Proton-induced fluorescence in modified quino[7,8-h]quinolines: dual sensing for protons and π-donors

Abstract

Expanded quino-quinoline and quinazolino-quinazoline ligands change their emission upon protonation and π-coordination, model proton transfer and work in biphasic solvent systems.

Synthesis and Basicity Studies of Quinolino[7,8-h]quinoline Derivatives

“…Quinolino­[7,8- h ]­quinoline is a fused ring system, considered to be two quinoline heterocyclic ring systems fused together. While prior publications have used the prefix quino- for the quinoline ring system, − ,− ,, we have adopted the quinolino- nomenclature because of updated IUPAC recommendations no longer listing quino- as an accepted contracted prefix . The naming of this compound is based on the numbering of the parent and substituent quinoline molecules (Figure a). − Fusion occurs at the face or two-atom bond, labeled h on the parent quinoline.…”

“…20,21 However, while there are >45,000 hits in SciFinder for unsubstituted phenanthroline-metal complexes, there are less than 20 for quinolinoquinolines (with any substitution pattern). 22 There are undoubtedly two compelling reasons for this disparity. The first is one of access.…”

“…The first is one of access. The synthesis of quinolinoquinoline 2 and its derivatives is not simple, and there has been a low supply of these compounds. ,− The second relates to coordination environment. The five-membered ring formed on coordination of phenanthroline to a metal 4 can accommodate a wide range of metals with little distortion to either the ligand or the metal.…”

“…This paper outlines the current state of syntheses of substituted quinolinoquinolines. ,,− As the basicity of these compounds influences their synthesis and complexation, a study of the basicity of these compounds as determined by p K aH values would be highly informative, and thus, an investigation of both computationally derived and experimentally obtained p K aH values has been undertaken and are provided.…”

Acid catalysis through N-protonation in undistorted carboxamides: improvement of amide proton sponge acylating ability

“…The choice of model 10a instead of model 9a is due to its smaller size, which generally makes model 10a more convenient to study. Among the considered parameters, the first group is geometric parameters: hydrogen bond length NHÁ Á ÁN (r 3 ), hydrogen bond angle NHÁ Á ÁN (a), distance NÁ Á ÁN between the NMe 2 group nitrogen and the amide nitrogen (r 1 ; good descriptor for peri-interactions [37][38][39][40] ), the torsional angle N 1 C 2 C 3 N 4 (o), the angle w N showing amide nitrogen pyramidalization, the angle of rotation around the amide bond t, the sum of w N and t parameters (Winkler-Dunitz parameter, 41 y), and the amide bond length C-N (r 2 ). The second group is electronic and energetic parameters: hydrogen bonding energy NHÁ Á ÁN (E HB ), charges on the carbonyl carbon atom C 5 -charge from natural population analysis (q NPA ), Merz-Kollman charge (q MK ), Hirshfeld charge (q H ), and chemical shift on the carbonyl carbon atom C 5 (d).…”