Retraction: Fabrication of hollow CoS1.097 prisms toward supercapactior performance

Retraction of ‘Fabrication of hollow CoS_1.097 prisms toward supercapactior performance’ by Ruili Zhang et al., RSC Adv., 2019, 9, 10814–10819.

We, the named authors, hereby wholly retract this RSC Advances article due to extensive overlap with the text, data and figures published in ref. 1, which means that this RSC Advances article is redundant. All the figures and tables in this RSC Advances article have been reproduced from ref. 1.The authors would like to apologise for any inconvenience to readers.Signed: Ruili Zhang and Ping Yang.Date: 8^th July 2019.We do not have current contact details for the second author of the article, Yuntao Yang, as he has graduated and therefore has not been able to comment on the retraction.Retraction endorsed by Andrew Shore, Executive Editor, RSC Advances.     

Correction: Direct electrodeposition of cationic pillar[6]arene-modified graphene oxide composite films and their host–guest inclusions for enhanced electrochemical performance

Correction for ‘Direct electrodeposition of cationic pillar[6]arene-modified graphene oxide composite films and their host–guest inclusions for enhanced electrochemical performance’ by Qunpeng Duan et al., RSC Adv., 2020, 10, 21954–21962, DOI: 10.1039/D0RA03138K.

The authors regret omitting a citation of their related paper published in Frontiers in Chemistry: ‘Facile one-step electrodeposition preparation of cationic pillar[6]arene-modified graphene films on glassy carbon electrodes for enhanced electrochemical performance’ (DOI: 10.3389/fchem.2020.00430) shown as ref. 1 here. The citation should appear as ref. 58 in the original article.¹The authors regret that it was not clear in the original article that the ErGO-CP6/GCE film had been previously reported by them in their related Frontiers in Chemistry paper¹ and therefore the sentence at the start of paragraph 3 on page 2 ‘In this work, we report for the first time preparation of CP6 functionalized graphene films on glassy carbon electrode (GCE) directly from GO-CP6 dispersions by facile one-step pulsed electrodeposition technique (Scheme 1).’ should be ‘In this work, we report the preparation of CP6 functionalized graphene films on glassy carbon electrode (GCE) directly from GO-CP6 dispersions by facile one-step pulsed electrodeposition technique (Scheme 1), which was previously reported by us.⁵⁸’.The authors also wish to clarify the differences between this RSC Advances paper and the Frontiers in Chemistry paper.¹ The papers use different guests molecules and different optimum pulse electrodeposition parameters and the RSC Advances paper reports an improvement in electrochemical performance with additional characterisation, stability studies and the analysis of real samples which are not reported in the Frontiers in Chemistry paper.¹The appropriate figure captions have been updated to reflect the data reproduced from the Frontiers in Chemistry paper.¹Scheme 1 Schematic illustration for the pulsed electrodeposition preparation of ErGO and ErGO-CP6 films on the surface of GCE and sensing the guest molecules by an electrochemical strategy. Reproduced with permission from ref. 1. Copyright 2020 Frontiers.Fig. 1 Characterization of materials. FTIR spectra (A), UV-vis absorption spectra (B), TGA curves of CP6, GO-CP6, and GO (C), and XPS survey spectra of GO and GO-CP6 (D). The data in (a, c and d) have been reproduced with permission from ref. 1. Copyright 2020 Frontiers.Fig. 4 (A) Raman spectra of GO and ErGO. (B) Raman spectra of GOCP6 and ErGO-CP6. Reproduced with permission from ref. 1. Copyright 2020 Frontiers.     

Retraction: Ligustrazine attenuates renal damage by inhibiting endoplasmic reticulum stress in diabetic nephropathy by inactivating MAPK pathways

Retraction of ‘Ligustrazine attenuates renal damage by inhibiting endoplasmic reticulum stress in diabetic nephropathy by inactivating MAPK pathways’ by Hongling Yang et al., RSC Adv., 2018, 8, 21816–21822, DOI: 10.1039/C8RA01674G.

