The development of catalytic asymmetric radical reactions is an attractive but formidable task.The high reactivity of radicals enables the use of readily accessible feedstocks and mild reaction conditions,but it leads...The development of catalytic asymmetric radical reactions is an attractive but formidable task.The high reactivity of radicals enables the use of readily accessible feedstocks and mild reaction conditions,but it leads to substantial difficulty for chiral catalysts to provide sufficient enantiocontrol.Moreover,a racemic background process is often inevitable,further deteriorating enantioselectivity.In this regard,an effective protocol has been established for enantioselective intermolecular[2+2]photocycloadditions to overcome the challenges,which is capitalising on the ground-state preassociations of chiral catalysts with photoactivated substrates.Here,we report the viability of substrate-differentiating synergistic catalysis for this important reaction.In this new platform,energy transfer occurs between DPZ as a photosensitizer and enones or(E)-2-substituted vinylazaarenes for producing triplet-state species,and chiral phosphoric acid interacts with ground-state 2-vinylazaarenes via hydrogen bonding for subsequent enantiofacial cycloaddition.Although all active species are dispersed in the reaction system,valuable enantioenriched mono-and di-azaarene-functionalized cyclobutanes are obtained efficiently and selectively.In addition to constructing all-carbon quaternary stereocentres,flexible modulation of azaaryl groups and other substituents on the cyclobutane ring is also operative.展开更多
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
The photocycloaddition of (4-methyl-7-coumarinyl) oxyacetic acid propanediol diester 1 (C_27H_24O_10) in chloroform produced a single product 2 characterized to be syn head-tail. Crystal structure of 2 has been determ...The photocycloaddition of (4-methyl-7-coumarinyl) oxyacetic acid propanediol diester 1 (C_27H_24O_10) in chloroform produced a single product 2 characterized to be syn head-tail. Crystal structure of 2 has been determined by X-ray diffraction analysis. The crystal belongs to orthorhombic system, space group Pbca, with cell parameters a=10. 745(5), b= 13. 443(4), c=33. 358(9) A, V=4791 (5) A￣3, M_r=508. 49,Z= 8, D_c=1. 41 g/cm￣3, μ= 1. 015 cm￣-1, F(000)=1064. The final R=0. 065 for 1587 observed reflections. Compound 2 has a large ring resulted from [2+2] photocycloaddition. The four-member ring of 2 has poor coplanarity, the two diagonal atoms of four-member ring are above the least-squares plane, and another diagonal atom couple is below the least-squares plane, the deviations of two couples are approximately equal.展开更多
To develop innovative photocycloadditions between excited carbonyl compounds with C-C bonds and address the absence of catalytic asymmetric ver-sions,herein we report a chiral Lewis acid-mediated catalytic enantiosele...To develop innovative photocycloadditions between excited carbonyl compounds with C-C bonds and address the absence of catalytic asymmetric ver-sions,herein we report a chiral Lewis acid-mediated catalytic enantioselective formal photocycloaddition of excited triplet aldehydes with C-C bond of ben-zocyclobutenones under low catalyst loading(as low as 0.5 mol%).A series of control experiments and density functional theory calculations have con-firmed the existence of diradical intermediates.The Lu(III)/N,N′-dioxide complex plays a crucial role in not only enhancing phosphorescence emission inten-sity but also extending the triplet lifetimes of alde-hydes,which makes it possible for addressing the formidable issue of enantioselective control with in-volved highly reactive triplet intermediates.This ap-proach offers a straightforward avenue to highly enantioenriched 3,4-dihydroisocoumarins in high yields,some of which exhibited anticancer activity upon testing.展开更多
An ortho-selective intermolecular photocycloaddition of commercially available quinolines has been developed using a strainrelease approach.This approach enabled the direct synthesis of quinoline-derived-semisaturated...An ortho-selective intermolecular photocycloaddition of commercially available quinolines has been developed using a strainrelease approach.This approach enabled the direct synthesis of quinoline-derived-semisaturated-fused rings in conjunction with cycloproarylketones as coupling partners.Mechanistic investigations have revealed that the generation of an electron donor acceptor complex between cycloproarylketones and camphorsulfonic acid,followed by radical addition with quinolines through a single electron transfer process,along with the excitation of the following adducts via energy transfer,is crucial for the observed photocycloaddition.展开更多
