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1.
Herein, silica nanoparticles were modified by 2,4-dihydroxybenzaldehyde and 5-bromosalicylaldehyde to produce new nanocomposites which were abbreviated as N1 and N2, respectively. The synthesized nanocomposites were used for efficient removal and preconcentration of Cu(ii) and Cd(ii) ions from water, blood, and fish muscles. FE-SEM, FT-IR, XRD, CHN elemental analysis, and nitrogen gas sorption analyzer were used to characterize the new nanocomposites. The XRD proved that the synthesized oxide is cristobalite with an average crystallite size of 54.80 nm. Due to the formation of the C N group, the intensity of the XRD peak at 2θ = 21.9° in the N1 and N2 nanocomposites decreased significantly. The FT-IR bands, which appeared at 1603 and 1629 cm−1 in the N1 and N2 nanocomposites, are attributable to the bending vibration of C N and/or OH, respectively. Also, the FE-SEM analysis shows the morphology of the silica nanoparticles which were identified as spherical and rod-like with slight agglomeration while the N1 and N2 nanocomposites have flaky surfaces due to the formation of C N groups. The maximum Cu(ii) ion adsorption capacities of the N1 and N2 nanocomposites are 64.81 and 40.93 mg g−1, respectively. The maximum Cd(ii) ion adsorption capacities of the N1 and N2 nanocomposites are 27.39 and 26.34 mg g−1, respectively. The adsorption of Cu(ii) or Cd(ii) ions using the synthesized nanocomposites is spontaneous, chemical, exothermic, and well-matched with the Langmuir equilibrium isotherm. The recovery findings demonstrate that the preconcentration process is accurate, adaptable, and resulted in quantitative separation because % Recovery is more than 95%. Furthermore, the % RSD was less than 3.5%, indicating good reproducibility.Herein, silica nanoparticles were modified by 2,4-dihydroxybenzaldehyde and 5-bromosalicylaldehyde to produce new nanocomposites which were abbreviated as N1 and N2, respectively. 相似文献
2.
Raman, fluorescence and FTIR experiments of prestine Sagittula stellata and Sagittula stellata–metal ion complexes grown in light and in dark were performed to probe the photosensitivity response of the cellular components in the marine bacterium. In the presence of Cu(ii) and Zn(ii) the frequency shifts of PO2−, C–O–C and C–O–P vibrations indicate metal binding to nucleic acids, carbohydrates and polysaccharides. We assign the observed bands in the 514.1 nm Raman spectra of the prestine S. Stellata and of the extracted carotenoids to the C C and C–C stretching vibrations. The fluorescence excitation–emission matrix (EEM) of S. stellata in light, dark and in the presence of metal ions are reported and compared with the Raman and FTIR data. The novel ability of S. stellata although heterotrophic, to show light-dependent metal binding ability may be an important feature property that maintains a stable heterotroph–prototroph interaction and a dynamic system.Raman, fluorescence and FTIR experiments of prestine Sagittula stellata and Sagittula stellata–metal ion complexes grown in light and in dark were performed to probe the photosensitivity response of the cellular components in the marine bacterium. 相似文献
3.
