Magdalena Wilk-Kozubek

Lanthanide-doped polymerized ionic liquids demonstrate excitation-wavelength-dependent emission, which renders them interesting candidates for flexible photonic applications.

This review article delves into the intriguing phenomenon of low-temperature thermochromism, whereby materials change color in response to temperature variations, with a particular focus on its applications in temperature-sensitive fields like medical storage. By closely examining thermochromic materials, this article highlights their potential to offer innovative solutions for monitoring and preserving thermolabile products that require strict temperature control. This leads to a special emphasis on polydiacetylenes (PDAs), a class of conjugated polymers with unique low-temperature thermochromic properties, positioning them as promising candidates for reliable temperature indicators. This article then explores the underlying mechanisms for fine-tuning the thermochromic behavior of PDAs, particularly discussing recent advancements in PDA design, such as structural alterations of monomers to achieve low-temperature thermochromism. These modifications, influenced by factors like side-chain length, hydrogen-bonding interactions, and the use of copolymers, are intended to result in irreversible color transitions at specific low temperatures, which is crucial to maintaining the integrity of thermally sensitive products. Finally, this article discusses the potential applications of PDAs as thermochromic sensors in tissue biobanking, where their ability to provide visual indications of temperature fluctuations could significantly enhance the monitoring and management of biological samples.

CnBA liquid crystals (n = 4, 5, 6) were utilized as color developers of BF leuco dye in novel thermochromic sensors, which exhibit a reversible, temperature-dependent shift in both observed and emission colors.

In this work, zinc oxide particles (ZnO NPs) green synthesis with the application of black tea extract (BT) is presented. A thorough investigation of the properties of the extract and the obtained materials was conducted by using Fourier transform infrared spectroscopy (FTIR), liquid chromatography-mass spectrometry (LC-MS), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and quadrupole mass spectroscopy (QMS). The obtained results indicated that the amount of used BT strongly influenced the morphology, chemical, and crystalline structure of the obtained particles. The investigation demonstrated that the substance present in black tea (BT) extract, which was adsorbed on the ZnO surface, was in fact gallic acid. It was found that gallic acid controls the crystallization process of ZnO by temporarily blocking the zinc cations. Additionally, these organic molecules interact with the hydroxide group of the precipitant. This blocks the dehydration process stabilizing the zinc hydroxide forms and hinders its transformation into zinc oxide. Performed measurements indicated that obtained ZnO particles have great antioxidant and antimicrobial properties, which are significantly correlated with ZnO–gallic acid interactions.

In this study, simple and efficient synthetic routes to a family of uncommon group 4–zinc heterometallic alkoxides were developed. Single-source molecular precursors with the structures [Cp₂TiZn(μ,η-OR)(THF)Cl₂] (1), [Zr₃Zn₇(μ₃-O)(μ₃,η²-OR)₃(μ-OH)₃(μ,η²-OR)₆(μ,η-OR)₆Cl₆] (2), and [Hf₃Zn₇(μ₃-O)(μ₃,η²-OR)₃(μ-OH)₃(μ,η²-OR)₆(μ,η-OR)₆Cl₆] (3) were prepared via reduction of Cp₂TiCl₂ with metallic zinc or protonolysis of the metal–cyclopentadienyl bond in Cp₂M′Cl₂ (M′ = Zr or Hf) in the presence of 2-methoxyethanol (ROH) and Zn(OR)₂. This synthetic route enables the creation of compounds with well-defined molecular structures and therefore provides precursors suitable for obtaining group 4–zinc oxides. Precursors 1–3 were characterized by elemental analysis, nuclear magnetic resonance and infrared spectroscopies, and single-crystal X-ray diffraction. Compound 1 decomposed at 800–900 °C to give a mixture of binary metal oxides (i.e., Zn₂Ti₃O₈, ZnTiO₃, or Zn₂TiO₄) and common polymorphs of TiO₂ and ZnO. After calcination at 1000 °C, only TiO₂ and the high-temperature-stable phase Zn₂TiO₄ were observed. Thermolysis of compounds 2 and 3 gave mixtures of ZnO and ZrO₂ or HfO₂, respectively. The obtained ZnO–ZrO₂ and ZnO–HfO₂ mixed oxide materials have constant phase compositions across a broad temperature range and therefore are attractive host lattices for Eu³⁺ for applications as yellow/red double-light-emitting phosphors. It was established that Eu³⁺ ions were successfully introduced into the ZnO and ZrO₂/HfO₂ lattices. It was revealed that Eu³⁺ ions prefer to occupy low-symmetry sites in ZrO₂/HfO₂ rather than in ZnO.

A set of different open framework iron phosphates have been synthesized ionothermally using a task-specific ionic liquid, 1-butyl-4-methylpyridinium hexafluorophosphate, that acts in the synthesis as the reaction medium and mineralizer: (NH₄)₂Fe₂(HPO₄)(PO₄)Cl₂F (1) and K₂Fe₂(HPO₄)(PO₄)Cl₂F (2) exhibit similar composition and closely related structural features. Both structures consist of {Fe₂(HPO₄)(PO₄)Cl₂F}^2– macroanions and charge balancing ammonium or potassium cations. Their open framework structure contains layers and chains of corner-linked {Fe(1)O₂Cl₄} and {Fe(2)F₂O₄} octahedra, respectively, interconnected by PO₄ tetrahedra forming 10-ring channels. KFe(PO₃F)F₂ (3) is built up by {Fe[(PO₃F)_4/3F_2/2]}{Fe(PO₃F)_2/3F_2/2F₂} layers separated by K⁺ cations. Chains of alternating {FeF₂O₄} and {FeO₂F₄} octahedra, which are linear for 1 but undulated for 2, are linked to each other via corner-sharing {PO₃F} tetrahedra with the fluorine pointing into the interlayer space. The compounds were characterized by means of single crystal and powder X-ray diffraction, infrared spectroscopy, and magnetic measurements. 1 reveals a strong ground state spin anisotropy with a spin 5/2 state and a magnetic moment of 5.3 μ_B/Fe³⁺. Specific heat and magnetic data unveil three magnetic transitions at 95, 50, and 3.6 K. Compound 2 has a very similar crystal structure as compared to 1 but exhibits a different magnetic behavior: a slightly lower magnetic moment of 4.7 μ_B/Fe³⁺ and a magnetic transition to a canted antiferromagnetic state below 90 K. Compound 3 exhibits typical paramagnetic behavior close to room-temperature (5.71 μ_B/Fe³⁺). There are no clear indications for a phase transition down to 2 K despite strong antiferromagnetic spin–spin interactions; only a magnetic anomaly appears at 50 K in the zero-field cooled data.