The preparation and photochemical properties of some 1,3-Diphenyl-2-pyrazolines containing a heteroaromatic substituent

1977 ◽  
Vol 30 (3) ◽  
pp. 629 ◽  
Author(s):  
J Lin ◽  
DE Rivett ◽  
JFK Wilshire
Keyword(s):  
Photochemical Reaction ◽  
Large Scale ◽  
Polar Solvent ◽  
Methanolic Solution ◽  
Pyrazoline Ring ◽  
Photochemical Properties

Several 1,3-diphenyl- and 1,3,5-triphenyl-2-pyrazolines containing a heteroaromatic substituent (viz. imidazol-1-yl, pyrazol-1-yl and 1,2,4- triazol-1-yl) have been synthesized. When compared with their unsubstituted analogues, these compounds (a) absorbed more intensely at a longer wavelength, (b) exhibited greater fluorescence in a polar solvent (methanol) and (c) possessed similar stability to light. ��� Large-scale irradiations of two 1,3,5-triphenyl-2-pyrazolines (viz. unsubstituted and that containing the 1,2,4-triazol-1-yl substituent) in methanolic solution revealed that, although dehydrogenation of the 2-pyrazoline ring was the major photochemical reaction, significant oxidation to the corresponding chalcone also occurred. In addition, phenol was detected among the irradiation products. ��� Several sulphonated analogues of the abovementioned pyrazolines were prepared. When applied to wool, these compounds exhibited excellent fluorescent whitening properties.

scholarly journals A unique clade of light-driven proton-pumping rhodopsins evolved in the cyanobacterial lineage

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Masumi Hasegawa ◽  
Toshiaki Hosaka ◽  
Keiichi Kojima ◽  
Yosuke Nishimura ◽  
Yu Nakajima ◽  
...  
Keyword(s):  
Large Scale ◽  
Expression System ◽  
Genomic Analysis ◽  
Proton Pumping ◽  
Spectroscopic Characteristics ◽  
Light Utilization ◽  
Photochemical Properties ◽  
Microbial Rhodopsin ◽  
Unique Clade ◽  
Biased Distribution

Abstract Microbial rhodopsin is a photoreceptor protein found in various bacteria and archaea, and it is considered to be a light-utilization device unique to heterotrophs. Recent studies have shown that several cyanobacterial genomes also include genes that encode rhodopsins, indicating that these auxiliary light-utilizing proteins may have evolved within photoautotroph lineages. To explore this possibility, we performed a large-scale genomic survey to clarify the distribution of rhodopsin and its phylogeny. Our surveys revealed a novel rhodopsin clade, cyanorhodopsin (CyR), that is unique to cyanobacteria. Genomic analysis revealed that rhodopsin genes show a habitat-biased distribution in cyanobacterial taxa, and that the CyR clade is composed exclusively of non-marine cyanobacterial strains. Functional analysis using a heterologous expression system revealed that CyRs function as light-driven outward H+ pumps. Examination of the photochemical properties and crystal structure (2.65 Å resolution) of a representative CyR protein, N2098R from Calothrix sp. NIES-2098, revealed that the structure of the protein is very similar to that of other rhodopsins such as bacteriorhodopsin, but that its retinal configuration and spectroscopic characteristics (absorption maximum and photocycle) are distinct from those of bacteriorhodopsin. These results suggest that the CyR clade proteins evolved together with chlorophyll-based photosynthesis systems and may have been optimized for the cyanobacterial environment.

Einfache photochemische Synthese von Benzylphosphanen / Facile Photochemical Synthesis of Benzylphosphines

1994 ◽  
Vol 49 (12) ◽  
pp. 1606-1614 ◽  
Author(s):  
Gerhard Müller ◽  
Martin Waldkircher ◽  
Martin Winkler
Keyword(s):  
Photochemical Reaction ◽  
Large Scale ◽  
Photochemical Synthesis ◽  
Product Selectivity ◽  
One Pot ◽  
Good Product ◽  
Consecutive Reactions ◽  
Soxhlet Apparatus ◽  
Short Period ◽  
By Products

Facile large-scale synthesis of the benzyl-dibromo-phosphines RPBr2 (R = C6H5CH2, 3,5-Me2C6H3CH2, 2-BrC6H4CH2) is accomplished by the photochemical reaction of toluene, mesitylene, and 2-bromotoluene, respectively, with PBr3 in the absence of solvent. If the reactions are carried out up to 50% completion the amount of by-products formed is remark­ ably low, rarely exceeding 10% of the total amount of products formed. The selectivity of the photoreaction may be improved up to 98% if it is carried out in a modified Soxhlet apparatus which allows the predominant irradiation of only the starting materials. The appar­ ent limitations imposed by the low turnovers required to achieve good product selectivity are by far outweighed by the large amounts of desired products formed in a short period of time and by the easy recovery of unreacted starting material by distillation. Thus in the case of 2-BrC6H4CH2PBr2, in a typical run 94 g (261 mmol) of product may be isolated after 2.5 h of irradiation of 970 mmol of 2-BrC6H5CH3 and 1.39 mol of PBr3. In this case the turnover is 32%. the isolated yield 27%, and the by-product 2-methylphenyl-dibromo-phosphine only amounts to less than 2%. The benzyl-dibromo-phosphines are easily methylated with two equivalents of MeMgCl to give the respective benzyl-dimethyl-phosphines in 79-93% yield. Tertiary benzylphosphines MePRR′ (R = 2-BrC6H4CH2, R′ = Me3SiCH2; R = R′ = 2-BrC6H4CH2) are obtained in easy one-pot syntheses by consecutive reactions of 2-BrC6H4CH2PBr2 with Me3SiCH2MgCl and MeMgCl, and with 2-BrC6H4CH2MgBr and MeMgCl, respectively.

