Correction: High-detectivity perovskite-based photodetector using a Zr-doped TiOx cathode interlayer

Correction for ‘High-detectivity perovskite-based photodetector using a Zr-doped TiO_x cathode interlayer’ by C. H. Ji et al., RSC Adv., 2018, 8, 8302–8309.

The authors regret that the names of the authors are shown incorrectly in the original article. The corrected author list is as shown above.In addition, the authors regret that an incorrect version of Fig. 4b was included in the original article. The correct version of Fig. 4 is as shown below.Open in a separate windowFig. 4Dynamic characteristics of photocurrent response times using a laser diode at a light intensity of 650 μW cm⁻² at 525 nm. (a) Photocurrent response time under −0.1 V at a pulsed frequency of 1 MHz. (b) Cut-off frequency for the perovskite photodetector under −0.1 V.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: iTRAQ-based quantitative proteomic analysis for identification of biomarkers associated with emodin against severe acute pancreatitis in rats

Correction for ‘iTRAQ-based quantitative proteomic analysis for identification of biomarkers associated with emodin against severe acute pancreatitis in rats’ by Hong Xiang et al., RSC Adv., 2016, 6, 72447–72457.

The authors regret that Fig. 2–4 were shown incorrectly in the original article. An incorrect section of the SAP group in the MPO-immunohistochemical staining (Fig. 2A) and HE staining (Fig. 3) experiments was used in error. In addition, Fig. 4 has been revised to show the zymogen granule, in order to better represent the ultrastructure of the pancreas. The correct versions of Fig. 2–4 are shown below.Open in a separate windowFig. 2Emodin down-regulated the MPO protein expression in pancreas of SAP rats. (A) Effect of emodin on MPO-immunopositive area (brown) staining of pancreatic tissue in SAP rats by immunohistochemical detection. (B) Effect of emodin on MPO-immunopositive area (red) staining of pancreatic tissue in SAP rats by immunofluorescence detection. Images are presented at 200× magnification. The data are presented as the mean ± SD, n = 6. **P < 0.01 versus SO; ^#P < 0.05 versus SAP, ^##P < 0.01 versus SAP.Open in a separate windowFig. 3Emodin improved pancreatic histopathology of SAP rats. Effect of emodin on H&E staining of pancreatic tissue in SAP rats. Images are presented at 200× magnification. The data are presented as the mean ± SD, n = 6. **P < 0.01 versus SO; ^#P < 0.05 versus SAP, ^##P < 0.01 versus SAP.Open in a separate windowFig. 4Emodin attenuated cellular structure changes in pancreas of SAP rats. Representative images of the cells’ ultrastructure in the SO (A), SAP (B), 60 mg kg⁻¹ emodin (C), 30 mg kg⁻¹ emodin (D) and 15 mg kg⁻¹ emodin (E) groups. Images are presented at 25 000× magnification.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Three-dimensional directional nerve guide conduits fabricated by dopamine-functionalized conductive carbon nanofibre-based nanocomposite ink printing

Correction for ’Three-dimensional directional nerve guide conduits fabricated by dopamine-functionalized conductive carbon nanofibre-based nanocomposite ink printing’ by Shadi Houshyar et al., RSC Adv., 2020, 10, 40351–40364, DOI: 10.1039/D0RA06556K.

The authors regret that an incorrect version of Fig. 2 was included in the original article. The correct version of Fig. 2 is presented below.Open in a separate windowFig. 2(a) FTIR spectra of pure PCL and PCL printed with CNF and DA (40 and 100 μg mL⁻¹), where circles emphasize the OH peak (3700 cm⁻¹) of the carboxylated CNF and NH peak (1565 cm⁻¹) of dopamine. (b) Shear stress of the CNF and CNF + DA nanocomposite inks versus shear rate. (c) Viscosity versus shear rate of the prepared nanocomposite inks.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Green-synthesised cerium oxide nanostructures (CeO2-NS) show excellent biocompatibility for phyto-cultures as compared to silver nanostructures (Ag-NS)

Correction for ‘Green-synthesised cerium oxide nanostructures (CeO₂-NS) show excellent biocompatibility for phyto-cultures as compared to silver nanostructures (Ag-NS)’ by Qaisar Maqbool, RSC Adv., 2017, 7, 56575–56585, https://doi.org/10.1039/c7ra12082f.

