Supramolecular control of the template-induced selective photodimerization of 4-methyl-7-O-hexylcoumarin.
A symmetric ditopic molecular receptor (3), containing two identical hydrogen-bonding recognition subunits, was designed and synthesized. These subunits are capable of binding substrates with complementary donor and acceptor sites to form a supramolecular complex through hydrogen bonding. Receptor 3 was designed to accept two guest molecules, which are held in close proximity within the supramolecular species. The substrate molecule, 4-methyl-7-O-hexylcoumarin (1 c), forms a 2:1 complex with a binding constant of 150 m(-1) for the second substrate, passing first through a 1:1 complex with an affinity constant of 510 m(-1). The orientation of two molecules of 1 c when bound to the template leads to the selective formation of the trans-syn [2+2] photoproduct 2 cB upon irradiation. Other photoproducts typically produced in the absence of the template are suppressed.
Skene
William G
WG
Laboratoire de Chimie Supramoléculaire, ISIS-Université Louis Pasteur, 8 allée Gaspard Monge, BP 70028, 67083 Strasbourg cedex, France.
Couzigné
Emilie
E
Lehn
Jean-Marie
JM
D003374:Coumarins / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D010777:Photochemistry
D003374:Coumarins