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(a) TGA of GO, AZO-GO and AZO-RGO hybrids; (b,c) Integration of the exothermic heat flow corresponding to cis → trans isomerization of AZO-GO and AZO-RGO.
Source publication
Incorporating photochromic chromophores into polymer composites provides the possibility of a reversible photoswitch of the intrinsic properties of these materials. In this paper we report a route to attach azobenzene (AZO) moiety covalently to graphene oxide (GO) to create chromophore/graphene oxide (AZO-GO) hybrid, in which GO is both part of the...
Contexts in source publication
Context 1
... amounts of AZO moiety functionalized on GO and RGO were also estimated by TGA (Fig. 4(a)). The TGA weight loss curve of GO shows two steps of weight losses in the temperature region of 25-500 °C. A mass loss of about 25% can be seen at 175 °C, which is resulted by the evaporation of physically adsorbed water on the GO surface. A sharper mass loss happens hereafter and the mass loss of about 45% can be seen at 200 °C, which ...
Context 2
... energy density of the AZO-GO and AZO-RGO hybrids were determined by DSC analyses. As shown in Fig. 4(b), the exothermic heat flow of cis-hybrid due to cis → trans isomerization is over 20-65 °C, which corre- sponds to a bulk gravimetric energy density of 240 Wh·kg −1 (199 Wh·kg −1 for AZO-RGO). Obviously, higher grafting density results in higher energy density. The energy density is much higher than previous reports about similar ...
Context 3
... to decide the energy density. First principles calculations of ΔH for per AZO moiety is performed based on density functional theory (DFT). The model is that one AZO moiety is supported by 24 carbon atoms of RGO. (Details of the calculations are presented in the supporting information.) Using the relaxed steric structures of trans-and cis-isomers (Fig. S4), the calcu- lated ΔH is about 0.86 eV/f.u., much larger than the value of ~0.56 eV of an unsubstituted AZO molecule in gas phase 3,7 . More importantly, due to the novel structure, where GO is not only the template but also acts as a com- ponent of the chromophore, the hybrid has much smaller molar mass than the other materials, which ...
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A series of m-bisazobenzene chromophores modified with various alkoxy substituents (1; methoxy, 2; ethoxy, 3; butoxy, 4; neopentyloxy) were developed for solvent-free molecular solar thermal fuels (STFs). Compounds (E,E)-1-3 in the crystalline thin film state exhibited photoliquefaction, the first example of photo-liquefiable m-bisazobenzenes. Mean...
Citations
... Another major concern with Azo and its derivatives is related to their thermal decomposition when heated up to 200 • C [29,30]. Because most solar thermochemical conversions are operated above 200 • C, the poor thermal stability of Azo and its derivatives limits their application in a solar thermochemical energy system [31,32]. ...
... Fig. 4 shows the TGA results of Azo-1 and Azo-1/g-C 3 N 4 . As other Azo derivatives, the Azo-1 performed poorly in thermal stability tests [30,41]. The evaporation of the water physically adsorbed on the surface of Azo-1 resulted in a minor reduction below 180 • C, accounting for about 5 % weight loss. ...
... There were three new peaks (1158/1160 cm −1 , 944/945 cm −1 , and 860/861 cm −1 ) appeared in the treated bacteria spectra (Fig. 4(c)). According to the α-terpineol spectra ( Fig. 4(a)), the peaks at 923 cm −1 might be assigned to CH 2 wagging vibration, and 837 cm −1 might be given to CH wagging vibration, which belongs to the ring (Amanzadeh et al. 2019; Baranska et al. 2005;Pang et al. 2019). The shifts of the two peaks revealed covalent interaction between α-terpineol and bacteria. ...
