Deep insights to explain the mechanism of carbon dot formation at various reaction times using the hydrothermal technique: FT-IR, 13C-NMR, 1H-NMR, and UV-visible spectroscopic approaches.

A well-explained mechanism for synthesizing carbon dots (CDs) is not yet explored and is still a subject of great debate and challenge. This study used a one-step hydrothermal method to prepare highly efficient, gram-scale, excellent water solubility, and blue fluorescent nitrogen-doped carbon dots (NCDs) with the particle size average distribution of around 5 nm from 4-aminoantipyrine. The effects of varying synthesis reaction times on the structure and mechanism formation of NCDs were investigated using spectroscopic methods, namely FT-IR, 13C-NMR, 1H-NMR, and UV-visible spectroscopies. The spectroscopic results indicated that increasing the reaction time affects the structure of the NCDs. As the hydrothermal synthesis reaction time is extended, the intensity of the peaks in the aromatic region decreases, and new peaks in the aliphatic and carbonyl group regions are generated, which display enhanced intensity. In addition, the photoluminescent quantum yield increases as the reaction time increases. The presence of a benzene ring in 4-aminoantipyrine is thought to contribute to the observed structural changes in NCDs. This is due to the increased noncovalent π-π stacking interactions of the aromatic ring during the carbon dot core formation. Moreover, the hydrolysis of the pyrazole ring in 4-aminoantipyrine results in polar functional groups attached to aliphatic carbons. As the reaction time prolongs, these functional groups progressively cover a larger portion of the surface of the NCDs. After 21 h of the synthesis process, the XRD spectrum of the produced NCDs illustrates a broad peak at 21.1°, indicating an amorphous turbostratic carbon phase. The d-spacing measured from the HR-TEM image is about 0.26 nm, which agrees with the (100) plane lattice of graphite carbon and confirms the purity of the NCD product with a surface covered by polar functional groups. This investigation will lead to a greater understanding of the effect of hydrothermal reaction time on the mechanism and structure of carbon dot synthesis. Moreover, it offers a simple, low-cost, and gram-scale method for creating high-quality NCDs crucial for various applications.

Crystal structure and Hirshfeld surface analysis of 3-[(1E)-(4-{4-[(E)-(3-hy-droxy-benzyl-idene)amino]-phen-oxy}phenyl-imino)-meth-yl]phenol.

In the crystal, the mol-ecule of the title compound, C26H20N2O3, has crystallographically imposed twofold rotation symmetry. The crystal packing consists of layers parallel to the ab plane formed by O-H⋯N and C-H⋯O hydrogen bonds. Between the layers, C-H⋯π inter-actions are observed.

Synthesis, Anti-Bacterial and Anti-Oxidant Activity of Azo-Oxazolone and Their Ring Opening Azo-Benzamide Derivatives.

This article describes the controlled synthesis and characterization of azo oxazolone scaffold compounds containing multifunctional groups such as carbonyl group, imine and carbon-carbon double bond. The reaction of the azo-oxazolone with aromatic amines led to the ring-opening of the azo-oxazolone into the corresponding azo-benzamide derivatives in a short time (average 10 min), resulting in high yield (>90%). All newly synthesized compounds were characterized by the common spectral analysis such as UV, IR, 1H-NMR, 13CNMR, Elemental analysis and MS spectrometry. OBJECTIVE: The aim of the study was to synthesize new bioactive azo-benzamides by using azo-oxazolone as a synthon utilizing its ring-opening function. MATERIALS AND METHODS: Azo-benzamide derivatives were prepared in very good yield via ring-opening reaction of azo-oxazolone with aromatic amines in the presence of acetic acid under reflux for few minutes. RESULTS AND DISCUSSION: Chemical structures of the newly synthesized compounds were characterized by UV, IR, 1H-NMR, 13C-NMR, Elemental analysis and MS spectrometry. CONCLUSION: The new azo-oxazolone 4 and azo-benzamide compounds 5a, 5c, 5f, 5h, 5j were screened against Escherichia coli as G(-ve) and Staphylococcus aureus as G(+ve) using ciprofloxacin as a standard. All compounds showed high inhibition potency against E-Coli but low inhibition for S-aureus. Compounds 4, 5c, and 5J showed more reactivity against E-coli. Others: Also, the compounds were tested for their anti-oxidant activity by both DPPH and FRAP methods. The results showed that some compounds possessed moderate anti-oxidant activity in comparison to ascorbic acid as control, typically the compounds bearing OCH3 and OCH2CH3 groups.

The structure of 9-(3-bromo-6-chloro-2-hy-droxy-phen-yl)-10-(2-hy-droxy-ethyl)-3,6-diphenyl-3,4,5,6,7,9-hexa-hydro-2H-acridine-1,8-dione.

In the structure of the title compound C33H29BrClNO4, (I), the hexa-hydro-2H-acridine ring system has a hy-droxy-ethyl substituent on the N atom and a 3-bromo-6-chloro-2-hy-droxy-phenyl substituent on the central C atom at the 9-position. An unusual feature of the mol-ecule is that the substituents at the 3- and 5-positions of the outer cyclo-hexenone rings are phenyl rings rather than the more common dimethyl substituents. C atoms on both of the cyclo-hexenone rings are disordered over two sites. In the crystal structure, O-H⋯O, C-H⋯O and C-H⋯π(ring) hydrogen bonds combine with an Br-O and unusual C-Br⋯π(ring) halogen bonds to generate a three dimensional network with mol-ecules stacked along the a-axis direction.

Crystal structure of (6E,20E)-3,24-di-fluoro-13,14,28,29-tetra-hydro-5H,22H-tetra-benzo[e,j,p,u][1,4,12,15]tetra-oxa-cyclo-docosine-5,22-dione.

The conformation of the title compound, C34H26F2O6, is cone-shaped, partially determined by intra-molecular C-H⋯O short contacts. The benzene rings at the top of the cone are inclined to one another by 73.10 (7)°, while the benzene rings at the bottom of the cone are inclined to one another by 35.49 (8)°. In the crystal, mol-ecules are linked by C-H⋯O and C-H⋯F hydrogen bonds, forming a three-dimensional supra-molecular structure. There are also C-H⋯π contacts present within the framework structure.