Metastability is a challenging problem in crystallization, where the metastable phase in a crystalline phase is usually thermodynamically unfavourable and unstable, but kinetically favourable and stable [1]. The aim of this study was to assess synthensized metastable N, N’-bis(4-chlorophenyl)thiourea for its stability status [2-4]. In line with this, N, N’-Dimethylformamide was used in a slow evaporation process. In this process, N, N’-Dimethylformamide formed a cocrystal (C₁₆H₁₇Cl₂N₃OS) witth N, N’-bis(4-chlorophenyl)thiourea via a network of classical N-H….O to avoid voids. The characterization technique of single X-ray crystallography confirmed the structure of the cocrystal, the ShelXT solution program solved the structure, and the Gauss–Newton 2017/1 version of olex2 refined the structure. The results revealed that C₁₆H₁₇Cl₂N₃OS (cocrystal) with Mr (370.30) and a crystal size of 0.17 x 0.12 x 0.10 mm appeared as a white crystal in a polygon-like shape in the P2_1/c monoclinic space group. Additional results revealed cell parameters of a = 92.360 (4) Å, b = 7.2232 (3) Å, c = 25.2555 (11) Å, β = 91.376 (3), α = γ = 90°, V= 1684.40 (12) Å3, T = 119. 94 (13) K, Z = 4, Z’ = 1, and the calculated density (gcm-1). The significance of this study is the application of cocrystals as desolution blockers in active pharmaceutical ingredients (API) and materials science.

References
1. Li, C., Zhang, C., Ren, Y. Growth and morphological control of metastable KDP crystals using defect-free seeds. RSC Advances, 2026, 11, 10012-10021.

2. Odularu, A.T., Ajibade, P. A., Mbese, J. Z., Oyedeji, ,O. O., Puschmann, H. Synthesis and crystal structure of N,N′-bis(4-chlorophenyl)thiourea N,N-dimethylformamide. Open Chemistry,. 2021, 19, 511– 517.
3. Jambi, SMS. Characterization and synthesis of novel thiourea derivatives. International Journal of Chemical and Technology Research, 2019, 12, 177–87.
4. Das, C, Zhang H, Li, R, Zou H. Synthesis and characterization of thiourea. Polish Journal of Chemical Technoology, 2019,. 1, 35–39.

Zinc–tin oxide (ZTO) is a ternary metal oxide that offers promising properties for applications in electronics, energy harvesting and sensing devices due to its high electron mobility, chemical stability and tunable optical properties [1]. Among the different synthesis techniques, microwave-assisted hydrothermal synthesis has emerged as an efficient approach for producing nanostructured materials due to its fast and homogeneous heating [2]. However, the morphology and crystalline phases obtained are strongly influenced by the synthesis parameters employed [3]. In this work, the influence of solution volume, microwave power and synthesis time on the formation of ZTO nanowires was systematically investigated. Two solution volumes (7.5 mL and 15 mL), two microwave powers (75 W and 100 W) and synthesis times ranging from 2 to 4 h were evaluated to identify optimal synthesis conditions. The resulting nanostructures were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to assess morphology, crystalline structure and chemical bonding. Overall, the results demonstrate that synthesis time, microwave power and solution volume play critical roles in controlling ZTO nanowire morphology and growth. By optimizing these parameters, ZnSnO₃ nanowires with comparable morphological and crystallinity quality to those obtained via conventional oven-based hydrothermal synthesis [4] were successfully produced in only 4 h, corresponding to a reduction of 20 h in synthesis time.

Acknowledgements: This work is funded by National Funds through FCT - Portuguese Foundation for Science and Technology, References LA/P/0037/2020, UIDP/50025/2020 and UIDB/ 50025/2020 and the project FOLOW (2023.11887.PEX). This work also received funding from the European Community's H2020 program [GA No. 101008701 (EMERGE)].

References

[1] Rovisco, A. et al., Discover Nano 2025, 20, 229.

[2] Rovisco, A. et al., Nanomaterials 2022, 12, 2119.

[3] Rovisco, A. et al., Nanomaterials 2019, 9, 1002.

[4] Rovisco, A. et al., ACS Appl. Nano Mater. 2018, 1, 3986–3997.

