A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes(Pr)and 3,9-diazatetracyclododecanes(P2)is reported for the first time.The types of re...A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes(Pr)and 3,9-diazatetracyclododecanes(P2)is reported for the first time.The types of reaction product clearly differ with solvent,regardless of the irradiation wavelength.The difference in Pi and P2 lies in the second step of the intramolecular[2+2]photocyclization.In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines,DFT and TDDFT theoretical calculations are performed.The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.展开更多
Supramolecular interactions can help recognize and organize substrates around an enzyme’s active sites and subsequently assemble a new molecule in a certain way.Inspired by nature’s control of reactions,in this work...Supramolecular interactions can help recognize and organize substrates around an enzyme’s active sites and subsequently assemble a new molecule in a certain way.Inspired by nature’s control of reactions,in this work we designed a template catalyst equipped with ditopic Au(I)–N-heterocyclic carbene(NHC)functional sites that direct olefin substrates into reactive geometries via collaboration of coordination-driven interactions.Notably,this catalyst enables the realization of catalytic[2+2]photocycloadditions with as low as 2 mol%catalyst loading in homogeneous solution and the delivery of a series of cyclobutane derivatives with excellent conversions and stereoselectivities.The success of gram-scale reactions further demonstrates the feasibility of this strategy,which lays a solid foundation for the large-scale preparation of cyclobutane derivatives in the future.展开更多
Photoresponsive supramolecular gels as intelligent non-invasive responsive materials can undergo changes in color,state,morphology and electronic properties upon photo irradiation,making them attractive for a variety ...Photoresponsive supramolecular gels as intelligent non-invasive responsive materials can undergo changes in color,state,morphology and electronic properties upon photo irradiation,making them attractive for a variety of applications.Herein,a novel supramolecular hydrogelator DBE with 1,4-divinylbenzene as the central core,connected via amide linkage to l-phenylalanine and peripheral hydrophilic groups,was designed to evaluate the effect of[2+2]photocycloaddition reaction on supramolecular hydrogels.UV irradiation decreases the solubility of the hydrogelator DBE and hence,causes the destruction of the gel.SEM images clearly show that irradiation with UV light could induce disintegration of the right-handed helical nanofibers entangled network,which turns into nanoparticles and eventually massive crystals.Circular dichroism and vibrational circular dichroism data also indicate the formation of right-handed helical nanofibers in DBE gel.FTIR and MALDI-TOF-MS spectrum confirm that the variation of stability and aggregated morphology of DBE gel after UV irradiation is attributed to[2+2]cycloaddition reaction of vinyl units.This study presents a wonderful model for regulating the stability and aggregated morphology of supramolecular hydrogels via photo irradiation,as well as offers new ideas for designing novel photo responsive materials.展开更多
In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward processes.In applications for which switchin...In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward processes.In applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are uncommon.Herein,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coordination polymer,CP1 and its monocyclobutane product,CP1a.It is possible to cycle at least ten times through a forward [2+2] photocycloaddition reaction and the reverse,photocleavage reaction.A single cycle can be completed within a few minutes.The transformation is accompanied by fast and distinct fluorescence changes,arising from optimisation of the reaction conditions.Density functional theory calculations allow rationalisation of the asymmetric reversible transformation between CP1 and CP1a rather than between CP1 and its dicyclobutane product CP1b.This work provides a clear illustration of reversible structural switching which approaches symmetric behaviour with respect to reaction rate and stimuli.The insights gained from this work also assist in the design of fast,reversible switching materials.展开更多
