On the structure of transition metals complexes with the new tridentate dye of thiazole series: Theoretical and experimental studies

Efficient extraction of nickel from chloride system using a cleaner extractant: Taking the example of processing nickel-aluminum slag remaining from spent hydroprocessing catalysts

The efficient recovery of nickel from chloride systems has long presented a challenge in the field. While solvent extraction is a viable approach, conventional extractants have been associated with drawbacks such as a high requirement for chloride ions and substantial consumption of acids and alkalis. In response to these challenges, this investigation developed and synthesized a novel thiazole-based extractant, N, N-Bis(4-thiazolylmethyl)octylamine (NNBT), tailored for the selective extraction of nickel from chloride systems. Findings from the study indicate that the nitrogen atom situated on the benzylamine framework within NNBT can interact synergistically with the chelating thiazole ring, facilitating effective nickel extraction and notably reducing the need for chloride ions. Furthermore, the extractant can be regenerated using deionized water, thereby obviating the necessity for additional consumption of acids and alkalis. Following the validation of NNBT as an environmentally sustainable and efficient nickel extractant within the chloride ion system, it was successfully employed to selectively and effectively extract nickel from the nickel-aluminum slag of spent HDP catalyst. The extracted nickel and aluminum were subsequently processed into electroplated nickel chloride and polyaluminum chloride, respectively, meeting the national standards of China. These outcomes underscore the eco-friendliness and promise of NNBT for nickel extraction from chloride systems.

Azobenzene as Antimicrobial Molecules

Azo molecules, characterized by the presence of a -N=N- double bond, are widely used in various fields due to their sensitivity to external stimuli, ch as light. The emergence of bacterial resistance has pushed research towards designing new antimicrobial molecules that are more efficient than those currently in use. Many authors have attempted to exploit the antimicrobial activity of azobenzene and to utilize their photoisomerization for selective control of the bioactivities of antimicrobial molecules, which is necessary for antibacterial therapy. This review will provide a systematic and consequential approach to coupling azobenzene moiety with active antimicrobial molecules and drugs, including small and large organic molecules, such as peptides. A selection of significant cutting-edge articles collected in recent years has been discussed, based on the structural pattern and antimicrobial performance, focusing especially on the photoactivity of azobenzene and the design of smart materials as the most targeted and desirable application.

Spectrophotometric Determination of Palladium(II) Ions Using a New Reagent: 4-(N’-(4-Imino-2-oxo-thiazolidine-5-ylidene)-hydrazino)-benzoic Acid (p-ITYBA)

The simple, rapid spectrophotometric method for palladium(II) ions determination using a new analytical reagent is described. The interaction of Pd(II) ions with a reagent, of the class of azolidones, 4-(N′-(4-imino-2-oxo-thiazolidine-5-ylidene)-hydrazino)-benzoic acid, in water medium results in the formation of a complex. The Pd(II)-p-ITYBA complex shows maximum absorbance at a wavelength of 450 nm. The molar absorptivity is 4.30 × 103 L·mol−1·cm−1. The optimal pH for complex formation is 7.0. The developed method has a wide linearity range of 0.64–10.64 µg·mL−1 for Pd(II). The detection limit is 0.23 µg·mL−1. It was found that Co(II), Ni(II), Zn(II), Fe(III), Cu(II), Al(III), and many anions do not interfere with the Pd(II) determination. The proposed method was tested in the analysis of model solutions and successfully applied for the determination of palladium in catalyst. The obtained results show that this method can be used for serial determinations of palladium in various objects.

Identification of tautomeric intermediates of a novel thiazolylazonaphthol dye - A density functional theory study

The recently synthesized thiazolylazo dye, 1-[5-benzyl-1,3-thiazol-2-yl)diazenyl]naphthalene-2-ol called shortly BnTAN, is studied by density functional theory (DFT) in three tautomeric forms in order to explain the available ¹H NMR, UV-Vis and FTIR spectra. An experimentally observed IR band at 1678 cm^-1, assigned to the CO bond stretching vibration, supports the notion that BnTAN retains in the less stable keto-form even in the solid state due to an ultrafast single-coordinate intramolecular proton transfer. This finding is also in a good agreement with an X-ray crystallography analysis which indicates an intermediate position of the proton between the -OH and -N=N- groups. Calculations also show that some experimentally observed ¹H NMR signals could be considered as being averaged values between theoretically calculated chemical shifts for the corresponding protons in the keto- and enol-tautomers. At the same time the UV-Vis spectra are almost insensitive to the tautomerization processes as the main single band absorption at 500 nm is present in all tautomers according to our TD DFT simulations. The minor differences in spectral features of the long-wavelength visible region are also noted and discussed with respect to the manifestation of the less stable tautomer form.