This study aimed to evaluate the antibacterial activities of α-terpineol against common foodborne pathogenic bacteria by agar well diffusion, broth microdilution, and colony counting assay. Propulsive research was conducted to reveal the antibacterial mechanisms, including morphology, infrared spectroscopy, membrane fluidity, membrane permeability, proton motive force, and oxidative phosphorylation. Results indicated that the antibacterial activity of α-terpineol decreased in the following order: Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, and Staphylococcus aureus. With an initial cell count of 8 log CFU/mL, α-terpineol at 0.8% (v/v) reduced E. coli O157:H7 and S. aureus by approximately 5.6 and 3.9 log CFU/mL within 1 h, respectively. Remarkable destruction in cell envelopes and intracellular organizations was observed. The hydroxyl of α-terpineol might form glycosidic bonds with carbohydrates and hydrogen bonds with PO2⁻ and COO⁻ via infrared spectroscopy analysis. Generalized polarization of Laurdan revealed that the polar head groups of phospholipids transformed into close packed. The anisotropy variations of trimethyl amino-diphenylhexatriene (TMA-DPH) and DPH suggested membrane fluidity decreased. The N-phenyl-1-naphthylamine intake assay indicated that α-terpineol impaired the cell wall. Propidium iodide staining was indicative of damaged plasma membranes. Electron transport in the cytoplasmic membrane was impaired, inducing reactive oxygen species accumulation. Both membrane electrical potential and membrane pH gradient collapsed. The disruption of proton motive force and the leakage of ATP resulted in a deficit of intracellular ATP. Our research revealed the interaction between the hydroxyl group of α-terpineol and bacteria affects membrane function contributing to the bacteria’s death.
Key points
• α-Terpineol hydroxy formed glycosidic bonds and hydrogen bonds with bacteria
• α-Terpineol increased the membrane gelation and reduced the membrane fluidity
• Proton motive force and oxidative phosphorylation were impaired
Graphical abstract
... So, this way of functionalization supports electron-donating or electron-withdrawing elements. Diazonium salt can also directly bond the GO to form the AZO moiety in situ (Figure 7), leading after isomerization to a weak C-H···π non-bonding interaction [97]. However, pre-formed AZO diazonium salt can be bonded to GO thanks to the good leaving properties of this function [98]. ...
... So, this way of functionalization supports electron-donating or electron-withdrawing elements. Diazonium salt can also directly bond the GO to form the AZO moiety in situ (Figure 7), leading after isomerization to a weak C-H···π non-bonding interaction [97]. However, preformed AZO diazonium salt can be bonded to GO thanks to the good leaving properties of this function [98]. ...
... The RGO-para-AZO has a thermal storage capacity of 269.8 kJ kg −1 with a single intermolecular hydrogen bond, while RGO-ortho-AZO has a thermal storage capacity of 149.6 kJ kg −1 (44.55% less) with several inter-and intra-molecular hydrogen-bonds of AZO. The AZO-GO hybrid has the potential to use as energy storage material with the good thermal stability of cis-hybrid and substantial energy density of around 240 Wh kg −1 because of the lightweight structure and significant grafting density of AZO moieties, as stated by Pang et al. [97]. They demonstrate how the C-H . . . ...
Citation: Sagadevan, S.; Rahman, M.Z.; Léonard, E.; Losic, D.; Hessel, V. Sensor to Electronics Applications of Graphene Oxide through AZO Grafting. Nanomaterials 2023, 13, 846. Abstract: Graphene is a two-dimensional (2D) material with a single atomic crystal structure of carbon that has the potential to create next-generation devices for photonic, optoelectronic, thermoelectric, sensing, wearable electronics, etc., owing to its excellent electron mobility, large surface-to-volume ratio, adjustable optics, and high mechanical strength. In contrast, owing to their light-induced conformations, fast response, photochemical stability, and surface-relief structures, azobenzene (AZO) polymers have been used as temperature sensors and photo-switchable molecules and are recognized as excellent candidates for a new generation of light-controllable molecular electronics. They can withstand trans-cis isomerization by conducting light irradiation or heating but have poor photon lifetime and energy density and are prone to agglomeration even at mild doping levels, reducing their optical sensitivity. Graphene derivatives, including graphene oxide (GO) and reduced graphene oxide (RGO), are an excellent platform that, combined with AZO-based polymers, could generate a new type of hybrid structure with interesting properties of ordered molecules. AZO derivatives may modify the energy density, optical responsiveness, and photon storage capacity, potentially preventing aggregation and strengthening the AZO complexes. They are potential candidates for sensors, photocatalysts, photodetectors, photocurrent switching, and other optical applications. This review aimed to provide an overview of the recent progress in graphene-related 2D materials (Gr2MS) and AZO polymer AZO-GO/RGO hybrid structures and their synthesis and applications. The review concludes with remarks based on the findings of this study.
