Two Pairs of Chiral “Tower‐Like” Ln 4 Cr 4 (Ln=Gd, Dy) Clusters: Syntheses, Structure, and Magnetocaloric Effect

Two pairs of novel chiral chromium lanthanide compounds, formulated as l ‐ and d ‐[Gd 4 Cr 4 (IN) 10 (μ 3 ‐OH) 4 (μ 4 ‐O) 4 (H 2 O) 12 ] ⋅ [IN] 2 ⋅ 8 H 2 O ( 1 and 3 ), and l ‐ and d ‐[Dy 4 Cr 4 (IN) 11 (μ 3 ‐OH) 4 (μ 4 ‐O) 4 (H 2 O) 8 ] ⋅ [IN] ⋅ 1.5 H 2 O ( 2 and 4 ) (HIN=isonicotinic acid) have been successfully synthesized and characterized. Structural analysis reveals that four Ln 3+ ions and four Cr 3+ ions connect with each other and yield a “tower‐like” [Ln 4 Cr 4 ] skeleton. Apart from the above featuring an aesthetically charming structure, circular dichroism (CD) spectra confirm that compounds 1 and 3 , 2 and 4 are enantiomers. To the best of our knowledge, these are the largest chiral chromium lanthanide compounds. In addition, magnetic interaction shows that Gd (the mixture of 1 and 3 ) exhibits significant cryogenic magnetocaloric effect (MCE) with −Δ S m =18.08 J kg −1  K −1 (34.69 mJ cm −3  K −1 ). Also, the observed second‐harmonic generation efficiencies of [Gd 4 Cr 4 (IN) 10 (μ 3 ‐OH) 4 (μ 4 ‐O) 4 (H 2 O) 12 ] ⋅ [IN] 2 ⋅ 8 H 2 O and [Dy 4 Cr 4 (IN) 11 (μ 3 ‐OH) 4 (μ 4 ‐O) 4 (H 2 O) 8 ] ⋅ [IN] ⋅ 1.5 H 2 O are 0.3 and 0.4 times that of urea, respectively.