Synthesis of two-dimensional triazine covalent organic frameworks at ambient conditions to detect and remove water pollutants.

Synthesis of fully triazine frameworks (C3N3) by metal catalyzed reactions at high temperatures results in carbonized and less-defined structures. Moreover, metal impurities affect the physicochemical, optical and electrical properties of the synthesized frameworks, dramatically. In this work, two-dimensional C3N3 (2DC3N3) has been synthesized by in situ catalyst-free copolymerization of sodium cyanide and cyanuric chloride, as cheap and commercially available precursors, at ambient conditions on gram scale. Reaction between sodium cyanide and cyanuric chloride resulted in electron-poor polyfunctional intermediates, which converted to 2DC3N3 with several hundred micrometers lateral size at ambient conditions upon [2 + 2+2] cyclotrimerization. 2DC3N3 sheets, in bulk and individually, showed strong fluorescence with 63% quantum yield and sensitive to small objects such as dyes and metal ions. The sensitivity of 2DC3N3 emission to foreign objects was used to detect low concentration of water impurities. Due to the high negative surface charge (-37.7 mV) and dispersion in aqueous solutions, they demonstrated a high potential to remove positively charged dyes from water, exemplified by excellent removal efficiency (>99%) for methylene blue. Taking advantage of the straightforward production and strong interactions with dyes and metal ions, 2DC3N3 was integrated in filters and used for the fast detection and efficient removal of water impurities.

Covalent Decoration of MoS2 Platforms by Silver Nanoparticles through the Reversible Addition-Fragmentation Chain Transfer Reaction.

Two-dimensional nanomaterials decorated by metal nanoparticles have gained great interest, due to their potential applications in different areas ranging from electrochemical sensing to photothermal therapy. However, metal nanoparticles that are noncovalently immobilized on the surface of two-dimensional nanomaterials can be dissociated from their surface in the complex mediums. This challenge can be overcome by covalent attachment of nanoparticles to the surface of these platforms. In this work, MoS2 sheets are decorated by silver nanoparticles (AgNPs) through a reversible addition-fragmentation chain transfer (RAFT) reaction. Reactive centers were created on the surface of freshly exfoliated MoS2 and a two-dimensional platform with the ability of initiating the RAFT reaction was obtained. Afterwards, silver nanoparticles with acrylamide functionality were synthesized and attached on the surface of MoS2 sheets by the RAFT reaction. MoS2-AgNPs hybrids were characterized by different spectroscopy and microscopy methods as well as thermal and elemental analyses, and then they were used for the electrochemical determination of dipyridamole in aqueous solution. Taking advantage of the straightforward synthesis and the possible MoS2-AgNPs distance adjustment, a variety of hybrid systems with unique physicochemical and optoelectronic properties can be constructed by using this method.

Preparation of a novel palladium catalytic hydrogel based on graphene oxide/chitosan NPs and cellulose nanowhiskers.

The present paper focuses on the synthesis of a novel hydrogel support by combining polysaccharides (chitosan NPs and dialdehyde cellulose nanowhiskers) and graphene oxide nanosheets to obtain a biocompatible material for catalytic applications. The hydrogel was synthesized via green chemistry processes and used as a support to prepare Pd nanoparticles. Finally, the hydrogel@Pd NPs was employed as the catalyst in the Mizoroki-Heck reaction to generate new C-C bonds. SEM analysis indicated that the hydrogel has macroporous morphology, which is in good correlation with its high crosslinking degree. The as-synthesized nanocomposite hydrogel exhibits beneficial properties such as ease of separation and excellent recyclability for at least six cycles without considerable loss in its activity. The yields of the products range from 81% to 98%. Additionally, this study provides the possibility to perform the Mizoroki-Heck reaction with aryl chloride in the presence of the as-prepared catalyst.

New bis[N-(4-pyridyl)-P-toluene sulfonamide] palladium dichloride a novel fluorophore for determination of lysine amino acid.

Here, we are describing the study of the chemiluminescence arising from the reaction of bis (2,4,6-trichlorophenyl) oxalate (TCPO) system with new bis [N-(4-pyridyl)-p-toluene sulfonamide] palladium dichloride (BSPC) as a novel luminescent. The optimum concentrations of all reagents such as sodium salicylate (SS) as catalyst, hydrogen peroxide as oxidizing reagent and the relationships between the chemiluminescence intensity and concentrations of TCPO, SS, hydrogen peroxide and BSPC are reported. After optimization the required reagents, the system were used for determination of amino acid lysine, as an effective and selective quencher in the solution functioning in a Stern-Volmer fashion. This resulted in the development of a facile and highly sensitive chemiluminescence detection scheme for the determination of lysine in biological samples. Ultimately, estimating quenching constant Kq of 4.29 × 10(3) M(-1) was successfully carried out. Under the optimal conditions, the evaluated lower and upper detection limits of measurable concentration of lysine are 1.17 × 10(-7) and 3.18 × 10(-4) M, respectively.