... The oxygen spectrum is resolved into two peaks, one at a higher BE of 532.8 eV corresponding to bridging oxygen (BO) and another at 531.6 eV due to non-bridging oxygen (NBO) [52]. The C 1 s scan is fitted with two peaks, one at 284.6 eV attributed to the photoelectrons from C -C/ C--C [53] and the other at 286.0 eV stems from the C bonded to oxygen, which may arise either from the epoxy group or from hydroxyl group [54]. The C 1 s fitting results indicates that the atomic percentage of C-C/C--C in C12A7:e -@G is about 90.08 %, while functionality is only 9.92 %. ...
... In the O 1s deconvolution spectrum, peaks exhibited at 531.36 eV, 532.51 eV and 533.47 eV for C=O, OÀ H/CÀ O-C and CÀ O bond, respectively ( Figure S10B). [64] The N1s deconvolution spectrum showed peaks at 399.12 eV, 400.09 eV, and 401.79 eV for azo N=N bond, [65] sp 3 hybridized CÀ N bond, [66] and sp 2 hybridized CÀ N bond ( Figure S11). [67] Thus, the XPS data confirms the formation of nanocomposite. ...
The presence of a highly toxic pyridine carboxamide insecticide, namely flonicamid in water bodies poses a serious risk to both the aquatic ecosystem and human health. Therefore, a graphene oxide (GO) decorated with azo‐functionalized calix[4]pyrrole i. e. GO‐azocalix[4]pyrrole (GACP) was synthesized to study the removal of flonicamid insecticide through adsorption. The nano‐adsorbent was characterized by IR, XPS, TGA, Raman, SEM, and TEM data. The effect of concentration of flonicamid solution, contact time, adsorbent dosage, temperature, and pH was investigated in the batch adsorption process. Experimental data suggested that equilibrium was attained within 40 min and adsorption efficiency was 93.28 %. The synergistic effect of GO and azocalix[4]pyrrole played an important role in the adsorption. The Langmuir isotherm was followed and the maximum adsorption capacity was found to be 11.43 mg/g. The pseudo‐second‐order kinetic data was well obeyed and thermodynamic investigation suggested the feasible and spontaneous nature of flonicamid onto GACP nanocomposite.
... Given that the edges and surfaces of GO are coated with -OH groups, it is reasonable to use GO as a coupling agent to obtain Azo-GO hybrids. Based on this consideration, Pang et al. [120] developed a method to covalently link the azobenzene moiety to GO and created a chromophore/ graphene oxide (Azo-GO) hybrid. This hybrid material has a high ED of nearly 240 Wh kg −1 , which may be attributed to the high grafting density of the Azo part and low quality of the new structure. ...
