Synthesis and Emission Properties of meso-Substituted Porphyrins

2014 ◽  
Vol 71 (1) ◽  
Author(s):  
Tan Ke Xin ◽  
Hendrik O. Lintang ◽  
Abdul Rahman Tamuri ◽  
Salasiah Endud ◽  
Mohd Bakri Bakar
Keyword(s):  
Electron Transfer ◽  
Organic Dyes ◽  
Red Light ◽  
Emission Spectra ◽  
Model Systems ◽  
Fluorescent Properties ◽  
Light Emitting ◽  
Absorption Energy ◽  
Energy And Electron Transfer ◽  
Artificial Photosynthetic

Discovering of various organic dyes including porphyrins have attracted considerable attention to mimic the energy and electron transfer process for the artificial photosynthetic model systems which can be applied in developing optoelectronic devices. The accessibility on tailoring porphyrin properties makes them a good candidate to, be developed as the red light emitting materials for these applications. Thus, symmetrical and unsymmetrical molecular models of porphyrins with appended fluorenyl components and extended π electrons conjugated system were synthesized towards increasing the efficiency of energy and electron transfer. In the photophysical studies, the emission spectra proposed the evidence of energy transfer of appended fluorenyl arms into the porphyrin macrocyclic whereas the extension of conjugating system in porphyrins exhibits lower absorption energy and intensified the red fluorescent properties.

Optical Properties of Lanthanide Metal Ion Polymer Complexes

1992 ◽  
Vol 277 ◽  
Author(s):  
Yoshi Okamoto ◽  
Junji Kido
Keyword(s):  
Metal Ion ◽  
Organic Dyes ◽  
Red Light ◽  
Laser Action ◽  
Electronic Energy ◽  
Luminescence Spectra ◽  
Fluorescent Properties ◽  
Polymer Complexes ◽  
Electronic Energy Transfer ◽  
Lanthanide Metal

ABSTRACTThe fluorescent characteristics of lanthanide chelates are of considerable interest in connection with electronic energy transfer processes and with their use in laser systems. We have synthesized various chelating groups, such as diketone and bypyridyl containing polymers and prepared their Tb3+ and Eu3+ complexes. Their fluorescent properties in connection with a possible laser action were investigated.Electroluminscence (EL) in organic compounds has been investigated from fundamental as well as practical point of views. Various organic dyes were utilized as emitter materials in EL devices. In these examples, owing to the broad nature of the luminescence spectra of organic dyes, the luminescent colors are dull. We have utilized lanthanide metal ion complexes as a luminescent emitter.Tb and Eu ion complexes emitted sharp green and red light, respectively. The configuration of the EL cell and experimental results are described.

A novel stibium phosphate, LiBa(SbO)2(PO4)3: synthesis, crystal structure and RE3+-activated (RE = Tb3+ and Eu3+) fluorescence performance

2019 ◽  
Vol 75 (9) ◽  
pp. 1234-1242
Author(s):  
Shi-Rui Zhang ◽  
Dan Zhao ◽  
Rui-Juan Zhang ◽  
Lin-Ying Shi ◽  
Shao-Jie Dai ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Red Light ◽  
Three Dimensional ◽  
Emission Spectra ◽  
Antimony Oxide ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
Host Matrix ◽  
Rietveld Refinements ◽  
Light Emitting

