Visible Light-Promoted Metal-Free Reduction of Organohalides by 2-Naphthyl or 2-Hydroxynaphthyl-Substituted 1,3-Dimethylbenzimidazolines

2015 ◽  
Vol 68 (11) ◽  
pp. 1648 ◽  
Author(s):  
Eietsu Hasegawa ◽  
Kazuma Mori ◽  
Shiori Tsuji ◽  
Kazuki Nemoto ◽  
Taku Ohta ◽  
...  
Keyword(s):  
Visible Light ◽  
Halogen Bond ◽  
Light Emitting Diode ◽  
Bond Cleavage ◽  
Ring Expansion ◽  
Single Electron Transfer ◽  
Reduction Reactions ◽  
Light Emitting ◽  
Reducing Ability ◽  
Carbon Radicals

The visible light-promoted reduction reactions of some organohalides were investigated using 2-aryl-1,3-dimethylbenzimidazolines (Ar-DMBIH) possessing 2-naphthyl or 2-hydroxynaphthyl substituents. In these reduction reactions, single-electron transfer from photo-excited Ar-DMBIH, attained by Xe lamp irradiation through an appropriate glass-filter (λ > 390 nm), to the halide substrates leads to the carbon–halogen bond cleavage, followed by the rearrangements of the formed carbon radicals such as 5-exo hexenyl cyclization and the Dowd–Beckwith ring expansion. Addition of 1,8-diazabicyclo[5.4.0]undec-7-ene was found to enhance the reducing ability of hydroxynaphthyl-substituted DMBIH. A household white light-emitting diode was also used as a light source for these reactions.

The Intellectual Lighting And Data Transmission System based On RGBW Light Emitting Diodes

2021 ◽  
pp. 63-68
Author(s):  
Daniil S. Shiryaev ◽  
Olga A. Kozyreva ◽  
Ivan S. Polukhin ◽  
Sergey A. Shcheglov ◽  
Svetlana A. Degtiareva ◽  
...  
Keyword(s):  
Visible Light ◽  
Data Transmission ◽  
Light Transmission ◽  
Transmission Rate ◽  
Light Emitting Diode ◽  
Spectral Characteristics ◽  
System Component ◽  
Transmission Channel ◽  
Error Vector Magnitude ◽  
Light Emitting

The system of intellectual lighting data transmission via visible light is developed and manufactured. Spectral characteristics of a downlink which uses the red crystal of a RGBW light emitting diode for data transfer were studied. The DALI protocol-based radiation chromaticity control system which allows us to set different lighting scenarios with constant data transmission rate was developed. The radiation chromaticity range covers almost the entire colour gamut in the colour space. The system of high-frequency matching of system component impedances was developed and frequency characteristics of the suggested scheme were studied for development of the system. Optimal parameters of the signal for visual light communication such as carrier frequency, modulation type and band were determined. Observation of the constellation diagram which represents different values of the complex amplitude of the keyed signal in the form of a complex number on a quadrature plane (cosine and sine components of the carrying signal) and of fixation of the amplitude of the error vector magnitude (EVM) was selected as a method of study of the transmission channel quality. The value of EVM in the visible light transmission channel was significantly lower for signals with amplitude modulation than for phase-manipulated signals. When implementing different lighting change scenarios, radiation of other crystals of the light emitting diode crystals not used for transmission did not lead to increase of EVM by more than one percent.