The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data.The images in the article were screened by an image integrity expert who confirmed that some of the western blot images in this paper had been duplicated in other articles. There are no common authors between the papers.The control bands (GAPDH) in Fig. 3A of this paper are identical to the western blot control bands (GAPDH) presented in Fig. 1E of ref. 1.The control bands (GAPDH) in Fig. 4A of this paper are identical to the western blot control bands (GAPDH) presented in Fig. 2C and Fig. 4G of ref. 2.One of the blots in the control band (GAPDH) in Fig. 4A has also been reused as a blot in Fig. 3D of ref. 3.The authors were asked to provide the raw data for this article but did not respond. Given the significance of the concerns about the validity of the data, and the lack of raw data, the findings presented in this paper are not reliable.The authors have been informed but have not responded to any correspondence regarding the retraction.Signed: Laura Fisher, Executive Editor, RSC Advances.Date: 7^th January 2021.     

Retraction: Synthesis and characterization of Co/Ti layered double hydroxide and its application as a photocatalyst for degradation of aqueous Congo Red

Retraction of ‘Synthesis and characterization of Co/Ti layered double hydroxide and its application as a photocatalyst for degradation of aqueous Congo Red’ by Priyadarshi Roy Chowdhury and Krishna G. Bhattacharyya, RSC Adv., 2015, 5, 92189–92206.

The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data in the published article.The XPS data in Fig. 4B, E and F have been duplicated in another publication, but reported as a different material.¹A repeating segment can be observed in the TEM image presented in Fig. 10C, which indicates that this image has been manipulated.There are unexpected similarities in the baseline of the EDX spectrum in Fig. 10F and the EDX spectra in other publications, which have all been reported as different materials.^1–3There are repeating motifs within the AFM image in Fig. 10G, which indicates that this image has been manipulated. Many of these motifs can also be observed in an AFM image in another publication, but representing a different material.²The image in Fig. 10I is unreliable as it has subsequently been reused in unpublished material to represent different materials.The FTIR data presented in Fig. 16B (blue, red and green spectra) illustrate duplication of data, given that these experiments were reported under different reaction conditions.Given the number and significance of the concerns about the validity of the data, the findings presented in this paper are no longer reliable.Priyadarshi Roy Chowdhury and Krishna G. Bhattacharyya were informed about the retraction of the article but did not respond.Signed: Laura Fisher, Executive Editor, RSC AdvancesDate: 12^th March 2020     

Correction: Nano N-TiO2 mediated selective photocatalytic synthesis of quinaldines from nitrobenzenes

Correction for ‘Nano N-TiO₂ mediated selective photocatalytic synthesis of quinaldines from nitrobenzenes’ by Kaliyamoorthy Selvam et al., RSC Adv., 2012, 2, 2848–2855, DOI: 10.1039/C2RA01178F.

