Blue-emissive nitrogen-doped chiral carbon dots (d-NCD230 and l-NCD230) exhibiting antipodal chiroptical activity, synthesized from the thermal pyrolysis of citric acid and d/l-aspartic acid in 1:2 molar ratios, have been explored as chirality-based fluorescent turn-off/on probes for the detection of Hg and l-cysteine (l-Cys). Circular dichroism (CD) spectroscopy revealed that the chiroptical activity originates from a synergy among intrinsic chirality, chiral precursors on the NCD surface, and hybridization of lower energy levels within the embedded chiral chromophore. Quantitative analysis of optical asymmetry using the Kuhn asymmetry factor () at the CD signal of 312 nm showed a higher value for d-NCD230 (1.
View Article and Find Full Text PDFThe hydrogenation of 4-nitrophenol using carbon dot-stabilized gold (Au) nanoparticles is well-studied, with Au-H species known to catalyze the reaction. However, the impact of specific nitrogen moieties in nitrogen-doped carbon dots on Au-H formation and catalytic activity remains unexplored. These nitrogen species, acting as surface ligands, may influence the catalytic properties through the generation of Au-H species via H radicals.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
November 2024
Breast cancer (BC) is the most common malignancy among females worldwide, and its high metastasis rates are the leading cause of death just after lung cancer. Currently, tamoxifen (TAM) is a hydrophobic anticancer agent and a selective estrogen modulator (SERM), approved by the FDA that has shown potential anticancer activity against BC, but the non-targeted delivery has serious side effects that limit its ubiquitous utility. Therefore, releasing anti-cancer drugs precisely to the tumor site can improve efficacy and reduce the side effects on the body.
View Article and Find Full Text PDFWhite light emission (WLE), particularly from heteroatom free carbon dots (CDs), is unusual. Besides, deciphering the origin of WLE from a H-aggregated molecular fluorophore in such kinds of CDs is a challenging task due to their non-fluorescent character resulting from a forbidden transition from a lower-energy excitonic state. Therefore, rigorous investigation on their elusive excited state photophysical properties along with their steady-state optical phenomena has to be carried out to shed light on the nature of distinct emissive states formed in the CDs.
View Article and Find Full Text PDFOptical asymmetry and structural complexity across different length scales were realized in flower-shaped CuO nanostructures, prepared through refluxing an aqueous solution of copper acetate, sodium hydroxide, and D-tartaric acid, as well as in their toroid-like forms obtained on calcination at 600 °C. Atomic scale chirality in the flower morphology could be visualized as putative Boerdijk-Coexter-Bernal like tetrahelical fragments, while that in the toroid form could be identified as screw dislocation-driven helicity. The fraction of asymmetry in the nanostructures has been evaluated from their chiroptical responses based on Kuhn asymmetry factor () from circular dichroism (CD) spectroscopy in the entire UV-vis range.
View Article and Find Full Text PDFFluorometric sensors for the detection of nerve agent mimics have received a lot of interest nowadays due to their high sensitivity and selectivity, ease of operation, and real-time monitoring. Pyridinic-N-rich carbon dots (NCDs) prepared through microwave-assisted pyrolysis of l-Malic acid and urea have been explored first time in this work as a novel turn-off fluorescent probe for the sensitive and selective detection of diethyl chlorophosphate (DCP), a nerve agent mimic. The as-prepared carbon dots contained a large amount of pyridinic nitrogen on their surface, which can modulate the photoluminescence properties of the NCDs.
View Article and Find Full Text PDFDefect engineering, such as modification of oxygen vacancy density, has been considered as an effective approach to tailor the catalytic performance on transition-metal oxide nanostructured surfaces. The role of oxygen vacancies (O) on the surface of the as-prepared, zinnia-shaped morphology of CuO nanostructures and their marigold forms on calcination at 800 °C has been investigated through the study of model catalytic reactions of reduction of 4-nitrophenol and aerobic oxidation of benzyl alcohol. The O on the surfaces of different morphologies of CuO have been identified and quantified through Rietveld analysis and HRTEM, EPR, and XPS studies.
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