The author regrets that Fig. 4 and ​and55 of the original article did not appropriately represent the findings.Open in a separate windowFig. 4Comparative TGA analysis of CeO₂-NS and Ag-NS.Open in a separate windowFig. 5FTIR spectrum of CeO₂-NS and Ag-NS.The correct version of Fig. 4 is shown below. In addition, the associated text on page 56578 “Experimental findings show total mass loss…” should be changed to “Experimental findings show total mass loss of 57.53% by CeO₂-NS and 61.12% by Ag-NS.” Fig. 5 of the original article shows only the plot of selected data points. In order to provide clarity to readers, it should be replaced with the following original FTIR plots (complete scan).The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: A sensitive OFF–ON–OFF fluorescent probe for the cascade sensing of Al3+ and F− ions in aqueous media and living cells

Correction for ‘A sensitive OFF–ON–OFF fluorescent probe for the cascade sensing of Al³⁺ and F⁻ ions in aqueous media and living cells’ by Lingjie Hou et al., RSC Adv., 2020, 10, 21629–21635, DOI: 10.1039/D0RA02848G.

The authors regret that an incorrect version of Fig. 4 was included in the original article. The correct version of Fig. 4 is presented below.Open in a separate windowFig. 4The ESI-MS spectrum of Al³⁺–HNS complex.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Thiophene-containing tetraphenylethene derivatives with different aggregation-induced emission (AIE) and mechanofluorochromic characteristics

Four thiophene-containing tetraphenylethene derivatives were successfully synthesized and characterized. All these highly fluorescent compounds showed typical aggregation-induced emission (AIE) characteristics and emitted different fluorescence colors including blue-green, green, yellow and orange in the aggregation state. In addition, these luminogens also exhibited various mechanofluorochromic phenomena.

Four thiophene-containing AIE-active TPE derivatives were synthesized. Furthermore, these luminogens exhibited various mechanofluorochromic phenomena.

