Theoretical studies on supramolecular complexes of anthyridone with various diaminopyridine derivatives

391-395At the ground state, the complexes formed by anthyridone (A) and 2,6-diaminopyridine-3,5-dialdehyde (B) derivatives have been studied using the AM1 method to obtain information on the binding energies. The UV, IR and NMR spectra for the complexes have been calculated with the INDO/CIS, AM1 and B3LYP/6-31G methods, respectively. The results demonstrate that the complexes can be formed by the two monomers owing to the negative binding energy. The binding energy increases with the decrease in the intramolecular hydrogen bonds, but decreases with the increase in electron density on monomer B. The bulky group next to the hydrogen bond in monomer A is unfavorable, whereas the electron-donating group without the steric effect is favorable for formation of the hydrogen bonds. The first absorption in the UV spectrum of the complex is red-shifted relative to those of the two monomers. On formation of the hydrogen bonds the stretching vibrations of the N-H bonds are weakened and shift to lower frequencies in the IR spectra. In the NMR spectra, the chemical shifts move downfield