Single crystals of SnS₂​ were grown using the direct vapor transport (DVT) technique in a dual-zone muffle furnace. Initially, an elemental stoichiometric proportion totaling 10 g was used to prepare the SnS₂​ compound at 550 K for 24 hours. This as-prepared compound was then used for the subsequent growth of single-crystalline SnS₂ ​via the DVT method. The resulting crystals are thin, shining, orange-colored, wafer-like flakes with maximum dimensions of 20 mm × 20 mm × 0.015 mm. The grown crystals were characterized to evaluate their microstructure, optical, and thermal properties. The growth mechanism observed on the as-grown single-crystal surfaces consists of growth layers originating from growth islands. No cracks or pinholes were observed in the grown crystals. Optical absorbance was recorded in the 200 nm to 3500 nm range. The grown SnS₂​ single crystals show high optical absorption between 382 nm and 570 nm. The direct optical bandgap was evaluated using a Tauc plot ((αhν)² versus hν) and was determined to be 2.2 eV. The thermal properties of the grown SnS₂​ single crystals were evaluated in the temperature range of 307 K to 1230 K using thermogravimetric analysis (TGA), differential thermal analysis (DTA), and derivative thermogravimetric (DTG) analysis in an inert N₂​ atmosphere with a heating rate of 5 °C/min, showing a total weight loss of 59.84%. Total decomposition occurred in two distinct steps: the first and second decomposition phases occurred from 855 K to 985.13 K and 1083 K to 1207 K, with weight losses of 14.85% and 40.68%, respectively. Two DTG peaks observed at 948.28 K and 1192.91 K corroborate these thermal decompositions. DTA analysis revealed two peaks at 948.80 K and 1140.67 K with an increase in negative potential, indicating endothermic behavior. Activation energy and other thermodynamic parameters were evaluated and are discussed in detail.

5-hydroxymethylfurfural (HMF), a six-carbon heterocyclic organic compound containing both aldehyde and alcohol functional groups, is produced from the dehydration of hexose sugars under acidic conditions. The hydroxymethyl and carbonyl groups of HMF can be oxidized to form various important furanic chemicals, which serve as platform molecules for further transformations. During the last years, research in the field of photocatalysis has expanded from degradation of harmful compounds to synthesis as a green chemistry tool to replace dangerous and polluting routes. Different catalysts were already reported as active in the selective oxidation of HMF under UV or visible light irradiation. Doping of TiO₂ with rare earth metals is a very efficient way to improve its photocatalytic performance as a result of different factors. In our work, TiO₂ containing different amounts of Er and Yb was prepared using the sol–gel method and then calcined at 500 and 750^oC, respectively. The characterization of these samples showed that the phase distribution of these is different than that of the pristine TiO₂. While the pristine TiO₂ calcined at 500^oC contained about 5% anatase along with the predominant rutile phase, the doped samples contained 100% anatase. The increased calcination temperature led to a content of about 66% in rutile for TiO₂, compared to the doped samples, which contained a maximum of 28% rutile for 1%Yb-TiO₂. These catalysts were active under UV irradiation, more active than the pristine TiO₂, but most of them oxidized HMF to lactic acid (LA, major product) and glycolic acid (GA). The activity increased with the amount of dopant, and decreased with the increase of the calcination temperature. The only catalysts that led to 2,5-hydroxymethylfurancarboxylic acid (HMFCA) as the reaction product were 1%Er-TiO₂ calcined at 750⁰C and 1%Er-1%Yb-TiO₂ calcined at 500⁰C, the samples with the smallest amount of rutile. No base was added in our experiments.

Rocks commonly referred to as Meas Sruoy in Cambodia resemble “fool’s gold,” a mineral that is frequently mistaken for real gold due to its similar appearance. In many Cambodian communities, these rocks are believed not only to contain gold but also to possess spiritual qualities that can ward off evil and bring prosperity, health, and happiness. To investigate the composition of these materials, Meas Sruoy samples collected from Battambang, Mondulkiri, Kratie, and Takeo provinces were analyzed using hand-held X-ray fluorescence (XRF), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The intact samples were first cleaned using an ultrasonic cleaner to remove surface contaminants and then dried prior to elemental characterization using a handheld XRF (X-MET8000). Elemental distribution was further examined using EDS. For elemental composition, the samples were ground into powders to improve homogeneity and subsequently analyzed by XRD (Malvern Panalytical Aeris, λ = 0.15406 nm), with diffraction patterns analyzed using MDI Jade 6 software. The analytical results revealed no detectable gold in any of the examined samples. Instead, the rocks exhibited diverse mineralogical compositions dominated by silica, iron, sulfur, and aluminum, along with trace levels of heavy metals, including arsenic, lead, chromium, and copper. Mineral phase analysis consistently identified quartz and pyrite, indicating a complex geological origin and confirming the visual resemblance to pyrite, commonly known as fool’s gold. These findings provide scientific evidence that contrasts with traditional beliefs surrounding Meas Sruoy while contributing valuable information regarding the mineralogical characteristics of rocks from different regions of Cambodia. Additionally, the detection of pyrite and trace heavy metals suggests potential environmental and public health considerations, particularly with prolonged exposure to these materials.

