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The aim of this work was to investigate the adsorptive performance of the polypyrrole-based KOH-activated carbon (PACK) in the removal of the basic dye crystal violet (CV) using a batch adsorption system. The equilibrium data, obtained at different initial CV concentrations ( C 0 = 50 – 500   mg / L ) and temperatures (25–45°C), were interpreted using the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, with the Langmuir model providing a better fit ( R 2 ≥ 0.9997 ) and a maximum adsorption capacity of 497.51 mg/g at 45°C. Under the examined conditions, the values of the thermodynamic parameters free energy, enthalpy, and entropy indicate a spontaneous, endothermic, and physisorption adsorption process. The kinetic data of the adsorption process were very well described by a pseudo-second-order model ( R 2 ≥ 0.9996 ). However, surface diffusion seems to be the main rate-controlling step. Thus, we concluded that PACK shows commercial potential for the removal of cationic dyes such as CV from industrial effluent.

Three new 1D coordination polymers of diorganotin(iv) dithiolates synthesized and the nature of their weak interactions addressed using computational techniques.

The aim of this study was to investigate the potential advantage of ZnFe2O4-incorporated activated carbon (ZFAC), fabricated via a simple wet homogenization, on the removal of cationic dye crystal violet (CV) from its aqueous solutions. The as-prepared ZFAC nanocomposite was characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscope (SEM), thermogravimetric analysis (TGA), and ultraviolet–visible (UV–Vis). Batch adsorption operating conditions such as the pH (3–11), CV concentration (25–200 ppm), ZFAC dose (10–50 mg), temperature (23–45 °C), and contact time were evaluated. The results indicate pH-dependent uptake (optimum at pH 7.2) increased with temperature and CV concentration increase and decreased as adsorbent dose increased. Modeling of experimental data revealed better fit to the Langmuir than Freundlich and Temkin isotherms, with maximum monolayer capacities (Qm) of 208.29, 234.03, and 246.19 mg/g at 23, 35, and 45 °C, respectively. Kinetic studies suggest pseudo-second order; however, the intra-particle diffusion model indicates a rate-limiting step controlled by film diffusion mechanism. Based on the thermodynamic parameters, the sorption is spontaneous (−ΔG°), endothermic (+ΔH°), and random process (+ΔS°), and their values support the physical adsorption mechanism. In addition to the ease of preparation, the results confirm the potential of ZFAC as a purifier for dye removal from polluted water.

A new Zn(II)-based coordination polymer (1) comprising the Schiff base ligand obtained by the condensation of 5-aminosalicylic acid and salicylaldehyde has been synthesized. This newly synthesized compound has been characterized by analytical and spectroscopic methods, and finally, by single-crystal X-ray diffraction technique in this study. The X-ray analysis reveals a distorted tetrahedral environment around the central Zn(II) center. This compound has been used as a sensitive and selective fluorescent sensor for acetone and Ag+ cations. The photoluminescence measurements indicate that in the presence of acetone, the emission intensity of 1 displays quenching at room temperature. However, other organic solvents caused meagre changes in the emission intensity of 1. Additionally, the fluorescence intensity of 1 has been examined in the presence of different ketones viz. cyclohexanone, 4-heptanone, and 5-nonanone, to assess the interaction between the C=O group of the ketones and the molecular framework of 1. Moreover, 1 displays a selective recognition of Ag+ in the aqueous medium by an enhancement in its fluorescence intensity, representing its high sensitivity for the detection of Ag+ ions in a water sample. Additionally, 1 displays the selective adsorption of cationic dyes (methylene blue and rhodamine B). Hence, 1 showcases its potential as an excellent luminescent probe to detect acetone, other ketones, and Ag+ with an exceptional selectivity, and displaying a selective adsorption of cationic dye molecules.

Here, a new cyano-bridged 3d–4f compound, a Dy(III)–Fe(III) molecular assembly ([Dy(DMF)4(H2O)3(μ-CN)Fe(CN)5.H2O] (1)), having a structure consisting of neutral one-dimensional (1D) chains, as well as an unbound aqua molecule, was synthesized and characterized using single crystal X-ray diffraction (XRD), infrared (IR), and elemental analyses. We then examined its structural topologies and studied its density functional theory (DFT), Hirshfeld surface analyses, and photophysical properties. The 1D chains were further linked by H-bond interactions, generating a three-dimensional (3D) motif which stabilizes the whole molecule. The weak interactions in 1 were assessed using Hirshfeld surface analyses, as well as fingerprint plots and DFT studies. Additionally, Hirshfeld surface analysis was performed to elucidate the roles of the weak interactions, such as the H⋯H, C⋯H, C–H⋯π, and van der Waals (vdW) interactions which are pivotal to stabilizing the crystal environment. Furthermore, the DFT studies were used to elucidate the bonding structure within the complex system. Complex 1 exhibits characteristic fluorescence as the Dy(III) complex is an excellent lime green luminescent material. Thus, it is considered to be a suitable material for preparing photoluminescent material.

This article outlines the magnetic features of a new six–coordinate high‐spin cobalt(II) complex cis‐[CoII(tmphen)2(NCS)2] (1) achieved via the reactions of cobalt(II) thiocyanate with 3,4,7,8‐tetramethyl‐1,10‐phenanthroline. The complex 1 was thoroughly characterized by different analytical and spectroscopic techniques and further confirmed by single X‐ray crystal diffraction pattern. Complex 1 is a neutral molecule and adopt highly distorted six‐coordinate CoN6 octahedral coordination sphere surrounded by two thiocyanate N atoms in cis locations and the equatorial plane is occupied by two imine N atoms from the two tmphen ligand while the remaining two imine N atoms reside in the axial positions. Magnetic susceptibility data of complex 1 revealed that the χΜT values decrease significantly to a value of 1.49 cm3·K·mol–1 at 2.0 K on decreasing temperatures below 100 K, mainly ascribed to the significant spin–orbit coupling (SOC) of six‐coordinate CoII ions. Furthermore, a field‐dependence measurement was performed at 2 K, which shows a positive curvature up to 27 kOe, while it becomes linear up to 2.01 NμB, which authenticated the fact that only the lowest Kramers doublet of ground state is appreciably populated.

The prepared complex 1 exhibited highly sensitive and selective fluorescence quenching (turn-off) effect in the presence of acetone as well as fluorescence enhancement (turn-on) effect toward Cd2+ ions in aqueous solutions.