Pt-rare-earth(PtRE)alloys are considered to be highly promising catalysts for oxygen reduction reaction(ORR)in acidic electrolytes.However,the wet-chemical synthesis of PtRE nanoalloys still faces significant challeng...Pt-rare-earth(PtRE)alloys are considered to be highly promising catalysts for oxygen reduction reaction(ORR)in acidic electrolytes.However,the wet-chemical synthesis of PtRE nanoalloys still faces significant challenges.The precise reaction mechanism for ORR of these catalysts is still unclear on significant aspects involving the rate-determining step and the nature of the ligand effect.Herein,we report a class of solvothermal synthesis of PtRE(RE is Dy or La)nanoalloys.Such PtRE nanoalloys here are active and stable in acidic media,with both high mass activities enhanced by 2-5 times relative to commercial Pt/C catalyst and high stabilities indicative of the little activity decay and negligible structure change after 10,000 cycles.Density functional theory calculations firmly confirm that the ligand effect of RE elements accelerates an O-O bond scission and steers the rate-determining steps from OH^(*)+H^(+)+e-→H_(2)O(on pure Pt surface)to HOOH^(*)+H^(+)+e-→OH^(*)+H_(2)O(on the PtRE nanoalloy surface)for the fast reaction kinetics,which could be fine-tuned by regulating the RE electronic structures and consequently endows the maximal rate of ORR catalysis with PtDy alloy catalysts.展开更多
Electrocatalytic valorization of disused poly(ethylene terephthalate)(PET)plastics into value-added chemicals emerges as a potential approach to address plastic pollution and resources upgrading,but it faces challenge...Electrocatalytic valorization of disused poly(ethylene terephthalate)(PET)plastics into value-added chemicals emerges as a potential approach to address plastic pollution and resources upgrading,but it faces challenges in the development of efficient catalysts for PET-derived ethylene glycol(EG)electrooxidation.Herein,we proposed pyramid arrays on sheet Fe-doped NiO/FeNi_(3)(SPA-NiFeO_(x)/FeNi_(3))heterostructure,which is derived from the pyrolysis of MOF-on-MOF heterostructure growth triggered by graphene quantum dots(GQDs).Such SPA-NiFeO_(x)/FeNi_(3)exhibits superior catalytic performance on the electrooxidation of EG(EGOR)from PET hydrolysate,with a formic acid(FA)selectivity of 91.5%and a Faradaic efficiency of 92%.The ligand effect of GQDs in both the catalyst design and improved electrocatalytic performance was studied with combined spectroscopy analysis and theoretical calculations,which revealed that such spatially separated NiFeO_(x)and FeNi_(3)components by GQDs possess more active sites to anticipate in electrocatalytic EGOR,and the large sp2 domains in GQDs possess a strong electron-withdrawing ability to reduce the electron density of bonded Ni and Fe,resulting in high-valenced Ni^(δ+)/Fe^(δ+)in FeNi_(3)and Ni(2+δ)in NiO,respectively.Furthermore,the coordination number of Ni and Fe centers was lowered due to the steric effect of GQDs.Therefore,the adsorption of EG on Ni^(δ+)for cascade dehydrogenation and C–C bond cleavage led to adsorbed FA that transferred to adjacent Fe for desorption,which was promoted by the enrichment of OH−on nearby Ni^((2+δ))sites,along with optimized Gibbs free energy change in the multistep reaction pathway.This work provides an efficient multi-active-site catalyst for disused PET plastics valorization,thereby presenting a new approach to enhance the efficiency of PET plastics valorization reactions.展开更多
Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developin...Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging.Herein,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the surface.These NWs possess uniform sizes and well-controlled atomic arrangements.Compared to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based catalysts.Additionally,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/C.The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.展开更多
We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed ...We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed by an Ag17 core with C3 symmetry and the remaining 15 Ag atoms bond to each other and coordinate with the 24 surface ligands.When applied as electrocatalyst for CO_(2) reduction reaction(CO_(2)RR),Ag_(32) exhibited the highest Faradaic efficiency(FE)of CO up to 96.44%at−0.8 V with hydrogen evolution being significantly suppressed in a wide potential range,meanwhile it has a reaction rate constant of 0.242 min−1 at room temperature and an activation energy of 45.21 kJ·mol−1 in catalyzing the reduction of 4-nitrophenol,both markedly superior than the thiolate and phosphine ligand co-protected Ag_(32) nanocluster.Such strong ligand effect was further understood by density functional theory(DFT)calculations,as it revealed that,one single ligand stripping off from the intact cluster can create the undercoordinated Ag atom as the catalytically active site for both clusters,but alkynyl-protected Ag_(32) nanocluster possesses a smaller energy barrier for forming the key*COOH intermediate in CO_(2)RR,and favors the adsorption of 4-nitrophenol.This study not only discovers a new member of homoleptic alkynyl-protected Ag nanocluster,but also highlights the great potentials of employing alkynyl-protected Ag nanoclusters as bifunctional catalysts toward various reactions.展开更多
