Synthesis and Properties of Polyfluorohydroxyacridines and Their Zn²⁺ Complexes:  New Materials for Solid State Emitting Systems

Abstract

1,2,3,4-tetrafluoroacridines are easily accessible by refluxing electron-rich aromatic amines with pentafluorobenzaldehyde. This procedure, however, fails when 4-hydroxyaniline is employed for the preparation of the corresponding tetrafluorohydroxyacridine. The synthesis of this substrate, here described, has been accomplished by an indirect methodology: the synthesis of the corresponding tetrafluoromethoxyacridine was followed by the ether function cleavage by refluxing them in 47% aqueous HBr. In the case of 1,2,3,4-tetrafluoro-9-methoxyacridine a peculiar reactivity has been observed, indeed the substitution of a fluorine by a bromine atom occurs contemporaneously with the ether hydrolysis. The position of bromine on acridine moiety has been ascertained by X-ray analysis on a single crystal of this compound. The fluorine substitution did not occur when the hydrolysis was carried out employing the ionic liquid triethylammonium eptachloro alluminate. The synthesized polifluorohydroxyacridines have been fully optically and spectroscopically characterized. 1,2,3,4-Tetrafluoro-9-hydroxyacridine and 2-bromo-1,3,4-trifluoro-9-hydroxyacridine were employed to prepare complexes with Zn2+. These complexes were optically characterized by optical absorption and photoluminescence both in solution and in the solid state, and a preliminary discussion about the photophysics of these complexes is presented.

Pentafluorobenzaldehyde and its utilizing in organic synthesis

“…This condensation products undergo S N Ar reactions of ortho-and para-fluorine in the presence of excess arylamine (Scheme 76 [611][612][613][614][615][616][617]). The ratio of two forming product (85, 86a-g) changes depended on the substituents and on amount aniline utilized.…”

Tetrahedral Zinc Complexes with Liquid Crystalline and Luminescent Properties: Interplay Between Nonconventional Molecular Shapes and Supramolecular Mesomorphic Order

“…An important example of the interplay between self-organization and luminescence is the recent report of a copper metallomesogen for security ink applications. 39 Zinc complexes with nitrogen ligands display interesting optical properties for LED devices and sensors, [42][43][44][45][46][47] but the tetrahedral geometry that the metal center usually tends to adopt has proven to be detrimental for mesomorphism. For example, in the extensively studied compounds with salicylaldiminate 48 or diketonate ligands, 16 complexes derived from Pd, Cu, VO, Ni, Fe, or Mn are LCs but the zinc analogs are not, 16,49 probably due to the unfavorable geometry and the lack of additional interactions between the metal centers.…”

Synthesis, Structure and Luminescent Properties of Rare‐Earth‐Metal Oxyacridinates

“…The complexes with Acr Me ligands (Sc (3), La (6), Sm (8), Gd (10) and Yb (12)) are compounds of red-burgundy color and with AcrBr ligands -red-violet color (Sc (4), La (7), Sm (9), Gd (11) and Yb (13)). All compounds are readily soluble in common organic solvents, stable in air in the solid state, while in the solution they decompose within a few minutes.…”

“…The assumption is confirmed by the properties of boron hydroxyacridine complexes which showed good photochemical stability and bright solid-state fluorescence. [11] However the luminescence activity of Mg, [5] Zn, [12] Co, Ni, Cu [13] and Pd [14] complexes was low and caused mainly by ancillary ligands in heteroligand systems. The oxyacridine complexes of Al, Ga and In were also obtained to compare the chelating ability, the steric and electronic properties of 8-hydroxyquinoline and HAcr derivatives.…”