China
Africa
Explore chapters and articles related to this topic
Mechanism in charge transfer and electrical stability
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
Wen Zheng, Jun Chen, Peter C. Innis
Peak shifts in FTIR spectra can also be observed for doped conjugated polymer compared with undoped ones. If the electronic conjugation is extended, the corresponding vibrational peak will shift toward a lower wavenumber (referred to as bathochromic shift). Furthermore, the structure differences can be detected in vibrational spectra based on changes in position and shape of FTIR bonds, such as N–H and C–H. Typical bands for PAn are ~1560 cm–1 (C=N quinoid ring [Q] stretching), ~1490 cm–1 (C–C benzenoid ring [B] stretching), ~1300 cm–1 (C–N stretching of secondary amine), ~1115 cm–1 (C–H in-plane bending of aromatic rings), ~817 cm–1 (C–H deformation in the Q ring), and ~796 cm–1 (C–H out-of-plane bending of aromatic rings) (Coskun et al. 2012). The region of 1400–1000 cm–1 is of particular interest because it corresponds to the stretching of intermediate CN bonds (i.e., the intermediate CN bonds between the single and double CN bonds). As shown in Figure 4.10, single and double CN stretching peaks are presented in 1224 and 1517 cm–1, respectively; peaks that emerge between those indicate the delocalization of π-electrons along the conjugated chain, which also reveals an increase in the conjugated chain length.
Chemical Synthesis of Nanoparticles
Published in M. H. Fulekar, Bhawana Pathak, Environmental Nanotechnology, 2017
The synthesis of a doped catalyst is an important approach in band gap engineering to change the optical response of the semiconducting nanoparticle. The doping is done to induce a bathochromic shift, that is, a decrease of the band gap or introduction of intra-band gap states that result in the absorption of more visible light. Synthesis of doping leads to photocatalytic systems that exhibit enhanced efficiency to maintain the integrity of the crystal structure of the photocatalyst (Aysin et al., 2011). In synthesis, it is easy to replace Ti4+ in TiO2 with a cation than to substitute O2− with another anion due to difference in the charge states and ionic radii.
t-Butyl 3-azido- and 3-amino-2,3-dideoxy-α-d -arabino-hexopyranosides: a concise protocol of structural and chemical profiles to identify metal ion binding modes
Published in Journal of Coordination Chemistry, 2021
Aleksandra M. Dąbrowska, Anna Barabaś, Artur Sikorski, Michał Wera, Jakub Brzeski, Marta Domżalska, Agnieszka Chylewska
For the azide chromophore under acidic conditions, as shown in Figure 7A, the molecule has absorption at 272 nm with an ε272=51.08. In addition to the extended chromophore, the molecule also contains an auxochrome in the form of hydroxyl groups, which under basic conditions have a lone pair of electrons that can interact with the chromophore to produce a bathochromic shift. Under acidic conditions, the azide group is protonated [56] and does not function as an auxochrome, but when the proton is removed from this group under basic conditions, a hypsochromic shift is produced and an absorption with λmax at 310 nm with ε310=0.316 appears. Even small differences in ε values do not prove that in the solution of 1, there are no equilibria between protonated and deprotonated species.
Synthesis and biological activity of iron(II), iron(III), nickel(II), copper(II) and zinc(II) complexes of aliphatic hydroxamic acids
Published in Journal of Coordination Chemistry, 2023
Ibrahima Sory Sow, Michel Gelbcke, Franck Meyer, Marie Vandeput, Mickael Marloye, Sergey Basov, Margriet J. Van Bael, Gilles Berger, Koen Robeyns, Sophie Hermans, Dong Yang, Véronique Fontaine, François Dufrasne
The electronic transitions n→π* (C = O) observed show a bathochromic shift towards a higher wavelength. This indicates that complexation has occurred between HA and the corresponding metal chloride [54]. The absorption maximum at 425 nm characterizes the ligand-metal charge transfer bands of complexes HAnFe2, HAnFeCl and HAnFe3 [55], those of HAnNi2 and HAnCu2 at λmax = 250 nm (Figures 1 and S4).