A novel pyridine-functionalized naphthoxazine: thermal stability, proton and metal ion-responsive optical sensing, and biological activity with DFT validation.
7 affiliations
- 1Chemistry Department, Faculty of Education and Science, Albaydha University, Rada'a, Albaydha, Yemen. [email protected].
- 2Department of Pharmacy, Faculty of Medicine and Health Sciences, Ar- Rasheed Smart University, Sana'a, Yemen. [email protected].
- 3Chemistry Department, School of Science, The University of Jordan, Amman, 11942, Jordan. [email protected].
- 4Chemistry Department, School of Science, The University of Jordan, Amman, 11942, Jordan.
- 5Department of Pharmaceutics and Pharmaceutical Technology, School of Pharmacy, The University of Jordan, Amman, 11942, Jordan.
- 6Department of Biopharmaceutics and Clinical Pharmacy, School of Pharmacy, The University of Jordan, Amman, 11942, Jordan.
- 7Chemistry Department, School of Science, The University of Jordan, Amman, 11942, Jordan. [email protected].
Abstract
Designing multifunctional polymers that combine thermal stability, selective optical response, and biological activity remains a key challenge in smart materials development. Herein, we report a novel pyridine-functionalized naphthoxazine monomer (Py-NZ) synthesized via a one-pot Mannich condensation and fully characterized by 1D/2D NMR, FTIR, and HRMS. DFT calculations confirmed the optimized geometry, showing excellent agreement with experimental data (RMSD = 0.018 Å; mean IR error = 0.43%), validating its extended π-conjugated structure. Thermogravimetric analysis of the cured Poly(Py-NZ) revealed outstanding thermal stability, with a char yield of 69% at 800 °C and a limiting oxygen index (LOI) of 45.1, indicating strong flame-retardant potential. UV-Vis and fluorescence spectroscopy demonstrated that metal coordination significantly modifies the optical behavior. Among the tested metal ions, Zn²⁺ induced a marked fluorescence enhancement due to its d¹⁰ configuration, which suppresses nonradiative decay and favors radiative emission. Py-NZ also exhibited strong acid-responsive fluorescence: high HCl concentrations quenched emission via protonation-induced nonradiative pathways, while lower acidity restored intensity, confirming its dual-responsive chemosensing capability for both metal ions and protons. Biological evaluation showed moderate antibacterial activity against Staphylococcus aureus and Escherichia coli, with the protonated form exhibiting enhanced activity against Gram-positive bacteria (MIC = 15.6 µg/mL). In DPPH antioxidant assays, all compounds displayed dose-dependent reductive activity comparable to ascorbic acid, with the Zn²⁺-coordinated complex showing the highest potency of nanomolarity radical scavenging affinities (IC₅₀ = 0.15 ± 0.01 vs. 0.041 ± 0.0062 for ascorbic acid). Overall, this work establishes a versatile platform for naphthoxazine-based multifunctional materials with potential applications in flame-retardant coatings, optical sensing, and biomedical fields.
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BibTeX
@article{mahdy2026novel,
title = {{A novel pyridine-functionalized naphthoxazine: thermal stability, proton and metal ion-responsive optical sensing, and biological activity with DFT validation.}},
author = {Abdulsalam Mahdy and Jalal A Zahra and Randa N Haddadin and Violet Kasabri and Murad A AlDamen},
journal = {BMC chemistry},
year = {2026},
month = jul,
doi = {10.1186/s13065-026-01887-x},
url = {https://europepmc.org/article/MED/42907927},
note = {CC BY},
}
RIS
TY - JOUR
TI - A novel pyridine-functionalized naphthoxazine: thermal stability, proton and metal ion-responsive optical sensing, and biological activity with DFT validation.
AU - Abdulsalam Mahdy
AU - Jalal A Zahra
AU - Randa N Haddadin
AU - Violet Kasabri
AU - Murad A AlDamen
PY - 2026
DA - 2026/07/01
JO - BMC chemistry
DO - 10.1186/s13065-026-01887-x
UR - https://europepmc.org/article/MED/42907927
AB - Designing multifunctional polymers that combine thermal stability, selective optical response, and biological activity remains a key challenge in smart materials development. Herein, we report a novel pyridine-functionalized naphthoxazine monomer (Py-NZ) synthesized via a one-pot Mannich condensation and fully characterized by 1D/2D NMR, FTIR, and HRMS. DFT calculations confirmed the optimized geometry, showing excellent agreement with experimental data (RMSD = 0.018 Å; mean IR error = 0.43%), validating its extended π-conjugated structure. Thermogravimetric analysis of the cured Poly(Py-NZ) revealed outstanding thermal stability, with a char yield of 69% at 800 °C and a limiting oxygen index (LOI) of 45.1, indicating strong flame-retardant potential. UV-Vis and fluorescence spectroscopy demonstrated that metal coordination significantly modifies the optical behavior. Among the tested metal ions, Zn²⁺ induced a marked fluorescence enhancement due to its d¹⁰ configuration, which suppresses nonradiative decay and favors radiative emission. Py-NZ also exhibited strong acid-responsive fluorescence: high HCl concentrations quenched emission via protonation-induced nonradiative pathways, while lower acidity restored intensity, confirming its dual-responsive chemosensing capability for both metal ions and protons. Biological evaluation showed moderate antibacterial activity against Staphylococcus aureus and Escherichia coli, with the protonated form exhibiting enhanced activity against Gram-positive bacteria (MIC = 15.6 µg/mL). In DPPH antioxidant assays, all compounds displayed dose-dependent reductive activity comparable to ascorbic acid, with the Zn²⁺-coordinated complex showing the highest potency of nanomolarity radical scavenging affinities (IC₅₀ = 0.15 ± 0.01 vs. 0.041 ± 0.0062 for ascorbic acid). Overall, this work establishes a versatile platform for naphthoxazine-based multifunctional materials with potential applications in flame-retardant coatings, optical sensing, and biomedical fields.
SN - 2661-801X
ER -