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Herein, a novel hydrogel (HG-cl-poly(AA)) was synthesized by grafting acrylic acid (AA) onto Hing gum (HG) using methylene-bis-acrylamide (MBA) as a cross-linker and ammonium persulfate (APS) as an initiator in a hot air oven. The percentage swelling of the hydrogel was examined by optimizing various reaction parameters to ensure its maximum swelling percentage. The formation of crosslinked networks was confirmed using Fourier-Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) techniques. The surface area and hydrophilicity of the prepared hydrogel were determined using Brunauer–Emmett–Teller analyzer and wettability studies, demonstrating a clear correlation with adsorption. The adsorption of crystal violet (CV) dye on the prepared hydrogel was studied via a batch adsorption system based on the amount of adsorbent, immersion time, pH level, and initial dye concentration. The prepared hydrogel showed a 99% removal rate and an excellent adsorption capacity of 492.61mg/g due to the electrostatic, H-bonding, and dipole–dipole interactions between the adsorbent surface and dye molecules. The results were further analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The study suggests consistency with the pseudo-second-order kinetic model ($R^2=0.998$), further supported by the best data fit with the Langmuir isotherm model ($R^2=0.991$). The thermodynamic study results indicated that the adsorption process is endothermic and spontaneous. Regeneration (desorption) studies showed that the prepared hydrogel could remove CV dye from an aqueous solution and maintain the highest adsorption capacity even after multiple adsorption and desorption cycles. Therefore, the prepared HG-cl-poly(AA) hydrogel could be a potential adsorbent for dye removal and have an admirable capacity for cleaning the aquatic environment.

Serendipity has been a major player in most dye discoveries, and phthalocyanines are no exception. The true account of their discovery in 1928 is given using information provided by one of the individuals involved (Ron Greig). One of the inventors, Drescher, after making a key observation as to the nature of the insoluble blue impurity formed in the routine manufacture of phthalimide from phthalic anhydride, was killed weeks later when, on his beloved Sunbeam motorcycle, he had a head-on collision with a steamroller on his way to work. The unique properties of phthalocyanine dyes and pigments make them the colorant of choice for most blue and green colours. Thus most blue and green cars, including sports cars, are coloured by phthalocyanine pigments. In addition to these traditional uses, phthalocyanines are also finding extensive use in modern hi-tech areas. They are used for their colour as, for example, cyan dyes in ink jet printing, and in colourless applications such as infrared absorbers in security. The discovery, traditional and hitech applications of phthalocyanines are described in detail in this paper.

We present our results on nonlinear optical (NLO) of chicago sky blue 6B doped polyvinyl alcohol (PVA) film. This film was studied at 633 nm and 532 nm using a continuous wave laser. We have evaluated the sign and magnitude of the third-order nonlinearity from the closed aperture Z-scan data while the nonlinear absorption properties were assessed using the open aperture data. The chicago sky blue 6B doped PVA film exhibited nonlinear saturated absorption and strong self-defocusing effect. The limiting effect of the sample was studied and the results indicate that the film possesses good characteristic of optical limiting.

A new dyad 9(ZnP-P) has been synthesized linking 5,15-bis(4-carboxyphenyl)-10,20-bis(4-nitrophenyl) porphyrin 4(P) and Zn(II) 5-(4-aminophenyl)-10,15,20-tris(4-methoxylphenyl) porphyrin 8(ZnP) by an amide bond. The structural moieties of dyad 9(ZnP-P) present both different singlet state energy and redox properties. Dyad 9 was designed to improve the intramolecular electron transfer capacity. The ZnP moiety bears electron-donating methoxy groups and a zinc ion, while the other porphyrin structure, P, is substituted by electron-withdrawing nitro groups. On the other hand, structure P bears a carboxylic acid group, which is able to benefit from the orientation of dyad 9 adsorbed on the SnO₂ electrode. Absorption spectroscopic studies indicated only a very weak interaction between the chromophores in the ground state. The fluorescence analysis shows that both porphyrin moieties in dyad 9 are strongly quenched and that the quenching increases in a polar solvent. The ZnP moiety acts like an antenna for porphyrin P, but, singlet-singlet energy transfer is not complete. Thermodynamically, dyad 9 presents a high capacity to form the photoinduced charge-separated state, ZnP^·+-P^·-. Dyad 9 sensitizes the SnO₂ electrode and the photocurrent action spectrum closely matches the absorption spectrum, which confirms that light absorption by dyad is the initial step in the charge transfer mechanism. The photocurrent efficiency of dyad 9 is considerably higher than those of porphyrin monomers used as models of ZnP and P structures. Two processes may be contributing to enhance the charge injection efficiency in dyad 9; one involves an antenna effect that produces energy transfer from ZnP to P and the other includes electron transfer from the ZnP moiety to the photooxidizable free-base P. This dyad design, with P in direct contact with the substrate through the free carboxylic acid group, is a promising architecture of organic material for spectral sensitization of semiconductor solar cells.

