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oai:figshare.com:article/34025300 2026-09-29T17:07:26Z category_1 category_4 category_146 category_915 category_21 category_873 category_734 portal_63 item_type_6 month_year_09_2026

Fluorescence Quenching Efficiency and Sensing Mechanism of Donor–Acceptor-Type Nitroaromatic Compounds Using Poly(3-thiophene ethoxide)-CTAB Complex Ittyedath Anjana (25138073) M. Jinish Antony (2197066) Pookkottu K. Sajith (13250678) Biophysics Biochemistry Space Science Physical Sciences not elsewhere classified Biotechnology Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified spectral overlap established provide additional contributions photoinduced electron transfer large stokes shift inner filter effect electron microscopy confirmed dynamic light scattering 9 × 10 9 ± 0 1 ± 0 ray photoelectron spectroscopy donor – acceptor donor (− nh computed molecular hyperpolarizability induced static quenching 3 ± 0 stable yellow emission 2 × 10 ctab complex exhibited 3 </ sup fluorescence quenching efficiency acceptor (− quenching efficiency fluorescence quenching ray diffraction ctab complex fluorescence lifetime − ch thiophene ethanol systematically investigated successful complexation subsequently complexed state lifetime sensing mechanism sample analysis results suggest quantum yield predominantly governed practical applicability photoluminescence properties nitroaromatic compounds nacs ). morphological transformation lumo energy like nanostructures like aggregates including nitroanilines dimethyl sulfoxide A surfactant-assisted strategy was employed to enhance the photoluminescence properties of polythiophene for the detection of nitroaromatic compounds (NACs). Poly(3-thiophene ethanol) (P3TE) was synthesized via chemical oxidative polymerization and subsequently complexed with cetyltrimethylammonium bromide (CTAB) to form a stable and soluble P3TE-CTAB complex. Structural characterization using Fourier transform infrared spectra, proton nuclear magnetic resonance spectra, powder X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy confirmed the successful complexation and revealed improved structural ordering and morphological transformation from flake-like aggregates to cylindrical coil-like nanostructures. The P3TE-CTAB complex exhibited a stable yellow emission in dimethyl sulfoxide with a quantum yield of 39.5% and a large Stokes shift of 132 nm. The fluorescence sensing behavior toward 12 structurally different nitroaromatic compounds, including nitroanilines, nitrophenols, and nitrotoluenes, was systematically investigated. Fluorescence quenching among para-substituted nitro compounds follows the order para-nitroaniline > para-nitrophenol > para-nitrotoluene with Stern–Volmer constants 9.1 ± 0.9 × 10³ M^–1, 2.9 ± 0.2 × 10³ M^–1, and 5.3 ± 0.2 M^–1, respectively. The quenching efficiency strongly depended on type of donor (−NH₂, −OH, −CH₃) and its position with respect to acceptor (−NO₂) groups in the analyte. Fluorescence lifetime, dynamic light scattering, and field emission scanning electron microscopy studies demonstrated that nitroaromatic analytes promote aggregation of the P3TE-CTAB complex without significant shortening of the excited-state lifetime. These results suggest that fluorescence quenching is predominantly governed by aggregation-induced static quenching, while photoinduced electron transfer (PET) and the inner filter effect (IFE) provide additional contributions. Correlation of quenching efficiency with DFT-computed molecular hyperpolarizability, LUMO energy, and spectral overlap established that analyte hyperpolarizability is the primary factor governing polymer aggregation and fluorescence quenching. Real-sample analysis further demonstrated the practical applicability of the P3TE-CTAB system for nitroaromatic detection. 2026-09-29T00:00:00Z Text Journal contribution 10.1021/acs.langmuir.6c02454.s001 https://figshare.com/articles/journal_contribution/Fluorescence_Quenching_Efficiency_and_Sensing_Mechanism_of_Donor_Acceptor-Type_Nitroaromatic_Compounds_Using_Poly_3-thiophene_ethoxide_-CTAB_Complex/34025300 CC BY-NC 4.0