The energy storage mechanism of azobenzene is based on the transformation of molecular cis and trans isomerization, while NBD/QC, DHA/VHF, and fulvalene dimetal complexes realize the energy storage function by changing the molecular structure. Acting as “molecular batteries,” they can exhibit excellent charging and discharging behavior by converting between trans and cis isomers or changing molecular structure upon absorption of ultraviolet light. Key properties determining the performance of STFs are stored energy, energy density, half-life, and solar energy conversion efficiency. This review is aiming to provide a comprehensive and authoritative overview on the recent advancements of azobenzene molecular photoswitch system in STFs fields, including derivatives and carbon nano-templates, which is emphasized for its attractive performance. Although the energy storage performance of Azo-STFs has already reached the level of commercial lithium batteries, the cycling capability and controllable release of energy still need to be further explored. For this, some potential solutions to the cycle performance are proposed, and the methods of azobenzene controllable energy release are summarized. Moreover, energy stored by STFs can be released in the form of mechanical energy, which in turn can also promote the release of thermal energy from STFs, implying that there could be a relationship between mechanical and thermal energy in Azo-STFs, providing a potential direction for further research on Azo-STFs.
... However, photoswitching has not yet being reported in 2D membranes to the best of our knowledge. On the other hand, grafted photosensible azobenzene fragments were already engaged recently for the modification of the graphene oxides to induce thermal energy storage, thus achieving reversible cis-trans isomerization under illumination, and the relaxation process was slow enough to produce switching behavior [28]. ...
... The results of the 1 H NMR and FT-IR of the extracted benzenediazonium chloride are provided in Supplementary Information S1. The mechanism of this reaction was suggested in [28]. The modifier solution was added dropwise to an MFGO suspension in an ammonium buffer (30 mL, 1 g·L -1 , pH = 9.5) at 0-5 °C. ...
... In addition, X-ray patterns were obtained for pure azobenzene and 4aminoazobenzene ( Figure S5). The absorption spectra of the azobenenzene-modified GO suspension reveals an upshift (~30 nm) of the charge transfer band, which are indicative of the changes in the molecular configuration of azobenzene due to the removal of the second benzene fragment with the condensation of the GO layer (Figure 1a) [28]. On the contrary, only a slight shift of ~3 nm appears in the case of 4-aminoazobenzene-modified GO ( Figure S3), which illustrates the preservation of the diazobenzene fragment during the modification procedure. ...
Here, we report on the fabrication of light-switchable and light-responsive membranes based on graphene oxide (GO) modified with azobenzene compounds. Azobenzene and para-aminoazobenzene were grafted onto graphene oxide layers by covalent attachment/condensation reaction prior to the membranes’ assembly. The modification of GO was proven by the UV-vis, IR, Raman and photoelectron spectroscopy. The membrane’s light-responsive properties were investigated in relation to the permeation of permanent gases and water vapors under UV and IR irradiation. Light irradiation does not influence the permeance of permanent gases, while it strongly affected that of water vapors. Both switching and irradiation-induced water permeance variation is described, and they were attributed to over 20% of the initial permeance. According to in situ diffraction studies, the effect is ascribed to the change to the interlayer distance between the graphene oxide nanoflakes, which increases under UV irradiation to ~1.5 nm while it decreases under IR irradiation to ~0.9 nm at 100% RH. The last part occurs due to the isomerization of grafted azobenzene under UV irradiation, pushing apart the GO layers, as confirmed by semi-empirical modelling.
... The CSAA strongly binds the GO surface by anion-cation interactions, which prevent its removal even after the water rinsing process. In addition, synergistic effects from other effects such as π-π stacking and CH/π interactions [26][27][28][29] likely further prevent CSAA removal. Previous studies examined the adsorption properties of anionic and cationic dyes for GO and reduced GO and showed that GO strongly adsorbs cationic dyes through electrostatic interactions, whereas reduced GO (with fewer anionic functional groups) adsorbs both anions and cations through charge-independent interactions (e.g., presumably through stacking interactions and/or van der Waals forces) 30,31 . ...