A new stibium phosphate, lithium barium bis(antimony oxide) tris(phosphate), LiBa(SbO)2(PO4)3, was prepared by the molten salt method with LiF as the flux. The crystal structure consists of an original three-dimensional anionic framework of [(SbO)2(PO4)3]∞ built from PO4 tetrahedra sharing their corners with SbO6 octahedra. This framework delimits one-dimensional tunnels where the lithium(I) and barium(II) ions are located. The UV–Vis spectrum shows that LiBa(SbO)2(PO4)3 was transparent from 350 to 800 nm, and is thus suitable as a luminescent host matrix. We then used Tb3+ and Eu3+ activators to test its luminous performance and the purities of the prepared phosphors were studied by powder X-ray diffraction analysis with Rietveld refinements. Photoluminescence (PL) studies reveal that the emission spectra of 1 mol% RE3+-doped (RE = Tb and Eu) samples can be excited by 371 and 394 nm light, emitting green and orange–red light, respectively, for Tb3+ and Eu3+. The CIE coordinates were measured to be (0.295, 0.571) and (0.6027, 0.3967), and the luminescent lifetimes were calculated as 0.178 and 1.159 ms, respectively.

Synthesis and luminescence properties of (Lu0.95−xCe0.05)2Ca1+2xMg2Si3O12 silicate garnet phosphors and its applications

2016 ◽  
Vol 09 (03) ◽  
pp. 1650049
Author(s):  
Wei Xia ◽  
Xiyan Zhang ◽  
Liping Lu
Keyword(s):  
Light Emitting Diode ◽  
Red Light ◽  
Emission Spectra ◽  
Peak Wavelength ◽  
Excitation Peak ◽  
Light Emitting ◽  
White Leds ◽  
Reducing Atmosphere ◽  
Color Rendering ◽  
Silicate Garnet

Silicate garnet phosphors (Lu[Formula: see text]Ce[Formula: see text]Ca[Formula: see text]Mg2Si3O[Formula: see text] with [Formula: see text], 0.05, 0.1, and 0.15 were prepared by high-temperature solid-state reaction in a reducing atmosphere. The crystal structure, photoluminescence and luminescence of the phosphors were investigated. The optimum excitation peak wavelength of the phosphors ranged from 450[Formula: see text]nm to 490[Formula: see text]nm, matching the emission spectra of a blue light-emitting diode chip. The phosphors emit orange-red light after excitation that can be tuned from 589[Formula: see text]nm to 597[Formula: see text]nm by changing the concentration of calcium ions. In addition, their emission made them suitable for use in warm-white LEDs with a high-color rendering index.

scholarly journals Luminescence properties of novel red-emitting phosphor InNb1-xPxO4:Eu3+ for white light emitting-diodes

2015 ◽  
Vol 33 (2) ◽  
pp. 331-334 ◽  
Author(s):  
An Tang ◽  
Tao Ma ◽  
Liduo Gu ◽  
Yongtao Zhao ◽  
Junhui Zhang ◽  
...  
Keyword(s):  
White Light ◽  
Luminescence Intensity ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Potential Candidate ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
White Light Emitting Diodes

AbstractInNb1-xPxO4:Eu3+ red phosphors were synthesized by solid-state reaction and their luminescence properties were also studied through photoluminescence spectra. The excitation and emission spectra make it clear that the as-prepared phosphors can be effectively excited by near-ultraviolet (UV) 394 nm light and blue 466 nm light to emit strong red light located at 612 nm, due to the Eu3+ transition of 5D0 → 7F2. The luminescence intensity is dependent on phosphorus content, and it achieves the maximum at x = 0.4. Excessive phosphorus in the phosphors can result in reduction of luminescence intensity owing to concentration quenching.With the increasing content of phosphorus, the phosphors are prone to emit pure red light. This shows that the InNb1.6P0.4O4:0.04Eu3+ phosphor may be a potential candidate as a red component for white light emitting-diodes.

scholarly journals Application of fluorescence technique in studying dental caries

2015 ◽  
Vol 18 (2) ◽  
pp. 49-58
Author(s):  
Mien Thi Mai Pham ◽  
Tien Van Tran ◽  
Linh Quang Huynh
Keyword(s):  
Low Cost ◽  
Red Light ◽  
Emission Spectra ◽  
Rapid Test ◽  
Test Time ◽  
Fluorescence Technique ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Different Types ◽  
Carious Teeth