Eight polycyclic furanobutenolide-containing norcembrane diterpenoids featuring C19 frameworks(1–8)were rapidly recognized and isolated from the Hainan soft coral Sinularia sp. by the HSQC-based small molecule accura...Eight polycyclic furanobutenolide-containing norcembrane diterpenoids featuring C19 frameworks(1–8)were rapidly recognized and isolated from the Hainan soft coral Sinularia sp. by the HSQC-based small molecule accurate recognition technology. Yonarolide A(1a), featuring an unprecedented 5/6/4/4/7 pentacyclic ring skeleton, was surprisingly obtained as a transformed product by leaving compound 1 under indoor natural light, and was further proved to be a [2 + 2] cycloaddition product of 1 by photochemical reaction. The absolute stereochemistry of 1a and the three known norcembrane diterpenoids 1, 4, and7 were determined by using X-ray diffraction(XRD) analyses. Further, with the aid of XRD analysis, the structure of scabrolide B(2), which was previously reported of possessing 5/6/7 tricyclic skeleton, was firmly revised as 2a with the rare inelegane skeleton featured by the highly oxygenated 5/7/6 tricyclic carbocycle.展开更多
Three novel bis-chalcone derivatives with different alkyldioxy spacers were synthesized and dispersed into polymethyl methacrylate (PMMA) chloroform solution with 6-nitro-1'-ethyl-3',3'-dimethylspiro-2H-1-benzopy...Three novel bis-chalcone derivatives with different alkyldioxy spacers were synthesized and dispersed into polymethyl methacrylate (PMMA) chloroform solution with 6-nitro-1'-ethyl-3',3'-dimethylspiro-2H-1-benzopyran-2,U-indoline (ESP) to prepare photochromic PMMA films in a facile way. After irradiation with 365 nm UV light, the photocrosslinking reaction between chalcone units was proved to retard the decolorization of merocyanine form of the photochromic spiropyran effectively, as results of the steric hindrance produced by photocycloaddition of chalcone groups. It has been found that the bis-chalcone molecule with the shortest spacer has the most effective stabilizing effect on retardation of decoloration of spiropyran. reserved.展开更多
In attempting to study the phototherapeutic action and the photosensitized oxygenation mechanism, we have determined the crystal structure of the main oxidized product of hypocrellin A (HA). It was crystallized in m...In attempting to study the phototherapeutic action and the photosensitized oxygenation mechanism, we have determined the crystal structure of the main oxidized product of hypocrellin A (HA). It was crystallized in monoclinic system with space group P2<sub>1</sub>. The cell data are: a=10.030(3), b=8.877(3), c=15.764(5), β=104.50(2)°, Z=2. The crystal structure has been determined by direct method and refined to a final R of 0.055 based on the 1408 observed reflections with l】2.5σ(Ⅰ). The photooxidized product is composed of a heptacyclic aliphatic hydrocarbon connecting with two α-naphthoquinone derivatives as its skeletal molecule. No peroxidic linkage has been found. On the basis of the crystal structure determined, we have deduced part of the process of formation of the oxide, ⅰ. e. firstly, the peroxide was formed by photocycloaddition of oxygen molecule to Hypocrellin A, then thermodissociation took place to form a stable oxide.展开更多
Single-chain nanoparticles represent an emerging class of nanomaterials designed to mimic protein's folding paradigm.Intrachain covalent crosslinking toward the formation of single-chain nanoparticles encounters c...Single-chain nanoparticles represent an emerging class of nanomaterials designed to mimic protein's folding paradigm.Intrachain covalent crosslinking toward the formation of single-chain nanoparticles encounters complex energy landscapes,leading to the potential occurrence of misfolding issues.While noncovalent crosslinking can circumvent this issue,the resulting single-chain nanoparticles exhibit lower structural stability compared to their covalently crosslinked counterparts.In this study,we present a novel approach for the synthesis of single-chain nanoparticles,achieved through the combination of non-covalent and covalent intramolecular crosslinking.Cyanostilbenes grafted onto the linear polymer form intrachain non-covalent stacks aided by hydrogen bonds,leading to the formation of non-covalently crosslinked single-chain nanoparticles.These nanoparticles undergo conversion to covalently crosslinked nanostructures through subsequent photo-irradiation using[2+2]photocycloaddition,a process facilitated by the supramolecular confinement effect.Consequently,the resulting single-chain nanoparticles demonstrate both intrachain folding efficiency and substantial stability,offering significant potential for advancing applications across diverse fields.展开更多
基金supported by the Beijing Natural Science Foundation(No.2192004).
文摘A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes(Pr)and 3,9-diazatetracyclododecanes(P2)is reported for the first time.The types of reaction product clearly differ with solvent,regardless of the irradiation wavelength.The difference in Pi and P2 lies in the second step of the intramolecular[2+2]photocyclization.In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines,DFT and TDDFT theoretical calculations are performed.The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.