This study reports on the synthesis, crystal structure, and Hirshfeld surface investigation of the nickel(II) complex [Ni(C₆H₂N₂)(H₂O)₄]SO₄. NiSO₄·6H₂O and 8-aminoquinoline were reacted in ethanol under reflux conditions at 60 °C for 30 minutes to create the complex. Slow evaporation of the reaction solution at room temperature yielded light-green single crystals suitable for X-ray diffraction investigation (75% yield). The results of the elemental analysis are in good agreement with the proposed molecular formula [Ni(C₉H₈N₂)(H₂O)₄]SO₄. The compound crystallizes in the monoclinic crystal system with the space group P21/c, according to single-crystal X-ray diffraction study. The unit-cell volume is 1473.33(14) ų, Z = 4, a = 12.0672(6) Å, b = 9.2001(4) Å, c = 14.4120(8) Å, and β = 112.953°.

The nickel (II) ion possesses a six-coordination number and a deformed octahedral shape generated by one nitrogen atom from the 8-aminoquinoline ligand and four coordinated water molecules, according to structural analysis. The Ni-N and Ni-O bonds measure 2.106 Å and 2.081(3) Å, respectively.
A large hydrogen-bonding network including coordinated water molecules, the ligand's amino group, and the sulfate anion helps to maintain the crystal packing. The cationic complex and sulfate anion form layered supramolecular structures through twelve hydrogen bonds of the N-H···O and O-H···O kinds, with sulfate oxygen atoms acting as acceptors.

Hirshfeld surface analysis was used to explore intermolecular interactions in the crystal structure. The findings show that H···O/O·· ·H interactions account for 45.0% of total contacts in crystal packing, followed by H···H (34.4%) and H···C/C···H (14.3%) interactions. Hydrogen bonding plays a crucial role in crystal structure stabilization, as evidenced by minor contributions from C···C (4.3%) and H···N/N···H (0.8%) contacts, which, although small, indicate that these interactions still contribute to the overall stability of the crystal structure.

In this study, a polymeric coordination compound with the composition C₁₀H₁₀MnN₂O₅ has been structurally characterised. The results indicate that the compound crystallises in the monoclinic crystal system with the space group P2₁/c. The unit cell parameters are a = 7.7002(6) Å, b = 10.2149(6) Å, c = 15.0286(12) Å, and β = 104.102(8)°, with a cell volume of 1146.48(15) ų.

The manganese(II) centre exhibits a coordination number of six, being surrounded by five oxygen atoms and one nitrogen atom, thereby forming a distorted octahedral geometry. The Mn–O bond lengths are in the range 2.154–2.176 Å, whereas the Mn–N bond length is 2.320 Å. These distances are consistent with those typically observed for Mn(II) coordination environments, confirming the expected bonding characteristics.

The organic ligand fragment contains an aromatic ring system that is essentially planar. The C–C bond lengths lie in the range 1.377(4)–1.400(4) Å, while the C–N bond lengths are 1.334(4)–1.345(4) Å, indicating the presence of a delocalised π-conjugated system. The carbonyl C–O bond distances, ranging from 1.226(5) to 1.254(4) Å, are in good agreement with expected values.

The crystal structure is primarily stabilised by metal–ligand coordination bonds together with weak supramolecular interactions, including C–H···O and C–H···π contacts. No significant solvent-accessible voids were observed within the lattice.

In the crystal packing, weak supramolecular interactions further contribute to stabilisation. In particular, weak C–H···π interactions are observed between aromatic rings, such as the C2A–H2AC···Cg1 contact with a distance of 2.839 Å. In addition, the centroid–centroid separation between adjacent aromatic rings is 5.456 Å, indicating weak π–π stacking interactions. Although no classical hydrogen bonds are present, weak C–H···O interactions also play a role in stabilising the crystal packing.

