria Nacional de Ciencia y Tecnología
Sistema Nacional de Investigadores

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