Shaikh A. Ali Shuaib A. Mubarak Ibrahim Y. Yaagoob Zeeshan Arshad Mohammad A. J. Mazumder 《RSC advances》2022,12(10):5938
t-Butyl hydroperoxide-initiated cycloterpolymerization of diallylaminoaspartic acid hydrochloride [(CH2 CHCH2)2NH+CH(CO2H)CH2CO2H Cl−] (I), maleic acid (HO2CH CHCO2H) (II) and cross-linker tetraallylhexane-1,6-diamine dihydrochloride [(CH2 CHCH2)2NH+(CH2)6NH+ (CH2CH CH2)2 2Cl−] (III) afforded a new pH-responsive resin (IV), loaded with four CO2H and a chelating motif of NH+⋯CO2− in each repeating unit. The removal of cationic methylene blue (MB) (3000 ppm) at pH 7.25 and Pb(ii) (200 ppm) at pH 6 by IV at 298, 313, and 328 K followed second-order kinetics with Ea of 33.4 and 40.7 kJ mol−1, respectively. Both MB and Pb(ii) were removed fast, accounting for 97.7% removal of MB within 15 min at 313 K and 94% of Pb(ii) removal within 1 min. The super-adsorbent resin gave respective qmax values of 2609 mg g−1 and 873 mg g−1 for MB and Pb(ii). IV was also found to trap anionic dyes; it removed 91% Eriochrome Black T (EBT) from its 50 ppm solutions at pH 2. The resin was found to be effective in reducing priority metal contaminants (like Cr, Hg, Pb) in industrial wastewater to sub-ppb levels. The synthesis of the recyclable resin can be easily scaled up from inexpensive starting materials. The resin has been found to be better than many recently reported sorbents.Cycloterpolymerization of diallylaminoaspartic acid hydrochloride (I), maleic acid (II) and a cross-linker (III) afforded a new pH-responsive resin (IV), loaded with four CO2H and a chelating motif of NH+⋯CO2− in each repeating unit. 相似文献
4.
Zhenghui Liu Peng Wang Hualin Ou Zhenzhong Yan Suqing Chen Xingxing Tan Dongkun Yu Xinhui Zhao Tiancheng Mu 《RSC advances》2020,10(13):7698
A Cu-based homogeneous catalytic system was proposed for the preparation of imides from alkene-tethered amides. Here, O2 acted as a terminal oxidant and a cheap and easily available oxygen source. The cleavage of C C bonds and the formation of C–N bonds were catalyzed by Cu(ii) salts with proper nitrogen-containing ligands under 100 °C. The synthesis approach has potential applications in pharmaceutical syntheses. Moreover, scaled-up experiments confirmed the practical applicability.A catalytic system comprising Cu(ii) and a nitrogen-based ligand for the oxygenation and cyclization of alkene-tethered amides. 相似文献
5.
To enhance the anti-biofouling properties and adsorption capability of poly(amidoxime) (PAO), vinylphosphonic acid (VPA, CH2 CH-PO3H2) was polymerized on poly(acrylonitrile) (PAN) surface by plasma technique, followed by amidoximation treatment to convert the cyano group (–C N) into an amidoxime group (AO, –C(NH2) N–OH). The obtained poly(vinylphosphonic acid)/PAO (PVPA/PAO) was used as an adsorbent in the uptake of U(vi) from seawater. The effect of environmental conditions on the anti-biofouling property and adsorption capability of PVPA/PAO for U(vi) were studied. Results show that the modified PVPA enhances the anti-biofouling properties and adsorption capability of PAO for U(vi). The adsorption process is well described by the pseudo-second-order kinetic model and reached equilibrium in 24 h. Adsorption isotherms of U(vi) on PVPA/PAO can be well fitted by the Langmuir model, and the maximum adsorption capability was calculated to be 145 mg g−1 at pH 8.2 and 298 K. Experimental results highlight the application of PVPA/PAO in the extraction of U(vi) from seawater.Our modified poly(vinylphosphonic acid) (PVPA) enhances the anti-biofouling properties and adsorption capability of poly(amidoxime) (PAO); the PVPA/PAO presents exceptional ability in the selective uptake of U(vi) from seawater. 相似文献
6.
We designed four series of energetic anions by replacing nitro group (NO2) with trinitromethyl group (C(NO2)3) or by inserting N-bridging groups (–NH–, –NH–NH–, –N N–, –N N(O)–) into the bistriazole frameworks. The properties of 40 energetic salts, based on the bistriazole-derived anions and hydroxylammonium cation, were studied by density functional theory (DFT) and volume-based thermodynamics calculations (VBT). It is found that the newly designed energetic salts have good detonation properties due to their larger nitrogen content and better oxygen balance. And one of their corresponding hydroxylammonium salts exhibits better detonation performance (D = 10.06 km s−1 and P = 48.58 GPa) than CL-20 (D = 9.54 km s−1 and P = 43.36 GPa). Moreover, 10 energetic salts not only exhibit excellent energetic properties superior to CL-20, but also have lower sensitivity than CL-20 (h50 = 13.81 cm). In addition, we rationally selected salt B6 from the 10 salts to predict its crystal structure under pressures. By converting energetic molecules with excellent detonation properties into energetic ions, some highly bistriazole-derived energetic salts with both excellent performance and low sensitivity could be developed strategically.We designed four series of energetic anions by replacing nitro group (NO2) with trinitromethyl group (C(NO2)3) or by inserting N-bridging groups (–NH–, –NH–NH–, –N N–, –N N(O)–) into the bistriazole frameworks. 相似文献
7.
Weifeng Li Shuangling Jin Rui Zhang Yabin Wei Jiangcan Wang Shuo Yang He Wang Minghe Yang Yan Liu Wenming Qiao Licheng Ling Minglin Jin 《RSC advances》2020,10(22):12908
The catalytic reduction of NO with NH3 (NH3-SCR) on phosphorus-doped carbon aerogels (P-CAs) was studied in the temperature range of 100–200 °C. The P-CAs were prepared by a one-pot sol–gel method by using phosphoric acid as a phosphorus source followed by carbonization at 600–900 °C. A correlation between catalytic activity and surface P content is observed. The P-CA-800vac sample obtained via carbonization at 800 °C and vacuum treatment at 380 °C shows the highest NO conversion of 45.6–76.8% at 100–200 °C under a gas hourly space velocity of 500 h−1 for the inlet gas mixture of 500 ppm NO, 500 ppm NH3 and 5.0 vol% O2. The coexistence of NH3 and O2 is essential for the high conversion of NO on the P-CA carbon catalysts, which can decrease the spillover of NO2 and N2O. The main Brønsted acid sites derived from P-doping and contributed by the C–OH group at edges of carbon sheets are beneficial for NH3 adsorption. In addition, the C3–P O configuration seems to have the most active sites for favorable adsorption and dissociation of O2 and facilitates the formation of NO2. Therefore, the simultaneous presence of acidic groups for NH3 adsorption and the C3–P O active sites for NO2 generation due to the activation of O2 molecules is likely responsible for the significant increase in the NH3-SCR activity over the P–CAs. The transformation of C3–P O to C–O–P functional groups after the reaction is found, which could be assigned to the oxidation of C3–P O by the dissociated O*, resulting in an apparent decrease of catalytic activity for P-CAs. The C–O–P based functional groups are also active in the NH3-SCR reaction.P species can effectively enhance the catalytic activity of carbon aerogels for NO reduction at low temperature. 相似文献
8.
Recently, inexpensive and readily available tBuOK has seen widespread use in transition-metal-free reactions. Herein, we report the use of tBuOK for S–S, S–Se, N N and C N bond formations, which significantly extends the scope of tBuOK in chemical synthesis. Compared with traditional methods, we have realized mild and general methods for disulfide, azobenzenes imine etc. synthesis.Inexpensive and readily available tBuOK can trigger a series of bond formation reactions, including S–S, S–Se, Se–Se, and N N and C N bonds. 相似文献
9.
Yadhav A. Imrit Hanusha Bhakhoa Tetiana Sergeieva Sergi Dans Nandini Savoo Mohamed I. Elzagheid Lydia Rhyman Diego M. Andrada Ponnadurai Ramasami 《RSC advances》2020,10(47):27884
A-234, [EtO–P( O)(F)–N C(Me)–N(Et)2], is the suspected A-type nerve agent used in the Skripal attack on the 4th of March 2018. Studies related to the structure and reactivity of this compound are limited. We, therefore, aimed at understanding the underlying hydrolysis mechanism of A-234 within the DFT framework. The attack of the water molecule can occur at the phosphinate and acetoamidine reactive centres. Our theoretical findings indicate that the hydrolysis at the acetoamidine centre is thermodynamically favoured compared to the hydrolysis at the phosphinate centre. The hydrolysis at the acetoamidine moiety may proceed via two pathways, depending on the nitrogen atom participating in the hydrolysis. The main pathway consists of four distinct channels to reach the final product, with the concerted 1,3-proton shift favoured kinetically and thermodynamically in the gas phase and water as solvent. The results are in good agreement with the literature, although some differences in the reaction mechanism were observed.A theoretical study of the hydrolysis mechanism of A-234 [EtO–P( O)(F)–N C(Me)–N(Et)2]; the suspected novichok agent in the Skripal attack. 相似文献
10.
Sandeep Kumar Dey Sonam Kumari Sonal Mandrekar Shashank N. Mhaldar Sarvesh S. Harmalkar Christoph Janiak 《RSC advances》2021,11(58):36850
Several salicylidene-based colorimetric and fluorimetric anion sensors are known in the literature. However, our 1H-NMR experimental results (in DMSO-d6) showed hydrolysis of imine (–N CH–) bonds in salicylidene-based receptors (SL, CL1 and CL2) in the presence of quaternary ammonium salts (n-Bu4N+) of halides (Cl− and Br−) and oxo-anions (H2PO4−, HSO4− and CH3COO−). The mono-salicylidene compound CL1 showed the most extensive –N CH– bond hydrolysis in the presence of anions. In contrast, the di-salicylidene compound CL2 and the tris-salicylidene compound SL showed comparatively slow hydrolysis of –N CH– bonds in the presence of anions. Anion-induced imine bond cleavage in salicylidene compounds could easily be detected in 1H-NMR due to the appearance of the salicylaldehyde –CHO peak at 10.3 ppm which eventually became more intense over time, and the –N CH– peak at 8.9–9.0 ppm became considerably weaker. Furthermore, the formation of the salicylidene O–H⋯X− (X− = Cl−/Br−) hydrogen-bonded complex, peak broadening due to proton-exchange processes and keto–enol tautomerism have also been clearly observed in the 1H-NMR experiments. Control 1H-NMR experiments revealed that the presence of moisture in the organic solvents could result in gradual hydrolysis of the salicylidene compounds, and the rate of hydrolysis has further been enhanced significantly in the presence of an anion. Based on 1H-NMR results, we have proposed a general mechanism for the anion-induced hydrolysis of imine bonds in salicylidene-based receptors.Salicylidene Schiff bases undergo imine bond hydrolysis in the presence of halides and oxo-anions in aprotic media, raising fundamental questions on the applicability of salicylidene-based receptors as anion sensors. 相似文献
11.
The correlations of the 1H NMR, 13C NMR and FT-IR spectral data from the R–O–C O groups in the alkyl carbamates and esters of homologous alcohols reveal R-group-dependent negative charge stabilization at the carbonyl oxygen and their donation to generic acceptors at Cα of even alkyl alcohols (R), which explains several of their apparently anomalous properties.NMR, FT-IR spectral correlations of the R–O–C O groups in carbamates and esters of homologous alcohols (R) reveal R-group-dependent negative charge stabilization at the carbonyl oxygen and its donation to generic acceptors at Cα of even alkyl R.Electronic interactions at the R–O–C O groups in carbamates and esters are less understood than that at the R–N–C O groups in amides. Carbamates in which both these groups are fused at the carbonyl C O bond, have several ester-like rather than amide-like features1,2 including comparable C–O bond lengths in crystals,3–6 favourable interactions between the dipoles of the C O and O–R bonds in the predominant s-trans rotamers of the R–O–C O groups and unfavourable lone pair repulsion between the two ester oxygens in their trace s-cis rotamers7–10 (Fig. 1a). However, several anomalous properties of carbamates and esters cannot be explained by these dipole and repulsive forces alone. For example, despite the electronic resonance at the O–C O group in esters and additionally at the N–C O group in carbamates (both of which augment the electron density at their carbonyl oxygens), their carbonyls have remarkably lower basicities than the carbonyls of amides11 and even those of ketones, which lack such resonance effects.12 The barriers to the C–N bond rotation for carbamates are 3–4 kcal mol−1 lower than those for analogous amides.13,14 Carbamate and ester carbonyl oxygens also have poor hydrogen bond accepting propensities compared to amides.15–20Open in a separate windowFig. 