We demonstrate the regioselective growth of Au on Au nanobipyramids,either with etching of the tips,uniform coating except the tips,or forming a single island on the axial tip or an island on the equatorial corner.Imp...We demonstrate the regioselective growth of Au on Au nanobipyramids,either with etching of the tips,uniform coating except the tips,or forming a single island on the axial tip or an island on the equatorial corner.Importantly,the regioselectivity not only arises from the local curvature,as suggested by the recent literature,but also critically depends on the extent of ligand coverage on the seed surface.It is important to consider the competitive growth together with the curvature−ligand interplay:when there are insufficient ligands,they bind preferentially to the sharp tip for high surface energy,so that the remaining growth materials are diverted elsewhere;when the bipyramid is fully covered by ligands,the growth then selectively occurs at the tips because of the larger gaps among the ligands there.Our results demonstrate the great potentials in the rational design and synthesis when constructing sophisticated hybrid structures for functional nanomaterials.展开更多
The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like ...The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like screening model. Association pathway and dissocia-tion pathway were investigated by the comparison of several energies. The cleavage energy of Pd（PR3）2 complex was calculated, as well as the oxidative addition reaction barrier energy of Pd（PR3）n （n=1,2） with aryl bromide in N,N-dimethylformamide solvent. This study proved that the ligands volume possessed a great impact on the mechanism of oxidative addition： less bulky ligand palladium associated with aryl bromide via two donor ligands,but larger bulky ligand palladium coordinated via monoligand.展开更多
The reactivity of the metalloporphyrins was closely related to their ligand effect at axial position. The electronic properties of six model Co（II） porphyrins are investigated by spectral and electrochemical methods...The reactivity of the metalloporphyrins was closely related to their ligand effect at axial position. The electronic properties of six model Co（II） porphyrins are investigated by spectral and electrochemical methods. Structural parameters of the COOI） complexes are directly obtained from their crystal structures. We demonstrate that the unpaired 3d electron of low-spin Co（II） ions in nonplanar Co（II） porphyrin complexes activated by core contraction of porphyrin macrocycles can be further activated by the axial ligation of imidazole. The activated electron can combine with a n orbital of the porphyrin ring to form a new d-π orbital, which can induce the Q-band of Co（II） porphyrins to visibly split. Addition of imidazole causes the Co（II）/Co（III） and Co（II）/Co（I） reactions to shift to more negative potential. Our results indicate that strong axial ligation and core contraction both play important roles in electron transfer in redox catalysis involving Co（II） complexes.展开更多
The stabilities of [M12Ag32（SR）30]4- （M = Ag, Au and SR = SPhF2, SPhCF3, SPhF） clusters having the same structure but different surface ligands or counter cations were systematically studied. It was clearly reveal...The stabilities of [M12Ag32（SR）30]4- （M = Ag, Au and SR = SPhF2, SPhCF3, SPhF） clusters having the same structure but different surface ligands or counter cations were systematically studied. It was clearly revealed that a subtle structural change in the surface ligands or counter cations could significantly alter the overall stability of [M12Ag32（SR）30]4 although they all had an electronic structure of 18-electron superatom shell closure. SPhF2 was found as a better surface ligand than SPhCF3 or SPhF to stabilize [M12Ag32（SR）30]4-. And the use of more bulky [（PPhj）2N]＋ as the counter cations was revealed to be more deleterious to the overall stability of [M12Ag32（SR）30]4- clusters than PPh4＋. [Au12Ag32（SR）30]4- was much more stable than [Ag44（SR）30]4 with the same surface ligands and counter cations. An exceptional stability was observed on （PPh4）4[Au12Ag32（SPhF2）30] which was stable in DMF for more than 8 days in air at 80 ℃. More research efforts are still needed to deeply understand why a small structural change could result in a significant change in the stability of noble metal nanoclusters.展开更多
The ligand effects have been extensively investigated in Au and Ag nanoclusters,while corresponding research efforts focusing on Cu nanoclusters remain relatively insufficient.Such a scarcity could primarily be attrib...The ligand effects have been extensively investigated in Au and Ag nanoclusters,while corresponding research efforts focusing on Cu nanoclusters remain relatively insufficient.Such a scarcity could primarily be attributed to the inherent instability of Cu nanoclusters relative to their Au/Ag analogues.In this work,we report the controllable preparation and structural determination of a hydride-containing Cu28 nanocluster with a chemical formula of Cu_(28)H_(10)(SPh^(p)OMe)_(18)(DPPOE)_(3).The combination of Cu_(28)H_(10)(SPh^(p)OMe)_(18)(DPPOE)_(3)and previously reported Cu_(28)H_(10)(SPh^(o)Me)_(18)(TPP)_(3)constructs a structure-correlated cluster pair with comparable structures and properties.Accordingly,the ligand effects in directing the geometric structures and physicochemical properties(including optical absorptions and catalytic activities towards the selected hydrogenation)of copper nanoclusters were analyzed.Overall,this work presents a structure-correlated Cu_(28)pair that enables the atomic-level under-standing of ligand effects on the structures and properties of metal nanoclusters.展开更多