High-efficiency organic fluorescent materials have attracted widespread attention due to their potential applications in organic light-emitting devices and fluorescent switches.^1–8 Meanwhile, smart materials sensitive to environmental stimuli have also aroused substantial interest. Mechanochromic luminescent materials exhibiting color changes under the action of mechanical force (such as rubbing or grinding) are one important type of stimuli-responsive smart materials, which can be used as pressure sensors and rewritable media.^9–18 Bright solid-state emission and high contrast before and after grinding are very significant for the high efficient application of mechanochromic fluorescence materials.^19–28 However, a majority of traditional emissive materials usually exhibit poor emission efficiency in the solid state due to the notorious phenomenon of aggregation caused quenching (ACQ), and the best way to solve the problem is to develop a class of novel luminescent materials oppositing to the luminophoric materials with ACQ effect. Fortunately, an unusual aggregation-induced emission (AIE) phenomenon was discovered by Tang et al. in 2001.²⁹ Indeed, the light emission of an AIE-active compound can be enhanced by aggregate formation.^30–32 Obviously, it is possible that AIE-active mechanochromic fluorescent compounds can be applied to the preparation of high-efficiency mechanofluorochromic materials. Numerous luminescent materials exhibiting mechanochromic fluorescent behavior have been discovered up to now.³³ Whereas, examples of fluorescent molecules simultaneously possessing AIE and mechanofluorochromic behaviors are still limited, and the exploitation of more AIE-active mechanofluorochromic luminogens is necessary. Organic solid emitters with twisted molecular conformation can effectively prevent the formation of ACQ effect, thus exhibiting strong solid-state luminescence. Tetraphenylethene is a highly twisted fluorophore. Meanwhile, it is also a typical AIE unit, which can be used to construct high emissive stimuli-responsive functional materials.^34–37The design and synthesis of novel organic emitters with tunable emission color has become a promising research topic at present. Only a limited number of organic fluorescent materials with full-color emission have been reported to date.^38,39 For example, in 2018, Tang et al. reported six tetraphenylpyrazine-based compounds. Interestingly, in film states, these luminogens exhibited different fluorescence colors covering the entire visible range, and this is the first example of realizing full-color emission based on the tetraphenylpyrazine unit.⁴⁰ It is still an urgent challenge to develop novel organic luminophors with tunable emission color basing on the same core structure.In this study, four organic fluorophores containing tetraphenylethene unit were successfully synthesized (Scheme 1). Introducing the thiophene and carbonyl units into the molecules possibly promoted the formation of weak intermolecular interactions such as C–H⋯S or C–H⋯O interaction, which was advantageous to the exploitation of interesting stimuli-responsive fluorescent materials. Indeed, all these compounds showed obvious AIE characteristics. Furthermore, these luminogens emitted a series of different fluorescent colors involving blue-green, green, yellow and orange in the aggregation state. In addition, these luminogens also exhibited reversible mechanofluorochromic phenomena involving different fluorescent color changes.Open in a separate windowScheme 1The molecular structures of compounds 1–4.To investigate the aggregation-induced properties of compounds 1–4, the UV-vis absorption spectra of 1, 2, 3 and 4 (20 μM) in DMF–H₂O mixtures of varying proportions were studied initially (Fig. S1^†). Obviously, level-off tails were obviously observed in the long-wavelength region as the water content increased. This interesting phenomenon is generally associated with the formation of nano-aggregates.⁴¹ Next, the photoluminescence (PL) spectra of 1–4 in DMF–H₂O mixtures with various water fraction (f_w) values were explored. As shown in Fig. 1, almost no PL signals were noticed when a diluted DMF solution of luminogen 1 was excited at 365 nm, and thus almost no fluorescence could be observed upon UV illumination at 365 nm, and the corresponding absolute fluorescence quantum yield (Φ) was as low as 0.04%. However, when the water content was increased to 50%, a new blue-green emission band with a λ_max at 501 nm was observed, and a faint blue-green fluorescence was noticed under 365 nm UV light. As the water content was further increased to 90%, a strong blue-green emission (Φ = 30.81%) could be observed. Furthermore, as shown in Fig. S2,^† the nano-aggregates (f_w = 90%) obtained were confirmed by dynamic light scattering (DLS). Therefore, the compound 1 with bright blue-green emission caused by aggregate formation showed typical AIE feature.Open in a separate windowFig. 1(a) Fluorescence spectra of the dilute solutions of compound 1 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different water contents (0–90%). Excitation wavelength = 365 nm. (b) Fluorescence images of 1 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different f_w values under 365 nm UV light.Similarly, as can be seen in Fig. 2–4, compounds 2–4 also showed obvious aggregation-induced green emission, aggregation-induced yellow emission, and aggregation-induced orange emission, respectively. When the water content was zero, the quantum yields of compounds 2–4 were 0.04%, 0.05% and 0.46%, respectively, while as the water content increased to 90%, the corresponding quantum yields of compounds 2–4 also increased to 30.67%, 45.57% and 26.53%, respectively. Hence, luminogens 2–4 were also AIE-active species. In addition, as shown in Fig. 5, the DFT calculations for the compounds 1–4 were performed. The calculated energy gaps (ΔE) of four compounds were 3.6178416 eV (compound 1), 3.276084 eV (compound 2), 3.3073755 eV (compound 3) and 3.0766347 eV (compound 4) respectively. Therefore, the various numbers and the various kinds of the substituents had slight effects on their molecular orbital energy levels of 1–4.Open in a separate windowFig. 2(a) Fluorescence spectra of the dilute solutions of compound 2 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different water contents (0–90%). Excitation wavelength = 365 nm. (b) Fluorescence images of 2 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different f_w values under 365 nm UV light.Open in a separate windowFig. 3(a) Fluorescence spectra of the dilute solutions of compound 3 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different water contents (0–90%). Excitation wavelength = 365 nm. (b) Fluorescence images of 3 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different f_w values under 365 nm UV light.Open in a separate windowFig. 