scholarly journals Spectroscopic studies on photodegradation of atorvastatin calcium

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Madalina Oprica ◽  
Miruna Iota ◽  
Monica Daescu ◽  
Szilard N. Fejer ◽  
Catalin Negrila ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Interaction ◽  
Uv Light ◽  
Chemical Compounds ◽  
Spectroscopic Studies ◽  
X Ray ◽  
Atorvastatin Calcium ◽  
Water Vapors ◽  
Photodegradation Products ◽  
High Share

AbstractIn this work, the photodegradation process of atorvastatin calcium (ATC) is reported as depending on: (1) the presence and the absence of excipients in the solid state; (2) the chemical interaction of ATC with phosphate buffer (PB) having pH equal to 7 and 8; and (3) hydrolysis reaction of ATC in the presence of aqueous solution of NaOH. The novelty of this work consists in the monitoring of the ATC photodegradation by photoluminescence (PL). The exposure of ATC in solid state to UV light induces the photo-oxygenation reactions in the presence of water vapors and oxygen from air. According to the X-ray photoelectron spectroscopic studies, we demonstrate that the photo-oxygenation reaction leads to photodegradation compounds having a high share of C=O bonds compared to ATC before exposure to UV light. Both in the presence of PB and NaOH, the photodegradation process of ATC is highlighted by a significant decrease in the intensity of the PL and photoluminescence excitation (PLE) spectra. According to PLE spectra, the exposure of ATC in the presence of NaOH to UV light leads to the appearance of a new band in the spectral range 340–370 nm, this belonging to the photodegradation products. Arguments concerning the chemical compounds, that resulted in this last case, are shown by Raman scattering and FTIR spectroscopy.

Compounds of Complex Halo and Pseudohalo Acids of the Group IIB Metals, Part V [1] Preparative and Spectroscopic Studies of the [Hg2I5]-, [Hg2I6]2- and [Hg3I8]2- Ions

1982 ◽  
Vol 37 (5) ◽  
pp. 646-648 ◽  
Author(s):  
S. P. Perlepes ◽  
Th. F. Zafiropoulos ◽  
A. K. Anagnostopoulos ◽  
A. G. Galinos
Keyword(s):  
Solid State ◽  
Spectroscopic Studies ◽  
Molar Conductance ◽  
X Ray ◽  
New Compounds ◽  
Complex Anions

The preparations of new compounds, containing the complex anions [Hg2l5]-, [Hg2l6]2- and [Hg3I8]2-, are reported.Distorted iodine-bridged configurations are proposed for the complexes in the solid state, utilising analyses, X-ray powder patterns, molar conductance measurements and spectral (IR, UV) data

Luminescence Properties of Self-Activated M3(VO4)2 (M = Mg, Ca, Sr, and Ba) Phosphors Synthesized by Solid-State Reaction Method

2016 ◽  
Vol 16 (4) ◽  
pp. 3684-3689 ◽  
Author(s):  
Xin Min ◽  
Zhaohui Huang ◽  
Minghao Fang ◽  
Yan’gai Liu ◽  
Chao Tang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Single Phase ◽  
Uv Light ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
Reaction Method ◽  
X Ray ◽  
Yield Decrease

In this paper, M3(VO4)2 (M = Mg, Ca, Sr, and Ba) self-activated phosphors were prepared by a solid-state reaction method at 1,000 °C for 5 h. The phase formation and micrographs were analyzed by X-ray diffraction and scanning electron microscopy. The Ca3(VO4)2 phosphor does not show any emission peaks under excitation with ultraviolet (UV) light. However, the M3(VO4)2 (M = Mg, Sr, and Ba) samples are effectively excited by UV light chips ranging from 200 nm to 400 nm and exhibit broad emission bands due to the charge transfer from the oxygen 2p orbital to the vacant 3d orbital of the vanadium in the VO4. The color of these phosphors changes from yellow to light blue via blue-green with increasing ionic radius from Mg to Sr to Ba. The luminescence lifetimes and quantum yield decrease with the increasing unit cell volume and V–V distance, in the order of Mg3(VO4)2 to Sr3(VO4)2 to Ba3(VO4)2. The emission intensity decreases with the increase of temperatures, but presents no color shift. This confirms that these self-activated M3(VO4)2 phosphors can be suggested as candidates of the single-phase phosphors for light using UV light emitting diodes (LEDs).

Formation and decomposition of the Sb(III)/Li cage [{Sb(P-t-Bu)3}2Li6·6THF]

2002 ◽  
Vol 80 (11) ◽  
pp. 1421-1427 ◽  
Author(s):  
Alan Bashall ◽  
Felipe García ◽  
Gavin T Lawson ◽  
Mary McPartlin ◽  
Alexander Rothenberger ◽  
...  
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Spectroscopic Studies ◽  
X Ray Diffraction ◽  
Initial Formation ◽  
X Ray ◽  
Cage Complex ◽  
Reaction Solution

The heterometallic Sb(III)/Li cage complex [{Sb(P-t-Bu)3}2Li6·6THF] (1) is obtained by the low-temperature (<0°C) reaction of Sb(NMe2)3 with t-BuPHLi (1:3 equiv) in THF. Thermolysis of this reaction solution leads to the formation of the bicyclic distibane [(t-BuP)3Sb]2 (2). 31P NMR spectroscopic studies reveal that this process involves initial formation of [(t-BuP)3Sb]– and [t-Bu(H)PP-t-Bu]– anions. Complexes 1 and 2 have been characterized in the solid state by X-ray diffraction studies.Key words: antimony, lithium, cage.