Dearomative photocycloaddition of heteroarenes is an efficient method for replacing planar arenes with three-dimensional(3D)scaffolds,such as bicyclo[2.1.1]-hexane(BCH)containing heterocycles.Herein,we report intramol...Dearomative photocycloaddition of heteroarenes is an efficient method for replacing planar arenes with three-dimensional(3D)scaffolds,such as bicyclo[2.1.1]-hexane(BCH)containing heterocycles.Herein,we report intramolecular dearomative[2π+2σ]photocycloadditions of bicyclo[1.1.0]butanes(BCBs)with(benzo)furans and(benzo)thiophenes.These photocycloadditions are initiated through an energy transfer pathway(EnT)or single electron transfer pathway(SET),efficiently yielding unique BCHpyrrolidinone-fused heterocyclic scaffolds.Moreover,the synthetic utility of this photochemical reaction was demonstrated on the basis of large-scale synthesis and diversified transformations.Mechanistic investigations,in conjunction with density functional theory(DFT)calculations,were taken to support the proposed reaction mechanisms.展开更多
Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promo...Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.展开更多
Flexible circuit switches have been widely used in electronic devices due to their outstanding flexibility and operability.In order to expand the types of flexible circuit switch materials,we develop a unique composit...Flexible circuit switches have been widely used in electronic devices due to their outstanding flexibility and operability.In order to expand the types of flexible circuit switch materials,we develop a unique composite material,which integrates a photoresponsive flexible substrate derived from a photoreactive coordination polymer(CP)with an elastic conductive adhesive tape(CAT)in this work.The photoreactive CP{[Cd(2,6-bpvn)(3,5-DBB)_(2)]·DMF}_(n)(1)is prepared through solvothermal reaction of Cd(NO_(3))_(2)·4H_(2)O with 2,6-bis((E)-2-(pyridin-4-yl)vinyl)naphthalene(2,6-bpvn)and 3,5-dibromobenzoic acid(3,5-HDBB).Upon irradiation with UV light,crystals of 1 can undergo[2+2]photocycloaddition reaction and exhibit photomechanical movements.The crystalline powder of 1 can be uniformly distributed in polyvinyl alcohol(PVA)to generate the composite film 1-PVA.After pasting a piece of CAT on the surface of a 1-PVA film,a conductive two-layer film of 1-PVA/CAT can be fabricated.This film bends rapidly upon UV light exposure,connecting the circuit and causing the bulb to light up.When the light source is removed,it reverts to its initial state and the circuit is disconnected and the bulb is extinguished.This process can be cycled at least 100 times,achieving precise turn-on and turn-off performances of the photocontrollable circuit switch.展开更多
Imposing conformational constraints on sp3-rich structures is emerging as an important strategy for structural modification and optimization,which can improve the bioactivity of drugs.Herein,we report a visible-light-...Imposing conformational constraints on sp3-rich structures is emerging as an important strategy for structural modification and optimization,which can improve the bioactivity of drugs.Herein,we report a visible-light-induced photosensitized[2+2]homo-cycloaddition and cross-cycloaddition of cyclopropenes to synthesize tricyclo[3.1.0.0^(2,4)]hexanes as rigidified 3,3,6,6-tetrasubstituted cyclohexanes.Trifluoroacetylsilanes,previously known as trifluoromethyl siloxycarbene precursors,were used as photocatalysts for the first time.The mechanism study supports that the aggregation of cyclopropenes is important to promote their sensitization by trifluoroacetylsilanes through energy transfer.展开更多
Photocycloaddition affords opportunities to engage in advanced fuels with high-strained cyclobutyl-containing structures.Herein,the one-step route for the synthesis of high-energy-density caged fuel,tetracyclo[4.2.1.0...Photocycloaddition affords opportunities to engage in advanced fuels with high-strained cyclobutyl-containing structures.Herein,the one-step route for the synthesis of high-energy-density caged fuel,tetracyclo[4.2.1.0^(2.5).0^(3,7)]nonane(TCN)with high-strained four-membered structure,has been developed via photosensitized[2+2]cycloaddition of 5-vinyl-2-norbornene(VNB).The reaction conditions are optimized to obtain a high conversion of VNB of 91.9%.The triplet quenching and Stern-Volmer quenching studies indicate that[2+2]photocycloaddition follows the triplet-triplet energy transfer process,and a kinetic model is expressed as a reaction rate equation correlated with the incident light flux.Importantly,the obtained TCN shows a high density of 1.003 g·cm^(-3)and volumetric net heat of combustion of 42.31 MJ·L^(-1),which can serve as an excellent high-energy additive for blending with liquid fuels.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