基金Financial support from the National Natural Science Fund for Distinguished Young Scholars of China(grant no.22025107)the National Youth Top-notch Talent Support Program of China,the Key Science and Technology Innovation Team of Shaanxi Province(grant nos.2019TD-007 and 2019JLZ-02)the FM&EM International Joint Laboratory of Northwest University is gratefully acknowledged.
文摘Supramolecular interactions can help recognize and organize substrates around an enzyme’s active sites and subsequently assemble a new molecule in a certain way.Inspired by nature’s control of reactions,in this work we designed a template catalyst equipped with ditopic Au(I)–N-heterocyclic carbene(NHC)functional sites that direct olefin substrates into reactive geometries via collaboration of coordination-driven interactions.Notably,this catalyst enables the realization of catalytic[2+2]photocycloadditions with as low as 2 mol%catalyst loading in homogeneous solution and the delivery of a series of cyclobutane derivatives with excellent conversions and stereoselectivities.The success of gram-scale reactions further demonstrates the feasibility of this strategy,which lays a solid foundation for the large-scale preparation of cyclobutane derivatives in the future.
基金This work was supported by the National Natural Science Foundation of China(NSFC 51833006)the Innovation Program of Shanghai Municipal Education Commission(201701070002E00061)+1 种基金start-up fund of Henan University for funding to J.Y.Liu(CX3050A0920135)Program for Professors of Special Appointment(Eastern Scholar)at the Shanghai Institutions of Higher Learning.
文摘Photoresponsive supramolecular gels as intelligent non-invasive responsive materials can undergo changes in color,state,morphology and electronic properties upon photo irradiation,making them attractive for a variety of applications.Herein,a novel supramolecular hydrogelator DBE with 1,4-divinylbenzene as the central core,connected via amide linkage to l-phenylalanine and peripheral hydrophilic groups,was designed to evaluate the effect of[2+2]photocycloaddition reaction on supramolecular hydrogels.UV irradiation decreases the solubility of the hydrogelator DBE and hence,causes the destruction of the gel.SEM images clearly show that irradiation with UV light could induce disintegration of the right-handed helical nanofibers entangled network,which turns into nanoparticles and eventually massive crystals.Circular dichroism and vibrational circular dichroism data also indicate the formation of right-handed helical nanofibers in DBE gel.FTIR and MALDI-TOF-MS spectrum confirm that the variation of stability and aggregated morphology of DBE gel after UV irradiation is attributed to[2+2]cycloaddition reaction of vinyl units.This study presents a wonderful model for regulating the stability and aggregated morphology of supramolecular hydrogels via photo irradiation,as well as offers new ideas for designing novel photo responsive materials.
基金supported by the National Natural Science Foundation of China (22271203)the State Key Laboratory of Organometallic Chemistry of Shanghai Institute of Organic Chemistry(KF2021005)+2 种基金the Collaborative Innovation Center of Suzhou Nano Science and Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Project of Scientific and Technologic Infrastructure of Suzhou (SZS201905)。
文摘In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward processes.In applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are uncommon.Herein,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coordination polymer,CP1 and its monocyclobutane product,CP1a.It is possible to cycle at least ten times through a forward [2+2] photocycloaddition reaction and the reverse,photocleavage reaction.A single cycle can be completed within a few minutes.The transformation is accompanied by fast and distinct fluorescence changes,arising from optimisation of the reaction conditions.Density functional theory calculations allow rationalisation of the asymmetric reversible transformation between CP1 and CP1a rather than between CP1 and its dicyclobutane product CP1b.This work provides a clear illustration of reversible structural switching which approaches symmetric behaviour with respect to reaction rate and stimuli.The insights gained from this work also assist in the design of fast,reversible switching materials.
