Optimization of Electrical Conductivity of SA-graphene Nanocomposites Using Response Surface Methodology

Synthesis and characterization of 4-{(E)-[(5-bromo-2-hydroxyphenyl)methylidene]amino}-N-carbamimidoylbenzene-1-sulfonamide(SA) and its composites with graphene(SA-GF) were performed. Compound SA and SA-GF were characterized by FTIR and ¹H NMR. The GF dispersion in the composites was analyzed by means of scanning electron microscopy(SEM) for morphology. Thermal properties of SA and nanocomposites were investigated using differential thermal analysis(DTA) and thermogravimetric analysis(TGA). The optimum electrical conductivity of the new sulfonamide-based Schiff base was determined to be 1.78×10^–5 S/cm at a frequency of 9923 Hz, an applied voltage of –19 V, a mass fraction of 9.38% for graphene loading using a central composite design in the response surface methodology. The significance of the selected parameters(frequency, voltage and GF amount) in the model was determined by the analysis of variance(ANOVA). The results showed that frequency and graphene loading represent important model terms and have considerable effects on the conductivity of SA.     

Monitoring intracellular pH fluctuation with an excited-state intramolecular proton transfer-based ratiometric fluorescent sensor

Intracellular pH is a key parameter related to various biological and pathological processes. In this study, a ratiometric pH fluorescent sensor ABTT was developed harnessing the amino-type excited-state intramolecular proton transfer (ESIPT) process. Relying on whether the ESIPT proceeds normally or not, ABTT exhibited the yellow fluorescence in acidic media, or cyan fluorescence in basic condition. According to the variation, ABTT behaved as a promising sensor which possessed fast and reversible response to pH change without interference from the biological substances, and exported a steady ratiometric signal (I₄₇₈/I₅₄₆). Moreover, due to the ESIPT effect, large Stokes shift and high quantum yield were also exhibited in ABTT. Furthermore, ABTT was applied for monitoring the pH changes in living cells and visualizing the pH fluctuations under oxidative stress successfully. These results elucidated great potential of ABTT in understanding pH-dependent physiological and pathological processes.     

A facile electrochemical method for the synthesis of new sulfonamide derivatives of potential biological significance

The electrochemical synthesis of some new sulfonamide derivatives was carried out via the electrochemical oxidation of 2,3-dihydrophthalazine-l,4-dione （1） in the presence of arylsulfinic acids （2a and 2b） as nucleophiles. The results show that, the electrogenerated phthalazine-l,4-dione （lox） participates in a Michael type addition reaction with 2a or 2b and via an EC mechanism to produce the corresponding sulfonamide derivatives. This method provides a one-pot procedure for the synthesis of new sulfonamide derivatives of potential biological significance in good yields without using toxic reagents at a carbon electrode in an environmentally friendly manner.     

Tandem chalcone-sulfonamide hybridization,cyclization and further Claisen–Schmidt condensation: Tuning molecular diversity through reaction time and order and catalyst

We here report the synthesis of novel chalcone-sulfonamide compounds based on the hybridization at 2′ position and nitro substitution at the side chalcone phenyl ring followed by tandem cyclization into quinolinone derivatives and then a further aldol condensation only as a function of the reaction time. Therefore, for the first time, we have controlled the sequential preparation of chalcone-sulfonamide hybrids, quinolinones and then (E)-3-ene-2,3-dihydroquinolinones simply stopping reaction over increasing time periods. Furthermore, a new molecular scaffold based on a chalcone-(bis)sulfonamide hybrid has been gotten through changing the sequence of coupling reactions and catalyst. This study means practical and useful ways of constructing in high yields new biologically active compounds bearing diversified molecular scaffolds.     

The hydroamination of alkenes with sulfonamides catalyzed by the recyclable silica gel supported triflic acid

The vast applications of triflic acid (TfOH) in catalysis are severely limited by its corrosive and fuming properties. Immobilization of TfOH on silica gel well solves these problems and affords efficient recovery and reusability of TfOH. Two types of supported TfOH, the prepared silica gel supported TfOH and the in situ silica gel adsorbed TfOH, both exhibit good catalytic activity and reusability in the hydroamination of alkene with sulfonamide. The in situ silica gel adsorbed catalyst has been used for 5 runs with maintained reactivities and yields, which are superior to the performance of the prepared silica gel supported TfOH. For a series of alkenes and various sulfonamides, the heterogeneous hydroamination reactions catalyzed by both types of silica gel supported TfOH to afford similar moderate to excellent yields.     

Sulfonylation of arenes with sulfonamides

In the presence of triflic anhydride, sulfonylation of arenes with sulfonamides proceeded smoothly in Cl₂CHCHCl₂ at 80-140 °C, which gave rise to the desired products in good to excellent yields.     

Superacid mediated reactions applied to 4-aminobenzofused sultams and fluorinated 4-aminobenzene sulfonamides synthesis

A novel series of 4-aminobenzofused sultams was prepared using an efficient synthetic procedure based on superacid mediated reactions followed either by copper-catalyzed coupling or S_NAr reactions. The synthetic potential of the method toward the divergent synthesis of novel potent bioactive (fluorinated) aminobenzofused sultams and fluorinated 4-aminobenzene sulfonamides was shown, making it a new valuable process to synthesize a large diversity of compounds in bioactive 4-aminobenzene sulfonamide family.     

Lanthanide/zinc centered photoactive hybrids with functional sulfonamide linkage: Coordination bonding assembly,characterization and photophysical properties

In this paper, two novel kinds of organic–inorganic monomer, SUA-APEMS and SUA-APS, have been achieved by modifying 5-sulfosalicylic acid (SUA) with 3-aminopropyl-methyl-diethoxylsilane (APEMS) and 3-aminopropyl trimethoxysilane (APS). These two organic–inorganic monomers were used as multi-functional bridged components, which can coordinate to metal ions (Tb³⁺/Eu³⁺/Zn²⁺) with carbonyl groups, strongly absorb ultraviolet and effectively transfer energy to metal ions through their triplet excited state, as well as involve in the sol–gel process with inorganic host precursor tetraethoxysilane (TEOS), resulting two series of molecular hybrid materials (named as SUA-APEMS/APS-RE) with double chemical bond (RE(Zn)–O coordination bond and Si–O covalent bond). The effective intra-molecular energy transfer process gives rise to the characteristic emission of metal ions and the chemical bond make the hybrid materials owning better properties.     

Synthesis of Patent Blue derivatized hydrophilic dendrons dedicated to sentinel node detection in breast cancer

In the last decade, methods for the precise localization of sentinel lymph node (SLN) have drawn tremendous attention by oncology surgeons and researchers in the field of medical diagnosis. The accurate identification and characterization of lymph nodes by imaging has important therapeutic and prognostic significance in patients with newly diagnosed cancers. The SLN is the first lymph node that receives lymphatic drainage from the site of a primary tumor. Two biocompatible dendronized phosphonates, one bearing a Patent Blue (PB VF) dye at its periphery, where synthesized. Indeed, such a blue dye is currently injected to label the lymph node system for its per-operative detection. Therefore, developing chemistry of Patent Blue VF to optimize early diagnosis is of great current interest.