[1,3]Thiazolo[3,2-b][1,2,4]triazol-7-ium salts: synthesis, properties and structural studies

The reactions of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium salts with nucleophiles were investigated. Theoretical investigation of reactivity descriptors and structural parameters of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium cation was carried out, and the reactivity centers of the model salts were located. An efficient general method for the synthesis of novel poly-functional derivatives of symmetric triazoles from [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium halides was developed. The structures of the synthesized compounds were confirmed using proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), Fourier-transform infrared spectroscopy (FTIR) and single-crystal X-ray analysis.

Benchmark of different charges for prediction of the partitioning coefficient through the hydrophilic/lipophilic index

A few different theoretical methods for assigning the partial atomic charges were benchmarked for calculation of the hydrophilic/lipophilic index (HLI). The coefficients were selected to produce the best correlation of the HLI values with the experimental octanol-water partition. Different parameters were checked in calculations of partial charges to get the best performance of the HLI values obtained. Thus, four partitioning schemes (Coulson, Mulliken, Merz-Kollman, Ford-Wang) were benchmarked for calculations of atomic charges with six semiempirical methods (AM1, PM3, RM1, PM6, PM6-D3H4, PM7). Moreover, five distinct types of partial atomic charges (Mulliken, Hirshfeld, Löwdin, CHELPG, NPA), obtained at the Hartree-Fock and DFT levels of theory with three basis sets, were tested for their ability to produce the HLI values with the best correlation to experimental logP coefficients of 50 mono-charged organic anions. In the case of the semiempirical methods, the best correlation between the HLI and logP values (the correlation coefficient r = 0.9216) was obtained with the AM1 Ford-Wang parametric electrostatic potential charges. The Mulliken and Coulson charges calculated with the PM7 method can be used as an alternative to AM1, with the r values of 0.9107 and 0.8984, respectively. In the case of the DFT, the PBE/def2-TZVP natural population analysis charges produce the best correlation (r = 0.9220). Nevertheless, in spite of a marginally lower performance (r = 0.9159), the NPA charges computed at the PBE/def2-SVP level are more robust and can be regarded as the optimum choice for calculating the HLI values. Graphical abstract The hydrophilic/lipophilic index (HLI).

Structural and spectrophotometric characterization of 2-[4-(dimethylamino)styryl]-1-ethylquinolinium iodide as a reagent for sequential injection determination of tungsten

Structure, spectrophotometric and protolytic properties of the styryl dye 2-[4-(dimethylamino)styryl]-1-ethylquinolinium iodide (R) as well as its complex with tungsten were studied. The selective protonation of dimethylamino group was confirmed by density functional theory investigation through the computation of Fukui function, NPA partial atomic charges, and NICS(0) aromaticity indexes. The TD-DFT study explains the experimental change of color by excluding the dimethylamino group from HOMO orbital upon protonation. The acid dissociation constant, the optimum wavelength and the molar absorptivity of R were found to be: 3.02, 501nm and 4.0×10⁴Lmol^-1cm^-1, respectively. The protolytic properties of the reagent were found to change significantly in the presence of tungsten(VI). Analysis of bond critical points between the anions and Quinaldine Red cation gives the selectivity raw HWO₄^->MoO₄^->H₂VO₄^->ReO₄^->ClO₄^-, that perfectly match with the experimental data. Based on this observation, a non-extractive sequential-injection spectrophotometric method for the determination of tungsten was developed. The absorbance of the colored extracts obeys Beer's law up to 55.2mgL^-1 of W at 520nm wavelength. The limit of detection calculated from a blank test (n=10) based on 3s was 0.96mgL^-1. The developed method was applied for the determination of tungsten in model samples.

A simple non-extractive green method for the spectrophotometric sequential injection determination of copper(ii) with novel thiazolylazo dyes

A facile sequential method for the determination of copper(ii) in tap and river waters with high sample throughput is proposed.