4(a) Fluorescence spectra of the dilute solutions of compound 4 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different water contents (0–90%). Excitation wavelength = 365 nm. (b) Fluorescence images of 4 (2.0 × 10⁻⁵ mol L⁻¹) in DMF–water mixtures with different f_w values under 365 nm UV light.Open in a separate windowFig. 5(a) HOMO and LUMO frontier molecular orbitals of molecule 1 based on DFT (B3LYP/6-31G*) calculation. (b) HOMO and LUMO frontier molecular orbitals of molecule 2 based on DFT (B3LYP/6-31G*) calculation. (c) HOMO and LUMO frontier molecular orbitals of molecule 3 based on DFT (B3LYP/6-31G*) calculation. (d) HOMO and LUMO frontier molecular orbitals of molecule 4 based on DFT (B3LYP/6-31G*) calculation.Subsequently, the mechanochromic fluorescent behaviors of compounds 1–4 were surveyed by solid-state PL spectroscopy. As shown in Fig. 6, the as-synthesized powder sample 1 exhibited an emission band with a λ_max at 444 nm, corresponding to a blue fluorescence under 365 nm UV light. Intriguingly, a new blue-green light-emitting band with a λ_max at 507 nm was observed after the pristine solid sample was ground. After fuming with dichloromethane solvent vapor for 1 min, the blue-green fluorescence was converted back to the original blue fluorescence. Therefore, luminogen 1 exhibited reversible mechanochromic fluorescence feature. Furthermore, this reversible mechanofluorochromic conversion was repeated many times by grinding-exposure without showing signs of fatigue (Fig. 10).Open in a separate windowFig. 6(a) Solid-state PL spectra of compound 1 before grinding, after grinding, and after treatment with dichloromethane solvent vapor. Excitation wavelength: 365 nm. Photographic images of compound 1 under 365 nm UV light: (b) the as-synthesized powder sample. (c) The ground sample. (d) The sample after treatment with dichloromethane solvent vapor.Open in a separate windowFig. 10Repetitive experiment of mechanochromic behavior for compound 1.Similarly, as evident from Fig. 7–9, luminogens 2–4 also exhibited obvious mechanofluorochromic characteristics. Moreover, the repeatabilities of their mechanochromic behaviors were also satisfactory (Fig. S3^†). Hence, all the compounds 1–4 showed reversible mechanofluorochromic phenomena involving different fluorescent color changes, and the various numbers of the substituents could effectively influence the mechanofluorochromic behaviors of 1–4. Obviously, luminogen 3 or 4 after grinding exhibited more red-shifted fluorescence in comparison with that of the corresponding luminogen 1 or 2 after grinding.Open in a separate windowFig. 7(a) Solid-state PL spectra of compound 2 before grinding, after grinding, and after treatment with dichloromethane solvent vapor. Excitation wavelength: 365 nm. Photographic images of compound 2 under 365 nm UV light: (b) the as-synthesized powder sample. (c) The ground sample. (d) The sample after treatment with dichloromethane solvent vapor.Open in a separate windowFig. 8(a) Solid-state PL spectra of compound 3 before grinding, after grinding, and after treatment with dichloromethane solvent vapor. Excitation wavelength: 365 nm. Photographic images of compound 3 under 365 nm UV light: (b) the as-synthesized powder sample. (c) The ground sample. (d) The sample after treatment with dichloromethane solvent vapor.Open in a separate windowFig. 9(a) Solid-state PL spectra of compound 4 before grinding, after grinding, and after treatment with dichloromethane solvent vapor. Excitation wavelength: 365 nm. Photographic images of compound 4 under 365 nm UV light: (b) the as-synthesized powder sample. (c) The ground sample. (d) The sample after treatment with dichloromethane solvent vapor.In order to further explore the possible mechanism of mechanofluorochromism of 1–4, the powder X-ray diffraction (PXRD) measurements of various solid states of 1–4 were carried out. As depicted in Fig. 11, the pristine solid powder 1 showed many clear and intense reflection peaks, suggesting its crystalline phase. However, after the pristine powder sample was ground, the sharp and intense diffraction peaks vanished, which indicated the crystalline form was converted to the amorphous form. Interestingly, when the ground solid sample was fumigated with dichloromethane solvent vapor for 1 min, the corresponding sample powder exhibited the PXRD pattern of the initial crystalline form. Meanwhile, the structural transformations of the solid samples of 2–4 were similar to that of 1 (Fig. S4–S6^†). Obviously, the morphological changes of solid samples of 1–4 from crystalline state to amorphous state and vice versa could be attributed to the reversible mechanical switching in compounds 1–4, and the mechanofluorochromic phenomena observed in 1–4 were related to the morphological transition involving the ordered crystalline phase and the disordered amorphous phase.Open in a separate windowFig. 11XRD patterns of compound 1: unground, ground and after treatment with dichloromethane solvent vapor.Fortunately, single crystals of compounds 1 and 2 were obtained by slow diffusion of n-hexane into a trichloromethane solution containing small amounts of 1 or 2. As shown in Fig. 12 and ​and13,13, the molecular structures of 1 and 2 exhibited a twisted conformation due to the existence of tetraphenylethene unit. Meanwhile, some weak intermolecular interactions, such as C–H⋯π interaction (d = 2.866 Å) for 1, π⋯π interaction (d = 3.371 Å) for 1, C–H⋯S interaction (d = 2.977 Å) for 2, and π⋯π interaction (d = 3.189 Å) for 2, were observed. These weak intermolecular interactions gave rise to a loose packing motif of 1 or 2, which indicated their ordered crystal packings might readily collapse upon exposure to external mechanical stimulus. Therefore, their solid-state fluorescence could be adjusted by mechanical force.Open in a separate windowFig. 12The structural organization of compound 1.Open in a separate windowFig. 13The structural organization of compound 2.In summary, four fluorescent molecules containing thiophene and tetraphenylethene units were successfully designed and synthesized in this study. All these compounds showed obvious AIE characteristics. Furthermore, these luminogens emitted various fluorescence colors involving blue-green, green, yellow and orange in the aggregation state. Meanwhile, these luminogens basing on the same core structure also exhibited reversible mechanofluorochromic phenomena involving different fluorescent color changes. The results of this study will be beneficial for the exploitation of novel luminophors with full-color emission.     

