Temperature gradient induced phase transitions and morphological changes in diamond thin film

The diamond films were deposited onto a wurtzite gallium nitride (GaN) thin film substrate using hot-filament chemical vapor deposition (HFCVD). During the film deposition a lateral temperature gradient was imposed across the substrate by inclining the substrate. As grown films predominantly showed the hexagonal phase, when no inclination was applied to the substrate. Tilting the substrate with respect to the heating filament by 6° imposed a lateral temperature gradient across the substrate, which induced the formation of a cubic diamond phase. Diamond grains were predominantly oriented in the (100) direction. However, a further increase in the substrate tilt angle to 12°, resulted in grains oriented in the (111) direction. The growth rate and hence the morphology of diamond grains varied along the inclined substrate. The present study focuses on the measurements of dominant phase formation and crystal orientation with varying substrate inclination using orientation-imaging microscopy (OIM). This technique enables direct examination of individual diamond grains and their crystallographic orientation.     

Laccase-catalysed reaction between Meldrum's acid and catechols/hydroquinones – An investigation

Enzymatic oxidation of catechols/hydroquinones in the presence of Meldrum's acid as a nucleophile in aqueous solution has been investigated in detail by applying laccase as a catalyst. Optimization of the reaction through the use of HBT/ABTS/HPI as a mediator allowed a yield of more than 65% of the isolated product. We derived some new compounds with catechol/hydroquinone ring with moderate yields based on enzymatic synthesis in environmentally benign aqueous solution. These types of reactions represent a milestone along the path to future sustainable green chemistry.     

Simultaneous Quantification of Flavonoids and Biflavonoids in Ginkgo biloba Using RP-HPTLC Densitometry Method

JPC – Journal of Planar Chromatography – Modern TLC - A reversed-phase high-performance thin-layer chromatography (RP-HPTLC) method was developed for the determination of flavonoids...     

Luminescence study of γ-ray and C5+ ion beam-irradiated LiCaBO3:Cu phosphor

Cu-doped LiCaBO₃ phosphors were prepared by modified solid-state synthesis and the formation of compound was confirmed by X-ray diffraction study. LiCaBO₃:Cu⁺ (Cu?=?0.02, 0.05, 0.1 and 0.2?mol%) were studied for photoluminescence (PL) study and prominent PL emission spectra were obtained for Cu⁺ with transition ³d₉⁴s₁?→?³d₁₀. The phosphors were further studied by thermoluminescence (TL) property for exposure to γ-ray irradiation of 1.2?rad with ¹³⁷Cs source. TL of LiCaBO₃:Cu was also studied for C⁵⁺ (3.75?×?10¹²?ion?cm^?2) beam irradiation for 1?min exposure time. Trapping parameters (activation energy and frequency factor) for single deconvoluted peaks were obtained by Chen's peak shape method.     

Effect of pH on simultaneous saccharification and isomerization by glucoamylase and glucose isomerase

pH and temperature play critical roles in multistep enzymatic conversions. In such conversions, the optimal pH for individual steps differs greatly. In this article, we describe the production of glucoamylase (from Aspergillus oryzae MTCC152 in solid-state fermentation) and glucose isomerase (from Streptomyces griseus NCIM2020 in submerged fermentation), used in industries for producing high-fructose syrup. Optimum pH for glucoamylase was found to be 5.0. For glucose isomerase, the optimum pH ranged between 7.0 and 8.5, depending on the type of buffer used. Optimum temperature for glucoamylase and glucose isomerase was 50 and 60°C, respectively. When both the enzymatic conversions were performed simultaneously at a compromised pH of 6.5, both the enzymes showed lowered activity. We also studied the kinetics at different pHs, which allows the two-step reaction to take place simultaneously. This was done by separating two steps by a thin layer of urease. Ammonia generated by the hydrolysis of urea consumed the hydrogen ions, thereby allowing optimal activity of glucose isomerase at an acidic pH of 5.0.     

Studies on the kinetics and mechanism of redox decomposition of 1,2,6-trinitrotriamminecobalt(III) and 1,2,6-trinitrodiethylenetriaminecobalt(III) complexes in aqueous acid

Summary In aqueous acid media the title complexes undergo decomposition ultimately forming cobalt(II). Detailed analysis of the kinetic data reveals that the reactions proceed in two consecutive stages, the initial step being the faster one. Evidence has been presented that the initial faster step involves aquation releasing one NO ₂ ^– ligand and forming an aquodinitro complex, which subsequently undergoes a slower intramolecular redox decomposition into Co²⁺. Each step, on the other hand, has been found to consist of two concurrent paths,viz. spontaneous and acid catalysed, respectively. Activation parameters corresponding to all these specific rate constants have been evaluated and a plausible mechanism for the overall reaction has been proposed.On leave from Agra College, Agra, India.     