The authors regret omitting citations of their related papers in Journal of Molecular Catalysis A: Chemical and Applied Catalysis A: General: ‘Cost effective one-pot photocatalytic synthesis of quinaldines from nitroarenes by silver loaded TiO₂’ (DOI: 10.1016/j.molcata.2011.09.014)¹ and ‘Mesoporous nitrogen doped nano titania—A green photocatalyst for the effective reductive cleavage of azoxybenzenes to amines or 2-phenyl indazoles in methanol’ (DOI: 10.1016/j.apcata.2011.11.011).² The citations should have appeared in the following places as ref. 36 (ref. 1, in the reference list here) and ref. 37 (ref. 2, in the reference list here):In the sentence starting on line 5 of paragraph 5 in the introduction:‘Photocatalytic synthesis of quinolone derivatives from nitrobenzene using TiO₂, metal doped TiO₂ and others had been reported earlier.^1,23–25’At the end of Section 3.12 with the addition of the following sentence:‘This catalyst was also found to be effective for the reductive cleavage of azoxybenzenes to amines or 2-phenyl indazoles in methanol.²’The authors regret that it was not clear in the original article that the bare TiO₂ and N-TiO₂ characterisation data had been reproduced from their related Journal of Molecular Catalysis A: Chemical, Applied Catalysis A: General and Catalysis Communications papers.^1–3 Although the Catalysis Communications article was cited as ref. 25 (ref. 3, in the reference list here) in the original article, it was not made clear that some of the data was reproduced from this article. The appropriate figure captions have been updated to reflect this.Fig. 2: Diffuse reflectance spectra of (a) bare TiO₂, (b) N-TiO₂ and (c) TiO₂-P25. The bare TiO₂ data in Fig. 2a have been reproduced with permission from ref. 1. Copyright 2011 Elsevier. The N-TiO₂ data in Fig. 2b have been reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 3: Photoluminescence spectra of (a) bare TiO₂, (b) TiO₂-P25 and (c) N-TiO₂. The bare TiO₂ data in Fig. 3a have been reproduced with permission from ref. 1. Copyright 2011 Elsevier. The N-TiO₂ data in Fig. 3c have been reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 4: HR-TEM analysis: (a and b) images at two different regions of N-TiO₂, (c) SAED pattern of N-TiO₂, (d) lattice fringes of N-TiO₂ and (e) particle size distribution of N-TiO₂. Fig. 4 has been entirely reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 5: X-ray photoelectron spectra of N-TiO₂: (a) survey spectrum, (b) Ti 2p peak, (c) O 1s peak, (d) N 1s peak and (e) C peak. Fig. 5 has been entirely reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 6: (a) N₂ adsorption–desorption isotherms of N-TiO₂ and (b) its pore size distribution. Fig. 6 has been entirely reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 8: GC-MS chromatograms at different reaction times for the photocatalytic conversion of nitrobenzene with N-TiO₂. Fig. 8 has been entirely reproduced with permission from ref. 3. Copyright 2011 Elsevier.The authors also wish to remove Fig. 1 from the original article due to similarities between two of the spectra and the raw data no longer being available. This does not affect the conclusions as the presence of nitrogen was confirmed by other techniques.The authors also wish to clarify the differences between this RSC Advances paper and the Journal of Molecular Catalysis A: Chemical, Applied Catalysis A: General and Catalysis Communications papers.^1–3 The Journal of Molecular Catalysis A: Chemical paper discusses the photocatalytic synthesis of quinaldines from nitroarenes by silver loaded TiO₂.¹ The Applied Catalysis A: General paper reports the reductive cleavage of azoxybenzenes to amines or 2-phenyl indazoles using mesoporous nitrogen doped nano titania.² The Catalysis Communications paper, ref. 25 in the original article, discusses the synthesis of quinaldines from nitroarenes with gold loaded TiO₂ nanoparticles.³ The original RSC Advances paper discusses the catalytic ability of N-TiO₂ in the synthesis of quinaldines from nitrobenzenes. In each paper, either a different catalyst was used or a different synthetic reaction was investigated.     

Retraction: Synthesis of non-toxic,biocompatible, and colloidal stable silver nanoparticle using egg-white protein as capping and reducing agents for sustainable antibacterial application

Retraction of ‘Synthesis of non-toxic, biocompatible, and colloidal stable silver nanoparticle using egg-white protein as capping and reducing agents for sustainable antibacterial application’ by Kalaiyarasan Thiyagarajan et al., RSC Adv., 2018, 8, 23213–23229, https://doi.org/10.1039/C8RA03649G.

I, the undersigned author, hereby wholly retract this RSC Advances article due to the following instances of matched/similar images that have been identified that weaken this article, which occurred due to honest human errors.Following the previous publication of a correction to replace Fig. 3D, instances of duplicating images have been identified that undermine this article.In Fig. 5, the panels E. coli MTCC No 62 6 μg ml⁻¹ and E. coli MTCC No 62 8 μg ml⁻¹ are identical. Furthermore, they are identical to panels in another article published by the authors in RSC Advances,¹ namely the panel for freshly prepared S. enterica MTCC-3219 2 μg ml⁻¹ 10⁻¹⁰ and the panel for S. typhirmurium MTCC-3224 4 μg ml⁻¹ 10⁻⁵ after one year of storage in Fig. 3 of ref. 1 and the panel 1 h treated with SBT@AgNPs in Fig. 7 of ref. 1.Thiyagarajan Kalaiyarasan and Vijay K. Bharti responded to all enquiries and submitted data related to the above concern. However, to avoid any future ambiguity to the readers, the article is retracted.Krishna Kumar and Vijay K. Bharti do not agree to the retraction. The other authors have been informed but have not responded to any correspondence regarding the retraction.Signed: Kalaiyarasan ThiyagarajanDate: 1/6/2022Retraction endorsed by Laura Fisher, Executive Editor, RSC Advances     

Retraction: Structural characterization of centipede oligopeptides and capability detection in human small cell lung carcinoma: inducing apoptosis

Retraction of ‘Structural characterization of centipede oligopeptides and capability detection in human small cell lung carcinoma: inducing apoptosis’ by JingQuan Zhao et al., RSC Adv., 2019, 9, 10927–10936, https://doi.org/10.1039/C8RA09018A.

