scholarly journals Polyol-Mediated Synthesis of Nitrogen-Containing Carbon-Dots from Tetracyanobenzene with Intense Red Fluorescence

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1470 ◽  
Author(s):  
Roman Lehmacher ◽  
Claus Feldmann
Keyword(s):  
Polyethylene Glycol ◽  
Liquid Phase ◽  
Quantum Yield ◽  
Carbon Dots ◽  
Emission Spectra ◽  
Excitation Wavelength ◽  
Polyethylene Glycol 400 ◽  
Strong Emission ◽  
Red Emission ◽  
Naked Eye

Nitrogen-containing C-dots were prepared by heating (160 °C, 1 h) 1,2,4,5-tetracyanobenzene (TCB) in polyethylene glycol 400 (PEG400). The as-prepared monocrystalline C-dots were 2–4 nm in diameter and contained 24.4 wt. % of nitrogen. They showed intense fluorescence under excitation at 400–500 nm as well as under excitation at 600–700 nm. In addition to an excitation-wavelength-depending emission at 400 to 650 nm, the emission spectra exhibited a strong emission peaking at 715 nm, whose position was independent from the wavelength of excitation. For this deep-red emission a remarkable quantum yield of 69% was detected. The synthesis of nitrogen-containing C-dotswas completely performed in the liquid phase. Moreover, the C-dots could be directly dispersed in water. The resulting aqueous suspensions of PEG400-stabilized nitrogen-containing C-dots also showed intense red emission that was visible to the naked eye.

The Influence of Processing Parameters on Photoluminescent Properties of Ba2ZnS3:Mn Phosphors by Double-Crucible Method

2004 ◽  
Vol 817 ◽  
Author(s):  
Yu-Feng Lin ◽  
Yen-Hwei Chang ◽  
Bin-Siang Tsai
Keyword(s):  
Doping Concentration ◽  
Raw Materials ◽  
Red Light ◽  
Emission Spectra ◽  
Processing Parameters ◽  
Excitation Wavelength ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Red Emission ◽  
Double Crucible

AbstractRed light emitting of Mn2+ doped Ba2ZnS3 phosphor powders have been synthesized by double-crucible method at different thermal treatments. XRD results indicate that the raw materials are completely sulfurized above 950°C, and the Ba2ZnS3: Mn2+ powders don't change its orthorhombic crystal structure with increasing doping concentration from 0 to 0.8 mol%. The photoluminescence of Ba2ZnS3: Mn2+ powders fulfilled the most efficient emission at the excitation wavelength λex=358 nm and showed the red emission light with peak wavelength λem=627nm at the doping concentration of Mn2+ ion between 0.2 and 0.8 mol%. The high-luminance red emission results from the 4T1 (4G)—6A1 (6S) transition in the Mn2+ ion. Ba2ZnS3: Mn2+ phosphors synthesized by double-crucible method have broad emission spectra (550nm∼750nm) with FWHM (full width at half maximum broadband) about 66nm. In our research, the Ba2ZnS3 doped with 0.4 mol% Mn2+ has the highest luminescent intensity as thermal treatment at 950°C for 16 hours and the CIE coordinate is x=0.66, y=0.33.

Photoluminescent Characteristics of ZnS Quantum Dots Synthesized in Non-Aqueous-Phase

2013 ◽  
Vol 750-752 ◽  
pp. 991-994
Author(s):  
Jing Liu ◽  
Ming Ying ◽  
Yu Ling Tan ◽  
Bo Xi
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Quantum Yield ◽  
Reaction Medium ◽  
Emission Spectra ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Zinc Blend ◽  
Red Emission ◽  
X Ray

ZnS quantum dots (ZnS QDs) synthesized in aqueous solution is easy to gather a mass, which always results in low quantum yield. So, in this study benzene was used as reaction medium in which ZnS QDs with different hues were synthesized, and the hues of ZnS QDs were depend on the molar ratio of Zn (CH3COO)2 and Na2S·9H2O. The results show the emission spectra of ZnS QDs shifts with the change of the precursor molar ratio but the absorption peak at 310nm is not. The emission peaks centered at 430nm and 580nm at higher molar ratio [Zn2+]/[S2-] with blue-violet emitting phosphors; but, ZnS QDs synthesized at higher molar ratio [S2-]/[Zn2+] have orange-red emission at 580nm only. The X-ray diffraction analysis shows the crystallinity of ZnS QDs is better at [Zn2+]/[S2-]=1:10, which are typical zinc blend with nanorod structure.

