Molecular properties and H-bonding in N-8-quinolinyl-2-hydroxynaphthaldimine and its Azo-analogue

Schiff bases are important class of molecular materials. in this computational organic chemistry study,the title compounds were exploited by dft/b3lyp based on the experimental studies recommendations by fita (chem. phys. lett.,2005,416,305) and fabian (j. phys. chem. a,2004,108,7603). the mp2 method was compared and showed some differences but with general qualitative agreement. in addition to the o/h-n1 h-bond,the study provides evidence on the involvement of the h-n1 proton in a second h-bond (n2/h-n1) and that it leads to substantial diverse effects on the structures,the nmr chemical shifts,the atomic charges,the orbitals interaction,the tautomerism energies,and the band gaps. examining the nbo results reveals that the n2/h-n1 interaction in the more stable keto-tautomer is critical and can enhance the electron delocalization through the π-system toward both the quinoline and the naphthalene segments. thus,the details are new addition to the h-bond theory. these compounds have several interesting features: 1. they are better conductors at the molecular level than a known schiff base molecular conductor,2. both frontier orbitals distribute over the extended conjugated π-system which permits efficient intermolecular interaction,3. their fluorescence is enhanced significantly after complexation with several metal ions,4. their synthesis is not complicated therefore,they are interesting models and building blocks for a variety of molecular technology applications,specially,switching and electroluminescence devices.