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23 pages, 3154 KB

Open AccessArticle

Lanthanide Tris-Acetylacetonate Complexes for Luminescent Thermometry: From Isolated Compounds to Hybrid Prussian Blue Core–Silica Shell Nanoparticles

by Aurore Larquey, Gautier Félix, Saad Sene, Joulia Larionova and Yannick Guari

Inorganics 2025, 13(9), 304; https://doi.org/10.3390/inorganics13090304 - 11 Sep 2025

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Abstract

Precise remote temperature sensing at the micro- and nanoscale is a growing necessity in modern science and technology. We report a series of luminescent tris-acetylacetonate lanthanide complexes, Ln(acac)₃(H₂O)₂ (Ln = Eu (1Eu), Tb (1Tb), [...] Read more.

Precise remote temperature sensing at the micro- and nanoscale is a growing necessity in modern science and technology. We report a series of luminescent tris-acetylacetonate lanthanide complexes, Ln(acac)₃(H₂O)₂ (Ln = Eu (1Eu), Tb (1Tb), Yb (1Yb)); acac⁻ = acetylacetonate), operating as self-referenced thermometers in the 290–350 K range, both in the solid state and when embedded in hybrid nanoparticles. Among the investigated systems, the Eu³⁺ complex exhibits excellent lifetime-based thermometric performance, achieving a maximum relative sensitivity (S_rmax) of 2.9%·K⁻¹ at 340 K with a temperature uncertainty (δT) as low as 0.02 K and an average temperature uncertainty (

\bar{δ T}

) of 0.5 K, placing it among the most effective ratiometric lanthanide-based luminescent thermometers reported to date. The Yb³⁺ analog enables intensity-based thermometry in the near-infrared domain with a good sensitivity S_rmax = 0.5%·K⁻¹ at 293 K, δT = 0.5 K at 303 K, and

\bar{δ T}

= 1.6 K. These molecular thermometers were further incorporated into the shell of Prussian Blue@SiO₂ core–shell nanoparticles. Among the resulting hybrids, PB@SiO₂-acac/(1Tb/1Eu) (with a Tb/Eu ratio of 2/8) stood out by enabling ratiometric temperature sensing based on the Eu³⁺⁵D₀ → ⁷F₂ lifetime, with satisfactory parameters (S_rmax = 0.9%·K⁻¹, δT = 0.21 K at 303 K, and

\bar{δ T}

= 1.1 K). These results highlight the potential of simple coordination complexes and their nanohybrids for advanced luminescent thermometry applications. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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13 pages, 6485 KB

Open AccessArticle

Investigations on the NIR Fluorescence Band Modulation of Bi-Doped Silica-Based Glasses and Fibers

by Qianhong Zheng, Genying Zeng, Chenxing Liao, Huoming Huang, Weixiong You, Xinyu Ye and Liaolin Zhang

Inorganics 2025, 13(5), 153; https://doi.org/10.3390/inorganics13050153 - 7 May 2025

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Abstract

Bi-doped glasses and fibers have been widely applied in solid-state and fiber lasers. However, the mechanism underlying near-infrared (NIR) luminescence remains unclear, and Bi-related luminescence centers (BLCs) are prone to alteration during fiber fabrication, making it challenging to achieve high-performance Bi-doped glass fibers. [...] Read more.