Maltol (3-hydroxy-2-methyl-4H-pyran-4-one) is a bidentate ligand that coordinates transition metal ions via its hydroxyl and carbonyl groups. Copper(II) forms stable complexes with oxygen-donor ligands due to its flexible coordination geometry and biological relevance. This study investigates the complexation of copper(II) nitrate trihydrate with maltol, forming a stable complex with distinct structural characteristics. The copper(II)–maltol complex was synthesized by reacting copper(II) nitrate trihydrate with maltol in aqueous solution under ambient conditions. The resulting solid was characterized using FT-IR, PXRD, and TGA/DSC to evaluate coordination modes, structure, thermal stability, and solution behavior. FT-IR analysis showed the absence of the C–OH stretching vibration at 3255 cm⁻¹, indicating deprotonation of maltol and coordination to the copper ion. The C=O stretching vibration shifted from 1616 cm⁻¹ in free maltol to 1568 cm⁻¹ in the complex, confirming chelation. A weak Cu–O band at 719 cm⁻¹ was observed, with no nitrate ions detected. Thermal analysis revealed a single-step degradation, with 70% mass loss attributed to the removal of maltol, and a sharp exothermic peak at 220°C in the DSC curve, consistent with CuO. X-ray diffraction confirmed the monoclinic crystal system (space group C2/c) with square-planar coordination around the copper ion, exhibiting Jahn–Teller distortion. This study successfully synthesized and characterized the copper(II)–maltol complex. FT-IR confirmed maltol coordination with copper, forming a stable chelate. Thermal analysis indicated good stability, and X-ray diffraction revealed a monoclinic structure with Jahn–Teller distortion. These findings enhance understanding of copper(II) coordination chemistry with maltol.

This research was funded by the European Union—NextGenerationEU Project “Advanced Interdisciplinary Approaches to Environmental Chemistry: From Materials to Sustainable Solutions for Pollution” (Grant number: 581-UNIOS-101).

Thin films of ZnO, CuO, and ZnO/CuO heterostructures were synthesized using the SILAR (Successive Ionic Layer Adsorption and Reaction) method with 50 deposition cycles, ensuring controlled thickness and uniform growth. The structural, morphological, and optical properties of the thin films were systematically characterized. X-ray diffraction (XRD) analysis confirmed the crystalline nature and phase purity of ZnO and CuO, as well as the successful formation of the heterostructure. Scanning electron microscopy (SEM) revealed uniform surface morphology with well-distributed grains, indicating good film quality. UV–Vis spectroscopy showed that ZnO films mainly absorb in the ultraviolet region, while CuO extends absorption into the visible region. The ZnO/CuO heterostructure exhibited improved optical absorption over a broader spectral range, thereby enhancing its photocatalytic potential. The photocatalytic performance of the films was evaluated through the degradation of methylene blue under UV–Vis light irradiation (λ = 310 nm). A 5 ppm methylene blue solution was used as a model pollutant. The results showed that the ZnO/CuO heterostructure film exhibited 17% methylene blue degradation compared to the individual ZnO (12%) and CuO (15%) films. This improvement is attributed to enhanced charge separation and reduced electron–hole recombination at the ZnO-CuO interface. Overall, this study highlights the potential of SILAR-fabricated ZnO/CuO thin films as efficient photocatalysts for environmental remediation applications.

This work reports a comprehensive investigation of the structural, dielectric, electrical, optical, and energy storage properties of Sr₅CaTi₂₋ₓZnₓNb₈O₃₀ (x = 0–0.08) tetragonal tungsten bronze ceramics synthesized via the solid-state reaction method. Rietveld refinement of X-ray diffraction data confirms the formation of a single-phase tetragonal tungsten bronze structure with Im2a space group, highlighting the successful incorporation of Zn ions into the lattice and the resulting modifications in crystallographic parameters. Microstructural analysis reveals dense ceramics with low porosity and uniformly distributed grains, with average grain sizes ranging from 15.01 to 17.16 µm. Dielectric measurements performed over a temperature range of 30–400 °C and frequencies from 1 kHz to 1 MHz exhibit two distinct anomalies corresponding to the ferroelectric phase transition (Tc) and a relaxation process (Ts), indicating diffuse phase transition behavior. Impedance spectroscopy, Nyquist plots, and electric modulus analysis demonstrate the significant contribution of grain and grain boundary effects to the electrical response, while activation energy calculations confirm thermally activated conduction mechanisms. The polarization–electric field hysteresis loops exhibit slim shapes, characteristic of relaxor ferroelectrics, which are favorable for energy storage applications. Compared to previous studies, this work provides deeper insight into the relationship between crystallographic structure and multifunctional properties, emphasizing the role of Zn substitution in tuning dielectric relaxation and enhancing energy storage performance in tungsten bronze ceramics.