M₆L₁₂ Nanospheres with Multiple C₇₀ Binding Sites for ¹O₂ Formation in Organic and Aqueous Media

Abstract

Singlet oxygen is a potent oxidant with major applications in organic synthesis and medicinal treatment. An efficient way to produce singlet oxygen is the photochemical generation by fullerenes which exhibit ideal thermal and photochemical stability. In this contribution we describe readily accessible M6L12 nanospheres with unique binding sites for fullerenes located at the windows of the nanospheres. Up to four C70 can be associated with a single nanosphere, presenting an efficient method for fullerene extraction and application. Depending on the functionality located on the outside of the sphere, they act as vehicles for 1O2 generation in organic or in aqueous media using white LED light. Excellent productivity in 1O2 generation and consecutive oxidation of 1O2 acceptors using C70⊂[Pd6L12], C60⊂[Pd6L12] or fullerene soot extract was observed. The methodological design principles allow preparation and application of highly effective multifullerene binding spheres.

The Biologically Inspired Abilities of Metallosupramolecular Architectures

“…[72] Very recently, Reek and coworkers reported M 6 L 12 nano-spheres that were able to bind multiple C 70 fullerene molecules in different pockets around the structures (Figures 6a and b). [73] Fullerene is known to act as a provider of singlet oxygen [74] -a powerful oxidizing agent with applications in clinical photodynamic therapy [71] -but has limited solubility in many organic solvents and is not soluble in water, hampering potential medical uses. By binding fullerene molecules the cage was able to solubilize them in a wide range of solvents and most importantly in aqueous media forming up to 1 : 4 host-guest adduct(s).…”

“…Reek and coworkers Pt(II) metallosphere. [73] A) Structure of ligand and scheme of formation for metallosphere and MMFF model. B) Encapsulation of C 70 fullerene (yellow sphere) by architecture forming a 1 : 4 host-guest complex.…”

“…Figure 6. Reek and coworkers Pt(II) metallosphere [73]. A) Structure of ligand and scheme of formation for metallosphere and MMFF model.…”

Chiral Self‐Sorting in Pd6L12 Metal‐Organic Cages

“…Coordination-driven self-assembly of certain bis-4-pyridyl ligands with Pd(II) ions are known to afford [Pd 6 L 12 ] 12 + cages. [24][25][26][27][28][29] Among them, chiral [Pd 6 L 12 ] 12 + cages are only a few, [24,30] and chiral self-sorting hasn't been examined from the racemic mixture of chiral ligands. Appropriately designed racemic mixture of the ligands can result in either high fidelity chiral narcissistic self-sorting to form a racemic mixture of homochiral cages, or chiral social self-sorting to form any heterochiral cages from several possible combinations of R and S isomers of the ligands in the ratio of 11 : 1, 10 : 2, 9 : 3, 8 : 4, 7 : 5 and 6 : 6, or a statistical mixture.…”

“…Coordination‐driven self‐assembly of certain bis‐4‐pyridyl ligands with Pd(II) ions are known to afford [Pd 6 L 12 ] 12+ cages [24–29] . Among them, chiral [Pd 6 L 12 ] 12+ cages are only a few, [24,30] and chiral self‐sorting hasn't been examined from the racemic mixture of chiral ligands.…”