Bi-doped glasses and fibers have been widely applied in solid-state and fiber lasers. However, the mechanism underlying near-infrared (NIR) luminescence remains unclear, and Bi-related luminescence centers (BLCs) are prone to alteration during fiber fabrication, making it challenging to achieve high-performance Bi-doped glass fibers. In this work, Bi-, Bi-Al-, and Bi-Ge-doped silica glasses were investigated to elucidate the origin of NIR luminescence. Two broad NIR fluorescence bands were observed in silica glasses, originating from distinct BLCs. The longer-wavelength fluorescence band at 1423 nm, demonstrating sensitivity to Bi doping concentration and homogeneity, is attributed to Bi clusters (aggregates of Bi⁺ ions), whereas the shorter-wavelength emission, independent of Bi concentration, originates from isolated Bi⁺ ions. A vacuum-assisted melting-in-tube method with a single-step heating process was employed to fabricate Bi-doped silica-based glasses and fibers. The fluorescence bands of the fibers remained consistent with those of the precursor glasses, indicating no new BLCs were formed during fiber fabrication. The modulation of fluorescence bands was primarily governed by Bi cluster formation. Suppressing Bi clustering through co-doping with Al/Ge or optimizing fabrication conditions offers an effective route to tailor the fluorescence properties of Bi-doped glasses and fibers. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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25 pages, 8071 KB

Open AccessArticle

The Interface Interaction of C₃N₄/Bi₂S₃ Promoted the Separation of Excitons and the Extraction of Free Photogenerated Carriers in the Broadband Light Spectrum Range

by Xingfa Ma, Xintao Zhang, Mingjun Gao, Ruifen Hu, You Wang and Guang Li

Inorganics 2025, 13(4), 122; https://doi.org/10.3390/inorganics13040122 - 12 Apr 2025

Cited by 1 | Viewed by 670

Abstract

Exciton generation and separation play an important role in the photoelectric properties and the luminescence performance of materials. In order to tailor the defects and grain boundaries and improve the exciton separation and light harvesting of the graphitic carbon nitride (g-C₃N [...] Read more.

Exciton generation and separation play an important role in the photoelectric properties and the luminescence performance of materials. In order to tailor the defects and grain boundaries and improve the exciton separation and light harvesting of the graphitic carbon nitride (g-C₃N₄) nanosheets, a C₃N₄/bismuth sulfide (Bi₂S₃) nanocomposite was synthesized. The photoelectric properties of the 405, 532, 650, 780, 808, 980 and 1064 nm light sources were studied using Au electrodes and graphite electrodes with 4B and 5B pencil drawings. The results indicate that the C₃N₄/Bi₂S₃ nanocomposite exhibited photocurrent switching behavior in the broadband light spectrum range. It is noted that even with zero bias applied, a good photoelectric signal was still measured. The resulting nanocomposite exhibited good photophysical stability. Physical mechanisms are discussed herein. It is suggested that the interfacial interaction of C₃N₄ and Bi₂S₃ in the nanocomposite creates a strong built-in electric field, which accelerates the separation of excitons. Therefore, as a dynamic process of photoexcitation, fluorescence, the photoelectric effect, and scattering are three main competing processes; the separation of excitons and the extraction of free photogenerated charge can be used as a reference for the fluorescent materials or other photoelectric materials studies as photophysical properties. This study also serves as an important reference for the design, defect and grain boundary modulation or interdisciplinary application of functional nanocomposites, especially for the bandgap modulation and suppression of photogenerated carrier recombination. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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10 pages, 1261 KB

Open AccessArticle

Optical Absorption and Luminescence Spectra of Terbium Gallium Garnet TbGaG and Terbium Aluminum Garnet TbAlG

by Nosirjon S. Bozorov, Ismailjan M. Kokanbayev, Akmaljon M. Madaliev, Mavzurjon X. Kuchkarov, Muxtarjan Meliboev, Kobiljon K. Kurbonaliev, Ravshan R. Sultonov, Khayrullo F. Makhmudov, Feruza O. Dadaboyeva, Nargiza Z. Mamadalieva and Shakhlo R. Kukanbaeva

Inorganics 2025, 13(2), 61; https://doi.org/10.3390/inorganics13020061 - 17 Feb 2025

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Abstract

In this paper, we investigate the optical absorption and luminescence spectra of rare-earth garnets activated by the terbium (Tb³⁺) ion, as well as their magneto-optical properties. Crystals of terbium gallium garnet (TbGaG) and terbium aluminum garnet (TbAlG) are considered. The focus [...] Read more.