A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assig...A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assigned to be the best catalyst,with 84%yield and exclusive3,4-selectivity.The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed,which is rarely reported in any copper catalyzed boracarboxylation.The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO_(2).The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation.The“pocket”confinement and suitableβ_(n)(92°–106°)of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex(the catalytic precursor)and1,3-diene substrate to decrease their interaction energyΔE_(int)(ζ)in 3,4-borocupration,thus promoting the 3,4-boracarboxylation.展开更多
The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of ...The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of Y ( Ⅲ) ions on the emission spectra of PMMA ligands in PMMA-Y ( Ⅲ) and the fluorescent enhance- ment of Y( Ⅲ) on Ce( Ⅲ) emission in PMMA-Ce-Y by Y( Ⅲ) ion were studied. It was also of interest to note that when Y ( Ⅲ) ions were added into PMMA and into bpy(bipyridine ) , respectively , the emission spectrum of PMMA ligands was split into fine structure bands by Y ( Ⅲ) , and the fluorescence intensities of bpy ligands in bpy-Y ( Ⅲ) complexes were considerably increased.展开更多
Bimetallic nanoparticles exhibit a synergistic effect that critically depends on their surface composition,but such promotion mechanisms become vague with varying surface compositions.Here,alumina supported Ag@Pd core...Bimetallic nanoparticles exhibit a synergistic effect that critically depends on their surface composition,but such promotion mechanisms become vague with varying surface compositions.Here,alumina supported Ag@Pd core–shell and PdAg alloy structure with controlled size and surface compositions were prepared to demonstrate synergetic mechanisms,particularly,ligand and strain effects on activity and ethylene selectivity for acetylene hydrogenation.The performance evaluation indicates that Ag@Pd catalysts with well-controlled Pd-shell thickness can effectively lower apparent activation energy and improve ethylene selectivity.Hydrogenation activity increases from 0.019 to 0.062 s^(-1) with decreasing Pd-shell thickness under mild conditions,which is 3–6 times higher than their alloyed and monometallic counterparts.Combined characterizations and density functional theory are conducted to reveal such shell-thickness-dependent performance.The ligand effect arising from Ag alloying in the interface of Ag@Pd2ML observes the strongest binding of acetylene,but it diminished sharply and the strain effect gets more prevailing with increasing shell thickness.The competition of ethylene desorption and deephydrogenation were also investigated to understand the selectivity governing factors,and the selectivity descriptor(0.5BE(C_(2)H_(4))–BE(H))was built to match the contribution of ligand and strain effect on the different surfaces of Pd-Ag bimetallic NPs.The exploration of synergetic mechanisms among bimetallic NPs with varied structure and surface compositions in this work can help us to deepen the understanding catalyst structure–activity relationship and provide a feasible way to optimize the overall catalytic performance.展开更多
The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,pe...The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,peptide containing —SH and amino acid containing imidazolyl en- hance the catalytic activity.The effect of imidazole amounts on the catalytic activity of CoTPP is studied.展开更多
The ligand exchange reaction is a typical reaction of ferrocenes. This reaction proceeds via the abstraction of a cyclopentadienyl ring by a Lewis acid followed by coordination of an aromatic compound to the resulting...The ligand exchange reaction is a typical reaction of ferrocenes. This reaction proceeds via the abstraction of a cyclopentadienyl ring by a Lewis acid followed by coordination of an aromatic compound to the resulting species. This reaction with conventional heating requires a long reaction time. Furthermore, the reactions with heterocycles are lower than those with the corresponding hydrocarbons, and do not produce any products in some cases. In this paper, the ligand exchange reaction of ferrocene and a heterocyclic aromatic compound during microwave irradiation and its effect are discussed. As a result, for some heterocycles, the decrease in the reaction time was confirmed. Furthermore, under the microwave irradiation conditions, the tendency in which the difference in their reactivities became low was confirmed.展开更多
A series of drug delivery systems based on a sodium alginate derivative were prepared by mixing glycyrrhetinic acid （GA） and doxorubicin （DOX） conjugates at different ratios. GA （a liver-targeting ligand） and D...A series of drug delivery systems based on a sodium alginate derivative were prepared by mixing glycyrrhetinic acid （GA） and doxorubicin （DOX） conjugates at different ratios. GA （a liver-targeting ligand） and DOX （an antitumor drug） were both conjugated to oligomeric glycol monomethyl ether-modified sodium alginate （ALG-mOEG） for prolonged duration of action. These NP-based delivery systems exhibited active cell uptake and cytotoxicity in vitro and liver-targeted distribution and anti-tumor activity in vivo. In addition, nanoparticles with a 1：1 （W：W） ratio of GA-ALG-mOEG and DOX-ALG-mOEG （NPs-3） showed the highest cellular uptake and cytotoxicity in vitro and liver-targeted distribution and anti-tumor activity in vivo. Specifically, when mixed nanoparticles defined as NPs-3 were injected in mice, liver DOX concentration reached 61.9 μg/g 3 h after injection, and AUC0-∞ and t1/2 of DOX in liver reached 4744.9 μg·h/g and 49.5 h, respectively. In addition, mice receiving a single injection of NPs-3 exhibited much slower tumor growth （88.37% reduction in tumor weight） 16 days after injection compared with placebo. These results indicate that effective cancer treatment may be developed using mixed NP delivery systems with appropriate ratio of targeted ligand and drug.展开更多