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
The photocycloadditions of 1,3-dimethyl-6-azathymine to 2-butyne-1,4-diol and 1,4-di- methoxyl-2-butyne have been studied. Three novel compounds, 7,8-bis(hydroxymethyl)-3,5-dioxo-2,4, 6-trimethyl-1,2,4-triazabicyclo [...The photocycloadditions of 1,3-dimethyl-6-azathymine to 2-butyne-1,4-diol and 1,4-di- methoxyl-2-butyne have been studied. Three novel compounds, 7,8-bis(hydroxymethyl)-3,5-dioxo-2,4, 6-trimethyl-1,2,4-triazabicyclo [4,2,0]-7-octene (1), 7,8-bismethoxymethy1-3,5-dioxo-2,4,6-trimethyl- 1,2,4-triazabicyclo[4,2,0]-7-octene (2) and 8,9-bismethoxymethy1-4-oxo-1,3,5-trimethyl-7-oxa-2,3,5- triazaspiro[5,3]-1,8-nonadiene (3) were obtained. The proposed reaction mechanism, which includes excited triplet complexes and biradicals as intermediates, was supported by kinetic ana photophysical studies.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
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
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
CONSPECTUS:The concept of photoresponsive coordination polymer(CP)single crystal platforms(CPSCPs)is based on photoresponsive olefin CP single crystals,which can undergo photocycloaddition reactions under light irradi...CONSPECTUS:The concept of photoresponsive coordination polymer(CP)single crystal platforms(CPSCPs)is based on photoresponsive olefin CP single crystals,which can undergo photocycloaddition reactions under light irradiation through a single-crystal-to-single-crystal(SCSC)transformation.Taking advantage of the coordination of olefin ligands to metal ions of Zn^(2+),Cd^(2+),etc.,a pair of C=C double bonds is positioned adjacent to each other in space at a suitable distance and orientation to allow[2+2]photocycloaddition triggered by UV−vis irradiation,affording cyclobutanes in the CPs.The single crystal nature of CPs allows their structures to be determined by X-ray diffraction,providing details of the arrangements in space of the C=C double bonds.These CPs are promising platforms for the synthesis of organic molecules,such as cyclobutanes and derivatives,with high regioselectivity and stereoselectivity without any catalyst.The[2+2]photocycloaddition reactions may induce structural modifications like expansion or shrinking of unit cells,resulting in macroscopic changes(e.g.,cracking,bending,etc.)of the whole CP single crystals and leading to changes in chemical and physical properties.Applications take advantage of their optical properties,including luminescence and absorption,and allow the detection of vip molecules and photomechanical motions.Although much effort has been devoted to such studies,it remains challenging to develop systematic investigations aiming at increasing the diversity of CPs and properties to meet practical needs.Moreover,more efficient methods are desirable to investigate the reaction mechanisms in the solid state and monitor the structural changes occurring during the process.In this Account,we introduce our research on the design and applications of photoresponsive CPSCPs.It is divided into three parts.First,the design and construction of various CPs with different olefin ligands are discussed.Through a suitable and sometimes sophisticated choice of metal ions and auxiliary carboxylate ligands,these olefin ligands meet the requirements to undergo[2+2]photocycloaddition reactions in CP structures,allowing for the precise synthesis of cyclobutanes and their derivatives.These compounds could be subsequently extracted from the CPs to give pure organic products.Second,we introduce new strategies,such as a combination of single crystal X-ray diffraction(SCXRD)with thermal/phototreatments of CPs and in situ fluorescence spectroscopy,to monitor the structural changes occurring on the olefin ligands during the reaction.Furthermore,the fast stepwise photoreaction could also be visualized with high resolution.These data significantly strengthen our understanding of solid-state[2+2]photocycloaddition reactions in CPs.Third,applications of photoresponsive CPs are described,which focus on optical and photoinduced mechanical properties.Considering the optical properties,the conjugated structures of the olefin ligands change during the reactions,and circular dichroism(CD)and fluorescence were used for their detection and imaging.Furthermore,the photoinduced mechanical properties of CPs could be significantly expanded through the combination of CP crystals with polymers.Lastly,we point out the challenges and directions for future research in the field.We hope this Account will provide an overview of research on photoresponsive CPSCPs,attract more attention from the community,and inspire future research.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
