Donor–acceptor interaction-mediated arrangement of hydrogen bonded dimers

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 and are incorporated with one ureidopyrimidone unit and one electron deficient pyromellitic diimide (PDI) or naphthalene diimide (NDI) unit, respectively, monomers and are incorporated with two ureidopyrimidone units and one PDI or NDI unit, respectively, whereas monomers and 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 and exist exclusively as homodimers, respectively. Adding 1 equiv. of to the solution of · and · induced them to partially or fully dissociate to produce heterodimers · and · due to intermolecular donor–acceptor interaction and the formation of a new binding mode between the ureidopyrimidone of or and the 2,7-diamido-1,6-naphthyridine unit of . Both and exist as cyclic monomer and dimer in chloroform. Adding 1 equiv. of to the solution of or in chloroform caused all the cyclic dimer and most of the cyclic monomer to de-cyclize to form new heterodimers · and ·, respectively. 1H NMR and UV–vis study revealed that heterodimer · has a structure in which the PDI of is not threaded through the cavity of the bis-p-phenylene[34]crown-10 unit of . In contrast, in addition to the heterodimer similar to ·, about 40% of heterodimer · is generated, in which the PDI of is threaded through the cavity of the bis-p-phenylene[3]crown-10 unit of 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.