We present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex, aiming to elucidate their influences on endocytosis of spherocylindrical nanoparticles （NPs）. It i...We present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex, aiming to elucidate their influences on endocytosis of spherocylindrical nanoparticles （NPs）. It is found that the dimension of ligand-receptor complex （δ） and the depletion effect interrelatedly govern the optimal conditions of NP endocytosis. The endocytosis phase diagram constructed in the space of NP radius and relative aspect ratio indicates that the endocytosis of NP is enhanced evidently by reducing the optimal radius and the threshold radius of endocytosed NP. Meanwhile, through thermodynamic and kinetic analysis of the diffusion of receptors, the dependence of diffusion length on depletion effect and the dimension of ligand-receptor complex can be identified in great detail. For small aspect ratio, diffusion length decreases with increasing concentration c of small bioparticles in cellular environment. Endocytosis speed corresponding to large radius R and high concentration c of small bioparticles strongly depends on the increasing （2r-δ）. These results may show some highlights into the conscious design of NPs for diagnostic agents and therapeutic drug delivery applications.展开更多
Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP ...Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP (enhanced green fluorescent protein) cDNA were linked together with IRES and then inserted into the eukaryotic expression vector pCI-Egr, which was constructed by substituting CMV promoter in pCIneo with the Egr-1 promoter (Egr-EF). The vector was transferred into human bone marrow stromal ...展开更多
Three novel Zn（II） complexes,[Zn4L1Cl4]-3H2O（1）,[Zn4L2Cl4]-2DMF（2） and[Zn4L^3Cl4]H2O（3）,have been synthesized and structurally characterized.In these complexes,interesting 32-membered dodecadentate macrocyclic...Three novel Zn（II） complexes,[Zn4L1Cl4]-3H2O（1）,[Zn4L2Cl4]-2DMF（2） and[Zn4L^3Cl4]H2O（3）,have been synthesized and structurally characterized.In these complexes,interesting 32-membered dodecadentate macrocyclic ligands were generated in situ by ＇2 ＋ 2＇ type condensation reactions between a tetraamine and various dialdehydes.All the complexes are isostructurally tetranuclear Zn（Ⅱ） complexes,containing endogenous alkoxo and phenoxo bridges.Applications of the macrocyclic ligands as Zn^2＋ sensors have been investigated.Take H4L^1 for example,it exhibits a 4-fold fluorescence enhancement upon the addition of 2 equiv.of Zn^2＋ in MeOH.展开更多
目的探究胡黄连苷Ⅱ(PⅡ)调节脂肪酸合成酶(Fas)/脂肪酸合成酶配体(FasL)信号通路对糖尿病肾病(DN)大鼠的治疗作用。方法用高糖高脂喂养联合注射链脲佐菌素(STZ)方法构建DN大鼠模型。将DN大鼠分为模型组(DN组)、PⅡ低、中、高剂量组(P-...目的探究胡黄连苷Ⅱ(PⅡ)调节脂肪酸合成酶(Fas)/脂肪酸合成酶配体(FasL)信号通路对糖尿病肾病(DN)大鼠的治疗作用。方法用高糖高脂喂养联合注射链脲佐菌素(STZ)方法构建DN大鼠模型。将DN大鼠分为模型组(DN组)、PⅡ低、中、高剂量组(P-L组、P-M组、P-H组)、P II高剂量组+Fas重组蛋白组(P-H+rh-Fas组),另选健康大鼠作Control组,每组18只。检测大鼠空腹血糖(FBG)、体质量、24 h尿蛋白(24 h UTP)、肾功能(SCr、BUN);用HE染色和Masson染色观察各组大鼠肾组织病理变化;Western blot检测RAGE、COL-Ⅳ和通路蛋白表达。结果与Control组比较,DN组大鼠肾小球基底膜增厚,系膜增生,肾小管变性、扩张、萎缩,有脂肪变性,大量胶原沉积,FBG、24 h UTP、SCr、BUN、TNF-α、IL-6、IL-1β水平上升,体质量下降,RAGE、COL-Ⅳ、Fas、FasL表达升高(P<0.05);与DN组比较,P-L、P-M、P-H组肾小球、肾小管病变减轻,胶原沉积减少,FBG、24 h UTP、SCr、BUN、TNF-α、IL-6、IL-1β水平降低,体质量上升,RAGE、COL-Ⅳ、Fas、FasL表达下降(P<0.05);与P-H组相比,P-H+rh-Fas组肾组织病变加重,FBG、24 h UTP、SCr、BUN、TNF-α、IL-6、IL-1β水平升高,体质量降低,RAGE、COL-Ⅳ、Fas、Fas L表达上升(P<0.05)。结论胡黄连苷Ⅱ通过抑制Fas/Fas L信号通路发挥对DN大鼠的治疗作用。展开更多
基金supported by the National Natural Science Foundation of China(No.21975151)China Postdoctoral Science Foundation(No.2023M733452).
文摘Pt-rare-earth(PtRE)alloys are considered to be highly promising catalysts for oxygen reduction reaction(ORR)in acidic electrolytes.However,the wet-chemical synthesis of PtRE nanoalloys still faces significant challenges.The precise reaction mechanism for ORR of these catalysts is still unclear on significant aspects involving the rate-determining step and the nature of the ligand effect.Herein,we report a class of solvothermal synthesis of PtRE(RE is Dy or La)nanoalloys.Such PtRE nanoalloys here are active and stable in acidic media,with both high mass activities enhanced by 2-5 times relative to commercial Pt/C catalyst and high stabilities indicative of the little activity decay and negligible structure change after 10,000 cycles.Density functional theory calculations firmly confirm that the ligand effect of RE elements accelerates an O-O bond scission and steers the rate-determining steps from OH^(*)+H^(+)+e-→H_(2)O(on pure Pt surface)to HOOH^(*)+H^(+)+e-→OH^(*)+H_(2)O(on the PtRE nanoalloy surface)for the fast reaction kinetics,which could be fine-tuned by regulating the RE electronic structures and consequently endows the maximal rate of ORR catalysis with PtDy alloy catalysts.