Presponsive smart organic crystalline materials(SOCMs)have emerged as an attractive research topic because of their many advantages,such as well-defined structures,high structural order,and the resulting fast response...Presponsive smart organic crystalline materials(SOCMs)have emerged as an attractive research topic because of their many advantages,such as well-defined structures,high structural order,and the resulting fast response speeds,as well as high energy conversion efficiency and remarkable dynamic optical/electronic changes or mechanical responses.In this review,we discuss the recent developments in SOCMs based on topochemistry beyond coordination compounds,which include[2+2]or[4+4]photocycloaddition of anthracene and olefin derivatives as well as 1,4-addition-polymerization of diacetylenes.The detailed design principles and mechanisms associated with smart behavior,photoresponsive physical and chemical properties(i.e.,photochromism,photo fluorochromism,and photodeformation),and structure–property relationships are discussed,along with their advanced applications in exciting fields such as intelligent microrobots,encryption,sensors,photoactua-tors,data storage,and displays.Finally,we summarize the current developments and discuss the major current challenges and future opportunities in this field.We expect that this review will inspire more innovative research into the development of advanced photoresponsive organic smart crystal materials with fast,accurate,and reversible responses,and promote the further development of smart materials and devices.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 mon...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_1. 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
文摘The development of catalytic asymmetric radical reactions is an attractive but formidable task.The high reactivity of radicals enables the use of readily accessible feedstocks and mild reaction conditions,but it leads to substantial difficulty for chiral catalysts to provide sufficient enantiocontrol.Moreover,a racemic background process is often inevitable,further deteriorating enantioselectivity.In this regard,an effective protocol has been established for enantioselective intermolecular[2+2]photocycloadditions to overcome the challenges,which is capitalising on the ground-state preassociations of chiral catalysts with photoactivated substrates.Here,we report the viability of substrate-differentiating synergistic catalysis for this important reaction.In this new platform,energy transfer occurs between DPZ as a photosensitizer and enones or(E)-2-substituted vinylazaarenes for producing triplet-state species,and chiral phosphoric acid interacts with ground-state 2-vinylazaarenes via hydrogen bonding for subsequent enantiofacial cycloaddition.Although all active species are dispersed in the reaction system,valuable enantioenriched mono-and di-azaarene-functionalized cyclobutanes are obtained efficiently and selectively.In addition to constructing all-carbon quaternary stereocentres,flexible modulation of azaaryl groups and other substituents on the cyclobutane ring is also operative.
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.
文摘The photocycloaddition of (4-methyl-7-coumarinyl) oxyacetic acid propanediol diester 1 (C_27H_24O_10) in chloroform produced a single product 2 characterized to be syn head-tail. Crystal structure of 2 has been determined by X-ray diffraction analysis. The crystal belongs to orthorhombic system, space group Pbca, with cell parameters a=10. 745(5), b= 13. 443(4), c=33. 358(9) A, V=4791 (5) A￣3, M_r=508. 49,Z= 8, D_c=1. 41 g/cm￣3, μ= 1. 015 cm￣-1, F(000)=1064. The final R=0. 065 for 1587 observed reflections. Compound 2 has a large ring resulted from [2+2] photocycloaddition. The four-member ring of 2 has poor coplanarity, the two diagonal atoms of four-member ring are above the least-squares plane, and another diagonal atom couple is below the least-squares plane, the deviations of two couples are approximately equal.
基金the National Key Research and Development Program of China(grant no.2022YFA1504301)the National Natural Science Foundation of China(grant no.92256302)for financial support.
