A microfluidic system was developed for the synthesis of trigonal selenium（t-Se） nanowires, which was composed of a glass microchip coupled with a poly（methyl methacrylate）（PMMA） microchip. In the glass microchi...A microfluidic system was developed for the synthesis of trigonal selenium（t-Se） nanowires, which was composed of a glass microchip coupled with a poly（methyl methacrylate）（PMMA） microchip. In the glass microchip, amorphous selenium（a-Se） colloid was prepared by reducing selenious acid with an excess amount of hydrazine at a temperature of 100 ℃. In the coupled PMMA microchip, a-Se was transformed into more stable t-Se seeds via sonication at room temperature. The residence time of the reactants in both microchips was optimized by varying the dimension and length of the microchannel each. The t-Se nanowires were formed by anisotropic growth of selenium crystallite during sonication and aging under the assistance of β-cyclodextrin（β-CD）. Various stages of the nanowires＇ growth were investigated. The as-synthesized products were characterized by powder X-Ray diffraction（XRD）, Raman spectroscopy, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and selected-area electron diffraction（SAED）.展开更多
A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr3+, Cu2+, glycine and imidazole in aqueous solution and characterized by X-ray structure ...A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr3+, Cu2+, glycine and imidazole in aqueous solution and characterized by X-ray structure analysis. The compound belongs to the trigonal R3 space group with a = b = 15.8761(2), c = 23.4943(5) ?, V = 5128.4(1) ?3, Z = 3, Dc = 1.965 g/cm3, μ = 2.869 mm-1, F(000) = 3012, the final R = 0.0332 and wR = 0.0844 for 3596 independent reflections. In the cation, the Pr3+ ion is situated at the center of a prism formed by six copper atoms and coordinates to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycine ligands and six imidazole terminal ligands participate in constructing the cluster.展开更多
With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes....With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes. Rectification behavior can be observed when the electrode-molecule contact distance is larger than 2.2 Å. The electronic transport is greatly improved in case of Fe terminal which is analyzed in terms of transmission spectra and density of states.展开更多
Six trigonal prismatic metallocages(TPMs)composed of 24 components,namely{(Cu_(3)L_(3))(Cu_(2)X_(2))_(3)(Cu_(3)L_(3))}·xG(HL=4-(quinoline-8-thio)-3,5-dimethyl-1H-pyrazole,G=benzene(B),methylbenzene(MB),1,3,5-trip...Six trigonal prismatic metallocages(TPMs)composed of 24 components,namely{(Cu_(3)L_(3))(Cu_(2)X_(2))_(3)(Cu_(3)L_(3))}·xG(HL=4-(quinoline-8-thio)-3,5-dimethyl-1H-pyrazole,G=benzene(B),methylbenzene(MB),1,3,5-triphenylbenzene(TPB),x=3 for B,MB and 1 for TPB),are reported.They were constructed by three rhombicCu_(2)X_(2)units as columns connecting two planar syn-Cu_(3)L_(3)faces,templated by G molecules.The structural analysis and EDA calculations reveal that C-H…πdominate their host-vip interactions.展开更多
This article presents a series of six mononuclear Co(II)complexes 1-6 featuring ligands derived from a hexadentate Schiff base family,originating from the condensation of(2-formylphenoxy)acetic acid with various diami...This article presents a series of six mononuclear Co(II)complexes 1-6 featuring ligands derived from a hexadentate Schiff base family,originating from the condensation of(2-formylphenoxy)acetic acid with various diamines.Notably,these complexes uniquely prefer a trigonal prism geometry,presenting a novel approach to synthesizing complexes with this distinctive shape.The compounds were characterized by elemental analysis,FT-IR spectroscopy,and single-crystal and powder XRD techniques.Furthermore,the magnetism was investigated by DC and AC magnetic measurements and also complemented by X-band EPR spectroscopy.The results reveal that the prepared complexes behave as field-induced single-molecule magnets,characterized by a substantial negative axial zero-field splitting D-parameter and spin reversal energetic barrier U_(eff) reaching values up to 72 K.The theoretical methods based on CASSCF/NEVPT2 calculations were applied to rationalize their magnetic properties.Moreover,these complexes hold promising potential for further functionalization,offering opportunities to enhance their properties,particularly towards developing zero-field single-molecule magnets as evidenced by the slow relaxation of magnetization in zero static magnetic field observed for the zinc-diluted complex 1Zn.展开更多
