A rare class of four tetranuclear lanthanide based quadruple stranded helicates namely, [Ln4L4(OH)2](OAc)2·xH2O (Ln = Gd(III)(1), Dy(III)(2) and x = 4, 5 respectively), [Er4L4(OH)2](NO3)2·9H2O (3), and [Dy4L4(NO3)](NO3)2·2CH3OH·H2O (4) were synthesized by employing succinohydrazone derived bis-tridentate ligand (H2L) and characterized. Structures of 1-3 are similar to each other except the nature of counterions and number of lattice water molecules. In 4, a distorted nitrate ion was arranged in a hexagonal manner holding four dysprosium centers in a slightly twisted manner. Because of the symmetrical nature of each complex, the C4 axis crosses the center of helicate resulting a pseudo-D4 coordination environment. Each ligand coordinates to lanthanide centers in helical manner forming mixture of left (Λ) and right (Δ) handed discrete units. Complex 1 exhibits antiferromagnetic exchange interaction between nearby Gd(III) centers and shows magnetic refrigeration (-ΔSm = 24.4 J kg(-1) K(-1) for ΔH = 7 T at 3 K). AC magnetic susceptibility measurements of 2 and 4 demonstrate slow relaxation behavior, with Ueff (effective energy barrier) of 20.5 and 4.6 K, respectively. As per our knowledge, complexes 1, 2, and 4 represent the first examples of aesthetically pleasing quadruple stranded helicates showing potential magnetocaloric effect and single-molecule-magnet-like behavior.

Two europium-based helicates, namely the dinuclear triplestranded helicate [Eu 2 L 3 ] (1) and tetranuclear quadruplestranded helicate [Eu 4 L 4 (NO 3 )] 3+ (2), were achieved by the self-assembly of the succinohydrazone derived bis-tridentate ligand (H 2 L) and Eu 3+ ions in 1:1 and 1:2 ratios, respectively. Both the helicates were characterized by single-crystal X-ray analysis. Structural analysis of both the helicates revealed optically inactive 50:50 mixtures of left-(Λ) and right-hand (Δ) helicates in one unit cell. In 1, both the europium centers [a]