Search

Ni55Mn22Ga23−xAlx (0 ≤ x ≤ 5) melt spun ribbons homogenized at 1073 K for 30 h exhibited an elevation in martensitic transformation onsets and a reduction in Curie temperature with increase in Al content. The phenomenon has been attributed to different site occupancy by Al, exchange coupling and paramagnetic martensite during thermal and magnetic transitions. Transmission Electron microscopy revealed systematic patterns of dislocations in alloy with x = 1, which become denser at high Al content. X = 1 alloy revealed high magnetic field induced strain (MFIS) value it is attributed to a critical combination of austenite and martensite phase.

The influence of melt spinning and heat treatment on the structure, phase transformation and magnetic field induced strain (MFIS) properties have been investigated for Ni55Mn22Ga22Al1 (at%) alloy. The microstructure showed distinct improvement in morphology of as spun ribbon as compared to ingot. Annealing further enhanced martensite state and displayed systematic arrangement of dislocations. It contributed to increase MFIS to 482 ppm in annealed ribbon as compared to 190 ppm and 28 ppm for as-spun ribbon and ingot, respectively.

A convenient methodology has been developed towards the synthesis of substituted phenanthridines and analogous benzo[ k ] and benzo[ i ] derivatives via aerobic ligand-free domino Suzuki coupling–Michael addition reaction in the presence of Pd(OAc) 2 and K 3 PO 4 as a catalytic system in H 2 O at 90 °C in good yields. Reaction was believed to be catalyzed by in situ generated palladium nanoparticles in water with the elimination of acetone.

We have successfully developed a transition metal free green methodology for the synthesis of carboxylic anhydrides from aldehydes via CDC pathway and have also demonstrated the reaction mechanism. The developed method has also been successfully applied for the synthesis of amides.

A one-pot simple and concise methodology has been developed for synthesizing aromatic carboxylic anhydrides starting from easily accessible aromatic aldehydes using cuprous chloride as the catalyst and TBHP as the oxidant in DMSO solvent to garner moderate to good yields via radical pathway in short and convenient reaction time at room temperature.

Selective oxidation of alcohol to its corresponding carbonyl compound is an important chemical process in biological as well as industrial reactions. The heme containing enzyme CytP450 has been known to selectively oxidize alcohols to their corresponding carbonyl compounds. The mechanism of this reaction, which involves high-valent Fe(IV)(O)-porphyrin(•+) intermediate with alcohol, has been well-studied extensively both with the native enzyme and with model complexes. In this paper, we report for the first time the mechanistic insight of alcohol oxidation with Fe(V)(O) complex of biuret TAML (bTAML), which is isoelectronic with Fe(IV)(O)-porphyrin(•+) intermediate form in CytP450. The oxidations displayed saturation kinetics, which allowed us to determine both the binding constants and first-order rate constants for the reaction. The K and k values observed for the oxidation of benzyl alcohol by Fe(V)(O) at room temperature (K = 300 M(-1), k = 0.35 s(-1)) is very similar to that obtained by CytP450 compound I at -50 °C (K = 214 M(-1), k = 0.48 s(-1)). Thermodynamic parameters determined from van't Hoff's plot (ΔH∼ -4 kcal/mol) suggest hydrogen bonding interaction between substrate and bTAML ligand framework of the Fe(V)(O) complex. Analysis of H/D KIE (kH/kD ∼ 19 at 303 K), Hammett correlation and linearity in Bell-Evans-Polyanski plot points to the C-H abstraction as the rate determination step. Finally, experiments using Fe(V)(O(18)) for benzyl alcohol oxidation and use of the "radical clock" cyclobutanol as a substrate shows the absence of a rebound mechanism as is observed for CytP450. Instead, an ET/PT process is proposed after C-H abstraction leading to formation of the aldehyde, similar to what has been proposed for the heme and nonheme model compounds.

A novel and efficient methodology for the synthesis of 6H-benzo[c]chromenes, 6H-benzo[c]chromen-6-ones, carbazoles, dibenzofurans, dibenzooxepins has been developed. The reaction goes through intramolecular O-/N-arylations with sp2C–Br bonds via typical SNAr pathway in presence of potassium-tert-butoxide base.

The title compounds are efficiently obtained by intramolecular aryl C—H oxidative lactonization of 2-arylbenzaldehydes using tBuOOH as oxidant and CuCl as low-cost catalyst.