Correction: Highly porous core–shell chitosan beads with superb immobilization efficiency for Lactobacillus reuteri 121 inulosucrase and production of inulin-type fructooligosaccharides

Correction for ‘Highly porous core–shell chitosan beads with superb immobilization efficiency for Lactobacillus reuteri 121 inulosucrase and production of inulin-type fructooligosaccharides’ by Thanapon Charoenwongpaiboon et al., RSC Adv., 2018, 8, 17008–17016.

The authors regret that Fig. 9 in the original article was displayed incorrectly. The correct version is shown below.Open in a separate windowFig. 9Batch reusability of INU-CSBs for IFOS synthesis. Reaction condition: 10 U mL⁻¹ of biocatalysts were incubated with 200 g L⁻¹ sucrose in acetate buffer pH 5.5, 40 °C and 2 h per batch.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Synthesis and characterization of AFe2O4 (A: Ni,Co, Mg)–silica nanocomposites and their application for the removal of dibenzothiophene (DBT) by an adsorption process: kinetics,isotherms and experimental design

Correction for ‘Synthesis and characterization of AFe₂O₄ (A: Ni, Co, Mg)–silica nanocomposites and their application for the removal of dibenzothiophene (DBT) by an adsorption process: kinetics, isotherms and experimental design’ by Fahimeh Vafaee et al., RSC Adv., 2021, 11, 22661–22676, https://doi.org/10.1039/D1RA02780H.

The authors regret an error in Fig. 4 where a section of the XRD for 4(a) and (b) is identical.Open in a separate windowFig. 4(a) The XRD pattern of sample 3 after adsorption of DBT. (b) The XRD pattern of sample 3 before adsorption of DBT.The authors have repeated the experiment and provided new data for Fig. 4. An independent expert has viewed the new data and has concluded that it is consistent with the discussions and conclusions presented. The correct Fig. 4 is shown below:The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: A novel biocompatible,simvastatin-loaded,bone-targeting lipid nanocarrier for treating osteoporosis more effectively

Correction for ‘A novel biocompatible, simvastatin-loaded, bone-targeting lipid nanocarrier for treating osteoporosis more effectively’ by Shan Tao et al., RSC Adv., 2020, 10, 20445–20459, DOI: 10.1039/D0RA00685H.

The authors regret that incorrect versions of Fig. 7, ​,99 and ​and1010 were included in the original article. The correct versions of Fig. 7, ​,99 and ​and1010 are presented below.Open in a separate windowFig. 7Histological analysis of organs from all experimental groups. H&E staining of heart, liver, spleen, lung, kidney, indicating the carrier has good biocompatibility. Scale bar = 50 μm.Open in a separate windowFig. 9Alkaline phosphatase (ALP) activity (arrows) and tartrate-resistant acid phosphatase (TRAP) assay results (arrowheads) of bone tissue sections. Scale bar = 50 μm. The ALP activity is much more high in SIM/LNPs and SIM/ASP₆-LNPs groups, while the TRAP activity is the opposite.Open in a separate windowFig. 10Histological assessment of bone formation in all experimental groups. (A) HE staining of femur bone. Scale bar = 50 μm. Histology of bone in the all experimental groups shows all ovariectomized groups had a higher amount of adipose tissue than Sham group. The trabecular bone is much more prominent in SIM/LNPs and SIM/ASP₆-LNPs groups. (B) Immunohistochemical staining for BMP-2 in typical newly-formed bone tissue (red arrows) and immunohistochemical staining for the osteogenic markers osteopontin (OPN, arrows) and osteocalcin (OCN, arrowheads). Scale bar = 50 μm. The BMP-2, OPN, OCN are much more prominent in SIM/LNPs and SIM/ASP₆-LNPs groups.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Improving the inhibitory effect of CXCR4 peptide antagonist in tumor metastasis with an acetylated PAMAM dendrimer

