Reactivity of monohydrogensulfide with a suite of pyridoxal-based complexes: A combined NMR, ESI-MS, UV–visible and fluorescence study

• Published in: Inorganica Chimica Acta Vol. 501; p. 119235
• Main Authors: Strianese, Maria, Lamberti, Marina, Persico, Alessandro, Pellecchia, Claudio
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-02-2020; Elsevier Science Ltd
• Subjects: Coordination compounds; Fluorescence; Ligands; Nickel; NMR; Nuclear magnetic resonance; Zinc
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2019.119235

In this work we studied the reactivity of HS− with a family of fluorescent pyridoxal-based complexes via a variety of spectroscopic techniques. In the case of complexes 1 and 3 we have evidences that the interaction with HS− results in the coordination of HS− to the metal center. Differently for complex 2 our data points to the hydrolysis of the coordinated ligand from the Zn center with the concomitant precipitation of ZnS.
[Display omitted]
•Interaction of HS− with a family of fluorescent metal complexes.•HS− fluorescent sensors.•Sensors functioning via a coordinative-based approach.
In the present work, we explored the reactivity of HS− with a family of fluorescent metal complexes via a variety of spectroscopic techniques. The complexes under investigation are obtained by complexation of zinc or nickel with pyridoxal-based ligands. More specifically complexes 1 and 2 are zinc complexes namely L1Zn(II) and L2Zn(II) where L1 stands for N,N′-phenylenebis(pyridoxyliminato) and L2 is N,N′-binaphthylenebis(pyridoxyliminato), whereas complex 3 is a nickel complex (L3Ni(II)) where L3 is N,N′-ethylenebis(pyridoxyliminato). A combination of NMR, ESI-MS, UV–vis and fluorescence experiments provide evidence that HS− binds the metal center in the case of complexes 1 and 3 whereas for complex 2, ZnS precipitation and hydrolysis of the organic ligand occur. Fluorescence experiments indicate that in the presence of HS− complex 1 undergoes a consistent fluorescence enhancement whereas for complex 3 the parent fluorescence exhibits a visible quenching. The results highlight the potential of complex 1 to be implemented as a HS− fluorescent sensor via a coordinative-based approach.