Pd(II) Coordination Sphere Engineering: Pyridine Cages, Quinoline Bowls, and Heteroleptic Pills Binding One or Two Fullerenes.

ABSTRACT: Fullerenes and their derivatives are of tremendous technological relevance. Synthetic access and application are still hampered by tedious purification protocols, peculiar solubility, and limited control over regioselective derivatization. We present a modular self-assembly system based on a new low-molecular-weight binding motif, appended by two palladium(II)-coordinating units of different steric demands, to either form a [Pd₂L¹₄]⁴⁺ cage or an unprecedented [Pd₂L²₃(MeCN)₂]⁴⁺ bowl (with L¹ = pyridyl, L² = quinolinyl donors). The former was used as a selective induced-fit receptor for C₆₀. The latter, owing to its more open structure, also allows binding of C₇₀ and fullerene derivatives. By exposing only a fraction of the bound guests' surface, the bowl acts as fullerene protecting group to control functionalization, as demonstrated by exclusive monoaddition of anthracene. In a hierarchical manner, sterically low-demanding dicarboxylates were found to bridge pairs of bowls into pill-shaped dimers, able to host two fullerenes. The hosts allow transferring bound fullerenes into a variety of organic solvents, extending the scope of possible derivatization and processing methodologies.

SUBMITTER: Chen B 

PROVIDER: S-EPMC6609009 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature