Protonated polycyclic aromatic nitrogen heterocyclics: Proton affinities, polarizabilities, and atomic and ring charges of 1-5-ring ions was written by Maclagan, Robert G. A. R.;Gronert, Scott;Meot-Ner, Michael. And the article was included in Journal of Physical Chemistry A in 2015.Electric Literature of C8H6N2 This article mentions the following:
Calculated proton affinities, polarizabilities, and some ionization energies and at. and ring NBO charges are reported for 31 polycyclic aromatic nitrogen heterocyclics (PANHs) with 1-5 rings, calculated on the on the M06-2X/6-311+g**//B3LYP/6-31g* level of theory. The calculated proton affinities from 226 to 241 kcal mol-1 for 3-5-ring compounds, predict well the relative exptl. values. The proton affinities increase with increasing mol. size and show a linear correlation with polarizabilities. Linear geometry and nitrogen located in the central ring also favor increased proton affinity. These trends estimate a PA > 241 kcal mol-1 for an infinite linear chain, end-ring-N PANH mol., and >261 kcal mol-1 for an edge-N-doped graphene sheet, making it a superbase. NBO anal. shows that from pyridineH+ to large 5-ring ions, the N-H nitrogen carries a constant q(N) = -0.46 ± 0.1 charge, and the N-H hydrogen a constant q(H) = 0.43 ± 0.01 pos. charge, similar to the q(H) in NH4+. Overall, the NH group is nearly elec. neutral, and a nearly full pos. charge is distributed on the aromatic hydrocarbon rings of the ions. When the nitrogen is in a central ring, that ring is neg., and the pos. ionic charge is delocalized toward the end rings. When the nitrogen is in an end ring, the ionic charge is distributed more evenly. Increasing proton affinities with increasing polarizability result not from increasing charge transfer from the proton to the aromatic rings, but from increasing delocalization of the transferred charge in the aromatic hydrocarbon rings of the ions. In two-nitrogen compounds, interactions between the ring nitrogens decrease the proton affinities, but this effect decreases in larger ions. In the experiment, the researchers used many compounds, for example, 2,6-Naphthyridine (cas: 253-50-9Electric Literature of C8H6N2).
2,6-Naphthyridine (cas: 253-50-9) belongs to naphthyridine derivatives. The naphthyridines and their derivatives exhibit various types of biological activity, and the organic chemistry has been frequently reviewed. Imidazonaphthyridines have been prepared through a ‘one-pot’ three-component ‘domino’ reaction between the keto-ester, acrolein, and ethylenediamine in presence of 4 Å molecular sieves.Electric Literature of C8H6N2
Referemce:
1,8-Naphthyridine – Wikipedia,
1,8-Naphthyridine | C8H6N2 – PubChem