Carbon Dots from a Single Source Exhibiting Tunable Luminescent Colors through the Modification of Surface Functional Groups in ORMOSIL Films

Abstract

A simple strategy to fabricate carbon dots (CDs) incorporated organically modified silica (ORMOSIL) films exhibiting tunable tricolor emission has been accomplished. First, the green-emitting CDs with excitation-independent nature and high quantum yield were prepared from o-phenylenediamine in ethanol by solvothermal method. These CDs after purification were dispersed in ORMOSIL sol, and their photoluminescence wavelengths were tuned to three intense luminescent colors (orange, yellow, and green) by adjusting the pH of the sol. It was observed that with pH tuning the functional groups residing on surfacepassivated CDs are undergoing chemical modifications, and accordingly the PL emission of CDs in ORMOSIL sol systematically changes to orange, yellow, and green emissions, respectively. Interestingly, the structure of such surface-modified CDs can be well-preserved in the ORMOSIL film-matrix with substantial concentration to obtain the above tricolor luminescent films on glass. A systematic X-ray photoelectron spectroscopy study revealed that the blue shifting in triluminous films (from 560 to 510 nm) with pH increment was originated due to the deprotonation of the surface groups (−CONH− → −CO(N − )−; −NH 3 + → −NH 2 ) associated with the CDs. The plausible mechanism behind the rationalization of pH-triggered engineering of surface-passivated CD-ORMOSIL sols and their confinement in films has been explored.

The role of carbon dots – derived underlayer in hematite photoanodes

“…The carbon underlayer has been produced from carbon dots using biomass as raw material through a facile hydrothermal process. Carbon dots feature unique photoluminescence, electron trapping and electron transfer properties, 38,39 are stable, low cost, nontoxic and easy to prepare. 40 Hematite (α-Fe 2 O 3 ) is considered one of the most exceptional photoanode candidates due to its nearly ideal bandgap, abundancy, nontoxicity, and chemical and photo stability.…”

Synthesis and Characterization of Cucurbit[6]uril Supported Copper Oxide Nanoparticles, CuO@CB[6]: Application as Nanocatalyst for the Synthesis of 2H‐indazoles

“…The peak binding energy of 530.6 eV, 399.2 eV, 284.5 eV were assigned to O, N, C, respectively. Furthermore, peaks observed at 933.4 eV and 953.3 eV corresponds to the spin‐orbit splitting component of Cu 2p 3/2 and Cu 2p 1/2 , respectively, along with a satellite peak at 942 eV, which confirms the presence of Cu(II) in the CuO@CB[6] nanocomposite …”

High Amplification of the Antiviral Activity of Curcumin through Transformation into Carbon Quantum Dots

“…Figure S4B (Supporting Information) shows that curcumin exhibited a fluorescence emission maximum centered at a wavelength of ≈450 nm upon excitation at a wavelength of 365 nm in water with a quantum yield (QY) of 0.3%, as assessed by comparison with quinine (QY, 53%) in 0.1 m H 2 SO 4 . Unlike most CQDs, [33][34][35][36][37] the Cur-CQDs ( Figure S4C, Supporting Information) did not exhibit excitation-dependent emission properties. However, we noted that the most purified Cur-CQDs exhibited similar solvent polarity-and pH-dependent fluorescence properties to curcumin ( Figure S5, Supporting Information), implying that curcuminlike structures are indeed present on the surfaces of CQDs.…”

“…[36] Many reports have suggested that nitrogen incorporated (doped) as pyridinyl, pyrrolyl, and amide moieties into the heterocyclic ring systems in CQDs can eliminate nonradiative electron−hole recombination centers from carboxyl and epoxy groups, thereby boosting the fluorescence QY of CQDs. [36,37] Although low fluorescent QY of CQDs is unfavorable to its tracking in vivo, the low QY of Cur-CQDs will not significantly affect its utility as an antiviral agent. We believe that digestion of tissue samples followed by HPLC coupled to UV-vis absorption detection may be the preferred method for the quantitation of Cur-CQDs.…”