Multifunctional luminescent sensor based on the Pb²⁺ complex containing a tetrazolato ligand

Li-Xin WANG, Jing XIANG, Dong XIANG, Shun-Cheung CHENG, Chi Fai LEUNG, Chi-Chiu KO, Jing XIANG

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5 Citations (Scopus)

Abstract

A series of luminescent Pb²⁺ complexes, [Pb(L¹)₂]n (1), [Pb(L²)₂]n (2), [Pb(L³)(NO₃)(H₂O)₂]n (3), [Pb(L³)(Br)(H₂O)]n (4), [Pb(L³)(Cl)(H₂O)]n (5), and [Pb(L⁴)(H₂O)₂] (6) have been synthesized by treatment of polydentate tetrazolato ligands with various hydrated Pb²⁺ salts (HL¹ = 2-(1H-tetrazol-5-yl)pyridine, HL² = 3-(1H-tetrazol-5-yl)isoquinoline, HL³ = 6-(1H-tetrazol-5-yl)-2,2′-bipyridine, and H₂L⁴ = 6,6′-bis(1H-tetrazol-5-yl)-2,2′-bipyridine). These complexes have been characterized by IR, TGA, and elemental analysis. Their crystal structures have been determined by X-ray crystallography, and the phase purity of bulk samples were further confirmed by PXRD. Their luminescence properties have been investigated in detail, and their emission origin may involve ligand-centered π–π* transition, metal-centered s-p transition and charge-transfer character. It is interesting to note that 5 exhibits obviously enhanced red-shifted emission, whose photoluminescence quantum yield (PLQY = 16.5%) is much higher than the other compounds (≤2%). Most importantly, the emission property of 5 was strongly affected by temperature. When the temperature rises from 295 to 493 K, the emission maximum gradually shifts to high energy due to the loss of the aqua ligand. In contrast, when the temperature is lowered from 295 to 13 K, two emission bands were observed. The low-energy emission band exhibits a slight blue shift, while a new high-energy emission band appears at around 520 nm, which is assigned to ligand-centered phosphorescence. After removal of the coordinated aqua ligand, the emission of 5–H₂O is very sensitive to the vapors of volatile primary amines and acids, although they have different response mechanisms. This result indicates that 5–H₂O may be a potential multifunctional sensor for temperature, volatile amines, and acids. To decipher the emission origin, DFT calculations have also been carried out based on the structure units of these compounds. Copyright © 2022 American Chemical Society.

Original languageEnglish
Pages (from-to)16831-16840
JournalInorganic Chemistry
Volume61
Issue number42
Early online dateOct 2022
DOIs
Publication statusPublished - 2022

Citation

Wang, L.-X., Xiang, J., Xiang, D., Cheng, S.-C., Leung, C.-F., Ko, C.-C., & Xiang, J. (2022). Multifunctional luminescent sensor based on the Pb²⁺ complex containing a tetrazolato ligand. Inorganic Chemistry, 61(42), 16831-16840. doi: 10.1021/acs.inorgchem.2c02783

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