Nanostructured Samarium Doped Fluorapatites and Their Catalytic Activity towards Synthesis of 1,2,4-Triazoles

Abstract

An investigation was conducted into the influence of the amino acids as organic modifiers in the facile synthesis of metal incorporated fluorapatites (FAp) and their properties. The nanostructured Sm doped fluorapatites (Sm-FAp) were prepared by a co-precipitation method using four different amino acids, namely glutamic acid, aspartic acid, glycine and histidine. The materials were characterized by various techniques including X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HR-TEM), N 2 -adsorption/desorption isotherm, temperature programmed desorption (TPD) and fluorescence spectrophotometry. Under similar conditions, Sm-FAp prepared using different amino acids exhibited distinctly different morphological structures, surface area and pore properties. Their activity as catalysts was assessed and Sm-FAp/Glycine displayed excellent efficiency in the synthesis of 1,2,4-triazole catalyzing the reaction between 2-nitrobenzaldehyde and thiosemicarbazide with exceptional selectivity and 98% yield in a short time interval (10 min). The study provides an insight into the role of organic modifiers as controllers of nucleation, growth and aggregation which significantly influence the nature and activity of the catalytic sites on Sm-FAp. Sm-FAp could also have potential as photoactive material.

Bi2O3/FAp, a sustainable catalyst for synthesis of dihydro‐[1,2,4]triazolo[1,5‐a]pyrimidine derivatives through green strategy

“…FAp also provided a satisfactory yield of the desired product (Table 1, Entry 19). FAp exhibits an amphoteric feature having both Lewis acid and basic sites, with the Ca 2+ accountable for the acidic sites, and F − and P–O − being liable for the basic sites . This combination allows effective conversions, which explains the superior catalytic performance of FA.…”

Transalkylidation reaction: green, catalyst-free synthesis of thiosemicarbazones and solving the NMR conflict between their acyclic structure and intramolecular cycloaddition products

“…Cyclocondensation of thiosemicarbazide with aldehydes could afford either 1,2,4-triazolidine-3-thiones or 2-amino-1,3,4-thiadiazoline using different reaction conditions (45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56). We observed that there is a structural elucidation confusion between the open structure of thiosemicarbazone and their cycloaddition product with aldehyde.…”

“…That was obvious in several published articles which reported identical spectral data for both thiosemicarbazones and their cycloaddition product (1,2,4-triazolidine-3-thiones). Thus, many authors incorrectly interpreted the NMR spectral data of alkylidene thiosemicarbazones and reported them as triazolidine-3-thiones (45)(46)(47)(48)54,55,57), this confusion arises from the presence of three exchangeable N-H signals in both structures. Herein, we would like to report a green and simple method for synthesis of alkylidene thiosemicarbazide and clarify the structural elucidation confusion between alkylidene thiosemicarbazide, and their cyclized forms.…”

Microwave‐Assisted Multicomponent Reaction: A Green and Catalyst‐Free Method for the Synthesis of Poly‐Functionalized 1,4‐Dihydropyridines

“…In continuation of our research efforts in the direction of synthesis of various heterocyclic molecules via MCRs under green conditions, recently we have reported the preparation of several novel heterocyclic protocols via multicomponent reaction in the presence of different heterogeneous catalysts . Further, we have also reported biological active heterocyclic molecules .…”