基金support from the National Natural Science Foundation of China(Grant No.22102140the Natural Science Foundation of Jiangsu Province(Grant No.BK20211602)+1 种基金the Qing Lan Project of Yangzhou Universitythe Postgraduate Research&Practice Innovation Program of Jiangsu Province(Yangzhou University,Grant No.SJCX23_1911).
文摘Electrocatalytic valorization of disused poly(ethylene terephthalate)(PET)plastics into value-added chemicals emerges as a potential approach to address plastic pollution and resources upgrading,but it faces challenges in the development of efficient catalysts for PET-derived ethylene glycol(EG)electrooxidation.Herein,we proposed pyramid arrays on sheet Fe-doped NiO/FeNi_(3)(SPA-NiFeO_(x)/FeNi_(3))heterostructure,which is derived from the pyrolysis of MOF-on-MOF heterostructure growth triggered by graphene quantum dots(GQDs).Such SPA-NiFeO_(x)/FeNi_(3)exhibits superior catalytic performance on the electrooxidation of EG(EGOR)from PET hydrolysate,with a formic acid(FA)selectivity of 91.5%and a Faradaic efficiency of 92%.The ligand effect of GQDs in both the catalyst design and improved electrocatalytic performance was studied with combined spectroscopy analysis and theoretical calculations,which revealed that such spatially separated NiFeO_(x)and FeNi_(3)components by GQDs possess more active sites to anticipate in electrocatalytic EGOR,and the large sp2 domains in GQDs possess a strong electron-withdrawing ability to reduce the electron density of bonded Ni and Fe,resulting in high-valenced Ni^(δ+)/Fe^(δ+)in FeNi_(3)and Ni(2+δ)in NiO,respectively.Furthermore,the coordination number of Ni and Fe centers was lowered due to the steric effect of GQDs.Therefore,the adsorption of EG on Ni^(δ+)for cascade dehydrogenation and C–C bond cleavage led to adsorbed FA that transferred to adjacent Fe for desorption,which was promoted by the enrichment of OH−on nearby Ni^((2+δ))sites,along with optimized Gibbs free energy change in the multistep reaction pathway.This work provides an efficient multi-active-site catalyst for disused PET plastics valorization,thereby presenting a new approach to enhance the efficiency of PET plastics valorization reactions.
基金the National Natural Science Foundation of China(No.22275009)SINOPEC(contact No.421028)Fundamental Research Funds for the Central Universities(No.XK2020-02).
文摘Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging.Herein,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the surface.These NWs possess uniform sizes and well-controlled atomic arrangements.Compared to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based catalysts.Additionally,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/C.The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.
基金supported by the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications(No.2021A07)support from Guangdong Natural Science Funds(No.2022A1515011840)+2 种基金the National Natural Science Foundation of China(No.21805170)the National Natural Science Foundation of China(No.21903008)the Chongqing Science and Technology Commission(No.cstc2020jcyj-msxmX0382).
文摘We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed by an Ag17 core with C3 symmetry and the remaining 15 Ag atoms bond to each other and coordinate with the 24 surface ligands.When applied as electrocatalyst for CO_(2) reduction reaction(CO_(2)RR),Ag_(32) exhibited the highest Faradaic efficiency(FE)of CO up to 96.44%at−0.8 V with hydrogen evolution being significantly suppressed in a wide potential range,meanwhile it has a reaction rate constant of 0.242 min−1 at room temperature and an activation energy of 45.21 kJ·mol−1 in catalyzing the reduction of 4-nitrophenol,both markedly superior than the thiolate and phosphine ligand co-protected Ag_(32) nanocluster.Such strong ligand effect was further understood by density functional theory(DFT)calculations,as it revealed that,one single ligand stripping off from the intact cluster can create the undercoordinated Ag atom as the catalytically active site for both clusters,but alkynyl-protected Ag_(32) nanocluster possesses a smaller energy barrier for forming the key*COOH intermediate in CO_(2)RR,and favors the adsorption of 4-nitrophenol.This study not only discovers a new member of homoleptic alkynyl-protected Ag nanocluster,but also highlights the great potentials of employing alkynyl-protected Ag nanoclusters as bifunctional catalysts toward various reactions.
基金support from the National Natural Science Foundation of China General Program(No.21673117,H.C.)Major Program(No.91956109,H.C.)+2 种基金Zhejiang Provincial Natural Science Foundation of China Major Program(No.2022XHSJJ002,H.C.)Jiangsu Science and Technology Plan(BK20211258)Start-up Fund from Westlake University.