Photodimerization of the α′-polymorph of ortho-ethoxy-trans-cinnamic acid in the solid state. I. Monitoring the reaction at 293 K

2004 ◽  
Vol 60 (3) ◽  
pp. 315-324 ◽  
Author(s):  
M. A. Fernandes ◽  
D. C. Levendis
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Cinnamic Acid ◽  
Structural Changes ◽  
Uv Light ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Short Period

Structural changes that occur during the [2 + 2] photodimerization of the metastable α′-polymorph of ortho-ethoxy-trans-cinnamic acid at 293 K are presented here. Crystals of the α′-polymorph were first stabilized by exposing the α-polymorph to UV light for a short period of time at 343 K. The photodimerization reaction was then carried out at 293 K and observed in situ by single-crystal X-ray diffraction. The α′-polymorph contains three molecules in the asymmetric unit, labelled A, B and C, which are arranged to form two potential reaction sites. The intermolecular distance between the C=C bonds of molecules A and B (making up the AB site) is 3.6 Å, and these were observed to undergo photodimerization at 293 K. The corresponding distance between centrosymmetrically related C=C bonds in the CC site (made up of C molecules) is 4.6 Å, and these remain unreacted even after 60 h irradiation at 293 K. The crystal of the final product, which corresponds to a 66.7% conversion (only two out of three molecules in the asymmetric unit take part in the photodimerization reaction at 293 K), contains an ordered arrangement of the photodimer and unreacted monomer. The crystal retains many structural features of the original monomer crystal, including carboxylic acid hydrogen bonds and C—H...O interactions. Single-crystal X-ray diffraction was used to monitor changes in the unit-cell parameters, reacting molecules and molecular conformations as the reaction progressed. The conformation of the photodimer obtained from the solid-state reaction differs from that of the photodimer obtained by recrystallization from solution.

scholarly journals Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1007
Author(s):  
Abdessalam Bouddouch ◽  
Elhassan Amaterz ◽  
Bahcine Bakiz ◽  
Aziz Taoufyq ◽  
Frédéric Guinneton ◽  
...  
Keyword(s):  
Solid State ◽  
Rhodamine B ◽  
Solid State Reaction ◽  
Uv Light ◽  
Morphological Changes ◽  
Degradation Mechanism ◽  
Light Irradiation ◽  
Temperature Phase ◽  
X Ray ◽  
Uv Light Irradiation

Polycrystalline bismuth phosphate BiPO4 was synthesized by solid-state reaction at different temperatures varying from 500 to 900 °C. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and Raman spectroscopy. The low-temperature phase of BiPO4 has monoclinic structure with a space group P21/n, and was transformed into the monoclinic phase P21/m with a slight distortion of monoclinic lattice when it was heated above 500 °C. The effect of the transformation on the structure, morphology and photocatalytic properties was examined. The photocatalytic activity of each sample, in presence of Rhodamine B (RhB) in aqueous solution, was carried out and analyzed under UV light irradiation. Photoexperiments showed that the material prepared at 500 °C is the best catalyst with degradation efficiency of the order of 96% after 12 min of reaction time under UV light irradiation. This high photocatalytic efficiency could be due to their structural and morphological changes. The photocatalytic degradation mechanism of RhB in the presence of the best photocatalyst BiP-500 °C is proposed. The stability of the catalyst was also examined by carrying out four successive tests of the degradation in the presence of BiP-500 °C. Total organic carbon (TOC) was used to further estimate the rate of mineralization in the presence of BiP-500 °C (83% TOC removal). Photoluminescence experiments performed under UV-laser light irradiation revealed emissions in the green-orange range, with optimal intensities for the mix systems observed at 550 °C.

Preparative and Vibrational Spectroscopic Studies of Anilinium Salts Containing the [Hg2Cl6]2-, [Hg2Cl4X2]2-, [CdHgI6]2-, [CdHgI4Br2]2- and [CdHgBr4I2]2- Ions (X = Br, I)

1991 ◽  
Vol 46 (11) ◽  
pp. 1532-1538 ◽  
Author(s):  
Theodoros F. Zafiropoulos ◽  
John C. Plakatouras ◽  
S. P. Perlepes
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Raman Spectra ◽  
Spectroscopic Studies ◽  
Ir And Raman Spectra ◽  
X Ray ◽  
Ir And Raman ◽  
Complex Anions

Synthetic procedures are described that allow access to anilinium salts containing the complex anions [Hg2Cl62-, [Hg2Cl4X2]2- (X = Br, I), [CdHgI6]2-, [CdHgI4Br2]2- and [CdHgBr4I2]2--. Isolated dimeric structures are proposed for the new complexes in the solid state, using X-ray powder patterns, Far-IR and Raman spectra. The spectral detail is greatly enhanced in measurements at low temperature (∼100 K).

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