Synthesis, Spectral Studies and Quantum-Chemical Investigations on the Powerful Fluorophores: Imidazo[4,5-a]acridines

Abstract

The new 3H-imidazo[4,5-a]acridine-11-carbonitriles were prepared from the reaction of 1-alkyl-5-nitro-1H-benzoimidazoles with 2-(4-methoxyphenyl)acetonitrile and benzyl cyanide by nucleophilic substitution of hydrogen in high yields. Physical spectral and analytical data have confirmed the structures of the synthesized dyes. The optical and solvatochromic properties of these compounds were investigated and the results showed that they show very interesting photophysical properties. Density functional theory (DFT) calculations of fluorescent dyes were performed to provide the optimized geometries and relevant frontier orbitals. Furthermore, intra- and intermolecular interactions in fluorescent imidazo[4,5-a]acridines were evaluated by AIM (Atoms in Molecules) analysis.

Synthesis, characterisation, optical properties and theoretical calculations of a new fluorescent heterocyclic system: 3H-benzo[a]pyrazolo[3,4-j]acridine

“…Based on our previous experiences that acridine moieties exhibit very interesting fluorescence properties, 18,19,21 compounds 3a-d were characterised by UV-Vis and fluorescence spectroscopy in the wavelength range of 200-1000 nm. Figure 1 shows the visible absorption and emission spectra of compounds 3a-d and numerical spectral data are presented in Table 1.…”

“…We recently focused on the synthesis of new fluorescent heterocyclic compounds [18][19][20][21][22] and the development of their application. 23 Prompted by the abovementioned optical properties of acridine and pyrazole heterocycles, we herein report a synthesis of a new pentacyclic heterocyclic system, the 3H-benzo[a]pyrazolo [3,4-j]acridines, with the purpose of studying their spectral and fluorescence properties.…”

Theoretical Investigation on the Kinetics and Mechanism of the Synthesis of Fluorescent 3,8-Disubstituted-3H-Imidazo [4,5-a] Acridine-11-Carbonitriles

“…Imidazo [4,5-a]acridones (imidazo [4,5-a]acridin-11(6H)-ones) and imidazo [4,5-a]acridines are found to exhibit very high activities against Escherichia coli HB101 (BA-7601C), Staphylococcus aureus (PTCC-1074), Pseudomonas aeruginosa (PTCC 1431), and Bacillus subtilis (PTCC 1365), comparable to streptomycin as a reference drug [15]. Also, substituted-3H-imidazo[4,5-a]acridine-11-carbonitriles show very interesting fluorescence properties with high quantum yields [16][17][18]. To the best of our knowledge, no detailed theoretical study has been reported on the proposed mechanism to explain the formation of the substituted-3H-imidazo[4,5-a]acridine-11-carbonitriles or similar compounds.…”