Ln8 (Ln= Gd, Ho, Er, Yb) Butterfly Core‐Exhibiting Magnetocaloric Effect and Field‐Induced SMM Behavior for Er Analouge. Issue 34 (7th December 2017)

• Record Type: Journal Article
• Authors: Bala, Sukhen; Adhikary, Amit; Bhattacharya, Sudeshna; Bishwas, Mousumi Sen; Poddar, Pankaj; Mondal, Raju
• Is Part Of: ChemistrySelect. Volume 2:Issue 34(2017)
• Page Start: 11341
• Page End: 11345
• Publication Date: 2017-12-07
• Subjects: Cluster -- Lanthanide -- Magnetism -- Magnetocaloric effect -- SMM; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201701905
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: In this article, we report four pyridyl‐pyrazolyl based polynuclear cluster complexes with Ln8 {Ln=[Gd III 8 (μ3 ‐OH)4 (L1 )4 (DEA)4 Cl4 ](DMF)2 (MeOH)(1), [Ho III 8 (μ3 ‐OH)4 (L1 )4 (DEA)4 Cl4 ](2), [Er III 8 (μ3 ‐OH)4 (L1 )4 (DEA)4 Cl4 ](DMF)(MeOH)(H2 O)(3 ), [Yb III 8 (μ3 ‐OH)4 (L1 )4 (DEA)4 Cl4 ](DMF)(MeOH)(4 ) [DEA = Diethanolamine] cores. The impetus for this study was to explore the magnetic behaviour of lanthanide ions which are often ignored or overlooked. X‐ray crystal analysis show that these complexes are isostructural and exhibit an interesting butterfly like topology. The semi‐rigidity and asymmetric nature of the ligand led to different coordination environment around the metal centres. The lanthanide ions adopt two types of geometry, a bicapped trigonal prism and a distorted square antiprismatic geometry around the metal center. Such dissimilar coordination environments around the lanthanide centre can have profound effects on their magnetic behaviour. Indeed, the magnetic measurements revealed significant magnetocaloric effect for octanuclear gadolinium complex1 with magnetic entropy change (−ΔSm ) of 31.4 J kg −1 K −1 for ΔH = 9 T at T = 3 K whereas Er analogue complex3 displayed SMM behavior. Abstract : Here we report four lanthanide cluster complexes with octanuclear butterfly cores using an asymmetric pyridyl‐pyrazolyl based ligand fitted with a semi‐rigid backbone. The magnetic measurement of complex1 reveals a significant magnetocaloric effect with a moderately high magnetic entropy change (−ΔSm) of 31.4 J kg−1 K−1 for ΔH=9 T at T=3 K. On other hand, complex3 containing Er, the metal ion that is often overlooked, displayed SMM behaviour with slow magnetic relaxation.