文摘We demonstrate the regioselective growth of Au on Au nanobipyramids,either with etching of the tips,uniform coating except the tips,or forming a single island on the axial tip or an island on the equatorial corner.Importantly,the regioselectivity not only arises from the local curvature,as suggested by the recent literature,but also critically depends on the extent of ligand coverage on the seed surface.It is important to consider the competitive growth together with the curvature−ligand interplay:when there are insufficient ligands,they bind preferentially to the sharp tip for high surface energy,so that the remaining growth materials are diverted elsewhere;when the bipyramid is fully covered by ligands,the growth then selectively occurs at the tips because of the larger gaps among the ligands there.Our results demonstrate the great potentials in the rational design and synthesis when constructing sophisticated hybrid structures for functional nanomaterials.
基金This work was supported by the National Natural Science Foundation of China （No.20776089） and the New Century Excellent Talents Program of Ministry of Education （No.NCET-05-0783）. The State Key Laboratory of Polymer Materials Engineering in Sichuan University was acknowledged for providing dmol3 modules and Prof. Ying Xue, Xiang-yuan Li, and Quan Zhu were grateful for the useful discussions.
文摘The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like screening model. Association pathway and dissocia-tion pathway were investigated by the comparison of several energies. The cleavage energy of Pd（PR3）2 complex was calculated, as well as the oxidative addition reaction barrier energy of Pd（PR3）n （n=1,2） with aryl bromide in N,N-dimethylformamide solvent. This study proved that the ligands volume possessed a great impact on the mechanism of oxidative addition： less bulky ligand palladium associated with aryl bromide via two donor ligands,but larger bulky ligand palladium coordinated via monoligand.
基金This work was supported by the National Natural Science Foundation of China （No. 21575166, and 21372069）, and the Scientific Research Fund of Hunan Provincial Education Department （No. 15K042）.
文摘The reactivity of the metalloporphyrins was closely related to their ligand effect at axial position. The electronic properties of six model Co（II） porphyrins are investigated by spectral and electrochemical methods. Structural parameters of the COOI） complexes are directly obtained from their crystal structures. We demonstrate that the unpaired 3d electron of low-spin Co（II） ions in nonplanar Co（II） porphyrin complexes activated by core contraction of porphyrin macrocycles can be further activated by the axial ligation of imidazole. The activated electron can combine with a n orbital of the porphyrin ring to form a new d-π orbital, which can induce the Q-band of Co（II） porphyrins to visibly split. Addition of imidazole causes the Co（II）/Co（III） and Co（II）/Co（I） reactions to shift to more negative potential. Our results indicate that strong axial ligation and core contraction both play important roles in electron transfer in redox catalysis involving Co（II） complexes.
基金the MOST of China(No.2011CB932403)the NSFC of China(Nos.21131005,21390390,21333008) for financial support
文摘The stabilities of [M12Ag32（SR）30]4- （M = Ag, Au and SR = SPhF2, SPhCF3, SPhF） clusters having the same structure but different surface ligands or counter cations were systematically studied. It was clearly revealed that a subtle structural change in the surface ligands or counter cations could significantly alter the overall stability of [M12Ag32（SR）30]4 although they all had an electronic structure of 18-electron superatom shell closure. SPhF2 was found as a better surface ligand than SPhCF3 or SPhF to stabilize [M12Ag32（SR）30]4-. And the use of more bulky [（PPhj）2N]＋ as the counter cations was revealed to be more deleterious to the overall stability of [M12Ag32（SR）30]4- clusters than PPh4＋. [Au12Ag32（SR）30]4- was much more stable than [Ag44（SR）30]4 with the same surface ligands and counter cations. An exceptional stability was observed on （PPh4）4[Au12Ag32（SPhF2）30] which was stable in DMF for more than 8 days in air at 80 ℃. More research efforts are still needed to deeply understand why a small structural change could result in a significant change in the stability of noble metal nanoclusters.
基金support of the NNSFC(22371003,22101001,and 22373082)the Ministry of Education,the University Synergy Innovation Program of Anhui Province(GXXT-2020-053)+1 种基金the Scientific Research Program of Universities in Anhui Province(2022AH030009)the Scientific Research Fund of Hunan Provincial Education Department(22B0154).
文摘The ligand effects have been extensively investigated in Au and Ag nanoclusters,while corresponding research efforts focusing on Cu nanoclusters remain relatively insufficient.Such a scarcity could primarily be attributed to the inherent instability of Cu nanoclusters relative to their Au/Ag analogues.In this work,we report the controllable preparation and structural determination of a hydride-containing Cu28 nanocluster with a chemical formula of Cu_(28)H_(10)(SPh^(p)OMe)_(18)(DPPOE)_(3).The combination of Cu_(28)H_(10)(SPh^(p)OMe)_(18)(DPPOE)_(3)and previously reported Cu_(28)H_(10)(SPh^(o)Me)_(18)(TPP)_(3)constructs a structure-correlated cluster pair with comparable structures and properties.Accordingly,the ligand effects in directing the geometric structures and physicochemical properties(including optical absorptions and catalytic activities towards the selected hydrogenation)of copper nanoclusters were analyzed.Overall,this work presents a structure-correlated Cu_(28)pair that enables the atomic-level under-standing of ligand effects on the structures and properties of metal nanoclusters.
