abstract
The sensing ability of 2-nitro-5,10,15,20-tetraphenylporphyrin (P-NO2) and of the corresponding Zn(II) complex (ZnP-NO2) towards hydrogen sulfide (H2S) was investigated using UV-vis absorption and emission spectroscopy. The presence of H2S induced strong alterations in the excited state of P-NO2 and ZnP-NO2. Specifically, the originally broad fluorescence emission observed around 700 nm was strongly quenched, while new sharp bands emerged at lower wavelengths. Both P-NO2 and ZnP-NO2 showed a clear sensitive and turn-ON response to the presence of H2S, with detection limits (LOD) of 3 mu M for P-NO2 and 7 mu M for ZnP-NO2. In the case of ZnP-NO2, the spectral shift enables a ratiometric sensing of H2S, making this approach particularly robust against variations in sensor concentration, environmental effects and instrumentation errors. Interestingly, the spectral changes induced by H2S were reversible suggesting that it is possible to reuse the sensor. The sensing mechanism was evaluated by 1H NMR and HRMS-ESI experiments and corroborated by density functional theory (DFT) calculations. Overall, the results emphasized that the beta-nitroporphyrins based probes are a powerful tool for the detection of H2S and present potential as a new sensing approach.
keywords
HYDROSULFIDE COMPLEXES; FLUORESCENT-PROBES; CHARGE-TRANSFER; PORPHYRINS; H2S; SPECTRA; BINDING; SENSOR; STATE
subject category
Chemistry; Engineering; Materials Science
authors
Santos, CIM; Santiago, AM; Dias, CJ; Cavaco, D; Araújo, AR; Justino, G; Melle-Franco, M; Faustino, MAF; Neves, MGPMS; Martinho, JG; Maçôas, EMS
our authors
Manuel Melle-Franco
Principal Researcheracknowledgements
This research work received financial support from Instituto Superior Tecnico (IST, Portugal), the University of Aveiro and FCT/MCTES (Fundacao para a Ciencia e Tecnologia and Ministerio da Ciencia, Tecnologia e Ensino Superior) to support the UID/50006-Laboratorio Associado para a Quimica Verde-Tecnologias e Processos Limpos (LA/P/0008/2020 DOI 10.54499/LA/P/0008/2020,UIDP/50006/2020 DOI 10.54499/UIDP/50006/2020 and UIDB/50006/2020 DOI 10.54499/UIDB/50006/2020), by IMS (LA/P/0056/2020, DOI 10.54499/LA/P/0056/2020) and CQE (UIDB/00100/2020, DOI: 10.54499/UIDP/00100/2020 and UIDP/00100/2020, DOI: 10.54499/UIDP/00100/2020) research units through national funds and, where applicable, was co-financed by the FEDER, within the PT2020 Partnership Agreement, and to the Portuguese NMR Network. In addition, this work received support from the project: 2022.05950.PTDC (https://doi.org/10.54499/2022.05950.PTDCC. C. I. M. Santos is also grateful to her research contract (2023.08400.CEECIND), https://doi.org/10.54499/2023.08 400.CEECIND/CP2830/CT0013) and CD for her grant (SFRH/BD/150676/2020).