The aim of the present study was to investigate the fluorescence properties of sound teeth and teeth with different types of lesions. Using light-emitting diodes operating in the near ultraviolet (UVA) spectral regions for excitation, the obtained fluorescence images and spectra of carious teeth were different from sound teeth spectra due to the presence of bacteria Streptococcus mutans producing metabolites called porphyrins. The sound teeth showed the blue fluorescence with broad emission spectra from 410 nm to 650 nm (maxima at 450 nm, 500 nm and 520 nm), while the carious regions illuminated the red light with three new peaks at 625 nm, 650 nm and 690 nm. The intensity of the red fluorescent signal depends on the density of the bacteria. Based on the red fluorescence emitted by porphyrins, not only the surface lesions but also the caries hiding under the enamel layer can be detected by UVA exciting. These results provide the ability to apply fluorescence technique in the development of an early dental diagnostic tool with a number of advantages such as safety, mobility, low cost and rapid test time.

scholarly journals A Brief History of Photoactive Interlocked Systems Assembled by Transition Metal Template Synthesis

Photochem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 411-433
Author(s):  
Vitor H. Rigolin ◽  
Liniquer A. Fontana ◽  
Jackson D. Megiatto
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Electron Donor ◽  
Metal Ion ◽  
Energy And Electron Transfer ◽  
Donor Acceptor ◽  
History Of ◽  
Artificial Photosynthetic ◽  
Covalently Linked ◽  
Electron Transfer Processes

More than three decades of research efforts have yielded powerful methodologies based on transition metal template-directed syntheses for the assembly of a huge number of interlocked systems, molecular knots, machines and synthesizers. Such template techniques have been applied in the preparation of mechanically linked electron donor–acceptor artificial photosynthetic models. Consequently, synthetic challenging photoactive rotaxanes and catenanes have been reported, in which the chromophores are not covalently linked but are still associated with undergoing sequential energy (EnT) and electron transfer (ET) processes upon photoexcitation. Many interlocked photosynthetic models produce highly energetic, but still long-living charge separated states (CSS). The present work describes in a historical perspective some key advances in the field of photoactive interlocked systems assembled by transition metal template techniques, which illustrate the usefulness of rotaxanes and catenanes as molecular scaffolds to organize electron donor–acceptor groups. The effects of molecular dynamics, molecular topology, as well as the role of the transition metal ion used as template species, on the thermodynamic and kinetic parameters of the photoinduced energy and electron transfer processes in the interlocked systems are also discussed.

Effects of removing temperature of reduction gas on the luminescence characteristics of Li2BaSiO4:0.003EU2+ green phosphor

2020 ◽  
Vol 34 (22n24) ◽  
pp. 2040159
Author(s):  
Jie Li ◽  
Yang-Ming Lu ◽  
Qing-Hao Yang ◽  
Cheng-Fu Yang
Keyword(s):  
Red Light ◽  
Green Light ◽  
Emission Spectra ◽  
Solid State Reaction Method ◽  
Green Phosphor ◽  
Xrd Pattern ◽  
Light Emitting ◽  
Reducing Gas ◽  
White Light Emitting Diodes ◽  
Luminescence Characteristics

We had successfully synthesized green-emitting phosphors based on Li2BaSiO4 material activated by bivalent europium ions (Eu[Formula: see text]) using a solid-state reaction method in a reducing gas environment and investigated their luminescence properties. The Li2BaSiO4:0.003Eu[Formula: see text] (LSB-Eu) phosphors were synthesized at 850[Formula: see text]C for 1 h, and the reduction gas was removed at 500[Formula: see text]C, 600[Formula: see text]C, 700[Formula: see text]C and 800[Formula: see text]C, respectively. XRD pattern showed that the Li2BaSiO4, Ba2SiO4 and Li4SiO4 phases were observed in the synthesized Li2BaSiO4 composition. As the reduction gas was removed at 800[Formula: see text]C, the LSB-Eu phosphor emitted a weak red light rather than a green light. Two weak emission peaks were found at about 588 nm and 613 nm corresponding to [Formula: see text] and [Formula: see text] transitions. As temperature to remove the reduction gas was lower than 800[Formula: see text]C, the emission spectra of LSB-Eu phosphors reveled a broad peak centered at 501 nm, which emitted a green color. The intensity of photoluminescence excitation (PLE) photoluminescence emission (PL) spectra increased as the removing temperature was decreased from 700[Formula: see text]C to 500[Formula: see text]C and saturated at 500[Formula: see text]C. These results show that LSB-Eu can be a noteworthy candidate of green-emitting phosphor for the investigation of white light-emitting diodes (WLEDs).

