Synthesis, electrochemistry, thin-layer UV-vis and fluorescence spectroelectrochemistry of a new salicylaldimine ligand and its copper complex

Ismail Yilmaz*

*Corresponding author for this work

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21 Citations (Scopus)

Abstract

The new asymmetric, fluorescent Schiff-base ligand, N-(pyrene)- salicylaldimine (L), and its copper complex having an ONNO donor set, [Cu(L) 2 ], were synthesized and characterized using elemental analysis, IR, UV-vis, 1H and 13C-NMR spectroscopies. Their electrochemical and spectroelectrochemical behaviors were investigated in a detail by using cyclic voltammetry (CV), square wave voltammetry (SWV), in-situ UV-vis, and fluorescence spectroelectrochemistry. The formation of the complex was monitored by the in-situ fluorescence technique based on the quenching of the fluorescence-probe ligand. Electrochemical studies showed that L exhibits a single irreversible reduction process. However, the SWV indicated that this process was not totally irreversible in the time scale of the measurement. The cathodic peak potential of the reduction process occurred at E pc = -1.35 V vs Ag/AgCl (scan rate: 0.025 Vs-1). On the other hand, [Cu(L) 2 ] showed one quasi-reversible one-electron reduction process in the scan rates of 0.025-0.50 Vs-1, which was assigned to metal-based one-electron process; [Cu(2+)(L)2] + e- → [Cu(+)(L)2]-. The value of half-wave potential (E 1/2) of the reduction process was -0.54 V vs Ag/AgCl (scan rate: 0.025 Vs-1). The time-resolved spectra showed, when the potential (E app = -1.60 V) was applied in a thin-layer cell, that the main and shoulder bands of (L) at 385, 336, and 407 nm almost disappeared and a new band at 443 nm with a shoulder formed during the reduction process. No change was observed on the final spectrum of the totally reduced ligand for long period under nitrogen atmosphere, which indicated that the singly reduced species remained stable and was not accompanied by a chemical reaction in the time scale of the spectroelectrochemical measurement. The spectral changes during the reduction process of [Cu(L) 2 ] confirmed the metal-centered reduction process. The fluorescence intensity of L decreased during the reduction process in the thin-layer cell, as result of the perturbation of the conjugated system of the reduced species.

Original languageEnglish
Pages (from-to)259-265
Number of pages7
JournalTransition Metal Chemistry
Volume33
Issue number2
DOIs
Publication statusPublished - Mar 2008

Funding

Acknowledgments The supports of State Planning Organization (DPT, Project no: 90177) is gratefully acknowledged. This work has also been supported, in part, by the Turkish Academy of Sciences in the framework of the Young Scientist Award Program (TUBA-GEBIP).

FundersFunder number
DPT90177
TUBA-GEBIP
Devlet Planlama Örgütü
Türkiye Bilimler Akademisi

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