Photocatalytic Reduction of Fluorescent Dyes in Sunlight by Newly Synthesized Spiroindenoquinoxaline Pyrrolizidines

Abstract

Spiroindenoquinoxaline pyrrolizidines (SIQPs)—7-nitro-2′-phenyl-5′,6′,7′,7a′-tetrahydrospiro[indeno[1,2- b ]quinoxaline-11,3′-pyrrolizine]-1′,1′(2′ H )-dicarbonitrile (SIQP I), 2′-(4-cyanophenyl)-7-nitro-5′,6′,7′,7a′-tetrahydrospiro[indeno[1,2- b ]quinoxaline-11,3′-pyrrolizine]-1′,1′(2′ H )-dicarbonitrile (SIQP II), and 2′-(4-methoxyphenyl)-7-nitro-5′,6′,7′,7a′-tetrahydrospiro[indeno[1,2- b ]quinoxaline-11,3′-pyrrolizine]-1′,1′(2′ H )-dicarbonitrile (SIQP III)—have been synthesized through a one-pot cascade Knoevenagel condensation reaction in acetonitrile (ACN) with 91, 98, and 87% yields, respectively. Structures are characterized by 1 H NMR and 13 C NMR spectroscopy, nuclear Overhauser enhancement spectroscopy (NOESY), Fourier transform infrared (FT-IR) and UV–vis spectroscopy, thermogravimetric analysis (TGA), high-resolution mass spectroscopy (HRTEM), fluorescence and Raman spectroscopy, and energy-dispersive analysis by X-ray (EDX) spectroscopy. SIQPs in ACN photocatalyzed methylene blue (MB) but not phenolphthalein (HIn). SIQPs distinguished the quaternary atoms and dipoles of the fluorescent dye (MB) contrary to the quinonoid HIn structure. In sunlight, SIQPs without electricity input acted as a photonic sensor to detect fluorescent dyes in waste effluents of textile, paper, dyes, and other industries. Activation energy ( E a ), enthalpy (Δ H ), entropy (Δ S ), and Gibbs free energy (Δ G ) calculated from UV–vis absorption spectra show photocatalytic reduction (PCR) activities in the order SIQP II > III > I. The N-atom of pyrrolizidine and −NO 2 of nitro-indenoquinoxaline (NIQ) induced the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) electrodynamics to enable the SIQPs to catalyze biochemical activities.

Spiroheterocyclic Photocatalyst for Reducing QHIn-Persistent Pollutants, Dyes, and Transition-Metal Ions Cocatalyzed with Electrolytes

“…The electrolytes induced the electronic oscillations in QHIn. The higher Raman intensities of SIQPII than I and III as 2LPE of OCH 3 delocalized with phenyl of III manifolding the EER by weakening a polarizability. The higher continuity in XRD peaks of SIQPII than III and I is due to a slightly high activity of EWG.…”

Study of molar properties of GO after doping with transition metals for photodegradation of fluorescent dyes

“…Thus, M v could help in the design of efficient solar cells, light emitting diodes, piezoelectric sensors and oscillatory sensors. 4,5…”

“…Thus, M v could help in the design of efficient solar cells, light emitting diodes, piezoelectric sensors and oscillatory sensors. 4,5 Solid exfoliated photocatalyst GO sheets are efficient but are still limited to h + and e − generation compared to higher surface areas with innite redox cycles. Molar GO could be doped with heterocyclic compounds and transitional metal sulde nanoparticles to study molar interfacial activities.…”

“…Molar GO could be doped with heterocyclic compounds and transitional metal sulde nanoparticles to study molar interfacial activities. 4,5 The photocatalytic activities of TMI-GO are high for the degradation of methylene blue (MB), and could be used to disintegrate this polymeric waste material into smaller alkyl chains to synthesize petrol and diesel. 6 TMI-GO resonating holes in the same phase offer a new dimension of photocatalytic chemistry.…”

Green Synthesis of Indeno[1,2-b]quinoxalines Using β-Cyclodextrin as Catalyst

“…They exhibit diverse biological properties, such as acetylcholinesterase (AChE) inhibitory activity (I) [1], antitumor activity (II) [2,3], α-glucosidase inhibition (III) [4], c-Jun N-terminal kinase (JNK) inhibition (IV) [5,6], and tryptophan-tRNA synthase (TrpRS) inhibition (V) [7]. Furthermore, functionally substituted indeno [2,3-b]quinoxalines show potential as acid corrosion inhibitors for mild steel surfaces (VI) [8] and can be used as a photonic sensor to detect fluorescent dyes in the waste effluents of textiles, paper, dyes, and other industrial products (VII) [9] (Figure 1). Therefore, a great deal of attention has been paid to the construction of indeno [1,2b]quinoxaline skeleton compounds [10].…”