One‐Pot Synthesis and Photophysical Studies of Styryl‐Based Benzo[f]pyrazolo[3,4‐b]quinoline and Indeno[2,1‐b]pyrazolo[4,3‐e]pyridines

Abstract

A new family of extended π‐conjugated dihydrobenzopyrazoloquinoline (DBPQ) and dihydroindenopyrazolopyridine (DIPP) molecules were synthesized, and their photophysical and electrochemical properties were studied. The DBPQ derivatives showed significantly higher molar absorption coefficients, and their absorption and emission wavelengths were red‐shifted with respect to those of the corresponding DIPP derivatives in chloroform solution. Dyes with no substitution and methoxy, nitro, and fluoro‐substituted derivatives showed poor dependence on solvent polarity. At the same time, DBPQ and DIPP derivatives with dimethylamino groups exhibited strong solvatochromism in the emission spectra. Due to the presence of a vinyl link with a cylindrical π‐cloud on the donor (dimethylamino group) molecule, they showed efficient positive solvatochromism with high quantum yields on increasing solvent polarity from non‐polar to polar solvents. Aggregation‐induced emission (AIE) properties were also investigated. AIE studies show that the emission of DBPQ and DIPP derivatives in the presence of THF/H2O mixture increased due to aggregation. However, DBPQ and DIPP derivatives were still strongly emissive in the solid state. Dimethylamino substituted derivatives exhibited acidochromism, which was caused by the addition of TFA and pTsA leading to prominent red‐shifts in the emission spectra owing to the protonation at the pyridine segment.

Synthesis of Pentacyclic Pyran Fused Pyrazolo Benzo[h]quinolines by Multicomponent Reaction and Their Photophysical Studies

“…Quantum yields were found in the range 0.243-0. Based on the literature reports, [20][21][22] we have proposed the mechanism for this three-component reaction for the synthesis of pentacyclic pyran fused pyrazolo benzo All spectra were recorded in CHCl 3 solution (c = 10 À 5 M) at room temperature.…”

“…Similarly, pyrazolo quinolines are another important fused heterocycles having wide applications in biological, [15][16] medicinal [17][18] and material chemistry. [19][20] Considering the huge potential of polycyclic pyrazole-fused heterocycles, over the years, several methods have been developed for their synthesis. Rajesh et al developed a Lproline catalysed sequential four-component reaction of 3-aminocrotononitrile, phenyl hydrazine, aromatic aldehydes and 2-hydroxy-1,4-naphthoquinone in water for the one-pot synthesis of fused ortho-quinones.…”

A novel fluorescent probe with a pyrazolo[4,3-c]quinoline core selectively recognizes c-MYC promoter G-quadruplexes

“…Generally, an ideal G-quadruplex fluorescent probe is assumed to consist of a fluorescent signaling unit specifically recognizing the G-quadruplex structure. Pyrazoloquinolines have been shown to be efficient organic emitters, [16][17][18] with applications in fluorescence sensing 19,20 and electroluminescence. 21 Recently, a derivative of this class of compounds showed a selective binding to human telomeric G4 multimers over monomeric ones.…”

Chemistry of Quinoline Based Heterocycle Scaffolds: A Comprehensive Review

“…Compounds pyrazolomine (237) , substituted cinnamaldehyde 238(a – e) and cyclic ketones (239) were condensed in presence of SnCl 2 catalyst, AcOH and ethyl alcohol with refluxing. This process takes place via formation of benzylidine intermediate followed by elimination and cylclisation to synthesise compound (240) [64] . (Scheme 49 )…”