基金the National Key R&D Program of China(No.2022YFB4101900)National Natural Science Foundation of China(Nos.22278305,U21B2096)Natural Science Foundation of Tianjin City(No.23JCZDJC00040)。
文摘A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assigned to be the best catalyst,with 84%yield and exclusive3,4-selectivity.The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed,which is rarely reported in any copper catalyzed boracarboxylation.The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO_(2).The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation.The“pocket”confinement and suitableβ_(n)(92°–106°)of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex(the catalytic precursor)and1,3-diene substrate to decrease their interaction energyΔE_(int)(ζ)in 3,4-borocupration,thus promoting the 3,4-boracarboxylation.
文摘The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of Y ( Ⅲ) ions on the emission spectra of PMMA ligands in PMMA-Y ( Ⅲ) and the fluorescent enhance- ment of Y( Ⅲ) on Ce( Ⅲ) emission in PMMA-Ce-Y by Y( Ⅲ) ion were studied. It was also of interest to note that when Y ( Ⅲ) ions were added into PMMA and into bpy(bipyridine ) , respectively , the emission spectrum of PMMA ligands was split into fine structure bands by Y ( Ⅲ) , and the fluorescence intensities of bpy ligands in bpy-Y ( Ⅲ) complexes were considerably increased.
基金supported by National Key Research&Development Program of China (2022YFA1506200)the National Natural Science Foundations of China (22078007, 21627813, 21706009,22002085)+3 种基金Guangdong Basic and Applied Basic Research Foundation (2020A1515110832)the Fundamental Research Funds for the Central Universities (buctrc201921, JD2223)Innovative Achievement Commercialization Service-Platform of Industrial CatalysisChemistry and Chemical Engineering Guangdong Laboratory for a startup funding support(2111001)
文摘Bimetallic nanoparticles exhibit a synergistic effect that critically depends on their surface composition,but such promotion mechanisms become vague with varying surface compositions.Here,alumina supported Ag@Pd core–shell and PdAg alloy structure with controlled size and surface compositions were prepared to demonstrate synergetic mechanisms,particularly,ligand and strain effects on activity and ethylene selectivity for acetylene hydrogenation.The performance evaluation indicates that Ag@Pd catalysts with well-controlled Pd-shell thickness can effectively lower apparent activation energy and improve ethylene selectivity.Hydrogenation activity increases from 0.019 to 0.062 s^(-1) with decreasing Pd-shell thickness under mild conditions,which is 3–6 times higher than their alloyed and monometallic counterparts.Combined characterizations and density functional theory are conducted to reveal such shell-thickness-dependent performance.The ligand effect arising from Ag alloying in the interface of Ag@Pd2ML observes the strongest binding of acetylene,but it diminished sharply and the strain effect gets more prevailing with increasing shell thickness.The competition of ethylene desorption and deephydrogenation were also investigated to understand the selectivity governing factors,and the selectivity descriptor(0.5BE(C_(2)H_(4))–BE(H))was built to match the contribution of ligand and strain effect on the different surfaces of Pd-Ag bimetallic NPs.The exploration of synergetic mechanisms among bimetallic NPs with varied structure and surface compositions in this work can help us to deepen the understanding catalyst structure–activity relationship and provide a feasible way to optimize the overall catalytic performance.
文摘The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,peptide containing —SH and amino acid containing imidazolyl en- hance the catalytic activity.The effect of imidazole amounts on the catalytic activity of CoTPP is studied.
文摘The ligand exchange reaction is a typical reaction of ferrocenes. This reaction proceeds via the abstraction of a cyclopentadienyl ring by a Lewis acid followed by coordination of an aromatic compound to the resulting species. This reaction with conventional heating requires a long reaction time. Furthermore, the reactions with heterocycles are lower than those with the corresponding hydrocarbons, and do not produce any products in some cases. In this paper, the ligand exchange reaction of ferrocene and a heterocyclic aromatic compound during microwave irradiation and its effect are discussed. As a result, for some heterocycles, the decrease in the reaction time was confirmed. Furthermore, under the microwave irradiation conditions, the tendency in which the difference in their reactivities became low was confirmed.