X-ray Crystal Structures of [Et3NH][{(CO)5Mo(P(OCH2CMe2CH2O)O)}2H] and (CO)5Mo{μ-Ph2POPPh2}Mo(CO)5, Two Complexes Derived from the Hydrolysis of Coordinated Chloro-Phosphorous-Donor Ligands

Abstract X-ray crystal structures of [Et₃NH][{(CO)₅Mo(P(OCH₂CMe₂CH₂O)O)}₂H], 3, and (CO)₅Mo{μ-Ph₂POPPh₂}Mo(CO)₅, 2, are reported. Crystallization of 3 occurs in P-1 space group with a = 9.6944(19) ?, b = 10.814(2) ?, c = 19.730(4) ?, α = 94.24(3)°, β = 92.23(3)°, γ = 113.47(3)°, Z = 4. Crystallization of 2 occurs in C2/c space group with a = 10.357(2) ?, b = 20.149(4) ?, c = 17.155(3) ?, α = 90°, β = 97.28(3)°, γ = 90°, Z = 8. Compound 2 is a bimetallic complex with a P–O–P bridging group containing bond distances similar to that of other complexes in which two metal centers are bridged by a single R₂POPR₂ ligand. Compound 3 contains intermolecular hydrogen bonded P–O–H–O–P linkages with bond distances comparable to those seen in similar structures with intramolecular hydrogen bonding suggesting that the distance is a function of the nature of the bond and not affected by the cis arrangement of the ligands about the metal center. Graphical abstract X-ray Crystal Structures of [Et ₃ NH][{(CO) ₅ Mo(P(OCH ₂ CMe ₂ CH ₂ O) O)} ₂ H] and (CO) ₅ Mo{μ-Ph ₂ POPPh ₂ }Mo(CO) ₅ , Two Complexes Derived from the Hydrolysis of Coordinated Chloro-Phosphorous-Donor Ligands Samuel B. Owens Jr., Abha A. Kaisare and Gary M. Gray X-ray crystal structures of [Et₃NH][{(CO)₅Mo(P(OCH₂CMe₂CH₂O)O)}₂H], 3, and (CO)₅Mo{μ-Ph₂POPPh₂}Mo(CO)₅, 2, have been determined.      

Synthesis of non-toxic anticancer active forskolin-indole-triazole conjugates along with their in silico succinate dehydrogenase inhibition studies

Biologically important three different pharmacophores, forskolin, indole and 1,2,3-triazoles are coupled to obtain a hybrid molecule. Here, we described the synthesis of novel series of forskolin-indole-triazole conjugates 5a-5l by using the Cu(I) catalyzed 1,3-dipolar cycloaddition reaction. Furthermore, the biological significance of the synthesized molecules was assessed by in silico and in vitro modes. All the synthesized compounds were evaluated for in vitro anticancer activity against PC-3, MCF-7, MDA-MB-231, COLO-205, HeLa, WRL-68, RAJI, CHANG and RAW-264.7 cell lines. Compound 5g was found to be the most potent in all the tested cell lines (IC₅₀ range 9.6–21.66 μg/ml, except COLO-205), 5a, 5b and 5k were observed to exert its effect only against WRL-68 (IC₅₀ range 27.69–48.18 μg/ml), when compared to parent 3 (IC₅₀ > 100 μg/ml, tested concentrations 10–50 μg/ml) and standard Doxorubicin (IC₅₀ range 0.42–3.16 μg/ml). The most potent compound 5g (MEF₅₀ 0.57) was found non-toxic to human erythrocytes as compared to control (MEF₅₀ 0.60) at tested concentration (50 μg/ml). In silico-based succinate dehydrogenase inhibition showed that the synthesized compounds were having potent binding affinity compared to forskolin. Predictive ADMET and toxicity risk assessment analysis revealed that most of the compounds were complying with the standard limit of Lipinski's rule of five for oral bioavailability.     

Recent advances in continuous flow synthesis of heterocycles

In the current scenario, flow chemistry is emerging as a significant technology in the field of organic synthesis. This miniaturized protocol including microreactors facilitates excellent heat transfer, low solvent wastage, lesser reaction time, a safer environment for reagent handling and appreciable yields of desired products. Thus, this “enabling technology” has a great scope in the synthesis and preparation of a variety of heterocycles that require toxic reagents as starting materials. This review discusses the recent advances (2020–2021) in continuous flow strategy for synthesis and derivatization of variety of heterocyclic entities, of different ring size, using different approaches. This also highlights the advantages of different combined techniques like Microwave assisted heating, electrochemical flow cell, LED light source, NMR and FT-IR analysis, etc., that enables utilization of various mechanisms and real-time monitoring of reactions leading to improved results.

Graphic abstract

     

Naturally occurring himachalenes to benzocycloheptene amino vinyl bromide derivatives: as antidepressant molecules

A new series of benzocycloheptene amino vinyl bromide derivatives (9a-9m) were synthesized from isomeric mixture of himachalenes through two-step synthesis. The unusual structure of benzocycloheptene amino vinyl bromide derivative (9a) was confirmed by NMR and X-ray crystallography analyses. The newly synthesized amino vinyl bromide derivatives of benzocycloheptene were further evaluated for their antidepressant activities. The compound 9c had shown significant reduction in the immobility period.