23 research outputs found
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<sup>− </sup> and Cu<sup>2+</sup>/Hg<sup>2+</sup> 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<sup>− </sup> and Cu<sup>2+</sup>/Hg<sup>2+</sup> ions. R<b>1</b> selectively recognised F<sup>− </sup> 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 Cu<sup>2+</sup> ions. Finally, R<b>1</b> was successfully applied to the bioimaging of Cu<sup>2+</sup> 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