基金financially supported by the National Natural Science Foundation of China(Nos.51073080 and 51273095)Natural Science Foundation of Tianjin(No.13JCYBJC25100)and PCSIRT(No.IRT1257)
文摘A series of drug delivery systems based on a sodium alginate derivative were prepared by mixing glycyrrhetinic acid （GA） and doxorubicin （DOX） conjugates at different ratios. GA （a liver-targeting ligand） and DOX （an antitumor drug） were both conjugated to oligomeric glycol monomethyl ether-modified sodium alginate （ALG-mOEG） for prolonged duration of action. These NP-based delivery systems exhibited active cell uptake and cytotoxicity in vitro and liver-targeted distribution and anti-tumor activity in vivo. In addition, nanoparticles with a 1：1 （W：W） ratio of GA-ALG-mOEG and DOX-ALG-mOEG （NPs-3） showed the highest cellular uptake and cytotoxicity in vitro and liver-targeted distribution and anti-tumor activity in vivo. Specifically, when mixed nanoparticles defined as NPs-3 were injected in mice, liver DOX concentration reached 61.9 μg/g 3 h after injection, and AUC0-∞ and t1/2 of DOX in liver reached 4744.9 μg·h/g and 49.5 h, respectively. In addition, mice receiving a single injection of NPs-3 exhibited much slower tumor growth （88.37% reduction in tumor weight） 16 days after injection compared with placebo. These results indicate that effective cancer treatment may be developed using mixed NP delivery systems with appropriate ratio of targeted ligand and drug.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11047022,11204045,and 11464004)the Tracking Key Program of Social Development of Guizhou Province,China(Grant Nos.SY20123089 and SZ20113069)+2 种基金the General Financial Grant from the China Postdoctoral Science Foundation(Grant No.2014M562341)the Research Foundation for Young University Teachers from Guizhou University(Grant No.201311)the College Innovation Talent Team of Guizhou Province,China(Grant No.(2014)32)
文摘We present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex, aiming to elucidate their influences on endocytosis of spherocylindrical nanoparticles （NPs）. It is found that the dimension of ligand-receptor complex （δ） and the depletion effect interrelatedly govern the optimal conditions of NP endocytosis. The endocytosis phase diagram constructed in the space of NP radius and relative aspect ratio indicates that the endocytosis of NP is enhanced evidently by reducing the optimal radius and the threshold radius of endocytosed NP. Meanwhile, through thermodynamic and kinetic analysis of the diffusion of receptors, the dependence of diffusion length on depletion effect and the dimension of ligand-receptor complex can be identified in great detail. For small aspect ratio, diffusion length decreases with increasing concentration c of small bioparticles in cellular environment. Endocytosis speed corresponding to large radius R and high concentration c of small bioparticles strongly depends on the increasing （2r-δ）. These results may show some highlights into the conscious design of NPs for diagnostic agents and therapeutic drug delivery applications.
基金National Natural Science Foundation of China(No 39900040)Natiorlal Natural Science Outstanding Youth Foundation of China(No 39825111).
文摘Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP (enhanced green fluorescent protein) cDNA were linked together with IRES and then inserted into the eukaryotic expression vector pCI-Egr, which was constructed by substituting CMV promoter in pCIneo with the Egr-1 promoter (Egr-EF). The vector was transferred into human bone marrow stromal ...
基金financially supported by NSFC,the Program for Professor of Special Appointment(Eastern Scholar) at Shanghai Institutions of Higher Learning,Program for New Century Excellent Talents in University(No.NCET-11-0638)Innovation Program of Shanghai Municipal Education Commission,the Fundamental Research Funds for the Central Universities(No.WK1013002)+1 种基金SRFDP(No.20100074110015)S.W.Ng is grateful for support by the University of Malaya(No.UM.C/625/1/H1R/033/10)
文摘Three novel Zn（II） complexes,[Zn4L1Cl4]-3H2O（1）,[Zn4L2Cl4]-2DMF（2） and[Zn4L^3Cl4]H2O（3）,have been synthesized and structurally characterized.In these complexes,interesting 32-membered dodecadentate macrocyclic ligands were generated in situ by ＇2 ＋ 2＇ type condensation reactions between a tetraamine and various dialdehydes.All the complexes are isostructurally tetranuclear Zn（Ⅱ） complexes,containing endogenous alkoxo and phenoxo bridges.Applications of the macrocyclic ligands as Zn^2＋ sensors have been investigated.Take H4L^1 for example,it exhibits a 4-fold fluorescence enhancement upon the addition of 2 equiv.of Zn^2＋ in MeOH.
文摘目的探究胡黄连苷Ⅱ(PⅡ)调节脂肪酸合成酶(Fas)/脂肪酸合成酶配体(FasL)信号通路对糖尿病肾病(DN)大鼠的治疗作用。方法用高糖高脂喂养联合注射链脲佐菌素(STZ)方法构建DN大鼠模型。将DN大鼠分为模型组(DN组)、PⅡ低、中、高剂量组(P-L组、P-M组、P-H组)、P II高剂量组+Fas重组蛋白组(P-H+rh-Fas组),另选健康大鼠作Control组,每组18只。检测大鼠空腹血糖(FBG)、体质量、24 h尿蛋白(24 h UTP)、肾功能(SCr、BUN);用HE染色和Masson染色观察各组大鼠肾组织病理变化;Western blot检测RAGE、COL-Ⅳ和通路蛋白表达。结果与Control组比较,DN组大鼠肾小球基底膜增厚,系膜增生,肾小管变性、扩张、萎缩,有脂肪变性,大量胶原沉积,FBG、24 h UTP、SCr、BUN、TNF-α、IL-6、IL-1β水平上升,体质量下降,RAGE、COL-Ⅳ、Fas、FasL表达升高(P<0.05);与DN组比较,P-L、P-M、P-H组肾小球、肾小管病变减轻,胶原沉积减少,FBG、24 h UTP、SCr、BUN、TNF-α、IL-6、IL-1β水平降低,体质量上升,RAGE、COL-Ⅳ、Fas、FasL表达下降(P<0.05);与P-H组相比,P-H+rh-Fas组肾组织病变加重,FBG、24 h UTP、SCr、BUN、TNF-α、IL-6、IL-1β水平升高,体质量降低,RAGE、COL-Ⅳ、Fas、Fas L表达上升(P<0.05)。结论胡黄连苷Ⅱ通过抑制Fas/Fas L信号通路发挥对DN大鼠的治疗作用。
