Here we present the synthesis and characterization of a hybrid vanadium-organic coordination polymer with robust magnetic order, a Curie temperature TC of ∼110 K, a coercive field of ∼5 Oe at 5 K, and a maximum mass magnetization of about half that of the benchmark ferrimagnetic vanadium(tetracyanoethylene)~2 (V·(TCNE)~2). This material was prepared using a new tetracyano-substituted quinoidal organic small molecule 7 based on a tricyclic heterocycle 4-hexyl-4H-pyrrolo[2,3-d:5,4-d′]bis(thiazole) (C6-PBTz). Single crystal X-ray diffraction of the 2,6-diiodo derivative of the parent C6-PBTz, showed a disordered hexyl chain and a nearly linear arrangement of the substituents in positions 2 and 6 of the tricyclic core. Density functional theory (DFT) calculations indicate that C6-PBTz-based ligand 7 is a strong acceptor with an electron affinity larger than that of TCNE and several other ligands previously used in molecular magnets. This effect is due in part to the electron-deficient thiazole rings and extended delocalization of the frontier molecular orbitals. The ligand detailed in this study, a representative example of fused heterocycle aromatic cores with extended π conjugation, introduces new opportunities for structure–magnetic-property correlation studies where the chemistry of the tricyclic heterocycles can modulate the electronic properties and the substituent at the central N-position can vary the spatial characteristics of the magnetic polymer.

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Published in RSC Advances, v. 8, issue 63, p. 36223-36232.

This journal is © The Royal Society of Chemistry 2018

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.

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This work was supported by the Center for Emergent Materials, an NSF MRSEC under award number DMR-1420451, NSF DMR-1523611, and Infrastructure Seed Award (NSF Grant #IIA-1301346). We acknowledge the NSF MRI Program (CHE-1726652) and the UNT for supporting the acquisition of the Rigaku XtaLAB Synergy-S X-ray diffractometer. The computational work at the University of Kentucky (UK) was supported in part by start-up funds received from the UK Vice President for Research and the UK Center for Applied Energy Research (CAER).

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Electronic supplementary information (ESI) available. CCDC 1819816, 1819817 and 1868490 for compounds 5, 6 and 7, respectively. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8ra05697h

c8ra05697h1.pdf (890 kB)
Supplementary information

c8ra05697h2.cif (261 kB)
Crystal structure data