scholarly journals One-Pot Hydrothermal Synthesis of Carbon Dots as Fluorescent Probes for the Determination of Mercuric and Hypochlorite Ions

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1831
Author(s):  
Hsin Lee ◽  
Yen-Chang Su ◽  
Hsiang-Hao Tang ◽  
Yu-Sheng Lee ◽  
Jan-Yee Lee ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Fluorescent Probes ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Tap Water ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Excitation Wavelength ◽  
One Pot ◽  
Fluorescence Emission Spectra

Nitrogen and sulfur codoped carbon dots (NSCDs) were synthesized via a one-pot hydrothermal method, and citric acid, ethylenediamine, and methyl blue were used as precursors. The obtained NSCDs were spherical with an average size of 1.86 nm. The fluorescence emission spectra of the NSCDs were excitation independent and emitted blue fluorescence at 440 nm with an excitation wavelength at 350 nm. The quantum yield of the NSCDs was calculated to be 68.0%. The NSCDs could be constructed as fluorescent probes for highly selective and sensitive sensing mercuric (Hg2+) and hypochlorite (ClO−) ions. As the addition of Hg2+ or ClO− ions to the NSCDs, the fluorescence intensity was effectively quenched due to dynamic quenching. Under the optimal conditions, the linear response of the fluorescence intensity ranged from 0.7 μM to 15 μM with a detection limit of 0.54 μM and from 0.3 μM to 5.0 μM with a limit of detection of 0.29 μM for Hg2+ and ClO− ions, respectively. Finally, the proposed method was successfully used for quantifying Hg2+ and ClO− ions in spiked tap water samples.

NIR Emission Analysis of Er3+/Yb3+ and Er3+/ Tm3+ Ions Doped Zinc lithium Boro Tellurite (ZLiBT) Glasses for Optical Fiber Amplification

2010 ◽  
Vol 123-125 ◽  
pp. 19-22
Author(s):  
B. Sudhakar Reddy ◽  
K. Vemasevana Raju ◽  
S. Sailaja ◽  
C. Nageswara Raju ◽  
D. Sreekantha Reddy
Keyword(s):  
Optical Fiber ◽  
Broad Band ◽  
Emission Spectra ◽  
Tunable Laser ◽  
Excitation Wavelength ◽  
Emission Analysis ◽  
Optical Amplification ◽  
Red Emission ◽  
Infra Red ◽  
Potential Applications

This paper reports on the development and the near infra-red emission(NIR) analysis of Er3+/Yb3+ and Er3+/ Tm3+ ions doped TeO2 - B2O3 – ZnO - Li2O glasses for tunable laser and optical fiber amplification. From the measured near infra-red emission spectra of Er3+/Yb3+, Er3+/Tm3+: ZLiBT glasses have revealed the prominent near infra-red emission bands at 1532 nm (4I13/2 → 4I15/2), with an excitation wavelength of λexci = 515 nm (Ar+ ion laser). The full width at half-maxima (FWHM) values are also estimated from the measured near infra-red emission spectra of the glasses. Based on spectral results, broad near infra-red emissions should have potential applications in broadly tunable laser sources and broad band optical amplification at low-loss telecommunication windows.

scholarly journals Preparation and Characterization of Bacterial Cellulose-Carbon Dot Hybrid Nanopaper for Potential Sensing Applications

2018 ◽  
Vol 9 (1) ◽  
pp. 107 ◽  
Author(s):  
Sakeena Quraishi ◽  
Sven Plappert ◽  
Bernhard Ungerer ◽  
Philip Taupe ◽  
Wolfgang Gindl-Altmutter ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Bacterial Cellulose ◽  
Optical Sensors ◽  
Carbon Dots ◽  
Carbon Nanodots ◽  
Excitation Wavelength ◽  
Single Digit ◽  
Water Contact ◽  
Isolation And Purification ◽  
Sensing Applications