Open metal sites are devised to dangle on cobalt trigonal prismatic secondary building units(SBUs)of a porous MOF,when a rigid octacarboxylate ligand,1,_(3),6,8-tetra(_(3),5-dicarboxylphenyl)pyrene,assembled with Co(N...Open metal sites are devised to dangle on cobalt trigonal prismatic secondary building units(SBUs)of a porous MOF,when a rigid octacarboxylate ligand,1,_(3),6,8-tetra(_(3),5-dicarboxylphenyl)pyrene,assembled with Co(NO_(3))_(2)under solvothermal conditions.The functional role of dangled open metal sites is exploited for CO_(2)capture studies.展开更多
The engineering of Cr(Ⅱ) complexes for spin crossover (SCO) phenomena remains poorly understood,primarily due to the limited number of reported examples and the associated challenges in their synthesis.In the context...The engineering of Cr(Ⅱ) complexes for spin crossover (SCO) phenomena remains poorly understood,primarily due to the limited number of reported examples and the associated challenges in their synthesis.In the context of Cr(Ⅱ) complexes with octahedral geometry,the pronounced Jahn–Teller distortion in the high-spin (HS) state significantly restricts the selection of co-ligands necessary for SCO to occur.In this study,we successfully synthesized a series of air-stable and solvent-free Cr(Ⅱ) complexes,[Cr(Tpm^(R))_(2)]X^(2)(Tpm^(R)= Tpm:X=[BF_(4)]^(−),1;X=[ClO_(4)]^(−),2;Tpm^(R)= Tpm:X=[BF_(4)]^(−),3;X=[ClO_(4)]^(−),4),where the Cr(Ⅱ) ions adopt a trigonal antiprism (aTPR) geometry rather than the conventional octahedral configuration.Notably,the Tpm-based complexes 1 and 2,with Cr(Ⅱ) ions in a nearly ideal aTPR geometry,exhibit complete SCO behavior with transition temperatures (T_(1/2)) of 190 K for 1 and 194 K for 2,respectively.In contrast,the Tpm-based complexes 3 and 4 display considerable axial elongation within the aTPR structure,leading to abrupt but incomplete SCO transition at a much lower temperature for 3 (T_(1/2)= 142 K) while 4 remains predominantly in the HS state.Further structural analysis reveals that substituting [BF_(4)]^(−)with [ClO_(4)]^(−)in 4 results in increased elongation and a denser packing arrangement that disfavour the spin transition.Our findings suggest that the aTPR configuration is advantageous for facilitating spin crossover,while the dynamics of spin transitions in these complexes are closely linked to the structural distortions of the [Cr(Tpm^(R))_(2)]^(2+)cations.Furthermore,all complexes demonstrate remarkable resistance to oxygen and maintain air stability,which can be attributed to their compact space-filling structures that effectively impede the diffusion of oxygen into the interstitial regions of the crystal lattice.展开更多
The mononuclear cobalt(Ⅱ)complexes[Co(LN_(8))](BPh_(4))_(2)·C_(4)H_(10O)(1-BPh_(4))and[Co(LN_(8))](NO_(3))_(2)·CH_(3)CN(2-NO_(3))(LN_(8)=1,4,7,10-tetrakis(2-pyridinemethyl)-1,4,7,10-tetraaza-cyclododecane)h...The mononuclear cobalt(Ⅱ)complexes[Co(LN_(8))](BPh_(4))_(2)·C_(4)H_(10O)(1-BPh_(4))and[Co(LN_(8))](NO_(3))_(2)·CH_(3)CN(2-NO_(3))(LN_(8)=1,4,7,10-tetrakis(2-pyridinemethyl)-1,4,7,10-tetraaza-cyclododecane)have been synthesized and fully characterized.They differ well beyond a formal replacement of the counter anions,with their Co(Ⅱ)centers in significantly different coordination geometries.In 1-BPh_(4),the Co(Ⅱ)ion is not only coordinated by six N atoms from the LN_(8) ligand but also associated with the two remaining N atoms of LN_(8) via weak interactions.In contrast,the Co(Ⅱ)ion in 2-NO_(3) is only six-coordinated in a distorted trigonal prismatic geometry.Magnetic anisotropy and slow magnetic dynamics are drastically affected by these different environments around Co(Ⅱ).The combination of dc magnetic data,high-frequency and-field electron paramagnetic resonance(HFEPR)and theoretical calculations unambiguously reveals large negative zero-field split(ZFS)parameters D for both complexes and a large difference between the D values.Both 1-BPh_(4) and 2-NO_(3) show slow magnetic relaxation at zero field.Magnetic dilution experiments reveal effective energy barriers of 54(4)cm^(-1) for 1-BPh_(4)@Zn and 95(5)cm^(-1) for 2-NO_(3)@Zn and confirm that the slow magnetic relaxation for both complexes originates from single molecule behaviour.Ab initio computational studies explain their electronic structures and the origin of the large negative magnetic anisotropy;they support the corresponding experimental observations.Further magneto-structural analyses reveal that different distortions from the ideal trigonal prismatic geometry exert drastic effects on D values and slow relaxation,and that the additional weak intramolecular interactions between Co and N reduce the axial anisotropy.展开更多