Large-scale and green synthesis of octahedral flower-like cupric oxide nanocrystals with enhanced photochemical properties

2014 ◽  
Vol 315 ◽  
pp. 169-177 ◽  
Author(s):  
Shi-Kuo Li ◽  
Yu-Yi Pan ◽  
Mi Wu ◽  
Fang-Zhi Huang ◽  
Chuan-Hao Li ◽  
...  
Keyword(s):  
Green Synthesis ◽  
Large Scale ◽  
Cupric Oxide ◽  
Photochemical Properties

Influence of pressure on molecular packing and photochemical properties in three chalcone analogs

2015 ◽  
Vol 230 (2) ◽  
Author(s):  
Julia Bąkowicz ◽  
Tomasz Galica ◽  
Ilona Turowska-Tyrk
Keyword(s):  
High Pressure ◽  
Free Space ◽  
Photochemical Reaction ◽  
Ambient Pressure ◽  
Molecular Packing ◽  
Mutual Orientation ◽  
Geometrical Parameters ◽  
Photochemical Properties

AbstractThe structures of 1-(4-methylphenyl)-3-(2-thienyl)prop-2-en-1-one, (I), 1-(5-bromo-2-hydroxyphenyl)-3-(2-furyl)prop-2-en-1-one, (II), and 1-(3-furyl)-3-[3-(trifluoromethyl)phenyl]prop-2-en-1-one, (III), were determined in ambient and high pressure conditions. The values of the intermolecular geometrical parameters describing possibilities of execution of [2+2] photodimerization were calculated and analysed. In the case of ambient pressure, for (I) they are close to the border valid for photoreactive compounds and for (II) and (III) they exclude the photochemical reaction in crystals. High pressure hardly changed the mutual orientation of adjacent molecules and largely the distance between them: in the case of (I), the distance was far below limits for compounds undergoing [2+2] photodimerization. The volume of free space was calculated for the studied compounds for different values of pressure and analysed in the context of possibilities of the [2+2] photodimerization.

The chemical and photochemical properties of some 1,3-Diphenyl-2-pyrazolines

1974 ◽  
Vol 27 (10) ◽  
pp. 2267 ◽  
Author(s):  
NA Evans ◽  
DE Rivett ◽  
JFK Wilshire
Keyword(s):  
Singlet Oxygen ◽  
Photochemical Reaction ◽  
Heterocyclic Ring ◽  
Photo Oxidation ◽  
Effect Of Substituents ◽  
Effect Of Solvent ◽  
Fluorescence Efficiency ◽  
Photochemical Properties ◽  
The Stability

The effect of solvent and structure on the stability to light of a series of 1,3-diphenyl-2-pyrazolines has been studied. The major photochemical reaction observed is dehydrogenation to the corresponding 1,3-diphenylpyrazole unless the 5-position is disubstituted when, as in the case of 1,3,5,5-tetraphenyl-2- pyrazoline, photo-oxidation, with either retention or destruction of the heterocyclic ring, occurs. Evidence is presented that singlet oxygen may be involved in the photodehydrogenation of 1,3- diphenyl-2-pyrazoline. The observation that the presence of bulky groups in both the 4- and 5-positions improved both the fluorescence efficiency and the stability to light of the 1,3-diphenyl-2-pyrazoline molecule may have significance for the design of pyrazoline whitening agents. Dehydrogenation of the same series of pyrazolines with chloranil has been studied in order to determine the effect of substituents on the yield of pyrazole.

scholarly journals The development of luminescent solar concentrator-based photomicroreactors: a cheap reactor enabling efficient solar-powered photochemistry

2021 ◽  
Author(s):  
Stefan D. A. Zondag ◽  
Tom M. Masson ◽  
Michael G. Debije ◽  
Timothy Noël
Keyword(s):  
Solar Energy ◽  
Photochemical Reaction ◽  
Large Scale ◽  
Organic Molecules ◽  
Scale Production ◽  
Chemical Transformations ◽  
Solar Concentrator ◽  
Luminescent Solar Concentrator ◽  
Large Scale Production ◽  
Solar Powered

AbstractSunlight strikes our planet every day with more energy than we consume in an entire year. Therefore, many researchers have explored ways to efficiently harvest and use sunlight energy for the activation of organic molecules. However, implementation of this energy source in the large-scale production of fine chemicals has been mostly neglected. The use of solar energy for chemical transformations suffers from potential drawbacks including scattering, reflections, cloud shading and poor matches between the solar emission and absorption characteristics of the photochemical reaction. In this account, we provide an overview of our efforts to overcome these issues through the development of Luminescent Solar Concentrator-based PhotoMicroreactors (LSC-PM). Such reactors can efficiently convert solar energy with a broad spectral distribution to concentrated and wavelength-shifted irradiation which matches the absorption maximum of the photocatalyst. Hence, the use of these conceptually new photomicroreactors provides an increased solar light harvesting capacity, enabling efficient solar-powered photochemistry. Graphical abstract

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

Some applications of electron beam microanalysis techniques in VLSI process evaluation

1983 ◽  
Vol 41 ◽  
pp. 160-161
Author(s):  
Simon Thomas
Keyword(s):  
Integrated Circuits ◽  
Process Evaluation ◽  
Large Scale ◽  
Technology Development ◽  
Analytical Techniques ◽  
Successful Implementation ◽  
Analysis Of Failures ◽  
Characterization Of Materials ◽  
Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

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