Synthesis, Crystal Structure, Spectroscopic Properties, and DFT Studies of 7,9-Dibromobenzo[h]quinolin-10-ol

Abstract

7,9-Dibromobenzo[h]quinolin-10-ol (1), a benzo[h]quinolin-10-ol derivative, was synthesized and characterized by single-crystal X-ray diffraction. The crystal belongs to monoclinic space group P2 1 /n, with a = 3.9573(4), b = 18.0416(18), c = 15.8210(16) Å, α = 90 • , β = 96.139 (3) • , and γ = 90 • . Compound 1 exhibits an intramolecular six-membered-ring hydrogen bond, from which excited-state intramolecular proton transfer takes place, resulting in a proton-transfer tautomer emission of 625 nm in cyclohexane. The crystal structure is stabilized by intermolecular π-π interactions, which links a pair of molecules into a cyclic centrosymmetric dimer. Furthermore, the geometric structures, frontier molecular orbitals, and potential energy curves (PECs) for 1 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations.

Multi‐Scale Modeling of Surface Second‐Harmonic Generation in Centrosymmetric Molecular Crystalline Materials: How Thick is the Surface?

“…Here, we chose a centrosymmetric material built from 7,9-Dibromobenzo[h]quinolin-10-ol molecules, a benzoquinolin-10-ol derivative, with a monoclinic space group P2 1 /n. [24] The centrosymmetry suggests a vanishing bulk first hyperpolarizability. A possible SHG signal in this material should exclusively come from the broken symmetry at the crystal surface.…”