Low-symmetry metal-organic cages(MOCs)have received increasing attention due to their complex structures and more advanced functions.Here,we report a new MOC cage with a unique trigonal bipyramidal configuration,[M_(5...Low-symmetry metal-organic cages(MOCs)have received increasing attention due to their complex structures and more advanced functions.Here,we report a new MOC cage with a unique trigonal bipyramidal configuration,[M_(5)L_(6)],constructed via the combination effects of coordination bonds and π…π interactions.A series of structures(BIF-136 to BIF-141)based on this[M_(5)L_(6)]cage were synthesized by the self-assembly of BH(bim)_(3)-ligands and Ni(II)ions under various solvothermal conditions.Each[M_(5)L_(6)]consists of two[M_(4)L_(3)]defective cubic cages sharing three metal nodes,which include two geometric types of flexible Ni(Ⅱ)centers(tetrahedral and octahedral).Benefiting from these modifiable metal centers,these cage-based crystals realized abundant coordination environments and a dimension transition from a 0D cage to a 1D cage-based chain,accompanied by modulations of conjugation degrees,electronic push-pull effects and band gaps.Due to their diverse structural features,we have systematically investigated their third-order nonlinear optical(NLO)properties.To our surprise,these structures show a typical reverse saturated absorption(RSA)response.In particular,BIF-141 achieves excellent optical limiting(OL)performance with a low minimum normalized transmittance(T_(min))of 0.20.This study not only provides a new strategy for constructing low-symmetry cages but also contributes to the understanding of the mechanism of their optical applications.展开更多
Hybrid perovskites have attracted enormous attention in the next generation resistive switching(RS)memristor for the artificial synapses,owing to their ambipolar charge transport,long diffusion length,and tunable visi...Hybrid perovskites have attracted enormous attention in the next generation resistive switching(RS)memristor for the artificial synapses,owing to their ambipolar charge transport,long diffusion length,and tunable visible bandgap.However,the variable switch,limited reproducibility,and poor endurance are the obstacles to the practical application of the perovskite memristors.Herein,we reported a multilevel RS nonvolatile memory based on a 3D trigonal HC(NH_(2))_(2)PbI_(3)(α‐FAPbI_(3))perovskite layer modified by 1‐cyanobutyl‐3‐methylimidazolium chloride([CNBmim]Cl)and sandwiched between ITO and Au electrodes(Au/[CNBmim]Cl/α‐FAPbI_(3)/SnO_(2)/ITO).In contrast to the bare memristor with failure switching from low resistance state(LRS)to high resistance state(HRS),the memristor device based on theα‐FAPbI_(3) modified with[CNBmim]Cl(Target device)shows the retention time over 10^(4) s with On/Off ratio(>10^(2))and endurance up to 550 cycles.The stable RS cycle benefits from the accelerated electrons de‐trapping from the reduced defects and fast charge separation in the interface ofα‐FAPbI_(3)/electrode,leading to the rupture of conductive filaments and transition of LRS to HRS.As a two‐terminal analog synaptic device,the target device can realize random handwritten digit recognition with an impressive accuracy of 89.3%on the condition of low learning phases(500 training cycles).展开更多
α-RuCl_(3)is a tantalizing playground to search for the quantum spin liquid states with leading Kitaev term due to the conformation of Jackeli-Khaliullin mechanism.Suppressing the non-Kitaev interaction to approach t...α-RuCl_(3)is a tantalizing playground to search for the quantum spin liquid states with leading Kitaev term due to the conformation of Jackeli-Khaliullin mechanism.Suppressing the non-Kitaev interaction to approach the Kitaev limit is the major objective in the experimental design of Kitaev-Jackeli-Khaliullin materials,for which the practical feasibility rests on the manipulation of the exact crystalline structure.A tensile strain,leading to the further compressive trigonal field splitting which would alter the spin-orbital entangled character and tune the intrinsic hopping exchanges,has been widely proposed as the promising strategy to enhance the comparative Kitaev interaction.In this work,we preform in-depth Scan Tunneling Microscope study on the electronic patterns of strainedα-RuCl_(3)monolayer on graphite substrate.Based on Chen’s derivative rule,a further trigonal field splitting is identified by analyzing the lateral-gradient imaging effect caused by an anisotropic tip.A spatial variation of the magnitude of trigonal crystal field due to the slight inhomogeneity of strain accords with the orbital polarization near the Mott gap.All evidences point to the facts that the compressive trigonal crystal field in the stretchedα-RuCl_(3)monolayer lifts the degeneracy of t2g states with higher eg and lower a1g orbitals,and the Coulomb interactions of the eg orbitals take the main responsibility for the Mott effect.展开更多