Novel complexes of cobalt(II) with sulfonated derivatives of phthalocyanines are synthesized. The influence of the sulfonated group's number in peripheral substituent on solubility of macrocycle and ability to form ordered structures in solution is showed. Transition from H-aggregates to monomeric phthalocyanine structures and sandwich-type dimers was found during formation of metallophthalocyanine complexes with 1,4-diazabicyclo[2.2.2]octane. The catalytic activity of metallophthalocyanines was studied on the model of Merox process.

It is interesting to obtain catalysts to degrade organic dye pollutants at room temperature for simultaneous purposes of environment-treating and energy-saving. In this work, a novel ZrHIO${}_6\cdot 4$H₂O catalyst was synthesized by reacting ZrO(NO${}_3{)}_2$ with H₅IO₆ in aqueous nitric acid. The catalyst was found effective in degradation of rhodamine B (RhB) or methylene blue (MB) dyes at room temperature without light illumination. We used the ultraviolet–visible (UV–Vis) absorption spectra of dye solution as well as X-ray photoelectron spectroscopy (XPS) of ZrHIO${}_6\cdot 4$H₂O to confirm that the dye degradation was due to its catalytic role. Importantly, the ZrHIO${}_6\cdot 4$H₂O catalyst can be recycled five times without obvious activity loss and it achieved higher mineralization efficiency than the previously reported analogue in the degradation experiments.

A new type of Cy5-encapsulated photostable fluorescent silica nanoparticles (FSNPs) bearing positive charges have been successfully fabricated by a reverse microemulsion synthesis in one-pot. The Cy5 dye containing four primary amines are embedded into silica via covalent bonds through a silane coupling agent (GPTMS), followed by co-condensation with tetraethylorthosilicate. The uniform-sized, spherical and monodispersed FSNPs have high fluorescence intensity and photostability. The FSNPs exhibit high stability, good biocompatibility as well as low cytotoxicity. These FSNPs can be internalized into live cells and thus fluorescently label the cells. This study provides a simple synthesis approach that can be applied to other water-soluble and amino-modified organic dye molecules for biological targeting and fluorescent cell imaging.

Effluents from dyeing companies are a major polluter of the environment and water bodies. An estimated 70 tons of dye are generated globally each year, with more than one-third of this amount lost to the environment. To combat this issue, novel chemical compounds that are more efficient than existing ones are proposed. The soft synthetic approach was used to create [Ni(II)(Tpy)₂] MOF by reacting nickel nitrate with terpyridine (Tpy). The melting point of the MOF was determined, as well as the EA, HSM, TGA, PXRD, and X-ray crystallographic studies. The MOF results support the synthesis and coordination of the nickel (II) ion with the two Tpy molecules. In application, [Ni(II)(Tpy)₂] MOF was utilized to study the adsorption of Congo red. After 30 min of adsorption time, 1 g of [Ni(II)(Tpy)₂] MOF adsorbed a high amount of Congo red (138.26 mg) at $25^{\circ }$C and a pH of 2. When compared to other isotherms, the Langmuir isotherm provided the best fit. Adsorption kinetics demonstrating electrostatic interaction between MOF and Congo red might be interpreted using the pseudo-second-order model.

Density functional theory, Monte Carlo, and molecular dynamics simulations of the [Ni(II)(Tpy)₂] MOF over Congo red dye were computed. Density functional theory calculations provide insights into the reactivity of the novel [Ni(II)(Tpy)₂] MOF by furnishing chemical reactivity parameters that explain the interactions and adsorption processes between the [Ni(II)(Tpy)₂] MOF and Congo red. The quantum mechanical calculations provide data for an insightful understanding of the reactivity of the MOF and its high adsorption on the Congo red surface. Low band gaps (1.40 and 1.43 eV in the gas phase and water, respectively) obtained for the [Ni(II)(Tpy)₂] MOF suggest that this will make an extrinsic semiconductor with high electrical conductivity. Thus, it would readily interact with and be adsorbed on the Congo red.