Design strategies of carbon nanomaterials in fluorescent sensing of biomolecules and metal ions -A review

Exceptional optical properties of nano-carbon have facilitated researchers to construct surplus of carbon nanomaterials in the field of fluorescent sensing adopting various sensing strategies. It would be effortless for nano-researchers to fabricate a sensor by disentangling those sensing strategies as there were no systematic reviews about sensing strategies reported till date. Hence the focus of this review is to diligently scrutinize to furnish a perspicuous view on sensing strategies adopted by carbonic nanomaterials such as Graphene quantum dots (GQDs), Carbon dots (CDs), Carbon nanotubes (CNTs), Graphene oxide (GO) and graphitic Carbon nitride (g-C3N4) especially in detection of metal ions and bio related analytes. This could pave way for facile fabrication of sensor to achieve detection of specific target. Finally, review is summarized with plausible ways to revamp those materials to reinforce its sensing performance

Asymmetric Henry reaction catalysed by transition metal complexes: A short review

87-108An asymmetric Henry reaction, the coupling of a nitro alkane and a carbonyl group is an important C-C bond forming reaction in organic chemistry giving chiral nitro alkanols which are useful versatile intermediates in synthetic organic chemistry. It is well known that the chiral nitroaldol products find increasing applications in the pharmaceutical industry. These converted products are important precursors of biologically active compounds. Chiral nitroalcohols can be further transformed into synthetically useful derivatives such as carboxylic acids, polyamino alcohols, polyhydroxylated amides and amino alcohols. For the catalytic asymmetric Henry reaction, among the catalysts reported so far, the transition metal complexes catalyse asymmetric Henry reaction plays an important role. Transition metal complexes catalyse the asymmetric Henry reaction efficiently and in most of the cases give the product chiral nitro alkanols in good yield and enantiomeric excess. This review summarizes the reported remarkable transition metal complex catalysts for asymmetric Henry reaction, their advantages, limitations, mechanism for their catalytic activity and the challenges that need to be addressed in this research area

Transition metal complexes of tridentate Schiff base ligand as efficient reusable catalyst for the synthesis of polycaprolactone and polylactide

344-352<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-gb;mso-fareast-language:ja;mso-bidi-language:ar-sa"="" lang="EN-GB">New Schiff base complexes of zinc (Zn(II)HBAB), cobalt (Co(II)HBAB) and iron (Fe(II)HBAB) are synthesized from transition metal salts and a tridentate ONO donor ligand, namely (E)-2-(2-hydroxybenzylideneamino)benzoic acid (HBAB), and fully characterized. The present investigation is focused on the catalytic activity of transition metal complexes (Zn+2, Co+2 and Fe+2) for solvent-free ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and D,L-lactide (LA). Firstly, several reaction conditions such as reaction temperature, time and catalyst amount are optimized. Among the three metal complexes used for catalysis, Zn(II)HBAB, yields polymers with high molecular weight 33,768 and 56,331g, high yield 91 and 82% and low polydispersity index values are obtained for the polycaprolactone (PCL) and polylactide (PLA) respectively; which makes the zinc complex an efficient catalyst for ROP as opposed to cobalt and iron complexes. The polyesters (PCL and PLA) obtained from ROP catalytic reaction are well characterized by Fourier transform infrared spectroscopy (FT-IR), 1H and 13C NMR), wide angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). Catalyst-reusablity and solvent-free nature of the polymerization reaction makes this synthetic route economical and environment-friendly.</span

Indium(III) Triflate-Catalyzed Reactions of Aza-Michael Adducts of Chalcones with Aromatic Amines: Retro-Michael Addition versus Quinoline Formation

The indium­(III) triflate-catalyzed reaction of aza-Michael adducts of chalcones with aromatic amines has been investigated. The Michael adducts derived from substituted anilines and chalcones underwent retro-Michael addition to give the original starting materials, whereas the adducts derived from 1-naphthylamines and chalcones afforded quinolines. A six-membered cyclic transition state has been proposed to explain the retro-Michael addition, while a Povarov mechanism has been put forward to explain the quinoline formation

Naphthalene thiourea derivative based colorimetric and fluorescent dual chemosensor for F⁻ and Cu²⁺/Hg²⁺ ions

<div><p>A structurally simple (<i>Z</i>)-2-(naphthalen-2-ylmethylene)-<i>N</i>-phenylhydrazinecarbothioamide (R<b>1</b>) was used as a colorimetric and fluorescent sensor for both F⁻ and Cu²⁺/Hg²⁺ ions. R<b>1</b> selectively recognised F⁻ ions as indicated by colour change from colourless to green. Fluorescence spectral data reveal that R<b>1</b> is an excellent fluorescence chemosensor for Cu²⁺ ions. Finally, R<b>1</b> was successfully applied to the bioimaging of Cu²⁺ ions in RAW 264.7 macrophage cells.</p></div

Ligand-free palladium-catalyzed C-S coupling reactions using water as solvent and microwaves

Herein we demonstrate for the first time a rapid and efficient method for the synthesis of aryl sulfides by the direct substitution reaction of aromatic thiols with aryl halides using water as solvent under microwave irradiation. This procedure offers a high yield in shorter reaction time as compared to conventional methods