Correction for ‘Improving the inhibitory effect of CXCR4 peptide antagonist in tumor metastasis with an acetylated PAMAM dendrimer’ by Changliang Liu et al., RSC Adv., 2018, 8, 39948–39956.

The authors regret that the term “CXCL12” was incorrectly displayed as “CXCR12” in Scheme 1 and Fig. 6(a)–(c) in the original article. The correct versions of Scheme 1 and Fig. 6(a)–(c) are presented below.Open in a separate windowScheme 1Schematic illustration of the preparation of the P_AC80–E5 complex and the process of anti-tumor metastasis of the E5 peptide in the presence of P_AC80.Open in a separate windowFig. 6(a–c) The inhibitory effect of E5 and P_AC80–E5 on: (a) MCF-7; (b) MDA-MB-231; and (c) 4T1 cells detected by transwell assay. The CXCL12 supplemented sample without E5 or P_AC80–E5 was set as 100% as the control. Error bars represent the standard deviation (n = 3).The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: A guanidyl-functionalized TiO2 nanoparticle-anchored graphene nanohybrid for enhanced capture of phosphopeptides

Correction for ‘A guanidyl-functionalized TiO₂ nanoparticle-anchored graphene nanohybrid for enhanced capture of phosphopeptides’ by Hailong Liu et al., RSC Adv., 2018, 8, 29476–29481.

The authors regret that there was an error in Fig. 3 of the original article, as the three parts of the figure were labelled incorrectly. The correct version of Fig. 3 is presented below.Open in a separate windowFig. 1MALDI-TOF mass spectra of tryptic digests of β-casein: (a) direct analysis and after enriched by (b) GF-TiO₂–GO and (c) TiO₂ (# dephosphorylated fragment).The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Ascorbic acid/Fe0 composites as an effective persulfate activator for improving the degradation of rhodamine B

Correction for ‘Ascorbic acid/Fe⁰ composites as an effective persulfate activator for improving the degradation of rhodamine B’ by Xiangyu Wang et al., RSC Adv., 2018, 8, 12791–12798.

The authors regret that the unit on the x-axis of Fig. 1 was incorrectly written as “% wt” rather than “‰ wt” in the original article. The correct version of Fig. 1 is presented below.Open in a separate windowFig. 1(a) Comparison of removal efficiency of RhB in different systems (C₀ = 50 mg L⁻¹, PS dosage = 1.4 g L⁻¹, Fe⁰ dosage = 1 g L⁻¹, H₂A/Fe⁰ dosage = 1 g L⁻¹, H₂A dosage = 1.6 g L⁻¹ and T = 298 K); (b) effect of H₂A concentration on removal efficiency of RhB in the H₂A/Fe⁰–PS system (C₀ = 50 mg L⁻¹, Fe⁰ dosage = 0.8 g L⁻¹, T = 298 K and the solution volume is 50 mL).The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Preparation of glycerol monostearate from glycerol carbonate and stearic acid

Correction for ‘Preparation of glycerol monostearate from glycerol carbonate and stearic acid’ by Li Han et al., RSC Adv., 2016, 6, 34137–34145.

The authors regret that Fig. 6 in the original article was incorrect. The caption referred to ¹³C NMR spectra, whereas the figure itself was an expanded version of the ¹H NMR shown in Fig. 5. The correct version of Fig. 6 is presented below.Open in a separate windowFig. 6 ¹³C NMR spectra of GMS.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

A julolidine-fused anthracene derivative: synthesis,photophysical properties,and oxidative dimerization

We describe the synthesis and characterization of a julolidine-fused anthracene derivative J-A, which exhibits a maximum absorption of 450 nm and a maximum emission of 518 nm. The fluorescent quantum yield was determined to be 0.55 in toluene. J-A dimerizes in solution via oxidative coupling. Structure of the dimer was characterized using single crystal X-ray diffraction.

