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The aim of this work is to compare the formation temperatures, structural, and macroscopic magnetic properties of Sr-hexaferrite (SrM) in the presence of different fuels. In this research, SrM powder was synthesized by a sol-gel auto-combustion route using different hydroxycarboxylic acids: citric acid, tartaric acid, sucrose (gluconic acid), and lactic acid. Completion of reaction was followed by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The obtained powders were further characterized by thermal gravimetric analysis-differential thermal analysis (TGA-DTA), energydispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Their magnetic properties were studied using Mössbauer spectroscopy and magnetic measurements were done by vibrating sample magnetometer (VSM). The influence of different fuels was reflected on the formation temperature, phase purity, and morphology of crystallites as well as on their magnetic properties. The results show the finest crystallite size has been obtained as 27.85 nm (from XRD) in the case of sucrose sample. The lowest

A new synthetic route was carried out via a one-pot reaction to prepare a novel series of amidine/amidinate cobalt complexes 8−10 by mixing ligand 2 (6-pyridin-2-yl-[1,3,5]triazine-2,4-diamine) with Co(II) in acetonitrile or benzonitrile. We observed that a change of solvent from methanol (used in complex 7, previously reported) to nitrile solvents (MeCN and PhCN) led to the in situ incorporation of the amidine group, ultimately forming 8−10. So far, this is a unique method reported to introduce amidine/amidinate groups into a pyridinyl-substituted diaminotriazine complex. Remarkably, the single crystal X-ray diffraction study (SCXRD) of these new compounds reveals associations involving Janus DATamidine and Janus DATamidinate. A mechanism is proposed to explain the formation of amidine/ amidinate groups by investigating the single crystal structures of the possible intermediates 11 and 12 where the cobalt ion acts as a template. These amidine/amidinate cobalt complexes were used as a model to assess the photocatalytic activity for the hydrogen evolution reaction (HER). Complexes 9 and 10 show a 74% and 86% enhancement, respectively, of the catalytic activity towards the HER compared to complex 7. This highlights the structure−property relationship. By examining the novel cobalt complexes described here, we discovered the following: (i) a method to introduce an amidine group into a pyridine DAT-based complex, (ii) the efficiency of amidine complexes to form multiple hydrogen bonds to direct the molecular organization, (iii) the plausible mechanism of formation of amidines based on the SCXRD study, (iv) the modification of the final structure and hence the final properties by varying the reaction conditions, and (v) the utility of amidine complexes towards photocatalytic HER activity.

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Decarboxylative A 3 -coupling of ortho-hydroxybenzaldehydes, secondary amines, and alkynoic acids is performed under catalyst and solvent-free conditions. The developed methodology provided a waste-free method for the synthesis of hydroxylated propargylamines which are versatile precursors for various bioactive heterocyclic scaffolds. The experimental and density functional theory studies revealed that the in situ-formed ortho-quinonoid intermediate (formed from ortho-hydroxybenzaldehyde and amine) undergoes a concerted Eschweiler−Clarke type decarboxylation with alkynoic acids. The synthesized compounds were evaluated for MAO-A, MAO-B, and AChE inhibitory activities as potential drug candidates for the treatment of various neurological disorders. Compound 4f was found to be the most potent and selective MAO-B (high selectivity over MAO-A) and AChE inhibitor in the series with IC 50 values of 4.27 ± 0.07 and 0.79 ± 0.03 μM, respectively.

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