Two types of drum-like 30- and 32-metal Cd–Ln nanoclusters [Ln₈Cd₂₄L₁₂(OAc)₄₈] (Ln = Sm (1), Yb (2), Er (3)) and [Er₈Cd₂₂L₁₂(OAc)₃₈(OH)₆] (4) were constructed using a designed Schiff base ligand built around a flexible (CH₂)₇ chain. Hydroxide (OH⁻) anions are found in the structure of 4, indicating that the basic environment favors the formation of the 30-metal cluster. The chromogenic Cd/L components in these clusters can act as efficient sensitizers for lanthanide luminescence. With the Ln(III) centers enclosed within the drum-like structures, 1–4 display the typical emission spectra of lanthanide ions. For the Cd–Er clusters, 3 exhibits better NIR luminescence properties than 4. The long-chain Schiff base ligands show “linear” configurations in these clusters, resulting in the large sizes of 1–4. The drum-like structures of 1–4 have inner cavities with the internal sizes approximately 6 × 11 × 11 Å, and some solvent molecules such as H₂O, MeOH and EtOH are enclosed in the drums. Interestingly, the Cd–Sm cluster 1 shows visible and NIR luminescent sensing of metal cations and exhibits high selectivity to Zn²⁺ and Fe³⁺ ions.

Two types of Zn–Ln nanoclusters [Nd₂Zn₂L₂(L′)₂(OAc)₂(NO₃)₂(H₂O)₂] (1) and [Ln₆Zn₆L₂(L′′)₂O₂(OAc)₁₈] (Ln = Nd (2) and Sm (3)) were prepared using one long Schiff base ligand (H₂L) with a naphthyl backbone and two short polydentate ligands (H₂L′ and H₂L′′). 1 and 2–3 show linear and planar structures with sizes of approximately 10 × 10 × 30 Å and 10 × 15 × 22 Å, respectively. The chromogenic Zn/ligand components can act as efficient sensitizers for lanthanide luminescence, and thus 1–3 show visible and NIR emissions. In these clusters, the Schiff base ligands display a “U-shaped” configuration, which is suitable to form π⋯π interactions and hydrogen bonds with nitro aromatic compounds. Interestingly, Zn–Sm cluster 3 shows visible and NIR luminescence sensing of nitro explosives and exhibits high sensitivity to 1,4-DNB and TNT at the ppb level.

Two 42-metal lanthanide nanorings [Ln₄₂L₁₄(OH)₂₈(OAc)₈₄] (Ln = Nd (1), La (2)) were constructed, and the Nd₄₂ cluster exhibits NIR luminescent sensing of metal cations and nitro explosives.

Two classes of NIR luminescent heterobimetallic d–f nanoclusters [Ln ₆ Cd ₂₄ (L ¹ ) ₁₁ (OAc) ₄₃ (OH)] and [Ln ₄ Zn ₈ (L ² ) ₂ (OAc) ₂₀ (OH) ₄ ] (Ln = Nd and Yb) were prepared using flexible long-chain Schiff base ligands which have (CH ₂ ) ₆ backbones.

Four luminescent 32-metal Cd–Tb nanoclusters, [Tb₈Cd₂₄(L¹)₁₂(OAc)₄₈] (1), [Tb₈Cd₂₄(L²)₁₂(OAc)₄₈] (2), [Tb₈Cd₂₄(L³)₁₂(OAc)₄₈] (3) and [Tb₈Cd₂₄(L²)₁₂(1,4-BDC)₄(OAc)₃₈(OH)₂] (4), were constructed from three specially designed chain-like Schiff base ligands H₂L^1–3 with flexible carbon–carbon backbones containing 5, 6 and 10 methylene units, respectively. The clusters exhibit drum-like structures and can be imaged using transmission electron microscopy (TEM). In addition to the Schiff base ligands (the primary energy transfer donors), four 1,4-BDC bridging units were successfully introduced into the structure of 4. In addition to providing increased structural stability, the 1,4-BDC units act as secondary energy transfer donors providing extra energy for lanthanide luminescence, which results in improved luminescence properties when compared to those of the related Cd–Ln nanoclusters without 1,4-BDC units. In vitro investigations on 4 with SGC and PANC cancer cells revealed an accumulation of the molecular nanoparticles in the cells, as confirmed by confocal microscopy. The cytotoxicity of 4 toward the SGC and PANC cells is moderate (IC₅₀ values of 4 lie in the range of 15–60 μM). ICP-MS analysis reveals that cellular uptakes of 4 in 1000 SGC and PANC cells after treatment for 3 hours are 0.0094 pmol and 0.015 pmol, respectively.

The NIR luminescence sensing responses of a 42-metal lanthanide nanowheel [Yb ₄₂ L ₁₄ (OH) ₂₈ (OAc) ₈₄ ] to anions, especially to fluoride, were investigated.