Synthesis and evaluation of a series of symmetrical hot brand bis azo reactive dyes using 4,4′-methylene-bis-metanilic acid on various fibre

4,4′-Methylene-bis-metanilic acid (A) was synthesized by the reaction between metanilic acid and formaldehyde. The compound (A) was used as a bifunctional middle component in the preparation of several symmetrical hot brand bis azo reactive dyes. The compound (A) was tetrazotized and coupled with various m-nitro anilino cyanurated coupling component to give various hot brand bis azo reactive dyes. The entired compounds have been identified by IR, ¹H NMR spectra and elemental analysis. The dyes were applied on silk, wool and cotton fabrics and their fastness properties were evaluated. All the dyes give good fastness properties. The percentage dye bath exhaustion was also been studied.     

Photocontrolled Translational Motion of a Microscale Solid Object on Azobenzene‐Doped Liquid‐Crystalline Films

On the move : Irradiation of azobenzene‐doped liquid crystalline films with UV/Vis light results in the photocontrolled translational motion of microscale solid object on the surface, which occurs through cis–trans isomerization of the azobenzene unit. Irradiation with an Ar⁺ laser (488 nm) resulted in precise control of the translational motion so that the particle always moved away from the irradiation position (see picture).

     

Hydrothermal Synthesis of Cadmium Sulfide Photocatalyst for Detoxification of Azo Dyes and Ofloxacin Antibiotic in Wastewater

The complete detoxification of harmful dyes and antibiotics from aqueous solution is essential for environmental remediation. The present work focuses on a facile hydrothermal synthesis of a cadmium sulfide (CdS) photocatalyst using thioacetamide as a sulfur source. The synthesized CdS showed a hexagonal phase with an energy gap of 2.27 eV, suggesting the promising visible-light-responsive semiconducting photocatalyst. The photoactivity of the prepared CdS was investigated by evaluating the degradation of the Reactive red 141 (RR141) dye, Congo red (CR) dye, and ofloxacin (OFL) antibiotic. After only 180 min of solar light illumination, a high performance of 98%, 97%, and 87% toward degradation of RR141, CR, and OFL was obtained. The photodegradation of the pollutants agrees well with the first-order kinetic model. The rate constant of 0.055 min⁻¹, 0.040 min⁻¹, and 0.026 min⁻¹, respectively, was reported toward degradation of RR141, CR, and OFL. Photogenerated holes and hydroxyl radicals play a vital role in removing toxic organic contaminants. The chemical stability of the prepared CdS was also confirmed. The synthesized CdS photocatalyst still maintains high photocatalytic performance even after five consecutive cycles of use, indicating its excellent cycling ability. The present research shows a facile route to fabricate a CdS photocatalyst to completely detoxify harmful organic pollutants, including dyes and antibiotics, in the environment.     

Facile One-Step Oxidation of N-Boc-Protected Diarylhydrazines to Diaryldiazenes with (Diacetoxyiodo)benzene under Mild Conditions

A study on the oxidation of N-Boc- and N,N'-bis-Boc-protected 1,2-diarylhydrazines with (diacetoxyiodo)benzene is reported. The reactions proceed quickly in acetic acid at slightly elevated temperatures, giving diaryldiazenes in good to excellent yields. Electron-donating and electron-withdrawing groups are well tolerated. This synthetic protocol also applies to synthesising (aryldiazenyl)pyridines and unsymmetrical 1,3,5-tris(arylazo)benzenes.