Magnetically bistable Co(ii) and Fe(ii) complexes featuring pentyl-decorated pyridyl-benzimidazole ligands: role of isomerism and chirality

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216305%3A26620%2F26%3A0200706" target="_blank" >RIV/00216305:26620/26:0200706 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubs.rsc.org/en/content/articlelanding/2025/qi/d5qi01269d" target="_blank" >https://pubs.rsc.org/en/content/articlelanding/2025/qi/d5qi01269d</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1039/d5qi01269d" target="_blank" >10.1039/d5qi01269d</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Magnetically bistable Co(ii) and Fe(ii) complexes featuring pentyl-decorated pyridyl-benzimidazole ligands: role of isomerism and chirality

Popis výsledku v původním jazyce

Three variants of 2-(pyridine-2-yl)-1H-benzimidazole bidentate ligands, with distinct pentyl substituents (n-pentyl (L1), (2S)-2-methylbutyl (L2S), and (2R)-2-methylbutyl (L2R)), were synthesized and employed to prepare magnetically bistable cobalt(ii) and iron(ii) complexes. The cobalt(ii) complexes [Co(L1)(kappa 2-NO3)2(CH3CN)] (1), [Co(L2S)(kappa 2-NO3)2(H2O)] (2S), [Co(L2R)(kappa 2-NO3)2(H2O)] (2R) and [Co(L2)(kappa 2-NO3)2(H2O)] (2rac) exhibit field supported slow relaxation of magnetisation, while the iron(ii) complexes [Fe(L2S)3](CF3SO3)2H2OCH3NO2C5H12O (3S) and [Fe(L2S)3]1.5H2O (3R) exhibit thermal spin crossover allocated above room temperature. Structural analysis revealed that the heptacoordinated cobalt(ii) complexes adopt a distorted pentagonal bipyramidal geometry, whereas the iron(ii) compounds contain hexacoordinated complex cations. Coordination compounds incorporating the chiral ligands L2S and L2R are optically active, with their enantiomeric relationship confirmed by circular dichroism spectroscopy. Computational studies provided insights into electron density distributions and bonding energetics (DFT and QT-AIM), predicted zero-field splitting parameters (CASSCF/NEVPT2), and quantified energies of the d-orbital, ligand field terms and their multiplets (via AILFT). Magnetic investigations of the cobalt(ii) complexes yielded experimental ZFS parameters and revealed distinct magnetization relaxation mechanisms: 1 exhibits relaxation governed by a phonon bottle-neck process, whereas 2S and 2R involve a combination of Raman and direct relaxation processes. Notably, compounds 2S and 2R, despite being enantiomers and isostructural, exhibited distinct relaxation dynamics, attributable to differential phonon coupling pathways modulated by the chiral substituents. This is the first report demonstrating enantiomer-dependent slow relaxation of magnetisation behaviour in cobalt(ii)-based SMMs. These findings underscore the critical role of stereochemistry in modulating spin dynamics and magnetic bistability, providing design principles for future chiral magnetic materials.

Název v anglickém jazyce

Magnetically bistable Co(ii) and Fe(ii) complexes featuring pentyl-decorated pyridyl-benzimidazole ligands: role of isomerism and chirality

Popis výsledku anglicky

Three variants of 2-(pyridine-2-yl)-1H-benzimidazole bidentate ligands, with distinct pentyl substituents (n-pentyl (L1), (2S)-2-methylbutyl (L2S), and (2R)-2-methylbutyl (L2R)), were synthesized and employed to prepare magnetically bistable cobalt(ii) and iron(ii) complexes. The cobalt(ii) complexes [Co(L1)(kappa 2-NO3)2(CH3CN)] (1), [Co(L2S)(kappa 2-NO3)2(H2O)] (2S), [Co(L2R)(kappa 2-NO3)2(H2O)] (2R) and [Co(L2)(kappa 2-NO3)2(H2O)] (2rac) exhibit field supported slow relaxation of magnetisation, while the iron(ii) complexes [Fe(L2S)3](CF3SO3)2H2OCH3NO2C5H12O (3S) and [Fe(L2S)3]1.5H2O (3R) exhibit thermal spin crossover allocated above room temperature. Structural analysis revealed that the heptacoordinated cobalt(ii) complexes adopt a distorted pentagonal bipyramidal geometry, whereas the iron(ii) compounds contain hexacoordinated complex cations. Coordination compounds incorporating the chiral ligands L2S and L2R are optically active, with their enantiomeric relationship confirmed by circular dichroism spectroscopy. Computational studies provided insights into electron density distributions and bonding energetics (DFT and QT-AIM), predicted zero-field splitting parameters (CASSCF/NEVPT2), and quantified energies of the d-orbital, ligand field terms and their multiplets (via AILFT). Magnetic investigations of the cobalt(ii) complexes yielded experimental ZFS parameters and revealed distinct magnetization relaxation mechanisms: 1 exhibits relaxation governed by a phonon bottle-neck process, whereas 2S and 2R involve a combination of Raman and direct relaxation processes. Notably, compounds 2S and 2R, despite being enantiomers and isostructural, exhibited distinct relaxation dynamics, attributable to differential phonon coupling pathways modulated by the chiral substituents. This is the first report demonstrating enantiomer-dependent slow relaxation of magnetisation behaviour in cobalt(ii)-based SMMs. These findings underscore the critical role of stereochemistry in modulating spin dynamics and magnetic bistability, providing design principles for future chiral magnetic materials.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10402 - Inorganic and nuclear chemistry

Projekt

<a href="/cs/project/GA25-16980S" target="_blank" >GA25-16980S: Pasivace černého fosforu jednomolekulárními magnety</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Inorganic Chemistry Frontiers

ISSN

2052-1553

e-ISSN

—

Svazek periodika

12

Číslo periodika v rámci svazku

24

Stát vydavatele periodika

CN - Čínská lidová republika

Počet stran výsledku

14

Strana od-do

8173-8186

Kód UT WoS článku

001562821400001

EID výsledku v databázi Scopus

2-s2.0-105017824542