Hydrogen bonded dimers of ketocoumarin in the solid state and alcohol:water binary solvent: fluorescence spectroscopy, crystal structure and DFT investigation

2019 ◽  
Vol 43 (23) ◽  
pp. 9090-9105 ◽  
Author(s):  
Kannan Ramamurthy ◽  
E. J. Padma Malar ◽  
Chellappan Selvaraju
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Binary Mixture ◽  
Fluorescence Spectroscopy ◽  
Emission Spectrum ◽  
Fluorescence Emission ◽  
Binary Solvent ◽  
Fluorescence Emission Spectrum ◽  
Hydrogen Bonded

Fluorescence emission spectrum of ketocoumarin dimers in an alcohol:water binary mixture and the solid state.

scholarly journals The Synthesis and Application of Nitrogen-Doped Graphene Quantum Dots on Brilliant Blue Detection

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Li Jin ◽  
Ying Wang ◽  
Fengkai Yan ◽  
Jianpo Zhang ◽  
Fangli Zhong
Keyword(s):  
Quantum Dots ◽  
Emission Spectrum ◽  
Graphene Quantum Dots ◽  
Fluorescence Emission ◽  
Fluorescence Decay ◽  
Brilliant Blue ◽  
Fluorescence Emission Spectrum ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Nitrogen-doped graphene quantum dots had been successfully synthesized and characterized by using transmission electron microscope, X-ray photoelectron spectroscopy, absorbance spectrum, fluorescence emission spectrum, and fluorescence decay curve. TEM results indicated that the diameters of the as-prepared nitrogen-doped graphene quantum dots were in the range of 2 - 5 nm and the lattice space is about 0.276 nm; Raman spectrum result indicated that there were two characteristic peaks, generally named D (~1408 cm−1) and G (~1640 cm−1) bands; both TEM and Raman spectrum results indicated that the as-synthesized product was graphene quantum dots. Deconvoluted high resolution XPS spectra for C1s, O1s, and N1s results indicated that there are -NH-, -COOH, and -OH groups on the surface of nitrogen-doped graphene quantum dot. Fluorescence emission spectrum indicated that the maximum fluorescence emission spectrum of nitrogen-doped graphene quantum dots was blue shift about 30.1 nm and the average fluorescence decay time of nitrogen-doped graphene quantum dots increased about 2 ns, compared with graphene quantum dots without doping of nitrogen. Then, the as-prepared nitrogen-doped graphene quantum dots were used to quantitatively analyze brilliant blue based on the fluorescent quenching of graphene quantum dots, and the effect of pH and reaction time on this fluorescent quenching system was also obtained. Under selected condition, the linear regression equations were F0/F=0.0087 (brilliant blue) + 0.9553 and F0/F=0.01205 (brilliant blue) + 0.6695, and low detection limit was 3.776 μmol/L (3.776 nmol/mL). Once more diluted N-GQDs (0.05 mg/mL) were used, the low detection limit could reach 94.87 nmol/L. Then, temperature-dependent experiment, absorbance spectra, and dynamic fluorescence quenching rate constant were used to study the quenching mechanism; all results indicated that this quenching process was a static quenching process based on the formation of complex between nitrogen-doped graphene quantum dots and brilliant blue through hydrogen bond. Particularly, this method was used to quantitatively analyze the wine sample, of which results have a high consistence with the results of the spectrophotometric method; demonstrating this fluorescence quenching method could be used in practical sample application.

New insights into the binding behavior of lomefloxacin and human hemoglobin using biophysical techniques: binary and ternary approaches

2019 ◽  
Vol 43 (21) ◽  
pp. 8132-8145 ◽  
Author(s):  
Parisa Mokaberi ◽  
Vida Reyhani ◽  
Zeinab Amiri-Tehranizadeh ◽  
Mohammad Reza Saberi ◽  
Sima Beigoli ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Energy Transfer ◽  
Emission Spectrum ◽  
High Probability ◽  
Fluorescence Emission ◽  
Fluorescence Emission Spectrum ◽  
Human Hemoglobin ◽  
Binding Behavior ◽  
Biophysical Techniques

Demonstrates the overlap that had been induced between the fluorescence emission spectrum of Hb and the absorption spectrum of drugs, which has proved that there is a high probability to the occurrence of energy transfer from Hb and LMF in the absence and presence of NRF.