The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to a significant amount of unattributed text overlap throughout the article, and particularly with ref. 1 in the Results and discussion section and ref. 2 in the Conclusion section.Jie Liu opposes the retraction. The other authors have been informed but have not responded to any correspondence regarding the retraction.Signed: Laura Fisher, Executive Editor, RSC AdvancesDate: 29^th March 2022     

Retraction: Amino acid derived highly luminescent,heteroatom-doped carbon dots for label-free detection of Cd2+/Fe3+, cell imaging and enhanced antibacterial activity

Retraction of ‘Amino acid derived highly luminescent, heteroatom-doped carbon dots for label-free detection of Cd²⁺/Fe³⁺, cell imaging and enhanced antibacterial activity’ by Paramita Karfa et al., RSC Adv., 2015, 5, 58141–58153.

The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data in the published article.A repeating pattern can be observed in the XPS spectra in Fig. 2C in the 390–396 eV range. The XPS data also duplicates data that was presented in another publication, but reported as a different material.¹The TEM image in Fig. 3A has been used in another publication, but reported as a different material.²The bacterial growth curves in Fig. 3F illustrate duplication of data, which were reported as different bacterial strains. The growth curves also duplicate data presented in other publications.^3,4The fluorescence microscopy images in Fig. 5A and B have been used in another publication, but reported as different materials.⁵The concentration stability data points in Fig. S2 have been duplicated in Fig. S3 as pH stability data points.Given the number and significance of the concerns, the validity of the data and, therefore, the conclusions presented in this paper are no longer reliable.The Royal Society of Chemistry apologises for the fact that these concerns were not identified during the peer review process.Paramita Karfa, Santanu Patra, Rashmi Madhuri and Prashant K. Sharma oppose the retraction. Ekta Roy, Sunil Kumar and Abhrajyoti Tarafdar were contacted but did not respond.Signed: Andrew Shore, Executive Editor, RSC Advances.Date: 23rd November 2018.     

Retraction: Salvianolic acid B inhibits inflammatory response and cell apoptosis via the PI3K/Akt signaling pathway in IL-1β-induced osteoarthritis chondrocytes

Retraction of ‘Salvianolic acid B inhibits inflammatory response and cell apoptosis via the PI3K/Akt signalling pathway in IL-1β-induced osteoarthritis chondrocytes’ by Bin Zhu et al., RSC Adv., 2018, 8, 36422–36429, DOI: 10.1039/C8RA02418A.

The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data.The images in the article were screened by an image integrity expert who confirmed that some of the western blots images in this paper had been duplicated in other articles. There are no common authors between the papers.The Col II band in Fig. 3B of this paper has been duplicated as the p62 band in Fig. 4A of ref. 1.One of the blots in the control band (GAPDH) in Fig. 3D has also been reused as a blot in Fig. 2C of ref. 1 and in Fig. 4A of ref. 2.The authors were asked to provide the raw data for this article but did not respond. Given the significance of the concerns about the validity of the data, and the lack of raw data, the findings presented in this paper are not reliable.The authors have been informed but have not responded to any correspondence regarding the retraction.Signed: Laura Fisher, Executive Editor, RSC AdvancesDate: 7^th January 2021     

Retraction: Magnetic Fe3O4@NiO hierarchical structures: preparation and their excellent As(v) and Cr(vi) removal capabilities

Retraction of ‘Magnetic Fe₃O₄@NiO hierarchical structures: preparation and their excellent As(v) and Cr(vi) removal capabilities’ by Shouwei Zhang et al., RSC Adv., 2013, 3, 2754–2764, DOI: 10.1039/C2RA22495J.

The Royal Society of Chemistry, with the agreement of the named authors, hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data in the published article. The authors requested to retract this article because they admitted that the TEM characterization of the Fe₃O₄@NiO hierarchical microspheres in Fig. 4c was duplicated from the characterization of Fe₃O₄@NiAl-LDH microspheres in Fig. S4B from a J. Am. Chem. Soc. paper by Mingfei Shao et al. without permission.¹ The authors would like to apologise to the authors of ref. 1, and for any inconvenience to readers.Signed: Shouwei Zhang, Jiaxing Li, Jinzhang Xu and Xiangke WangDate: 11th August 2021Tao Wen was contacted but did not respondRetraction endorsed by Laura Fisher, Executive Editor, RSC Advances     

Correction: Improved lateral heat spreading performance for polyvinylidene fluoride composite film comprising silver nanowire in light-emitting diode

Correction for ‘Improved lateral heat spreading performance for polyvinylidene fluoride composite film comprising silver nanowire in light-emitting diode’ by Zhao Li et al., RSC Adv., 2016, 6, 35844–35891.