Luminescence Properties of Magnesium Sodium Borate Glasses Doped Sm3+, Dy3+ and Eu3+

2020 ◽  
Vol 307 ◽  
pp. 314-320
Author(s):  
Abd Rahman Tamuri ◽  
Aryna Abdul Majid ◽  
Rosli Husin
Keyword(s):  
Light Emitting Diode ◽  
Energy Levels ◽  
Red Light ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Sodium Borate ◽  
Borate Glasses ◽  
Absorption Bands ◽  
Light Emitting ◽  
Color Displays

The luminescence properties Dy3+, Eu3+ and Sm3+ doped magnesium sodium borate glasses were investigated. The glasses samples containing the composition 30MgO-70Na2B4O7.10H2O-xRE2O3 (where RE = Dy3+, Eu3+, and Sm3+, x = 0.1, 0.5, and 1.0 mol %) are prepared by the conventional melt quenching technique. The optical properties have been evaluated using Ultraviolet-Visible Spectroscopy and Photoluminescence Spectroscopy. The X-ray Diffraction pattern was studied to confirm the amorphous nature of the prepared glass. The absorption spectra yield the most intense absorption bands and transition energy levels for Dy3+, Eu3+, and Sm3+ located at 347 nm (6H15/2 → 6P7/2), 393 nm (7F0 → 5L6), and 403 nm (6H5/2 →6P5/2) respectively. The emission spectra demonstrate the highest emission intensity centered at 463 nm (4F9/2 → 6F11/2 + 6H9/2), 612 nm (5D0 → 7FJ), and 599 nm (4G5/2 → 6H7/2) for Dy3+, Eu3+, and Sm3+ respectively. Dy3+ emits combination of blue, yellow, and red light, Eu3+ emits red light and Sm3+ emits orange to red light. The higher the content of Dy3+, Eu3+, and Sm3+, the higher the spectral or peak intensity for both absorption and emission. The findings could be useful for development of laser, light emitting diode (LED), and color displays applications. KEY WORDS: Luminescence, Borax glass, Magnesium, Dysprosium, Europium, Samarium.

Photoluminescence and Energy Transfer from Sm3+ to Eu3+ in Na3YSi2O7 Phosphor for Light-Emitting Diodes

2014 ◽  
Vol 597 ◽  
pp. 117-120 ◽  
Author(s):  
Jia Yue Sun ◽  
Dian Peng Cui ◽  
Qiu Mei Di ◽  
Qi Guang Xu ◽  
Liu Han
Keyword(s):  
Energy Transfer ◽  
Uv Light ◽  
Red Light ◽  
Emission Spectra ◽  
X Ray Diffraction ◽  
Solid State Reaction Technique ◽  
Light Emitting ◽  
X Ray ◽  
Effective Energy Transfer ◽  
Light Excitation

A series of Na3YSi2O7: Eu3+, Sm3+ samples have been synthesized via solid-state reaction technique. The phase structure and luminescence properties are characterized using powder X-ray diffraction, photoluminescence excitation and emission spectra. Effective energy transfer occurs from Sm3+ to Eu3+ and Sm3+/Eu3+-codoped Na3YSi2O7 shows more intense red light compared to that of Eu3+-doped sample under UV light excitation.

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