A bulk superconductor hosting intrinsic surface superconductivity provides a unique platform for exploring Majorana bound states.Trigonal γ-PtBi_(2),a superconductor,is a promising candidate,as both surface supercond...A bulk superconductor hosting intrinsic surface superconductivity provides a unique platform for exploring Majorana bound states.Trigonal γ-PtBi_(2),a superconductor,is a promising candidate,as both surface superconducting gaps and topological surface states have been observed.However,the simultaneous presence of bulk and surface superconductivity has remained unresolved.In this study,we directly visualize coexisting bulk and surface superconducting gaps in trigonal PtBi_(2) using ultra-low-temperature scanning tunneling microscopy/spectroscopy.The bulk gap,Δ,is∼0.053 meV,with a critical temperature(T_(c))of∼0.5K and a critical field below 0.01 T,accompanied by a vortex lattice and vortex bound states and yielding a coherence length of∼200 nm.Remarkably,certain surface regions exhibit a much larger gap(Δ)of∼0.42 meV,persisting up to a T_(c)value of∼3K and surviving magnetic fields of up to 2 T,yet lacking a static vortex lattice.This coexistence of robust surface and bulk superconductivity establishes γ-PtBi_(2)as a unique platform for exploring the interplay between bulk and surface Cooper pairings in topological superconductors.展开更多
This article summarizes the nursing experience with a patient who underwent resection of a lateral ventricle trigone meningioma via a contralateral interhemispheric approach.Key nursing measures included preoperative ...This article summarizes the nursing experience with a patient who underwent resection of a lateral ventricle trigone meningioma via a contralateral interhemispheric approach.Key nursing measures included preoperative health education and psychological care,baseline neurological assessment,and comprehensive physiological preparation.Postoperative care focused on intensive vital sign monitoring and support,comprehensive neurological evaluation and early rehabilitation,as well as a proactive strategy for preventing secondary epilepsy and controlling intracranial infection.Through active treatment and systematic nursing care,the patient achieved an uncomplicated recovery and was discharged on postoperative day 9.The successful implementation of these structured nursing interventions contributed to favorable postoperative outcomes,offering a valuable reference for the perioperative management of similar complex neurosurgical cases.展开更多
The electron paramagnetic resonance spectra of trigonal Mn^(2+)centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals are studied on the basis of the complete energy matrices for a d5 configuration ...The electron paramagnetic resonance spectra of trigonal Mn^(2+)centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals are studied on the basis of the complete energy matrices for a d5 configuration ion in a trigonal ligand field.It is demonstrated that the local lattice structure around a trigonal Mn2+center has an elongation distortion along the crystalline c3 axis,and when Mn2+is doped in the ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals,there is a similar local distortion.From the EPR calculation,the local lattice structure parameters for trigonal Mn2+centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)are determined.展开更多
