Solvent influence on the orthogonality of noncovalently functionalized terpolymers

Poly(norbornene) terpolymers containing palladated sulfur-carbon-sulfur (SCS) pincer complexes, cyanuric acid, and thymine moieties in their side-chains were synthesized by ring-opening metathesis polymerization. Functionalization of the terpolymers was achieved by self-assembling (i) the Hamilton wedge to the cyanuric acid receptor, (ii) diaminopyridine to the thymine receptor, and (iii) pyridine to the palladated pincer complexes. While all three noncovalent interactions are fully orthogonal to each other in dichloromethane, the employment of a dioxane/chloroform solvent mixture results in the quantitative disassembly of one of the hydrogen bonding recognition units (the Hamilton wedge:cyanuric acid pair) during the metal-coordination event. This disassembly is completely independent from the diaminopyridine: thymine hydrogen-bonding pair and allows for the selective removal of one of the side-chain functionalities. This removal occurs with a switch-type mechanism: as one functionality is put on (the pyridine), another one (the Hamilton-wedge receptor) is taken off quantitatively. (C) 2008 Wiley Periodicals, Inc.