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Sánchez F, Gutiérrez M, Douhal A. Taking Advantage of a Luminescent ESIPT-Based Zr-MOF for Fluorochromic Detection of Multiple External Stimuli: Acid and Base Vapors, Mechanical Compression, and Temperature. ACS APPLIED MATERIALS & INTERFACES 2023; 15:56587-56599. [PMID: 37983009 DOI: 10.1021/acsami.3c14348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
Luminescent materials responsive to external stimuli have captivated great attention owing to their potential implementation in noninvasive photonic sensors. Luminescent metal-organic frameworks (LMOFs), a type of porous crystalline material, have emerged as one of the most promising candidates for these applications. Moreover, LMOFs constructed with organic linkers that undergo excited-state intramolecular proton-transfer (ESIPT) reactions are particularly relevant since changes in the surrounding environment induce modifications in their emission properties. Herein, an ESIPT-based LMOF, UiO-66-(OH)2, has been synthesized, spectroscopically and photodynamically characterized, and tested for detecting multiple external stimuli. First, the spectroscopic and photodynamic characterization of the organic linker (2,5-dihydroxyterephthalic acid (DHT)) and the UiO-66-(OH)2 MOF demonstrates that the emission properties are mainly governed by the enol → keto tautomerization, occurring in the organic linker via the ESIPT reaction. Afterward, the UiO-66-(OH)2 MOF proves for the first time to be a promising candidate to detect vapors of acid (HCl) and base (Et3N) toxic chemicals, changes in the mechanical compression (exercised pressure), and changes in the temperature. These results shed light on the potential of ESIPT-based LMOFs to be implemented in the development of advanced optical materials and luminescent sensors.
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Affiliation(s)
- Francisco Sánchez
- Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain
| | - Mario Gutiérrez
- Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain
| | - Abderrazzak Douhal
- Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain
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Shekhovtsov NA, Nikolaenkova EB, Berezin AS, Plyusnin VF, Vinogradova KA, Naumov DY, Pervukhina NV, Tikhonov AY, Bushuev MB. Tuning ESIPT-coupled luminescence by expanding π-conjugation of a proton acceptor moiety in ESIPT-capable zinc(II) complexes with 1-hydroxy-1 H-imidazole-based ligands. Dalton Trans 2022; 51:15166-15188. [PMID: 36129344 DOI: 10.1039/d2dt02460h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The emission of ESIPT-fluorophores is known to be sensitive to various external and internal stimuli and can be fine-tuned through substitution in the proton-donating and proton-accepting groups. The incorporation of metal ions in the molecules of ESIPT fluorophores without their deprotonation is an emerging area of research in coordination chemistry which provides chemists with a new factor affecting the ESIPT reaction and ESIPT-coupled luminescence. In this paper we present 1-hydroxy-5-methyl-4-(pyridin-2-yl)-2-(quinolin-2-yl)-1H-imidazole (HLq) as a new ESIPT-capable ligand. Due to the spatial separation of metal binding and ESIPT sites this ligand can coordinate metal ions without being deprotonated. The reactions of ZnHal2 with HLq afford ESIPT-capable [Zn(HLq)Hal2] (Hal = Cl, Br, I) complexes. In the solid state HLq and [Zn(HLq)Hal2] luminesce in the orange region (λmax = 600-650 nm). The coordination of HLq by Zn2+ ions leads to the increase in the photoluminescence quantum yield due to the chelation-enhanced fluorescence effect. The ESIPT process is barrierless in the S1 state, leading to the only possible fluorescence channel in the tautomeric form (T), S1T → S0T. The emission of [Zn(HLq)Hal2] in the solid state is blue-shifted as compared with HLq due to the stabilization of the ground state and destabilization of the excited state. In CH2Cl2 solutions, the compounds demonstrate dual emission in the UV (λmax = 358 nm) and green (λmax = 530 nm) regions. This dual emission is associated with two radiative deactivation channels in the normal (N) and tautomeric (T) forms, S1N → S0N and S1T → S0T, originating from two minima on the excited state potential energy surfaces. High energy barriers for the GSIPT process allow the trapping of molecules in the minimum of the tautomeric form, S0T, resulting in the possibility of the S0T → S1T photoexcitation and extraordinarily small Stokes shifts in the solid state. Finally, the π-system of quinolin-2-yl group facilitates the delocalization of the positive charge in the proton-accepting part of the molecule and promotes the ESIPT reaction.
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Affiliation(s)
- Nikita A Shekhovtsov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Elena B Nikolaenkova
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 9, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia
| | - Alexey S Berezin
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Victor F Plyusnin
- Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, 3, Institutskaya str., Novosibirsk, 630090, Russia
| | - Katerina A Vinogradova
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Dmitry Yu Naumov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Natalia V Pervukhina
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Alexsei Ya Tikhonov
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 9, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia
| | - Mark B Bushuev
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
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