Spin-based interdisciplinary research has attracted considerable attention, and various applications in magnetic memory, quantum science, and precision measuring technology have been reported. In this study, we induced a fluorescence property in a spin-active molecule by supramolecular assembly and realized a synergistic modulation of its spin and fluorescence properties. A Saturn-shaped supramolecular complex was synthesized using a spin-active metallofullerene Sc₃C₂@C₈₀ with a fluorescent nanohoop of tetra-benzothiadiazole-based [12]cycloparaphenylene (TB[12]CPP), and its spin and fluorescence properties were comprehensively investigated. Temperature-dependent electron paramagnetic resonance (EPR) spectroscopy and fluorescence analyses were conducted. Synchronous changes in the EPR signals and fluorescence peaks were discovered in the temperature range of 170–290 K. Based on nuclear magnetic resonance observations and theoretical calculations, a temperature-dependent host–guest interaction between Sc₃C₂@C₈₀ and a nanohoop was demonstrated, which explained the synchronous changes in the EPR signals and fluorescence peaks for Sc₃C₂@C₈₀⊂TB[12]CPP. The application of Sc₃C₂@C₈₀ as a molecular spin system to probe the host–guest interaction was also evaluated. These results show that the supramolecular assembly can be used to design advanced spin systems coupled with optical and magnetic behaviors based on paramagnetic and luminescent molecules.

Paramagnetic endohedral metallofullerenes with well protected unpaired spin have potential applications in molecular-scale qubit processing and magnetoreception system. In this study, a paramagnetic metallofullerene Sc₃C₂@C₈₀ dimer with covalently bonded two spin centers was synthesized. Electron paramagnetic resonance (EPR) results further revealed the varied spin-nuclei couplings and paramagnetic property for Sc₃C₂@C₈₀ dimer. Briefly, the Sc₃C₂@C₈₀ dimer in toluene solution shows EPR hyperfine splittings originating from the spin-Sc couplings. However, the Sc₃C₂@C₈₀ dimer in solid state shows the disappearance of hyperfine structure and a single EPR signal caused by its two-spin-center structure. The transformation of EPR signals can be further finely modulated by controlling the dynamic motion of Sc₃C₂@C₈₀ dimer in chloronaphthalene. The Sc₃C₂@C₈₀ dimer with two spin centers possesses varied paramagnetic properties, demonstrating its potential as new magnetic material.

Magneto-luminescent molecules have significant applications in data storage and quantum computing. However, design of these bi-functional molecules coupled with magnetic behavior and photoluminescence is still challenging. In this work, we report a metallofullerene DyErScN@Ⅰ_h-C₈₀ exhibiting single-molecule magnet (SMM) behavior and near-infrared emission. For DyErScN@Ⅰ_h-C₈₀, two functional lanthanide metal ions of Dy³⁺ (SMM function) and Er³⁺ (luminescent function) are integrated inside a fullerene cage using a trimetallic nitride template, and its structure has been unambiguously characterized by single-crystal X-ray diffraction. Magnetic measurements revealed that DyErScN@Ⅰ_h-C₈₀ behaves as a SMM with a blocking temperature up to 9 K resulting from the intramolecular magnetic interaction between Dy³⁺ and Er³⁺ ions. Moreover, DyErScN@Ⅰ_h-C₈₀ exhibits temperature-dependent near-infrared emission around 1.5 µm with multiple splitting peaks from Er³⁺, which arises from the influence of Dy³⁺ ion. This study provides a new strategy to synthesize new magneto-luminescent molecule materials.