Conformation- and Coordination Mode-Dependent Stimuli-Responsive Salicylaldehyde Hydrazone Zn(II) Complexes

Zheng, Huifang; Yang, Dongdong; Shi, Yongliang; Xiao, Tong; Tan, Hongwei; Zheng, Xiang‐Jun

doi:10.1021/acs.inorgchem.3c00035

Cited by 14 publications

(4 citation statements)

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“…The HL H ligand was rationally designed to accommodate a metal ion and the mobile H + ion, i.e., it has both the N,N -metal binding site and the O,N -ESIPT site. Such a design strategy allows one to obtain ESIPT-capable metal complexes, an extraordinarily rare class of ESIPT dyes (Scheme , top). ,,− , Recently, we synthesized and characterized HL , which differs from HL H by the number and position of CH 3 groups and by the position of hydroxyphenyl and pyrazole substituents to the central pyrimidine core. The reaction of HL with ZnCl 2 in equimolar ratio yielded an ESIPT-capable [Zn(HL)Cl 2 ] complex (Scheme , top) .…”

Section: Results and Discussionmentioning

confidence: 99%

“…Due to the large variety of emissive excited states, the emission of ESIPT-capable molecules is sensitive to various stimuli. − The breaking of the intramolecular hydrogen bond due to the interaction of the ESIPT site of the molecule with other molecules or ions or due to deprotonation causes strong changes in the luminescence response of ESIPT-capable molecules. The protonation of ESIPT-capable molecules can proceed at the hydrogen bond-accepting atom switching the ESIPT reaction off or at other heteroatoms leading to modulating ESIPT and ESIPT-coupled luminescence. − Binding metal ions by ESIPT dyes which is accompanied by the deprotonation in most cases (only rare examples of ESIPT-capable metal complexes are known) ,,− also results in strong changes of emission. − This sensitivity allows one to switch the emission of ESIPT-capable molecules between various emission mechanisms and makes them a multivariate platform for the design of stimuli-responsive emissive materials, probes, and sensors.…”

Section: Introductionmentioning

confidence: 99%

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Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms

Shekhovtsov,

Vorob’eva,

Nikolaenkova

et al. 2023

Inorg. Chem.

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A rare example of pyrimidine-based ESIPT-capable compounds, 2-(2-hydroxyphenyl)-4-(1H-pyrazol-1-yl)-6-methylpyrimidine (HL H ), was synthesized (ESIPT�excited state intramolecular proton transfer). Its reactions with zinc(II) salts under basic or acidic conditions afforded a dinuclear [Zn 2 L H 2 Cl 2 ] complex and an ionic (H 2 L H ) 4 [ZnCl 4 ] 2 • 3H 2 O solid. Another ionic solid, (H 2 L H )Br, was obtained from the solution of HL H acidified with HBr. In both ionic solids, the H + ion protonates the same pyrimidinic N atom that accepts the O−H•••N intramolecular hydrogen bond in the structure of free HL H , which breaks this hydrogen bond and switches off ESIPT in these compounds. This series of compounds which includes neutral HL H molecules and ionic (L H ) − and (H 2 L H ) + species allowed us to elucidate the impact of protonation and coordination coupled deprotonation of HL H on the photoluminescence response and on altering the emission mechanism. The neutral HL H compound exhibits yellow emission as a result of the coexistence of two radiative decay channels: (i) T 1 → S 0 phosphorescence of the enol form and (ii) anti-Kasha S 2 → S 0 fluorescence of the keto form, which if feasible due to the large S 2 −S 1 energy gap. However, owing to the efficient nonradiative decay through an energetically favorable conical intersection, the photoluminescence quantum yield of HL H is low. Protonation or deprotonation of the HL H ligand results in the significant blue-shift of the emission bands by more than 100 nm and boosts the quantum efficiency up to ca. 20% in the case ofand (H 2 L H )Br have the same (H 2 L H ) + cation in the structures, their emission properties differ significantly, whereas (H 2 L H )Br shows dual emission associated with two radiative decay channels: (i) S 1 → S 0 fluorescence and (ii) T 1 → S 0 phosphorescence, (H 2 L H ) 4 [ZnCl 4 ] 2 •3H 2 O exhibits only fluorescence. This difference in the emission properties can be associated with the external heavy atom effect in (H 2 L H )Br, which leads to faster intersystem crossing in this compound. Finally, a huge increase in the intensity of the phosphorescence of (H 2 L H )Br on cooling leads to pronounced luminescence thermochromism (violet emission at 300 K, sky-blue emission at 77 K).

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Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms

Shekhovtsov,

Vorob’eva,

Nikolaenkova

et al. 2023

Inorg. Chem.

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“…In addition, these compounds have been found to be an important class of organic materials used as hole-transporting materials [4] or sensors [9]. It has also been shown that acylhydrazones form stable chelate complexes with transition metal cations, using their oxygen and imine nitrogen as donor atoms [10]. Accordingly, additional donor sites (i.e., methoxy groups) can be introduced into their structure to increase the number of coordination sites of the resulting ligand and thus their affinity for metal ions [11,12].…”

Section: Introductionmentioning

confidence: 99%

New Insights into Acylhydrazones E/Z Isomerization: An Experimental and Theoretical Approach

Fernández-Palacios,

Matamoros,

Morato Rojas

et al. 2023

IJMS

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A family of acylhydrazones have been prepared and characterized with the aim of investigating their potential as information storage systems. Their well-established synthetic methodologies allowed for the preparation of seven chemically stable acylhydrazones in excellent yields that have been photophysically and photochemically characterized. In addition, DFT and TD-DFT calculations have been performed to gain more insights into the structural, energetic and photophysical properties of the E/Z isomers. Our results reveal that E/Z configurational isomerization upon irradiation is highly dependent on the stabilization of the E or Z isomers due to the formation of intramolecular H bonds and the electronic/steric effects intrinsically related to their structures. In addition, Raman spectroscopy is also used to confirm the molecular structural changes after the formation of hydrogen bonds in the isomers.

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“…Stimuli-responsive materials are promising materials capable of changing one or more of their properties in response to an external stimulus. , Due to their ability to vary their optical characteristics and luminescence in response to mild stimuli (such as vapor exposure, − manual grinding, , natural light, etc. ), these materials have caught great interest in the development of environmental sensors.…”

mentioning

confidence: 99%

Pyridine-Triggered Fluorescent Switching in Coordination-Induced Allosteric Crystal Transformation

Feng,

Xue,

Zou

et al. 2024

Crystal Growth & Design

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Two zinc complexes with stimuli-responsive properties have been realized in [Zn(L) 2 ] (1) and [Zn(L) 2 (py)]•py (2) (HL = N-(2-hydroxybenzylideneamino)-1,8naphthalimide, py = pyridine). The crystal-to-crystal transformation between 1 and 2 is achieved by coordination/decoordination of pyridine, leading to an allosteric effect of the naphthalimide fluorophore. Thus, this pyridine-mediated twisted π-conjugated nature of the ligand between 1 and 2 is responsible for the selective and reversible fluorescent switching, which offers a profound insight into the fascinating field of solid-state stimuli-responsive luminescence materials and promotes the development of novel materials.

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Conformation- and Coordination Mode-Dependent Stimuli-Responsive Salicylaldehyde Hydrazone Zn(II) Complexes

Cited by 14 publications

References 50 publications

Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms

Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms

New Insights into Acylhydrazones E/Z Isomerization: An Experimental and Theoretical Approach

Pyridine-Triggered Fluorescent Switching in Coordination-Induced Allosteric Crystal Transformation

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