A julolidine fused anthracene derivative with unique photophysical and redox properties was presented.

Julolidine¹ is a popular structural subunit in various fluorescent dyes (Chart 1).² The restricted motion and strong electron-donating capability of the fused julolidine moiety are quite effective for improving the photophysical properties. For instance, julolidine-fused fluorophores normally display desirable photophysical characteristics, such as high quantum yield, red-shifted absorption and emission, and good photostability. Recently, julolidine derivatives have been widely exploited in various applications such as sensing,³ imaging,⁴ and nonlinear optical materials.⁵ Several julolidine dyes have been used in dye-sensitized solar cells due to their large π-conjugated system and the promising electron donating property.⁶Open in a separate windowChart 1The structure of julolidine, J-A and DAA.In this paper, we report a julolidine-fused anthracene derivative J-A, which exhibits attractive photophysical properties not observed in DAA, a dimethyl-amino substituted analogue. Both the absorption and emission of J-A show a dramatic red-shift (ca. 74 and 131 nm, respectively), compared with the unmodified anthracene (Fig. 2). The fluorescence quantum yield of J-A was determined to be 0.55 in toluene, while the emission of DAA was completely quenched. The observed spectral properties were rationalized by DFT calculations. In addition, we found that J-A was stable in the solid state, but reactive in solution. J-A dimer was formed through oxidative coupling at the para-position of the N-atom in a dichloromethane solution under air atmosphere. The structure of the dimerized product was characterized using single crystal X-ray diffraction, which unambiguously reveals the structural feature of the julolidine-fused anthracene compound. Preparation of J-A is shown in Scheme 1. Detailed synthesis and characterizations are provided in the ESI.^†Open in a separate windowScheme 1Synthetic route of J-A.Open in a separate windowFig. 2(A) Absorption spectra of J-A, AN, and DAA (1 × 10⁻⁴ mol L⁻¹ in dichloromethane); (B) emission spectra of J-A, AN, and DAA (1 × 10⁻⁵ mol L⁻¹ in dichloromethane). Excitation wavelength: 350 nm. 1 cm cuvette was used in both of the experiments. Inset: visualized fluorescence in solution was shown. ¹H-NMR signals of J-A shift to the high-field significantly, compared with DAA (Fig. 1), which indicates that the fused structure of J-A facilitates electron delocalization from the nitrogen atom to the anthracene moiety, and thus resulting in a stronger shielding effect. In the case of DAA, however, electron delocalization from the dimethyl amino group to the anthracene core is essentially inhibited due to steric hindrance, which will explain the fact that it displays a spectral feature similar to that of the unmodified anthracene.Open in a separate windowFig. 1Comparison of the ¹H-NMR spectrum between J-A and DAA in CDCl₃. Partial resonance signals in aromatic region are shown.Fusing with julolidine will exert significant effects on the photophysical properties of anthracene. The absorption and fluorescence spectra of J-A, DAA, and anthracene are shown in Fig. 2. The maximum absorption of J-A is 450 nm, which displays a red-shift of about 70 nm compared with the unmodified anthracene. J-A emits green light (^maxλ_em = 518 nm, Φ = 0.55), while anthracene emits blue light (^maxλ_em = 380 nm, Φ = 0.22). In contrast, the absorption of DAA essentially overlaps with that of anthracene, with only a minor red shift of ca. 10 nm, but its fluorescence is quenched significantly (Fig. 2). This spectral feature indicates that the dimethyl amino group is electronically separated from the anthracene moiety in the ground state, a result in good accordance with the ¹H-NMR data shown above. The quenched fluorescence of DAA may result from the photo-induced electron transfer⁷ from the lone pair of the nitrogen atom to the anthracene moiety in the excited state.The observed photophysical properties of J-A were reproduced by DFT calculations. The HOMO and LUMO orbitals are evenly distributed over the anthracene moiety and the N-atom in the julolidine, indicating the existence of a conjugated structure. The HOMO–LUMO transition (f = 0.10) corresponds to the absorption band at 450 nm. The sharper absorption at 390 nm can be assigned to the HOMO to LUMO + 1 transition. In contrast, the HOMO and LUMO orbitals of DAA resemble those of anthracene, because the dimethyl-amino group is orthogonal to the conjugated π-system (Fig. 3).Open in a separate windowFig. 