The authors wish to apologise to the readers and draw their attention to our closely related paper, published in Journal of Applied Polymer Science,¹ which should have been cited in this RSC Advances paper.In the RSC Advances paper, we report a lateral heat spreader film fabricated by silver nanowire (AgNW) and polyvinylidene fluoride (PVDF) film via a bar-coating approach. In order to distinguish the composite film in this paper from that in our previous work,¹ we are renaming the composite film as “AgNW@AgNW/PVDF”, which indicated that AgNW was coated on the AgNW/PVDF film. In this work, the results come from the AgNW@AgNW/PVDF composite film, while in our previous work,¹ they come from the AgNW/PVDF film, which are fundamentally different. In ref. 1, we used AgNW as an additive to a PVDF/DMF precursor, and then synthesized a AgNW/PVDF composite film for heating transfer. The work focused on the improvement of the thermal conductivity of the film; however, its application was never mentioned.In this paper, AgNW was added into PVDF as an additive, but it was also coated on the surface of the AgNW/PVDF film by a bar-coating approach. Thus, this work can promote the thermal conductivity from inside and outside due to the high thermal conductivity of AgNW. Additionally, we set up a temperature monitoring system using the infrared imager, which can capture the temperature image while the composite film is being heated. We compared experimental with theoretical analysis by simulation (ANSYS Icepak) of the physical process, and they matched very well. Finally, the AgNW@AgNW/PVDF composite film was used as a lateral heat spreader in a LED device that we devised. The good result obtained from detecting the temperature of the LED by thermometer showed its excellent heat dissipation performance.In addition to the lacking citation to the Journal of Applied Polymer Science paper, the authors also regret that there is unattributed overlap in text and Fig. 1, 3a, c, 4, 6b and c between this RSC Advances paper and ref. 1. The figures were reproduced from ref. 1 for the readers’ information.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Correction: Porous conducting polymer and reduced graphene oxide nanocomposites for room temperature gas detection

Correction for ‘Porous conducting polymer and reduced graphene oxide nanocomposites for room temperature gas detection’ by Yajie Yang et al., RSC Adv., 2014, 4, 42546–42553.

The authors wish to draw the reader’s attention to their previous related study, published in ACS Applied Materials & Interfaces,¹ which was not cited in this RSC Advances paper. The RSC Advances paper is a valuable and necessary supplement to the publication in ACS Applied Materials & Interfaces and focused on the reduced gas sensing performance of the devices instead of film characterization and film conductive performance.The authors regret not giving correct attribution to Fig. 1–6 which duplicate data from ref. 1 and therefore should be attributed to that paper. Additionally, there are portions of overlapping text in the discussion of these figures and the Introduction and Conclusion sections of the RSC Advances paper, which should be attributed to ref. 1.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Retraction: A rapid and novel method for the synthesis of 5-substituted 1H-tetrazole catalyzed by exceptional reusable monodisperse Pt NPs@AC under the microwave irradiation

Retraction for ‘A rapid and novel method for the synthesis of 5-substituted 1H-tetrazole catalyzed by exceptional reusable monodisperse Pt NPs@AC under the microwave irradiation’ by Esma Erken et al., RSC Adv., 2015, 5, 68558–68564, DOI: 10.1039/C5RA11426H.

