Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights

Abstract Stabilizing large easy‐axis type magnetic anisotropy in molecular complexes is a challenging task, yet it is crucial for the development of information storage devices and applications in molecular spintronics. Achieving this requires a deep understanding of electronic structure and the rel...

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Main Authors: Vijaya Thangaraj, Daniele Sartini, Dipanti Borah, Deepanshu Chauhan, Vasudha Sharma, Lorenzo Sorace, Gopalan Rajaraman, Mauro Perfetti, Maheswaran Shanmugam
Format: Article
Language:English
Published: Wiley 2025-03-01
Series:Advanced Science
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Online Access:https://doi.org/10.1002/advs.202415624
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author Vijaya Thangaraj
Daniele Sartini
Dipanti Borah
Deepanshu Chauhan
Vasudha Sharma
Lorenzo Sorace
Gopalan Rajaraman
Mauro Perfetti
Maheswaran Shanmugam
author_facet Vijaya Thangaraj
Daniele Sartini
Dipanti Borah
Deepanshu Chauhan
Vasudha Sharma
Lorenzo Sorace
Gopalan Rajaraman
Mauro Perfetti
Maheswaran Shanmugam
author_sort Vijaya Thangaraj
collection DOAJ
description Abstract Stabilizing large easy‐axis type magnetic anisotropy in molecular complexes is a challenging task, yet it is crucial for the development of information storage devices and applications in molecular spintronics. Achieving this requires a deep understanding of electronic structure and the relationships between structure and properties to develop magneto‐structural correlations that are currently unexplored in the literature. Herein, a series of five‐coordinate distorted square pyramidal CoII complexes [Co(L)(X2)].CHCl3 (where X = Cl (1), Br (2), or I (3)) is reported, all exhibiting easy‐axis magnetic anicotropy. The size of the zero field splitting axial parameter (D) is quantitatively determined (1 = −72; 2 = −67 and 3 = −25 cm−1) using a cantilever torque magnetometry which is further firmly supported by magnetic susceptibility, and EPR measurements. The study of the magnetization relaxation dynamics reveals field‐induced slow relaxation of magnetization due to the predominant Raman relaxation process. Theoretical calculations on 1–3 and optimized model complexes of 1 reveal insights into the electronic structure and highlight the impact of steric and electronic effects on modulating the D values. Overall, the studies reported pave the way for designing a new generation of CoII complexes with enhanced  axiality and a lower rhombicity.
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spelling doaj-art-3bb23cddcbb844e987571c817aa4adcb2025-08-20T03:27:46ZengWileyAdvanced Science2198-38442025-03-01129n/an/a10.1002/advs.202415624Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical InsightsVijaya Thangaraj0Daniele Sartini1Dipanti Borah2Deepanshu Chauhan3Vasudha Sharma4Lorenzo Sorace5Gopalan Rajaraman6Mauro Perfetti7Maheswaran Shanmugam8Department of Chemistry Indian Institute of Technology Bombay Powai Mumbai Maharashtra 400076 IndiaDipartimento di Chimica “Ugo Schiff” and UdR INSTM Università degli Studi di Firenze Via della Lastruccia 3−13 Sesto Fiorentino 50019 ItalyDepartment of Chemistry Indian Institute of Technology Bombay Powai Mumbai Maharashtra 400076 IndiaDepartment of Chemistry Indian Institute of Technology Bombay Powai Mumbai Maharashtra 400076 IndiaDepartment of Chemistry Indian Institute of Technology Bombay Powai Mumbai Maharashtra 400076 IndiaDipartimento di Chimica “Ugo Schiff” and UdR INSTM Università degli Studi di Firenze Via della Lastruccia 3−13 Sesto Fiorentino 50019 ItalyDepartment of Chemistry Indian Institute of Technology Bombay Powai Mumbai Maharashtra 400076 IndiaDipartimento di Chimica “Ugo Schiff” and UdR INSTM Università degli Studi di Firenze Via della Lastruccia 3−13 Sesto Fiorentino 50019 ItalyDepartment of Chemistry Indian Institute of Technology Bombay Powai Mumbai Maharashtra 400076 IndiaAbstract Stabilizing large easy‐axis type magnetic anisotropy in molecular complexes is a challenging task, yet it is crucial for the development of information storage devices and applications in molecular spintronics. Achieving this requires a deep understanding of electronic structure and the relationships between structure and properties to develop magneto‐structural correlations that are currently unexplored in the literature. Herein, a series of five‐coordinate distorted square pyramidal CoII complexes [Co(L)(X2)].CHCl3 (where X = Cl (1), Br (2), or I (3)) is reported, all exhibiting easy‐axis magnetic anicotropy. The size of the zero field splitting axial parameter (D) is quantitatively determined (1 = −72; 2 = −67 and 3 = −25 cm−1) using a cantilever torque magnetometry which is further firmly supported by magnetic susceptibility, and EPR measurements. The study of the magnetization relaxation dynamics reveals field‐induced slow relaxation of magnetization due to the predominant Raman relaxation process. Theoretical calculations on 1–3 and optimized model complexes of 1 reveal insights into the electronic structure and highlight the impact of steric and electronic effects on modulating the D values. Overall, the studies reported pave the way for designing a new generation of CoII complexes with enhanced  axiality and a lower rhombicity.https://doi.org/10.1002/advs.202415624ab initio calculationscobaltcoordination chemistryEPRtorque magnetometry
spellingShingle Vijaya Thangaraj
Daniele Sartini
Dipanti Borah
Deepanshu Chauhan
Vasudha Sharma
Lorenzo Sorace
Gopalan Rajaraman
Mauro Perfetti
Maheswaran Shanmugam
Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights
Advanced Science
ab initio calculations
cobalt
coordination chemistry
EPR
torque magnetometry
title Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights
title_full Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights
title_fullStr Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights
title_full_unstemmed Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights
title_short Quantifying Magnetic Anisotropy of Series of Five‐Coordinate CoII Ions: Experimental and Theoretical Insights
title_sort quantifying magnetic anisotropy of series of five coordinate coii ions experimental and theoretical insights
topic ab initio calculations
cobalt
coordination chemistry
EPR
torque magnetometry
url https://doi.org/10.1002/advs.202415624
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