3Molecular orbitals of J-A and DAA calculated at the B3LYP/6-31G(d) level of theory (iso value = 0.02). Orbital energies were given in parentheses. Excitation energies were computed by TD-DFT at the same level. Values in parentheses represent the oscillator strengths (f).J-A is stable in the solid state, but reactive in solution. The cyclic voltammetry (CV) diagram of J-A shows an irreversible oxidation potential at 0.007 V (vs. Fc/Fc⁺), indicating that J-A is easy to be oxidized (Fig. S3^†). Single crystals suitable for X-ray diffraction study were obtained by slow evaporation of a dichloromethane solution of J-A under air atmosphere. To our surprise, instead of J-A, X-ray data discloses the formation of a dimeric product (Scheme 2) of J-A. We hypothesized that the dimeric compound 5 formed via oxidative coupling reaction, a mechanism well-documented for the dimerization of the dimethylaniline compounds.⁸ The ¹H-NMR spectrum of 5 is distinct from that of J-A. All protons of the anthracene part (b′–d′) appear as a group of multiplet resonance signals (6.93–7.04 ppm) (Scheme 2). In addition, mass spectrometric analysis indicates that two hydrogen atoms were removed after the dimerization of J-A. Compound 5 exhibits a maximum absorption at 460 nm and a very weak emission (^maxλ_em = 530 nm, Φ = 0.03, Fig. S1^†). Two quasi-reversible oxidation waves were identified in the CV diagram of 5 at −0.010 V and 0.135 V (vs. Fc/Fc⁺), respectively (Fig. S5^†).Open in a separate windowScheme 2Oxidative dimerization of J-A. Inset: partial ¹H-NMR of 5 is shown.X-ray structure of 5 is shown in Fig. 4. The two connected anthracene planes are found to be orthogonal to each other with a dihedral angle of 90.17°, as a result of steric repulsion. Specifically, the bond length of N–C3 is 1.389 Å, which is similar to those of the other reported julolidine compounds (1.359–1.393 Å), while significantly shorter than that of the dimethyl-amino anthracene (1.433 Å).⁹ This result testifies the presence of electron delocalization between the fused julolidine nitrogen and the anthracene π-plane, which is in good agreement with the DFT calculations (Fig. 3). However, the two anthracene π-planes connected by the single bond (C4–C5, 1.489 Å) might not exhibit electron delocalization because of the orthogonal conformation. The fused julolidine ring-i and -ii are symmetric to each other, and both of them adopt an “envelope” conformation. The fused julolidine is nonplanar (bond angle, C3–N–C2, 115.73°, C3–N–C1, 115.92°, C1–N–C2, 113.81°). 5 is closely packed in the crystal (Fig. 4B), and no intercalated solvent molecules were observed. The closest distance between two adjacent anthracene planes is 3.922 Å, indicating a weak π–π stacking. Detailed crystal data are summarized in Table S5.^†Open in a separate windowFig. 4(A) Single crystal X-ray structure of 5. (B) View along a-axis.In summary, we report the synthesis and characterizations of a julolidine-fused anthracene derivative J-A, which demonstrates significantly red-shifted absorption (^maxλ_ab = 450 nm) and emission (^maxλ_em = 518 nm, Φ = 0.55), compared with the unmodified anthracene. The photophysical properties of J-A also contrast dramatically with a dimethyl-amino analogue DAA, which were rationalized by DFT calculations. In addition, J-A could be transformed into 5, a dimeric product, whose single crystal X-ray structure unambiguously confirmed the structural feature of the julolidine-fused anthracene.     

Correction: An indenocarbazole-based host material for solution processable green phosphorescent organic light emitting diodes

Correction for ‘An indenocarbazole-based host material for solution processable green phosphorescent organic light emitting diodes’ by Eun Young Park et al., RSC Adv., 2021, 11, 29115–29123. DOI: 10.1039/D1RA04855D.

The authors regret that an incorrect version of Fig. 1 was included in the original article. The correct version of Fig. 1 is presented below.Open in a separate windowFig. 1HOMO, LUMO distributions and energy level of PCIC predicted through DFT and TD-DFT calculations.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.