China
Africa
Explore chapters and articles related to this topic
Organic Small-Molecule Materials for Organic Light-Emitting Diodes
Published in Zhigang Rick Li, Organic Light-Emitting Materials and Devices, 2017
Shijian Su, Norman Herron, Hong Meng
Kim et al. designed and synthesized a series of iridium(III) complexes with methylated phenyl ring and quinoline ring and have ancillary ligands, such as acac and tmd groups [496]. They found that addition of an electron-donating methyl group to the metallated phenyl ring (mphq) exhibited a bathochromic shift compared with Ir(phq)2acac (453), while the additional introduction of methyl group to the quinoline ring (mphmq ligand) led to a hypsochromic shift compared with the spectral range of the mphq ligand. In addition, the change of ancillary ligand to a tmd moiety from an acac moiety results in a significant improvement of device efficiency. However, it is interesting that all metallated products exhibited higher QE than Ir(phq)2acac. The device structure in this research is ITO/DNTPD (40 nm)/Bebq2:3 wt.% dopants (30 nm)/Bebq2 (20 nm)/LiF (0.5 nm)/Al (100 nm). Ir(mphmq)2acac (454)-based devices gave high efficiencies with a current efficiency of 29.9 cd/A, a power efficiency of 25.4 lm/W, and CIE of (0.65, 0.35) at a brightness of 1000 cd/m2.
Mechanism of Ni(Fe)ARD action in methionine salvage pathway, in biosynthesis of ethylene, and role of Tyr-fragment as regulatory factor
Published in A. K. Haghi, Lionello Pogliani, Eduardo A. Castro, Devrim Balköse, Omari V. Mukbaniani, Chin Hua Chia, Applied Chemistry and Chemical Engineering, 2017
Ludmila I. Matienko, Larisa A. Mosolova, Vladimir I. Binyukov, Elena M. Mil, Gennady E. Zaikov
As can be seen from Figure 18.9, when an aqueous solution of Tyr is added to the Ni(acac)2 aqueous solution, a decrease in absorption intensity of acetylacetonate ion (acac) (Xmax = 296 nm) and a small short-wavelength shift of the absorption maximum (to Xmax ~ 294 nm) (hypsochromic shift of the absorption maximum) takes place. A similar change in the intensity of the (acac)absorption band is observed in the absorption spectra of Ni(acac)2when it is coordinated with monodentate ligand MP, or crown-ether 18C6, and in the case of the coordination of axial monodentate ligands with the other metal acetylacetonates.5
Use of Ultraviolet in Photochemical Synergistic Oxidation Processes in Water Sanitation
Published in Willy J. Masschelein, Rip G. Rice, Ultraviolet Light in Water and Wastewater Sanitation, 2017
Willy J. Masschelein, Rip G. Rice
A preliminary conclusion can be formulated as follows: The absorbance (base 10) of oxygen at 185 nm is about 0.1 cm−1 atm−1; in other words, it is much lower than the Hartley absorbance of ozone in the 260-nm region (134 cm−1 atm−1), so that the photostationary balance of ozone formation vs. ozone decomposition with traditional Hg lamps is unfavorable.Optical filters, as existing (see Section 2.7.6, Chapter 2) cut off emissions at lower UV wavelengths, thus balancing the photostationary equilibrium in less favor of ozone formation vs. ozone photolysis.If by doping the Penning gas a hypsochromic shift of the emission could be achieved, an increase in the absorbance by oxygen at a given wavelength by a factor of 10 to 100 could result (see Figure 98); this could reverse the photostationary balance.Developing continuously emitting UV lamps on the basis of xenon emission gas is a challenge for future improvement [Fassler and Mehl, 1971].Unpublished observations [Bossuroy and Masschelein, 1987 to 1992] show, however, that aging of the quartz of the lamp or the enclosures of mercury lamps emitting at the 185-nm wavelength (so-called ozone positive lamps) occurs very fast, resulting in loss of transmission at these wavelengths by at least 50% after 500 to 700 h. This observation, to be confirmed, can be of significant importance in the solarization of the quartz and the enclosure material of UV lamps. Ozone-free lamps are obtained by incorporating ozone inhibitors into the quartz (e.g., titanium dioxide).Xenon excimer lamps are proposed for ozone generation in an oxygen flow in the controlled vacuum UV (VUV) range. The process [Hashem et al., 1996] initiating oxygen–ozone-related oxidants at wavelengths lower than 200 nm is promising. Aging of hardware is not yet thoroughly established.