Green and facile approaches aiming at the manufacture of biocompatible paper-based optical sensors reporting the presence of photoluminescence (PL) modulating compounds is an emerging field of research. This study investigates the preparation of bacterial cellulose nanopaper containing covalently immobilized carbon dots for potential biosensing applications. Preliminary work of this feasibility study included TEMPO-mediated ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl-mediated) oxidation and nanofibrillation of bacterial cellulose (TOBC) on the one hand as well as synthesis and comparative analysis of different types of carbon dots (CDs) on the other hand. The two source materials of the targeted functional nanopaper were finally linked to each other by two different N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/ N-hydroxysuccinimide (EDC/NHS) coupling approaches to clarify whether grafting of CDs prior to or after TOBC paper formation would be the method of choice. Synthesis of the carbon nanodots was accomplished by microwave-assisted co-hydrothermolysis of appropriate precursor compounds. After isolation and purification by dialysis particles in the single-digit nanometer-range were obtained and characterized with regard to their photoluminescence properties in terms of emission wavelength, pH stability, and quantum yield. All types of synthesized CDs reached their PL maxima (450–480 nm; light blue) in a narrow excitation wavelength range of 340–360 nm. Variation of molar (C/N) ratio of the CD precursors and substitution of the nitrogen donor EDEA by urea increased PL and quantum yield (QY), respectively. The highest relative QY of nearly 32% was obtained for CDs synthesized from citric acid and urea. PL of all CDs was virtually insensitive to pH changes in the range of 4–10. Tensile testing of hybrid nanopaper prepared after EDC/NHS-mediated grafting of GEA-type CDs onto TOBC (0.52 mmol·g−1 COOH) in dispersion state revealed that both stiffness and strength are not compromised by incorporation of carbon dots, while plastic deformation and elongation at break increased slightly compared to nanopaper formed prior to decoration with CDs. Water contact angle of the nanopaper is unaffected by introduction of carbon dots which is supposedly due to the presence of surface amino- and amide groups compensating for the loss of carboxyl groups by grafting.

Development, Evaluation and Optimization of Osmotic Controlled Tablets of Aceclofenac for Rheumatoid Arthritis Management

2019 ◽  
Vol 9 (1) ◽  
pp. 29-36
Author(s):  
Bijaya Ghosh ◽  
Niraj Mishra ◽  
Preeta Bose ◽  
Moumita D. Kirtania
Keyword(s):  
Rheumatoid Arthritis ◽  
Polyethylene Glycol ◽  
Sodium Chloride ◽  
Cellulose Acetate ◽  
Hydroxypropyl Methylcellulose ◽  
Release Profile ◽  
Polyethylene Glycol 400 ◽  
Permeable Membrane ◽  
Cumulative Release ◽  
The Core

Objective: Rheumatoid arthritis is a dreaded disease, characterized by pain, inflammation and stiffness of joints, leading to severe immobility problems. The disease shows circadian variation and usually gets aggravated in early morning hours. Aceclofenac, a BCS Class II compound is routinely used in the treatment of pain and inflammation associated with rheumatoid arthritis. The objective of this study was to develop an osmotic delivery system of Aceclofenac that after administration at bedtime would deliver the drug in the morning hours. </P><P> Methods: A series of osmotically controlled systems of aceclofenac was developed by using lactose, sodium chloride and hydroxypropyl methylcellulose K100M as osmogens. Cellulose acetate (2% w/v in acetone) with varying concentrations of polyethylene glycol-400 was used as the coating polymer to create semi permeable membrane and dissolution was carried out in 290 mOsm phosphate buffer. Formulation optimization was done from four considerations: cumulative release at the end of 6 hours (lag time), cumulative release at the end of 7 hours (burst time), steady state release rate and completeness of drug release. </P><P> Results: A formulation having swelling polymer hydroxypropyl methylcellulose in the core and lactose and sodium chloride as osmogens, polyethylene glycol-400 (16.39 %) as pore former, with a coating weight of 5% was a close fit to the target release profile and was chosen as the optimum formulation. Conclusion: Aceclofenac tablets containing lactose, HPMC and sodium chloride in the core, given a coating of cellulose acetate and PEG-400 (5% wt gain), generated a release profile for optimum management of rheumatoid arthritic pain.

scholarly journals Liquid‐Phase Synthesis of Hydrophilic Luminescent Carbon Dots Using Porous Silica as a Nanotemplate

2021 ◽  
Vol 218 (15) ◽  
pp. 2170045
Author(s):  
Andrii Vasin ◽  
Dmytro Kysil ◽  
Stanislav Sevostianov ◽  
Oksana Isaieva ◽  
Galyna Rudko ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Carbon Dots ◽  
Porous Silica ◽  
Phase Synthesis
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