Donor–acceptor interaction-mediated arrangement of hydrogen bonded dimers

Abstract

The donor–acceptor interaction-driven supramolecular arrangement of a new series of quadruply hydrogen-bonded homo- and heterodimers have been investigated in chloroform with 1H NMR and UV–Vis spectroscopy. Two kinds of structurally complementary monomers have been prepared. Monomers 3 and 4 are incorporated with one ureidopyrimidone unit and one electron deficient pyromellitic diimide (PDI) or naphthalene diimide (NDI) unit, respectively, monomers 5 and 6 are incorporated with two ureidopyrimidone units and one PDI or NDI unit, respectively, whereas monomers 7 and 8 consist of one electron rich bis- p-phenylene[34]crown-10 unit and one or two 2,7-diamido-1,6-naphthyridine units, respectively. Compounds 3 and 4 exist exclusively as homodimers, respectively. Adding 1 equiv. of 7 to the solution of 3 · 3 and 4 · 4 induced them to partially or fully dissociate to produce heterodimers 3 · 7 and 4 · 7 due to intermolecular donor–acceptor interaction and the formation of a new binding mode between the ureidopyrimidone of 3 or 4 and the 2,7-diamido-1,6-naphthyridine unit of 7 . Both 5 and 6 exist as cyclic monomer and dimer in chloroform. Adding 1 equiv. of 8 to the solution of 5 or 6 in chloroform caused all the cyclic dimer and most of the cyclic monomer to de-cyclize to form new heterodimers 5 · 8 and 6 · 8 , respectively. 1H NMR and UV–vis study revealed that heterodimer 5 · 8 has a structure in which the PDI of 5 is not threaded through the cavity of the bis- p-phenylene[34]crown-10 unit of 8 . In contrast, in addition to the heterodimer similar to 5 · 8 , about 40% of heterodimer 6 · 8 is generated, in which the PDI of 6 is threaded through the cavity of the bis- p-phenylene[3]crown-10 unit of 8 due to the increased donor–acceptor interaction between NDI and bis- p-phenylene[34]crown-10. Steric hindrance and mismatching of the hydrogen bonding moiety play important roles in the arrangement of the new homo- and heterodimers.