Long-Distance Visible Light Communication Based on Light Emitting Diode Source

2017 ◽  
Vol 54 (5) ◽  
pp. 050602
Author(s):  
张宇飞 Zhang Yufei ◽  
张洪明 Zhang Hongming ◽  
王鹏 Wang Peng ◽  
刘涛 Liu Tao ◽  
孙德栋 Sun Dedong ◽  
...  
Keyword(s):  
Visible Light ◽  
Light Emitting Diode ◽  
Visible Light Communication ◽  
Long Distance ◽  
Light Emitting

scholarly journals A Full-Duplex LED-to-LED Visible Light Communication System

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1713
Author(s):  
Hyunwoo Jung ◽  
Sung-Man Kim
Keyword(s):  
Visible Light ◽  
Bit Error Rate ◽  
Error Rate ◽  
Signal To Noise Ratio ◽  
Light Emitting Diode ◽  
Visible Light Communication ◽  
Full Duplex ◽  
Signal To Noise ◽  
Light Emitting ◽  
Half Duplex

We experimentally demonstrated full-duplex light-emitting diode (LED)-to-LED visible light communication (VLC) using LEDs as the transmitter and receiver. Firstly, we investigated the performance dependency on the wavelengths of the LED transmitter and receiver by measuring the rise time and signal-to-noise ratio (SNR). Through the investigation, we were able to choose the optimal LED color set for LED-to-LED VLC using Shannon’s channel capacity law. The bit error rate (BER) results of full-duplex and half-duplex LED-to-LED VLC systems with the optimal LED sets are shown to compare the performance. Furthermore, we discuss major distortions and signal losses in the full-duplex LED-to-LED VLC system.

scholarly journals Visible-Light-Driven Photocatalytic Activity of Magnetic BiOBr/SrFe12O19 Nanosheets

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 735 ◽  
Author(s):  
Taiping Xie ◽  
Jiao Hu ◽  
Jun Yang ◽  
Chenglun Liu ◽  
Longjun Xu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electron Microscope ◽  
Visible Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Active Species ◽  
Composite Catalyst ◽  
Light Emitting ◽  
Transmission Electron ◽  
Visible Light Driven

Magnetic BiOBr/SrFe12O19 nanosheets were successfully synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-visible diffused reflectance spectra (UV-DRS), and the magnetic properties were tested using a vibration sample magnetometer (VSM). The as-produced composite with an irregular flaky-shaped aggregate possesses a good anti-demagnetization ability (Hc = 861.04 G) and a high photocatalytic efficiency. Under visible light (λ > 420 nm) and UV light-emitting diode (LED) irradiation, the photodegradation rates of Rhodamine B (RhB) using BiOBr/SrFe12O19 (5 wt %) (BOB/SFO-5) after 30 min of reaction were 97% and 98%, respectively, which were higher than that using BiOBr (87%). The degradation rate of RhB using the recovered BiOBr/5 wt % SrFe12O19 (marked as BOB/SFO-5) was still more than 85% in the fifth cycle, indicating the high stability of the composite catalyst. Meanwhile, after five cycles, the magnetic properties were still as stable as before. The radical-capture experiments proved that superoxide radicals and holes were main active species in the photocatalytic degradation of RhB.

scholarly journals Passive Visible Light Detection of Humans

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1902 ◽  
Author(s):  
Kenneth Deprez ◽  
Sander Bastiaens ◽  
Luc Martens ◽  
Wout Joseph ◽  
David Plets
Keyword(s):  
Visible Light ◽  
Detection Rate ◽  
Detection System ◽  
Light Emitting Diode ◽  
Line Of Sight ◽  
Controlled Environment ◽  
Ambient Light ◽  
Light Emitting ◽  
Light Sensing ◽  
Reflected Light

This paper experimentally investigates passive human visible light sensing (VLS). A passive VLS system is tested consisting of one light emitting diode (LED) and one photodiode-based receiver, both ceiling-mounted. There is no line of sight between the LED and the receiver, so only reflected light can be considered. The influence of a human is investigated based on the received signal strength (RSS) values of the reflections of ambient light at the photodiode. Depending on the situation, this influence can reach up to ± 50 % . The experimental results show the influence of three various clothing colors, four different walking directions and four different layouts. Based on the obtained results, a human pass-by detection system is proposed and tested. The system achieves a detection rate of 100% in a controlled environment for 21 experiments. For a realistic corridor experiment, the system keeps its detection rate of 100% for 19 experiments.

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