1(a) Dipole–dipole, electronic and steric interactions governing the rotamer stabilities at R–O–C O frameworks in carbamates and esters; (b) earlier report of n → π* O⋯Cα interaction in phenyl carbamates; (c) current finding of generic donor → acceptor interactions: (i) charge → HCR* (ii) charge → σ*; (d) list of carbamates (1–8), esters (9–16) and alcohols (17–20) investigated. HCR is hyperconjugative resonance along the Cα–Cβ bond of alcohol groups in carbamates and esters.Of particular current interest is the apparent anomaly that in the crystals of phenyl carbamates, the phenyl ring plane is oriented perpendicular to the carbamate plane21,22 (Fig. 1b). The presence of an extraordinary n → π* orbital overlap interaction (O⋯Cαphenyl) between the lone-pair electrons on the carbonyl (C O) oxygen and the π* orbital of the phenyl ring has been proposed as the stabilizing force for this conformer based on natural bond orbital (NBO) analysis.22 This is interesting for several reasons: (i) despite a decrease in the stretching frequency of C O in the FT-IR spectrum for this conformer, which indicates a decrease in the bond order and concomitant improvement in the charge density at the carbonyl oxygen, a discussion on the origin and role of such charge on this O⋯Cαalcohol interaction is lacking. Rather, the interaction is assumed to originate from the lone pair on oxygen. (ii) Our investigation of CCDC revealed that the O⋯Cαalcohol distances at the Cα–O–C O groups are quite non-variant (2.62–2.81 Å) for both aliphatic and aromatic carbamates and esters,3–6,23–27 notwithstanding the variations in the structure resolutions. These invoked the following questions: is the O⋯Cα interaction specific to the π* acceptors at Cαalcohol? Can any antibonding orbital at Cαalcohol act as an acceptor of the electrons from carbonyl oxygen? What is the generic nature and role of this O⋯Cα interaction in the Cα–O–C O groups? Here, we present the first spectral evidence for the generic nature of the O⋯Cα interactions even with non-π* orbital acceptors (like σ* and hyperconjugative resonance bonds) at Cα in the Cα–O–C O groups (Fig. 1c) of a variety of model homologous aliphatic carbamates and esters (Fig. 1d). The charge at the carbonyl oxygen is interdependent on the alkoxy groups and forms charge → acceptor O⋯Cα interactions, which influence the rotational states of the O–Cα bonds in the carbamates and esters.To explore the possibility of the O⋯Cα interactions at Cα–O–C O in aliphatic carbamates and esters, we investigated the 1H NMR, 13C NMR and FT-IR spectra of the secondary and tertiary carbamates (1–4 and 5–8), acetates (9–12) and benzoates (13–16) of homologous aliphatic alcohols (H–CαH2–OH, MeOH; CH3–CαH2–OH, ethanol; (CH3)2–CαH–OH, isopropanol; and (CH3)3–Cα–OH, tert-butanol, 17–20) ( 13C NMR (δ ppm) ν (cm−1) 1H NMR (δ ppm) O–Cα OCα–Cβ O C C O* OCα–Hα OCα–Cβ–Hβ 1 52.1 (50.4) NA (NA) 155.5 1685 3.69 (3.68) NA (NA) 5 52.3 NA 154.1 1705 3.78 NA 9 51.6 NA 171.5 1748 3.67 NA 13 51.5 NA 165.9 1725 3.92 NA 2 60.5 (58.3) 14.6 (18.4) 155.0 1679 4.13 (3.72) 1.26 (1.24) 6 61.1 14.5 153.6 1701 4.23 1.31 10 60.5 14.2 171.4 1740 4.12 1.25 14 60.8 14.3 166.5 1720 4.33 1.33 3 67.6 (64.5) 22.1 (25.1) 154.7 1674 4.92 (4.03) 1.23 (1.20) 7 68.7 22.1 153.7 — 5.05 1.30 11 67.6 21.8 170.6 1736 4.99 1.23 15 68.3 21.9 166.1 1716 5.24 1.35 4 78.7 (69.1) 28.4 (31.2) 154.5 1683 NA (NA) 1.46 (1.27) 8 80.4 28.3 152.7 1689 NA 1.51 12 80.1 28.1 170.4 1738 NA 1.45 16 80.9 28.2 165.8 — NA 1.58