Muharrem Kaya and İbrahim Esirden hereby wholly retract this RSC Advances article due to concerns with the reliability of the data in the published article.The high-resolution transmission electron micrograph inset in Fig. 2 that represents Md-Pt NPs@AC is the same as Fig. 2c in a Chemistry Select article by Haydar Göksu, Betül Çelik, Yunus Yıldız, Fatih Şen and Benan Kılbaş,¹ which is a high-resolution transmission electron micrograph representing a CoPd NP. Fatih Sen provided replacement data for consideration. However, an expert reviewed the author’s response and concluded that it did not satisfactorily address the concerns, and that the replacement figure did not fully support the conclusions. Given the significance of the concerns about the validity of the data, the findings presented in this paper are no longer reliable.Muharrem Kaya approves the retraction of this article due to concerns with the structural characterisation of the catalyst and therefore the conclusions presented may not be valid. Muharrem Kaya also states that the figures under question are out of their expertise and that they did not contribute to the data collection or processing of these figures. Muharrem Kaya contributed to the evaluation of the catalytic performances of the composite materials only.Fatih Sen opposes this retraction. Esma Erken was contacted but did not respond.Signed: Muharrem Kaya and İbrahim EsirdenDate: 23^rd September 2021Retraction endorsed by Laura Fisher, Executive Editor, RSC Advances     

Correction: A review on fluorescent inorganic nanoparticles for optical sensing applications

Correction for ‘A review on fluorescent inorganic nanoparticles for optical sensing applications’ by Sing Muk Ng et al., RSC Adv., 2016, 6, 21624–21661.

This correction is being published to alert readers that Fig. 9, 19 and 21 have been reproduced from a Sensors and Actuators B: Chemical article, which has now been retracted. The article was cited as ref. 16 in this RSC Advances paper. The retraction notice of the Sensors and Actuators B: Chemical article,¹ states that “this article reports a TEM image of the MAA capped CdS QDs (Fig. 2) which shows clear signs of manipulation (copy-pasting of the particles)”. Fig. 2 of the Sensors and Actuators B: Chemical article was reproduced in this RSC Advances article as Fig. 9.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Retraction: Tuning the chemistry of graphene oxides by a sonochemical approach: application of adsorption properties

Retraction of ‘Tuning the chemistry of graphene oxides by a sonochemical approach: application of adsorption properties’ by Yubing Sun et al., RSC Adv., 2015, 5, 24886–24892, DOI: 10.1039/C5RA02021B.

The Royal Society of Chemistry, with the agreement of the named authors, hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data in the published article.The TEM image in Fig. 1B duplicates data published in another publication by Pan et al., but presented as different materials.¹The AFM images in Fig. 1C and D illustrate duplication of data, given that these experiments were reported under different reaction conditions.The EXAFS spectra in Fig. 4 duplicate data in another publication, but reported as different materials.²Given the number and significance of the concerns about the validity of the data, the findings presented in this paper are no longer reliable.Signed: Yubing Sun, Shubin Yang, Congcong Ding and Wencai ChengDate: 27^th March 2020Zhongxiu Jin was contacted but did not respond.Retraction endorsed by Laura Fisher, Executive Editor, RSC Advances     

E–Z isomerization of 3-benzylidene-indolin-2-ones using a microfluidic photo-reactor

Here, we report controlled E–Z isomeric motion of the functionalized 3-benzylidene-indolin-2-ones under various solvents, temperature, light sources, and most importantly effective enhancement of light irradiance in microfluidic photoreactor conditions. Stabilization of the E–Z isomeric motion is failed in batch process, which might be due to the exponential decay of light intensity, variable irradiation, low mixing, low heat exchange, low photon flux etc. This photo-μ-flow light driven motion is further extended to the establishment of a photostationary state under solar light irradiation.

(E)-3-Benzylidene-indolin-2-ones were efficiently converted to their corresponding (Z) -isomers at low temperature in the presence of light.