In this paper, we investigate the optical absorption and luminescence spectra of rare-earth garnets activated by the terbium (Tb³⁺) ion, as well as their magneto-optical properties. Crystals of terbium gallium garnet (TbGaG) and terbium aluminum garnet (TbAlG) are considered. The focus is on the physical and optical properties and structural features of the energy levels of rare-earth ions in the crystal field of garnets. This work highlights the importance of studying intraconfigurational 4f-4f and interconfigurational 4f-5d transitions, as well as the influence of the crystal field on the magnetic and optical properties of materials. Integrated methods are used, including absorption spectroscopy, luminescence and magneto-optical studies, which allows us to obtain detailed information on the excited states of rare-earth ions. The experimental results show the presence of significant Zeeman shifts, as well as anisotropy of the absorption and luminescence spectra, depending on the orientation of the crystal lattice and the external magnetic field. This work contributes to our understanding of the mechanisms of light absorption and emission in rare-earth garnets, which may facilitate the development of new optoelectronic devices based on them. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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15 pages, 7521 KB

Open AccessArticle

A Novel Fluorescent Chemosensor Based on Rhodamine Schiff Base: Synthesis, Photophysical, Computational and Bioimaging Application in Live Cells

by Oyedoyin Aduroja, Roosevelt Shaw, Sisay Uota, Isaac Abiye, James Wachira and Fasil Abebe

Inorganics 2025, 13(1), 5; https://doi.org/10.3390/inorganics13010005 - 27 Dec 2024

Cited by 3 | Viewed by 1301

Abstract

A novel rhodamine-6G derivative RdN was synthesized by condensing rhodamine glyoxal and 3-hydroxy-2-naphthoic hydrazide using a microwave irradiation-assisted reaction. Colorimetric and photophysical studies have demonstrated that the molecule produced can selectively sense Pb²⁺ and Cu²⁺ ions in a solution of CH [...] Read more.

A novel rhodamine-6G derivative RdN was synthesized by condensing rhodamine glyoxal and 3-hydroxy-2-naphthoic hydrazide using a microwave irradiation-assisted reaction. Colorimetric and photophysical studies have demonstrated that the molecule produced can selectively sense Pb²⁺ and Cu²⁺ ions in a solution of CH₃CN/H₂O (9:1, v/v). The spirolactam ring of RdN opens upon complexation with the cations, forming a highly fluorescent complex and a visible color change in the solution. The compound RdN was further studied with the help of computational methods such as the Density Functional Theory (DFT) method and time-dependent density theory (TD-DFT) calculations to study the binding interactions and properties of the molecule. DFT calculations and job plot data supported the 2:1 complex formation between RdN and Pb²⁺/Cu²⁺. The limit of detection for Pb²⁺ was determined to be 0.112 µM and 0.130 µM for Cu²⁺. The probe RdN was applied to the image of Pb²⁺ and Cu²⁺ ions in living cells and is safe for biomedical applications. It is used to monitor Pb²⁺ in environmental water samples. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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11 pages, 3069 KB

Open AccessArticle

Photoluminescence Properties of X-Ray Generated Divalent Sm in Mechanochemically Prepared Nanocrystalline CaF₂:Sm³⁺

by Z. Siti Rozaila, Nicolas Riesen and Hans Riesen

Inorganics 2024, 12(12), 332; https://doi.org/10.3390/inorganics12120332 - 20 Dec 2024

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Abstract

In this study, the mechanochemical preparation of nanocrystalline CaF₂:Sm³⁺ by ball milling calcium acetate hydrate, samarium (III) acetate hydrate, and ammonium fluoride is reported. The photoluminescence of the as-prepared CaF₂:Sm³⁺ shows predominantly Sm^3+ 4G_5/2 → [...] Read more.