A short and convenient hetero-annulation protocol has been developed for the synthesis of substituted phenanthridines via domino Suzuki coupling and condensation between N -(2-iodo-aryl)-formamide derivatives and 2-formylphenylboronic acid in the presence of Pd(OAc) 2 , Cs 2 CO 3 and PPh 3 as catalytic system in dry DMF at 85–90 °C for 6–7 h. The intermediate after Suzuki coupling and deprotection of nitrogen under the same catalytic system, furnishes the corresponding phenanthridines in good yields after immediate condensation and dehydration.

The reaction yields decrease with an increasing electron-withdrawing effect of the substituents.

Phthalides have been synthesized exclusively in one pot via Pd-free Sonogashira coupling. A Cu-catalyzed domino Sonogashira coupling and 5-exo-dig cyclization between suitable substituted ortho-bromobenzoic acids and terminal alkynes afforded phthalides in good yields under mild reaction conditions.

An efficient method has been developed for the synthesis of bis-exocyclic conjugated diene containing 1,2,3,4-tetrahydroquinoline derivatives via palladium-catalyzed intramolecular Heck cyclization of (2-bromo-allyl)-(2-phenylethynyl-phenyl)-amines. The reaction followed 6-exo-dig cyclization to yield the desired products in moderate to good yields.

A convenient and short methodology has been developed towards the synthesis of highly substituted phenanthridines and their analogous benzo[k] and benzo[i] derivatives in a single step via Suzuki coupling and condensation between suitably substituted aromatic ortho-bromoaldehydes and ortho-aminobenzeneboronic acids in good to excellent yields.

As per the statistics provided by Statista, Facebook holds 18% market share in the space of online and social media and has over 1, 590 million active users worldwide (Chaffey, 2016). This statistic is interesting to analyze in the Indian context where the total internet penetration is about 28% which means 375 million active internet users, according to the 2016 report by We Are Social. The same report states that 48% of the Indian population uses the internet every day and Facebook is the most active social media platform with 13% of the total users. In this group, users in the age group of 20–29 years comprise 51% of the total users, with a further bifurcation of 38% male users and 13% female users. The aforementioned statistics build a very crucial context for investigating social media behaviors of Indian youth in general. This is also significant to explore the most important topics or subjects that this group engages with on a social media platform like Facebook.

Two efficient hetero-annulation protocols have been developed for the synthesis of stable substituted c-fused thiophene derivatives with moderate to high yield. 3-(2-formyl-phenyl)-acrylic acid esters afforded benzo[c]thiophenes in the presence of phosphorus pentasulfide in refluxing benzene while 3-(2-formyl-cycloalkenyl)α,β-unsaturated esters resulted in the formation of c-fused thiophene derivatives when reacted with sodium sulfide in refluxing tetrahydrofuran.

A facile, mild, efficient, and copper-free method has been developed for the synthesis of 2-substituted indoles via domino Sonogashira coupling/cyclization reaction catalyzed by ZnCl2 and palladium on carbon with simultaneous formations of C–C and C–N bonds.

A convenient and short methodology has been developed towards the synthesis of highly substituted phenanthridines and their analogous benzo[k] and benzo[i] derivatives in a single step via Suzuki coupling and condensation between suitably substituted aromatic ortho-bromoaldehydes and ortho-aminobenzeneboronic acids in good to excellent yields.

An Fe(V)(O) complex has been synthesized from equimolar solutions of (Et4N)2[Fe(III)(Cl)(biuret-amide)] and mCPBA in CH3CN at room temperature. The Fe(V)(O) complex has been characterized by UV-vis, EPR, Mossbauer, and HRMS and shown to be capable of oxidizing a series of alkanes having C-H bond dissociation energies ranging from 99.3 kcal mol(-1) (cyclohexane) to 84.5 kcal mol(-1) (cumene). Linearity in the Bell-Evans-Polayni graph and the finding of a large kinetic isotope effect suggest that hydrogen abstraction is engaged the rate-determining step.

The synthesis of the title compounds is achieved from aryl bromides and 2-aminophenylboronic acid under mild reaction conditions.

Two efficient hetero-annulation protocols have been developed for the synthesis of stable substituted c-fused thiophene derivatives with moderate to high yield. 3-(2-formyl-phenyl)-acrylic acid esters afforded benzo[c]thiophenes in the presence of phosphorus pentasulfide in refluxing benzene while 3-(2-formyl-cycloalkenyl)α,β-unsaturated esters resulted in the formation of c-fused thiophene derivatives when reacted with sodium sulfide in refluxing tetrahydrofuran.

An Fe(III) complex of a biuret-amide based macrocyclic ligand that exhibits both excellent reactivity for the activation of H(2)O(2) and high stability, especially at low pH and high ionic strength, is reported.