The exfoliation of graphene from pristine graphite in a liquid phase was achieved successfully via sonication followed by centrifugation method. Ultraviolet–visible (UV–vis) spectra of the obtained graphene dispersions at different exfoliation time indicated that the concentration of graphene dispersion increased markedly with increasing exfoliation time. The sheet-like morphology of the exfoliated graphene was revealed by Scanning Electron Microscopy (SEM) image. Further, the morphological change in different exfoliation time was investigated by Atomic Force Microscopy (AFM). A complete structural and defect characterization was probed using micro-Raman spectroscopic technique. The shape and position of the 2D band of Raman spectra revealed the formation of bilayer to few layer graphene. Also, Raman mapping confirmed the presence of uniformly distributed bilayer graphene sheets on the substrate.

The synthesis, characterization, and electrochemical behavior of some acridinedione derivatives are reported. Cyclic voltammetric studies show that all the dyes undergo irreversible oxidation irrespective of the substitution on the nitrogen. The product formed on oxidation is the aromatic derivative in the case of N-H compounds and the acridinium salt in the case of the N-substituted compounds, which have been isolated and characterized. Formation of an intermediate carbon-centered radical is observed as evidenced by ESR spin-trapping experiments. A mechanistic scheme for the electrochemical oxidation is proposed. On carrying out reduction after oxidation, different products are formed depending on the substitution on the nitrogen. There is no reduction of the oxidized product in the case of N-H compounds, and compounds with substitution on nitrogen undergo reduction consistent with the observation in N-alkylpyridinium salts.

A novel colorimetric and fluorescent chemosensor ADDTU-1 bearing dual receptor sites, which shows specific optical signaling for AcO-, H2PO4-, and F- over other anions and dual response toward AcO- and F- via PET and ICT mechanisms, is described. [structure: see text]

Synthesis of 10‐aryl‐3,4,6,7,9,10‐hexahydro‐1,8(2H,5H)‐acridinedione as a new class of laser dyes is reported. These dyes lase around 475–495 nm and are compared to the standard dye coumarin 102.

Synthesis of 9‐alkyl, 10‐alkyl, 9,10‐dialkyl, and 10‐aryl‐3,4,6,7,9,10‐hexahydro‐1,8(2H,5H)acridinedione (2a–r) are described as a new class of laser dyes. Reactions of diamines with methylene bis(cyclohexane‐1,3‐dione) yielded the respective bisacridinediones (3a–e). These dyes lase around 478–494 nm and are compared with the standard dye coumarin‐102. © 1996 John Wiley & Sons, Inc.