文摘To develop innovative photocycloadditions between excited carbonyl compounds with C-C bonds and address the absence of catalytic asymmetric ver-sions,herein we report a chiral Lewis acid-mediated catalytic enantioselective formal photocycloaddition of excited triplet aldehydes with C-C bond of ben-zocyclobutenones under low catalyst loading(as low as 0.5 mol%).A series of control experiments and density functional theory calculations have con-firmed the existence of diradical intermediates.The Lu(III)/N,N′-dioxide complex plays a crucial role in not only enhancing phosphorescence emission inten-sity but also extending the triplet lifetimes of alde-hydes,which makes it possible for addressing the formidable issue of enantioselective control with in-volved highly reactive triplet intermediates.This ap-proach offers a straightforward avenue to highly enantioenriched 3,4-dihydroisocoumarins in high yields,some of which exhibited anticancer activity upon testing.
基金supported by the National Natural Science Foundation of China(21925103,22271077,21901062)the Natural Science Foundation of Henan Province(222301420046,232300421078)+1 种基金the Program for Science&Technology Innovation Talents in Universities of Henan Province(24HASTIT001)the China Postdoctoral Science Foundation(2021M690890)。
文摘An ortho-selective intermolecular photocycloaddition of commercially available quinolines has been developed using a strainrelease approach.This approach enabled the direct synthesis of quinoline-derived-semisaturated-fused rings in conjunction with cycloproarylketones as coupling partners.Mechanistic investigations have revealed that the generation of an electron donor acceptor complex between cycloproarylketones and camphorsulfonic acid,followed by radical addition with quinolines through a single electron transfer process,along with the excitation of the following adducts via energy transfer,is crucial for the observed photocycloaddition.
基金supported by the National Key R&D Program of China(2022YFC2303100)the National Natural Science Foundation of China(22305261,21372250,21121062,21302203,20732008,21772037,21772226,21861132014,91956115,22171078)+1 种基金the Shanghai Municipal Science and Technology Major Project(2018SHZDZX03)the Fundamental Research Funds for the Central Universities(222201717003)。
文摘Dearomative photocycloaddition of heteroarenes is an efficient method for replacing planar arenes with three-dimensional(3D)scaffolds,such as bicyclo[2.1.1]-hexane(BCH)containing heterocycles.Herein,we report intramolecular dearomative[2π+2σ]photocycloadditions of bicyclo[1.1.0]butanes(BCBs)with(benzo)furans and(benzo)thiophenes.These photocycloadditions are initiated through an energy transfer pathway(EnT)or single electron transfer pathway(SET),efficiently yielding unique BCHpyrrolidinone-fused heterocyclic scaffolds.Moreover,the synthetic utility of this photochemical reaction was demonstrated on the basis of large-scale synthesis and diversified transformations.Mechanistic investigations,in conjunction with density functional theory(DFT)calculations,were taken to support the proposed reaction mechanisms.
基金the support from National Key R&D Program of China (2021YFC2103704)the National Natural Science Foundation of China (22222808)+4 种基金the Natural Science Foundation of Shandong Province (ZR2023QB152)the Youth Innovation Team Plan of Shandong Province (2022KJ270)the China National Postdoctoral Program for Innovative Talents (BX20240251)the Aeronautical Science Foundation of China (2023Z073048003)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.
基金support from the National Natural Science Foundation of China(No.U24A20507,22271203)the State Key Laboratory of Organometallic Chemistry,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences(No.2024KF005)Open Research Fund of State Key Laboratory of Coordination Chemistry,School of Chemistry and Chemical Engineering of Nanjing University and the Collaborative Innovation Centre of Suzhou Nano Science and Technology.
文摘Flexible circuit switches have been widely used in electronic devices due to their outstanding flexibility and operability.In order to expand the types of flexible circuit switch materials,we develop a unique composite material,which integrates a photoresponsive flexible substrate derived from a photoreactive coordination polymer(CP)with an elastic conductive adhesive tape(CAT)in this work.The photoreactive CP{[Cd(2,6-bpvn)(3,5-DBB)_(2)]·DMF}_(n)(1)is prepared through solvothermal reaction of Cd(NO_(3))_(2)·4H_(2)O with 2,6-bis((E)-2-(pyridin-4-yl)vinyl)naphthalene(2,6-bpvn)and 3,5-dibromobenzoic acid(3,5-HDBB).Upon irradiation with UV light,crystals of 1 can undergo[2+2]photocycloaddition reaction and exhibit photomechanical movements.The crystalline powder of 1 can be uniformly distributed in polyvinyl alcohol(PVA)to generate the composite film 1-PVA.After pasting a piece of CAT on the surface of a 1-PVA film,a conductive two-layer film of 1-PVA/CAT can be fabricated.This film bends rapidly upon UV light exposure,connecting the circuit and causing the bulb to light up.When the light source is removed,it reverts to its initial state and the circuit is disconnected and the bulb is extinguished.This process can be cycled at least 100 times,achieving precise turn-on and turn-off performances of the photocontrollable circuit switch.