基金financially supported by the National Key Research and Development Program of China (No. 2021YFF0502400)the National Natural Science Foundation of China (Nos. 81991521, 82022069 and 42076099)+2 种基金the Shanghai Rising-Star Program (No. 20QA1411100)“Youth Innovation Promotion Association” of Chinese Academy of Sciences (No. Y202065)the SKLDR/SIMM Project (No. SIMM2103 ZZ-06)。
文摘Eight polycyclic furanobutenolide-containing norcembrane diterpenoids featuring C19 frameworks(1–8)were rapidly recognized and isolated from the Hainan soft coral Sinularia sp. by the HSQC-based small molecule accurate recognition technology. Yonarolide A(1a), featuring an unprecedented 5/6/4/4/7 pentacyclic ring skeleton, was surprisingly obtained as a transformed product by leaving compound 1 under indoor natural light, and was further proved to be a [2 + 2] cycloaddition product of 1 by photochemical reaction. The absolute stereochemistry of 1a and the three known norcembrane diterpenoids 1, 4, and7 were determined by using X-ray diffraction(XRD) analyses. Further, with the aid of XRD analysis, the structure of scabrolide B(2), which was previously reported of possessing 5/6/7 tricyclic skeleton, was firmly revised as 2a with the rare inelegane skeleton featured by the highly oxygenated 5/7/6 tricyclic carbocycle.
基金the financial support from the National High Technology Research and Development Program of China(No.2005AA320030)SJTU-Aeronautics Industry Joint Program(No.0304)
文摘Three novel bis-chalcone derivatives with different alkyldioxy spacers were synthesized and dispersed into polymethyl methacrylate (PMMA) chloroform solution with 6-nitro-1'-ethyl-3',3'-dimethylspiro-2H-1-benzopyran-2,U-indoline (ESP) to prepare photochromic PMMA films in a facile way. After irradiation with 365 nm UV light, the photocrosslinking reaction between chalcone units was proved to retard the decolorization of merocyanine form of the photochromic spiropyran effectively, as results of the steric hindrance produced by photocycloaddition of chalcone groups. It has been found that the bis-chalcone molecule with the shortest spacer has the most effective stabilizing effect on retardation of decoloration of spiropyran. reserved.
文摘In attempting to study the phototherapeutic action and the photosensitized oxygenation mechanism, we have determined the crystal structure of the main oxidized product of hypocrellin A (HA). It was crystallized in monoclinic system with space group P2<sub>1</sub>. The cell data are: a=10.030(3), b=8.877(3), c=15.764(5), β=104.50(2)°, Z=2. The crystal structure has been determined by direct method and refined to a final R of 0.055 based on the 1408 observed reflections with l】2.5σ(Ⅰ). The photooxidized product is composed of a heptacyclic aliphatic hydrocarbon connecting with two α-naphthoquinone derivatives as its skeletal molecule. No peroxidic linkage has been found. On the basis of the crystal structure determined, we have deduced part of the process of formation of the oxide, ⅰ. e. firstly, the peroxide was formed by photocycloaddition of oxygen molecule to Hypocrellin A, then thermodissociation took place to form a stable oxide.
基金supported by the National Natural Science Foundation of China(Nos.22371272 and 22301295)the Fundamental Research Funds for the Central Universities(Nos.YD2060002036 and WK5290000004)+1 种基金International Partnership Program of the Chinese Academy of Sciences(No.123GJHZ2022064MI)the Collaborative Innovation Program of Hefei Science Center,CAS(No.2022HSC-CIP014)。
文摘Single-chain nanoparticles represent an emerging class of nanomaterials designed to mimic protein's folding paradigm.Intrachain covalent crosslinking toward the formation of single-chain nanoparticles encounters complex energy landscapes,leading to the potential occurrence of misfolding issues.While noncovalent crosslinking can circumvent this issue,the resulting single-chain nanoparticles exhibit lower structural stability compared to their covalently crosslinked counterparts.In this study,we present a novel approach for the synthesis of single-chain nanoparticles,achieved through the combination of non-covalent and covalent intramolecular crosslinking.Cyanostilbenes grafted onto the linear polymer form intrachain non-covalent stacks aided by hydrogen bonds,leading to the formation of non-covalently crosslinked single-chain nanoparticles.These nanoparticles undergo conversion to covalently crosslinked nanostructures through subsequent photo-irradiation using[2+2]photocycloaddition,a process facilitated by the supramolecular confinement effect.Consequently,the resulting single-chain nanoparticles demonstrate both intrachain folding efficiency and substantial stability,offering significant potential for advancing applications across diverse fields.