Functionalized 3-benzylidene-indolin-2-ones are an important structural motif in organic chemistry and are embedded in many naturally occurring compounds.¹ They found wide applications in molecular-motors,² energy harvesting dyes,³ pharmaceutical chemistry (sunitinib, tenidap),⁴ protein kinase inhibitors,⁵ pesticides,⁶ flavors,⁷ and the fragrance industry.⁸ In the last few decades, numerous protocols have been developed for the synthesis of novel indolin-2-ones. For instance, palladium (Pd)-catalysed intramolecular hydroarylation of N-arylpropiolamides,⁹ Knoevenagel condensation of oxindole and aldehyde,¹⁰ two-step protocols such as Ni-catalyzed CO₂ insertion followed by coupling reaction,¹¹ Pd-catalysed C–H functionalization/intramolecular alkenylation,¹² Pd(0)/monophosphine-promoted ring–forming reaction of 2-(alkynyl)aryl isocyanates with organoboron compound, and others.¹³Knoevenagel condensation is one of the best methods for the preparation of 3-benzylidene-indolin-2-ones, but often it gives mixture of E/Z isomeric products. Otherwise, noble metal-catalysed protocols received enormous interest. However, the limited availability, high price, and toxicity of these metals diminished their usage in industrial applications. Therefore, several research groups have been engaged in search of an alternative greener and cleaner approach under metal-free conditions. To address the diastereoisomeric issue, Tacconi et al. reported a thermal (300–310 °C) isomerization reaction of 3-arylidene-1,3-dihydroindol-2-ones,¹⁴ which suffers from poor reaction efficiency and E/Z selectivity. Therefore, transformations controlling E/Z ratio of 3-benzylidene-indolin-2-ones remains a challenging task and highly desirable (Scheme 1).Open in a separate windowScheme 1Functionalized 3-benzylidene-indolin-2-ones and alkenes in bioactive compounds and the accessible methods.On the other hand, selective E/Z stereo-isomerization of alkenes has been well established using various methods in the presence of light stimuli,^15a cations,^15b halogens or elemental selenium,¹⁶ palladium-hydride catalyst,¹⁰ cobalt-catalyst,¹⁷ Ir-catalyst,¹⁸ organo-catalysts.¹⁹ Among these, light-induced photostationary E/Z stereoisomerization is very attractive, due to its close proximity towards the natural process. In recent years, several light-driven molecular motors (controlled motion at the molecular level), molecular propellers,²⁰ switches,²¹ brakes,²² turnstiles,²³ shuttles,²⁴ scissors,²⁵ elevators,²⁶ rotating modules,²⁷ muscles,²⁸ rotors,²⁹ ratchets,³⁰ and catalytic self-propelled objects have been developed.³¹ Further, equipment''s relying on molecular mechanics were rapidly developed, particularly in the area of health care.Till date, controlled photo-isomerization of functionalized 3-benzylidene-indolin-2-ones is one of the puzzling problems to the scientific community. Photochemical reactions in batch process have serious drawbacks with limited hot-spot zone due to inefficient light penetration with increasing light path distance through the absorbing media, and the situation becomes poorer when the reactor size increases.^32,33 In contrast, the capillary microreactor platform has emerged as an efficient the artificial tool with impressive advantages, such as excellent photon flux, uniform irradiation, compatibility with multi-step syntheses, excellent mass and heat transfer, which lead to significant decrease the reaction time with improved yield or selectivity over batch reactors.^33a,34 To address the aforementioned challenges, it is essential to develop a highly efficient photo-microchemical flow approach for the controlled isomerization of functionalized 3-benzylidene-indolin-2-ones in catalyst-free and an environment friendly manner.     

Synthesis of novel benzopyran-connected pyrimidine and pyrazole derivatives via a green method using Cu(ii)-tyrosinase enzyme catalyst as potential larvicidal,antifeedant activities

A series of benzopyran-connected pyrimidine (1a–g) and benzopyran-connected pyrazole (2a–i) derivatives were synthesized via Biginelli reaction using a green chemistry approach. Cu(ii)-tyrosinase was used as a catalyst in the synthesis of compounds 1a–g and 2a–ivia the Biginelli reaction. The as-synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, mass spectroscopy, and elemental analysis. The as-synthesized compounds were screened for larvicidal and antifeedant activities. The larvicidal activity was evaluated using the mosquito species Culex quinquefasciatus, and the antifeedant activity was evaluated using the fishes of Oreochromis mossambicus. The compounds 2a–i demonstrated lethal effects, killing 50% of second instar mosquito larvae when their LD₅₀ values were 44.17, 34.96, 45.29, 45.28, 75.96, and 28.99 μg mL⁻¹, respectively. Molecular docking studies were used for analysis based on the binding ability of an odorant binding protein (OBP) of Culex quinquefasciatus with compound 2h (binding energy = −6.12 kcal mol⁻¹) and compound 1g (binding energy = −5.79 kcal mol⁻¹). Therefore, the proposed target compounds were synthesized via a green method using Cu(ii)-enzyme as a catalyst to give high yield (94%). In biological screening, benzopyran-connected pyrazole (2h) was highly active compared with benzopyran-connected pyrimidine (1a–g) series in terms of larivicidal activity.

Cu(ii)-tyrosinase catalytic help with the synthesis of benzopyran-connected pyrimidine and pyrazole derivatives and their larvicidal activity.