基金National Key R&D Program of China(No.2022YFA1506100)National Natural Science Foundation of China(Nos.22471201,21901191)+1 种基金Fundamental Research Funds for the Central Universities(No.2042023kf0202)Wuhan University for financial support。
文摘Imposing conformational constraints on sp3-rich structures is emerging as an important strategy for structural modification and optimization,which can improve the bioactivity of drugs.Herein,we report a visible-light-induced photosensitized[2+2]homo-cycloaddition and cross-cycloaddition of cyclopropenes to synthesize tricyclo[3.1.0.0^(2,4)]hexanes as rigidified 3,3,6,6-tetrasubstituted cyclohexanes.Trifluoroacetylsilanes,previously known as trifluoromethyl siloxycarbene precursors,were used as photocatalysts for the first time.The mechanism study supports that the aggregation of cyclopropenes is important to promote their sensitization by trifluoroacetylsilanes through energy transfer.
基金the support from the National Natural Science Foundation of China(22408272,22222808,U24A20547)the Aeronautical Science Foundation of China(2023Z073048003)+1 种基金the China National Postdoctoral Program for Innovative Talents(BX20240251)the China Postdoctoral Science Foundation(2023M742592)。
文摘Photocycloaddition affords opportunities to engage in advanced fuels with high-strained cyclobutyl-containing structures.Herein,the one-step route for the synthesis of high-energy-density caged fuel,tetracyclo[4.2.1.0^(2.5).0^(3,7)]nonane(TCN)with high-strained four-membered structure,has been developed via photosensitized[2+2]cycloaddition of 5-vinyl-2-norbornene(VNB).The reaction conditions are optimized to obtain a high conversion of VNB of 91.9%.The triplet quenching and Stern-Volmer quenching studies indicate that[2+2]photocycloaddition follows the triplet-triplet energy transfer process,and a kinetic model is expressed as a reaction rate equation correlated with the incident light flux.Importantly,the obtained TCN shows a high density of 1.003 g·cm^(-3)and volumetric net heat of combustion of 42.31 MJ·L^(-1),which can serve as an excellent high-energy additive for blending with liquid fuels.
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.
文摘The photocycloadditions of 1,3-dimethyl-6-azathymine to 2-butyne-1,4-diol and 1,4-di- methoxyl-2-butyne have been studied. Three novel compounds, 7,8-bis(hydroxymethyl)-3,5-dioxo-2,4, 6-trimethyl-1,2,4-triazabicyclo [4,2,0]-7-octene (1), 7,8-bismethoxymethy1-3,5-dioxo-2,4,6-trimethyl- 1,2,4-triazabicyclo[4,2,0]-7-octene (2) and 8,9-bismethoxymethy1-4-oxo-1,3,5-trimethyl-7-oxa-2,3,5- triazaspiro[5,3]-1,8-nonadiene (3) were obtained. The proposed reaction mechanism, which includes excited triplet complexes and biradicals as intermediates, was supported by kinetic ana photophysical studies.
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.
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.
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supported by the National Natural Science Foundation of China(Grant Nos.U24A20507,22271203,and 22301204)the State Key Laboratory of Organometallic Chemistry,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences(Grant No.2024KF005)+1 种基金Open Research Fund of State Key Laboratory of Coordination Chemistry,School of Chemistry and Chemical Engineering,Nanjing University,the Collaborative Innovation Centre of Suzhou Nano Science and Technology,the Priority Academic Program Development of Jiangsu Higher Education Institutions,the Project of Scientific and Technologic Infrastructure of Suzhou(Grant No.SZS201905)Soochow University Starting Grant(No.NH10902124 to Q.L.).
