X-ray and vibrational studies of 8-aminoquinoline. Evidence for a three-center hydrogen bond

Abstract

The x-ray structure of 8-aminoquinoline indicates that one of the NH bonds of the NH 2 group forms a three-center hydrogen bond, the major component being the intramolecular hydrogen bond and the minor component the intermolecular hydrogen bond. The IR and Raman spectra of 8-aminoquinoline and of its N-deuterated counterpart reflect the non-equivalence of the two NH(D) bonds and the weakness of the hydrogen bridge. ©

Bis(azido-κ N )bis(quinolin-8-amine-κ 2 N , N ′)iron(II) monohydrate

“…N-C and C-C bond lengths and angles in the quinoline ring systems of the two ligands (labeled with suffixes A and B; Fig. 4) are comparable to those of the pure AQ molecule (van Meervelt et al, 1997) or the AQ molecules in the unhydrated Fe II complex (Setifi, Moon et al, 2016) as are the bond lengths and angles of the attached NH 2 groups. Both amine groups act as hydrogen donors in hydrogen bonds to the oxygen atom O1 of the water molecule and to the terminal nitrogen atoms of the azide ligands: N2A to the N6 atom of the second azide ion and N2B to N3 of the first one.…”

Role of Topological Charge Stabilization in Protomeric Tautomerism

“…Neutron diffraction, refs and . j See reviews in refs and . k X-ray, ref . l References and . Speculation on imino form in ref is probably incorrect. m Reference . n Reference . o Reference . p References and . q Reference . r References and . s All the aminoquinolines are detected by fluorescence to be amino-type, not imino type. All the enol and keto types of aminoquinoline are also distinguished by low p K a (<10, see ref ). …”

8-Aminoquinoline Functionalized Silica Nanoparticles: A Fluorescent Nanosensor for Detection of Divalent Zinc in Aqueous and in Yeast Cell Suspension

“…The fluorescence emission intensity of 6 increases approximately 2.8-fold with a redshift of 55 nm upon addition of 1.0 μM Zn(II), and the quantum yield of the Zn(II) complex was calculated to be 0.1204. Within the ligand framework, the excited state proton transfer in combination with intramolecular PET causes the fluorescence to suppress, resulting in a low quantum yield. ,, Zn(II), however, can interrupt this excited state proton transfer in 8-aminoquinoline and its derivatives, and by blocking the PET process a fluorescence enhancement is observed along with an increase in the quantum yield. Zn(II), as against other late transition metals, is not capable of one-electron redox activity and, having a filled d- shell, cannot participate in electron transfer or energy transfer mechanisms …”