Benzopyrans (coumarins) are an important group of naturally occurring compounds widely distributed in the plant kingdom and have been produced synthetically for many years for commercial uses.¹ In addition, these core compounds are used as fragrant additives in food and cosmetics.² The commercial applications of coumarins include dispersed fluorescent brightening agents and as dyes for tuning lasers.³ Some important biologically active natural benzopyran (coumarin) derivatives are shown in Fig. 1. Mosquitoes are the vectors for a large number of human pathogens compared to other groups of arthropods.⁴ Their uncontrollable breeding poses a serious threat to the modern humanity. Every year, more than 500 million people are severely affected by malaria. The mosquito larvicide is an insecticide that is specially targeted against the larval life stage of a mosquito. Particularly, the compound bergapten (Fig. 1), which shows the standard of larivicidal activity,⁵ is commercially available, and it was used as a control in this study for larvicidal screening. Moreover, the antifeedant screening defense mechanism makes it a potential candidate for the development of eco-friendly ichthyocides. Coumarin derivatives exhibit a remarkably broad spectrum of biological activities, including antibacterial,^6,7 antifungal,^8–10 anticoagulant,¹¹ anti-inflammatory,¹² antitumor,^13,14 and anti-HIV.¹⁵Open in a separate windowFig. 1Biologically active natural benzopyran compound.Coumarin and its derivatives can be synthesized by various methods, which include the Perkin,¹⁶ Knoevenagel,¹⁷ Wittig,¹⁸ Pechmann,¹⁹ and Reformatsky reactions.Among these reactions, the Pechmann reaction is the most widely used method for the preparation of substituted coumarins since it proceeds from very simple starting materials and gives good yields of variously substituted coumarins. For example, coumarins can be prepared by using various reagents, such as H₂SO₄, POCl₃,²⁰ AlCl₃,²¹ cation exchange resins, trifluoroacetic acid,²² montmorillonite clay,²³ solid acid catalysts,²⁴ W/ZrO₂ solid acid catalyst,²⁵ chloroaluminate ionic liquid,²⁶ and Nafion-H catalyst.²⁷Keeping the above literature observations, coumarin derivatives 1a–g and 2a–i are usually prepared with the conventional method involving CuCl₂·2H₂O catalysis with using HCl additive. This reduces the yield and also increases the reaction time. To overcome this drawback, we used mushroom tyrosinase as a catalyst without any additive, a reaction condition not reported previously. The as-synthesized compounds were used for the biological screening of larvicidal and antifeedant activities (marine fish). In addition, in this study, we considered the molecular docking studies study based on previous studies for performing the binding ability of hydroxy-2-methyl-4H-pyran-4-one (the root extract of Senecio laetus Edgew) with the odorant binding protein (OBP) of Culex quinquefasciatus.²⁸     

Retraction: Olefin epoxidation with chiral salen Mn(iii) immobilized on ZnPS-PVPA upon alkyldiamine

Retraction of ‘Olefin epoxidation with chiral salen Mn(iii) immobilized on ZnPS-PVPA upon alkyldiamine’ by J. Huang et al., RSC Adv., 2016, 6, 19507–19514, DOI: 10.1039/C6RA00002A.

The Royal Society of Chemistry, with the agreement of the authors, hereby wholly retracts this RSC Advances article due to extensive overlap with other published articles by these authors, including the text, data and figures published in ref. 1, which was not cited in this article. Although there are sections of original work, there are significant portions of text overlap, particularly in the Results and discussion section. Fig. 1, 3, 4 and 5, Tables 1 and 2 and Schemes 1 and 2 in the RSC Advances article have also been reproduced from ref. 1.Signed: J. Huang, D. W. Qi, J. L. Cai and X. H. ChenDate: 19^th November 2020Retraction endorsed by Laura Fisher, Executive Editor, RSC Advances     

Correction: Oxidative carboxylation of olefins with CO2: environmentally benign access to five-membered cyclic carbonates

Correction for ‘Oxidative carboxylation of olefins with CO₂: environmentally benign access to five-membered cyclic carbonates’ by Liang Wang et al., RSC Adv., 2020, 10, 9103–9115.

The Royal Society of Chemistry regrets that incorrect details were given for Ref. 10b, 11b and 11c in the original article. The correct versions of Ref. 10b, 11b and 11c are given below as Ref. 1, 2a and 2b, respectively.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.