文摘CONSPECTUS:The concept of photoresponsive coordination polymer(CP)single crystal platforms(CPSCPs)is based on photoresponsive olefin CP single crystals,which can undergo photocycloaddition reactions under light irradiation through a single-crystal-to-single-crystal(SCSC)transformation.Taking advantage of the coordination of olefin ligands to metal ions of Zn^(2+),Cd^(2+),etc.,a pair of C=C double bonds is positioned adjacent to each other in space at a suitable distance and orientation to allow[2+2]photocycloaddition triggered by UV−vis irradiation,affording cyclobutanes in the CPs.The single crystal nature of CPs allows their structures to be determined by X-ray diffraction,providing details of the arrangements in space of the C=C double bonds.These CPs are promising platforms for the synthesis of organic molecules,such as cyclobutanes and derivatives,with high regioselectivity and stereoselectivity without any catalyst.The[2+2]photocycloaddition reactions may induce structural modifications like expansion or shrinking of unit cells,resulting in macroscopic changes(e.g.,cracking,bending,etc.)of the whole CP single crystals and leading to changes in chemical and physical properties.Applications take advantage of their optical properties,including luminescence and absorption,and allow the detection of vip molecules and photomechanical motions.Although much effort has been devoted to such studies,it remains challenging to develop systematic investigations aiming at increasing the diversity of CPs and properties to meet practical needs.Moreover,more efficient methods are desirable to investigate the reaction mechanisms in the solid state and monitor the structural changes occurring during the process.In this Account,we introduce our research on the design and applications of photoresponsive CPSCPs.It is divided into three parts.First,the design and construction of various CPs with different olefin ligands are discussed.Through a suitable and sometimes sophisticated choice of metal ions and auxiliary carboxylate ligands,these olefin ligands meet the requirements to undergo[2+2]photocycloaddition reactions in CP structures,allowing for the precise synthesis of cyclobutanes and their derivatives.These compounds could be subsequently extracted from the CPs to give pure organic products.Second,we introduce new strategies,such as a combination of single crystal X-ray diffraction(SCXRD)with thermal/phototreatments of CPs and in situ fluorescence spectroscopy,to monitor the structural changes occurring on the olefin ligands during the reaction.Furthermore,the fast stepwise photoreaction could also be visualized with high resolution.These data significantly strengthen our understanding of solid-state[2+2]photocycloaddition reactions in CPs.Third,applications of photoresponsive CPs are described,which focus on optical and photoinduced mechanical properties.Considering the optical properties,the conjugated structures of the olefin ligands change during the reactions,and circular dichroism(CD)and fluorescence were used for their detection and imaging.Furthermore,the photoinduced mechanical properties of CPs could be significantly expanded through the combination of CP crystals with polymers.Lastly,we point out the challenges and directions for future research in the field.We hope this Account will provide an overview of research on photoresponsive CPSCPs,attract more attention from the community,and inspire future research.
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Support Program(CL6J024)of Xi’an Jiaotong University,the National Natural Science Foundation Youth Program(52203337)Shaanxi Provincial High-Level Talent Plan Youth Project(2023SYJ10)Qin Chuang Yuan High-Level Talents(2021QCYRC4-34).
文摘Presponsive smart organic crystalline materials(SOCMs)have emerged as an attractive research topic because of their many advantages,such as well-defined structures,high structural order,and the resulting fast response speeds,as well as high energy conversion efficiency and remarkable dynamic optical/electronic changes or mechanical responses.In this review,we discuss the recent developments in SOCMs based on topochemistry beyond coordination compounds,which include[2+2]or[4+4]photocycloaddition of anthracene and olefin derivatives as well as 1,4-addition-polymerization of diacetylenes.The detailed design principles and mechanisms associated with smart behavior,photoresponsive physical and chemical properties(i.e.,photochromism,photo fluorochromism,and photodeformation),and structure–property relationships are discussed,along with their advanced applications in exciting fields such as intelligent microrobots,encryption,sensors,photoactua-tors,data storage,and displays.Finally,we summarize the current developments and discuss the major current challenges and future opportunities in this field.We expect that this review will inspire more innovative research into the development of advanced photoresponsive organic smart crystal materials with fast,accurate,and reversible responses,and promote the further development of smart materials and devices.
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_1. 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.