In this study, the mechanochemical preparation of nanocrystalline CaF₂:Sm³⁺ by ball milling calcium acetate hydrate, samarium (III) acetate hydrate, and ammonium fluoride is reported. The photoluminescence of the as-prepared CaF₂:Sm³⁺ shows predominantly Sm^3+ 4G_5/2 → ⁶H_J(J = 5/2, 7/2, 9/2, and 11/2) f-f luminescence, but intense electric dipole allowed 4f⁵5d (T_1u) → 4f^6 7F₁ (T_1g) luminescence by Sm²⁺ was generated upon X-irradiation. In comparison with the co-precipitated CaF₂:Sm³⁺, the conversion of Sm³⁺

\to

Sm²⁺ in the ball-milled sample upon X-irradiation is significantly lower. Importantly, the present results indicate that the crystallite size and X-ray storage phosphor properties of the lanthanide-doped nanocrystalline CaF₂ can be modified by adjusting the ball milling time, dopant concentration and post-annealing treatment, yielding crystallite sizes as low as 6 nm under specific experimental conditions. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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8 pages, 2451 KB

Open AccessArticle

Large-Scale Synthesis of Carbon Dots Driven by Schiff Base Reaction at Room Temperature

by Jifen Shi, Shuai Chang, Yating Gao, Jian Lv, Ruocan Qian, Binbin Chen and Dawei Li

Inorganics 2024, 12(12), 310; https://doi.org/10.3390/inorganics12120310 - 27 Nov 2024

Cited by 1 | Viewed by 1460

Abstract

Photoluminescent carbon dots (CDs) have received increasing attention because of their admirable photophysical performances. The current strategies for synthesizing CDs typically require high energy consumption levels, and the ability to synthesize CDs at ambient temperature would be highly desirable. Herein, we design an [...] Read more.

Photoluminescent carbon dots (CDs) have received increasing attention because of their admirable photophysical performances. The current strategies for synthesizing CDs typically require high energy consumption levels, and the ability to synthesize CDs at ambient temperature would be highly desirable. Herein, we design an energy-efficient approach to synthesize CDs through a Schiff base crosslinking between 2,5-dihydroxy-1,4-benzoquinone and tetraethylenepentamine at room temperature. The obtained CDs possess maximum photoluminescence (PL) emissions of 492 nm. Moreover, the proposed CDs possess good stability and a concentration-dependent PL and their maximum emissions can redshift from 492 to 621 nm as the CDs concentration increases. Because of their good luminescent properties, the CDs can be employed as optical probes for doxorubicin detection using the inner filter effect. This study develops a powerful approach for the large-scale synthesis of CDs with a superior performance. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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Review

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13 pages, 1573 KB

Open AccessReview

Recent Progress of Carbon Dots in Fluorescence Sensing

by Xiao-Tian Lou, Lei Zhan and Bin-Bin Chen

Inorganics 2025, 13(8), 256; https://doi.org/10.3390/inorganics13080256 - 31 Jul 2025

Viewed by 627

Abstract

Carbon dots (CDs) have attracted much attention as new types of luminescent carbon nanomaterials in recent years because of their tunable fluorescence, good biocompatibility, high stability, and low cost. In this review, the classification of CDs is overviewed based on their differences in [...] Read more.

Carbon dots (CDs) have attracted much attention as new types of luminescent carbon nanomaterials in recent years because of their tunable fluorescence, good biocompatibility, high stability, and low cost. In this review, the classification of CDs is overviewed based on their differences in structure. Subsequently, the latest research progress of CDs in fluorescence sensing is systematically summarized and various sensing principles are elucidated in detail, including fluorescence resonance energy transfer, aggregation-induced emission, aggregation-caused quenching, electron transfer, and the inner filter effect. Finally, the challenges and future direction of CD fluorescent probes are discussed in detail. The purpose of this review is to stimulate the design of advanced CD fluorescent probes and achieve the accurate and reliable measurement of analytes in complex samples. Full article

(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)

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