Synthesis and Light-Emission Properties of Manganese-Doped Calcium Zirconate Phosphor and Manganese-Doped Strontium Zirconate Phosphor

2012 ◽  
Vol 234 ◽  
pp. 1-6 ◽  
Author(s):  
Bai Bin Wang ◽  
Chi Fen Chang ◽  
Yan Ru Li ◽  
Thanh Nam Chau ◽  
Wein Duo Yang
Keyword(s):  
Crystal Structure ◽  
Energy Level ◽  
Fluorescence Spectroscopy ◽  
Emission Spectrum ◽  
Powder Diffraction ◽  
Calcium Zirconate ◽  
Strontium Zirconate ◽  
X Ray ◽  
Level Transition ◽  
Energy Level Transition

This study successfully synthesized manganese-doped calcium zirconate phosphor and manganese-doped strontium zirconate phosphor using the sol-gel method. We employed X-ray powder diffraction and fluorescence spectroscopy to analyze the crystal structure and spectral characteristics of both phosphors. In X-ray powder diffraction analysis, data related to manganese-doped calcium zirconate phosphor and manganese-doped strontium zirconate phosphor were compared using X-ray diffraction comparison software to confirm the crystal structures of both phosphors. The crystal structure of manganese-doped calcium zirconate phosphor was in accordance with orthorhombic perovskites belonging to the Pnma {62} space group. The lattice parameters were a=5.762 Å, b=8.017 Å, and c=5.591 Å; c/a=0.97; volume=258.3 Å3, and density=4.611 g/cm3. The crystal structure of manganese-doped strontium zirconate phosphor conformed to orthorhombic perovskites belonging to the Pnma {62} space group, and the lattice parameters were a=5.818 Å, b=8.204 Å, c=5.797 Å; c/a=0.996; volume=276.7 Å3, and density=5.446 g/cm3. Fluorescence spectroscopy indicated that the primary broadband peak of manganese-doped calcium zirconate phosphor was located at 396.6 nm in the excitation spectrum corresponding to the 4T2(4G)4T1(4P) energy level transition. In the emission spectrum, the primary broadband peak was located at 596.6 nm, corresponding to the 4T2(4D)4T2(4G) energy level transition. For manganese-doped strontium zirconate phosphor, the primary broadband peak was located at 496.6 nm in the excitation spectrum and at 696.6 nm in the emission spectrum, corresponding to the 4T1(4G)4T2(4D) and 4E(4G)4T1(4G) energy level transitions, respectively.

Changes in the Fluorescence Emission Spectrum of Chlorella emersonii Induced by Cold Treatment; a Possible Regulative Feature of Energy Uptake

1982 ◽  
Vol 37 (5-6) ◽  
pp. 448-451 ◽  
Author(s):  
G. Harnischfeger ◽  
H. Jarry
Keyword(s):  
Emission Spectrum ◽  
Membrane Structure ◽  
Cold Treatment ◽  
Fluorescence Emission ◽  
Membrane Properties ◽  
Fluorescence Emission Spectrum ◽  
Isolated Chloroplasts

Abstract Algae, when slowly cooled down to around -5 °C, undergo a change in the fluorescence emission spectrum subsequently taken at liqu. nitrogen temperature. This change resembles the magnesium effect described by Murata [BBA 189,171 - 181, (1969)] for isolated chloroplasts. Evidence is shown, that both effects are indeed analogous. Cooling the organisms seems to in­ crease the permeability of the thylakoids for cations and, thus, a depletion with concomitant changes in membrane structure. The system serves as a model for the probable in vivo control of pigment interaction through alteration of membrane properties.

The Hexakis(N,N'-Dimethylurea)Cobalt(Ii) Cation: A Flexible Building Block for the Construction of Hydrogen Bonded Networks

2003 ◽  
Vol 58 (1) ◽  
pp. 74-84 ◽  
Author(s):  
Giannis S. Papaefstathiou ◽  
Robby Keuleers ◽  
Constantinos J. Milios ◽  
Catherine P. Raptopoulou ◽  
Aris Terzis ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Spectroscopic Data ◽  
Low Frequency ◽  
Great Stability ◽  
Structure Determinations ◽  
Interionic Hydrogen ◽  
Hydrogen Bonded

AbstractThe ligand N.N'-dimethylurea (DMU) is used to propagate the octahedral coordination geom- etry of [Co(DMU)6]2+ into 1D and 2D assemblies via a combination of coordinative bonds and interionic hydrogen-bonding. Compounds [Co(DMU)6](ClO4)2 (1), [Co(DMU)6](BF4)2 (2) and [Co(DMU)6](NO3)2 (3) have been prepared from the reactions of DMU and the appropriate hydrated cobalt(II) salts in EtOH. MeCN or Me2CO (only for 1) in the presence of 2,2-di- methoxypropane. Crystal structure determinations demonstrate the existence of [Co(DMU)6]2+ cations and CIO4- , BF4- or NO3- counterions. The great stability of the [Co(DMU)6]2+ cation in the solid state is attributed to a pseudochelate effect which arises from the existence of strong intracationic N-H···O(DMU) hydrogen bonds. The [Co(DMU)6]2+ cations and counterions self- assemble to form a hydrogen-bonded ID architecture in 1, and different 2D hydrogen-bonded networks in 2 and 3. The precise nature of the resulting supramolecular structure is influenced by the nature of the counterion. Two main motifs of intermolecular (interionic) hydrogen bonds have been observed: N-H ···O(ClO4-, NO3-) or N-H ··· F(BF4-) and weak C-H F(BF4- ) or C-H-O(NO3- ) hydrogen bonds. The complexes were also characterized by vibrational spec- troscopy (IR, far-IR. low-frequency Raman). The spectroscopic data are discussed in terms of the nature of bonding and the know;n structures.

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