DFT computational insights into structural, electronic and spectroscopic parameters of 2-(2-Hydrazineyl)thiazole derivatives: a concise theoretical and experimental approach
Published in Journal of Sulfur Chemistry, 2021
Vishnu A. Adole, Thansing B. Pawar, Bapu S. Jagdale
The first excited absorption energies (λ in nm), oscillator strength (ƒ), and transitions are given in Table S5 (supporting information). In the present exploration, the effect of substituents (attached to ring B) (Figure 7) on absorption energies is also discussed. Our study revealed that the presence of substituents like NO2, OMe, Me, and Ar on ring B augmented the absorption wavelength, i.e. results in the bathochromic shift. On the contrary, the substituents like Cl, F, and Br have declined the absorption wavelength, i.e. results in the hypsochromic shift. The nitro substituent has been linked with a greater increment in the absorption wavelength as compared to the other substituents. This is because of the extended conjugation from the alkoxy substituent up to nitro substituent through aromatic double bonds.
Smart textiles: an overview of recent progress on chromic textiles
Published in The Journal of The Textile Institute, 2021
Heloisa Ramlow, Karina Luzia Andrade, Ana Paula Serafini Immich
Solvatochromic textiles change reversibly its absorption or emission spectrum that is induced by the action of solvents. The color change is the consequence of the absorption maximum shift, which occurs due to differences between the solvation energy of the initial and excited state in various solvents (Van Langenhove, 2007). Positive solvatochromism corresponds to bathochromic shift (or red shift) with increasing solvent polarity. The corresponding hypsochromic shift is termed negative solvatochromism.
The influences of lateral groups on 4-cyanobiphenyl-benzonitrile- based dimers
Published in Liquid Crystals, 2022
Srinatha M K, Ayesha Zeba, Anjali Ganjiwale, Ashwathanarayana Gowda, Gurumurthy Hegde, Mohamed Alaasar, G. Shanker
UV-visible absorption spectra were recorded for the dimers (X-Dn) as a function of concentration in dichloromethane (DCM). As an example, the electronic absorption of CN-D9 is shown in Figure 3, three distinct peaks are observed between 200 and 350 nm of B band, indicating the effect of polar substituents and the methylene spacer connecting two promesogenic units. The electron-withdrawing cyano group small in size provides excellent stability under UV irradiation. The position of cyano groups in phthalonitrile segment is vital for strong photophysical properties [63]. Three noticeable peaks in the B band at λ = 300, 265, 228 nm display the characteristics of hypsochromic shift (shorter wavelength) with increased intensity as variation in concentration. Further, on dilution these peaks break down into smaller ones and disappears at 3.125 × 10−6 M, indicating a decrease in the intermolecular interactions as a result of weak n – π* transition with no conjugation arising from cyano group. The absence of any Q-band is surprising inspite of having three – CN group in this dimer, which have greater tendency to induce the dipole–dipole interactions. The aggregation in the B-band results due to intermolecular interaction and found to be maximum around λ = 300 nm and peak size reduces further before disappearing below 220 nm. The peak intensity has the ratio of 1:0.7:0.85 and strong aggregation visible in the first peak and continues to disintegrate the aggregation size as visible in second and third peaks. Reminiscent aggregational behaviour observed for the F-D8 dimer of fluoro series, three distinct B-band peaks at λ = 300, 285, 250 nm (See ESI) but the H-Dn dimers display only two peaks (λ = 300, 250 nm), which also emphasise on the influence of polar substituents of the dimers (Figure S4-S6, ESI). Overall, the aggregation of dimers could be attributed to the self-assembly of molecules, the Vander waals force of attraction and polar group interaction, which help to stack one above the other in the formation of hypsochromic (H)-aggregates (Figure 3).