Antimicrobial surfactants contained in mouthrinse have excellent efficacy, but are not retained on the tooth surface (are rinsed away) due to their low water resistance and thus do not exhibit sustained antibacterial activity. We have developed a new coating method using graphene oxide (GO) that retains the surfactant on the tooth surface even after rinsing with water, thus providing a sustained antibacterial effect. Ultra-thin films of GO and an antimicrobial agent were prepared by (1) applying GO to the substrate surface, drying, and thoroughly rinsing with water to remove excess GO to form an ultrathin film (almost a monolayer, transparent) on the substrate surface, then (2) applying antimicrobial cationic surface active agents (CSAAs) on the GO film to form a composite coating film (GO/CSAA). GO/CSAA formation was verified by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and ζ-potential and contact angle measurements. GO/CSAA was effective at inhibiting the growth of oral pathogens for up to 7 days of storage in water, and antibacterial activity was recovered by reapplication of the CSAA. Antibacterial GO/CSAA films were also formed on a tooth substrate. The results suggest that GO/CSAA coatings are effective in preventing oral infections.
... The CSAA strongly binds the GO surface by anion-cation interactions which prevent its removal even after the water rinsing process. In addition, synergistic effects from other effects such as π-π stacking and CH/ π interactions [24,25,26,27] likely further prevent CSAA removal. Previous studies examined the adsorption properties of anionic and cationic dyes for GO and reduced GO and showed that GO strongly adsorbs cationic dyes through electrostatic interactions, whereas reduced GO (with fewer anionic functional groups) adsorbs both anions and cations through charge-independent interactions (e.g., presumably through stacking interactions or van der Waals forces) [28,29]. ...
Antimicrobial surfactants contained in mouthrinse have excellent efficacy but are not retained on the tooth surface (are rinsed away) due to their low water resistance and thus do not exhibit sustained antibacterial activity. We have developed a new coating method using graphene oxide (GO) that retains the surfactant on the tooth surface even after rinsing with water, thus providing a sustained antibacterial effect.
Ultra-thin films of GO and antimicrobial agent were prepared by (1) applying GO to the substrate surface, drying, and thoroughly rinsing with water to remove excess GO to form an ultrathin film (almost a monolayer, transparent) on the substrate surface, then (2) applying antimicrobial cationic surface active agents (CSAAs) on the GO film to form a composite coating film (GO/CSAA).
GO/CSAA formation was verified by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and ζ-potential and contact angle measurements. GO/CSAA was effective at inhibiting the growth of oral pathogens even after up to 7 days of storage in water, and antibacterial activity was recovered by reapplication of the CSAA. Antibacterial GO/CSAA films were also formed on a tooth substrate. The results suggest that GO/CSAA coatings are effective in preventing oral infections.
... The minus sign confirms that the interaction is exothermic. The trans-cis photoisomerization is restricted to its steric influence, and hence, the reaction barricades are predominant by the electronic arrangement of the ÀN ¼ NÀ groups (33). Figure 2c illustrates the chemical structures for the trans -AlN-AO7 thin film and the cis -AlN-AO7 thin film. ...
The photoisomerization kinetics of photoswitchable thin films based on nanostructure/molecular layers of AlN-AO7 have been studied, investigated, and reported. The trans → cis isomerization process occurs by UV-light irradiation. The cis-isomer could be turned back to the trans-isomer by either thermal or optical relaxation. The kinetics and time-evolution of the photoisomerization and reverse isomerization mechanism of AlN-AO7 thin films are investigated by UV-Vis absorbance spectra using relevant models. All phases of AlN-AO7 thin film, initial trans-, cis-, optical trans-, thermal trans-phases, were investigated using UV-Vis absorbance spectra, FTIR spectra, XRD, and SEM. Transforming AlN-AO7 thin film from the initial trans-phase into cis-phase leads to curvature in the AO7 leaves and increases in the strain inside the structure. Going back to the trans-phase by either optical or thermal relaxation leads to vanishing the curvature and decreasing the structure's strain. Finally, the energy storage capacity was calculated using DSC and found 36.38 J/g, simultaneously realizing multi-source solar energy storage and environmental heat.