The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl36H2O with apoHCl (apo = 2璦mino pyridine N璷xide) in acetonitrile. The result shows that CH3CN has been hydrolysised ...The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl36H2O with apoHCl (apo = 2璦mino pyridine N璷xide) in acetonitrile. The result shows that CH3CN has been hydrolysised with the water from FeCl36H2O dissolving, and then the hydrolysised product condenses with apo to give aapo. A single-crystal X璻ay study of Fe(aapo)2Cl3 shows it belongs to the monoclinic system, space group C2/c with a = 15.873(3), b = 10.322(2), c = 11.987(2) ? b = 106.35(1), V = 1884.5(6) 3, Z = 4, Mr = 466.51, Dc = 1.644 g/cm3, m(MoKa) = 1.253 mm-1, F(000) = 948, R = 0.0377 and wR = 0.0749 for 1262 observed reflections with I > 2(I). Fe (Ⅲ) is coordinated by a trigonal bipyramidal geometry with three chlorine atoms lying on the equatorial plane and two oxygen atoms connected with the nitrogen atoms of pyridine rings occupying the axial positions, while the iron and Cl(1) atoms lie on the crystallographic 2-fold axis. The dihedral angle of two pyridine rings is 71.74(9). There exist N(2)H(2)…O(1)?hydrogen bonds in the crystal structure.展开更多
The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with M...The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with Mr = 420. 99, a= 6. 716(1), b=22- 860(8), c= 11. 891 (3) A, V= 1826(1) A3, Z=4,Dx= 1. 53 Mg. m-3,A= 0. 71073A, μ= 1. 684 mm-l, and F(000) =872. The structure was solved by direct methods. The final refinement is converged with unweighted and weighted agreement factors of 0. 047 and 0. 064 for 1610 observed reflections with I≥3δ(I). The results of structure analysis indicate that the framework of this five-coordinated germanium compound is a distorted trigonal bipyramid(TBP).展开更多
基金Supported by the Natural Science Foundation of Zhejiang Province,China(No.Z407029)the Hangzhou Qianjiang Scholar Foundation,China(No.HZ2010-41)
文摘A microfluidic system was developed for the synthesis of trigonal selenium（t-Se） nanowires, which was composed of a glass microchip coupled with a poly（methyl methacrylate）（PMMA） microchip. In the glass microchip, amorphous selenium（a-Se） colloid was prepared by reducing selenious acid with an excess amount of hydrazine at a temperature of 100 ℃. In the coupled PMMA microchip, a-Se was transformed into more stable t-Se seeds via sonication at room temperature. The residence time of the reactants in both microchips was optimized by varying the dimension and length of the microchannel each. The t-Se nanowires were formed by anisotropic growth of selenium crystallite during sonication and aging under the assistance of β-cyclodextrin（β-CD）. Various stages of the nanowires＇ growth were investigated. The as-synthesized products were characterized by powder X-Ray diffraction（XRD）, Raman spectroscopy, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and selected-area electron diffraction（SAED）.
基金This research was supported by the State Key Laboratory of Structural Chemistry the National Science and Technology of China (001CB1089)+8 种基金 the Chinese Academy of Sciences (CAS) the National Science Foundation of China (20333070 2027307390206040) and the Science Foundation of CAS and Fujian Province (2002F0142003J0422004J0412004H201-1)
文摘A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr3+, Cu2+, glycine and imidazole in aqueous solution and characterized by X-ray structure analysis. The compound belongs to the trigonal R3 space group with a = b = 15.8761(2), c = 23.4943(5) ?, V = 5128.4(1) ?3, Z = 3, Dc = 1.965 g/cm3, μ = 2.869 mm-1, F(000) = 3012, the final R = 0.0332 and wR = 0.0844 for 3596 independent reflections. In the cation, the Pr3+ ion is situated at the center of a prism formed by six copper atoms and coordinates to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycine ligands and six imidazole terminal ligands participate in constructing the cluster.
文摘With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes. Rectification behavior can be observed when the electrode-molecule contact distance is larger than 2.2 Å. The electronic transport is greatly improved in case of Fe terminal which is analyzed in terms of transmission spectra and density of states.
基金supported by the National Natural Science Foundation of China(No.21731002,21975104,22071141,21471094)the Guangdong Major Project of Basic and Applied Research(No.2019B030302009)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515012162)the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications(No.2020A05)。
文摘Six trigonal prismatic metallocages(TPMs)composed of 24 components,namely{(Cu_(3)L_(3))(Cu_(2)X_(2))_(3)(Cu_(3)L_(3))}·xG(HL=4-(quinoline-8-thio)-3,5-dimethyl-1H-pyrazole,G=benzene(B),methylbenzene(MB),1,3,5-triphenylbenzene(TPB),x=3 for B,MB and 1 for TPB),are reported.They were constructed by three rhombicCu_(2)X_(2)units as columns connecting two planar syn-Cu_(3)L_(3)faces,templated by G molecules.The structural analysis and EDA calculations reveal that C-H…πdominate their host-vip interactions.
基金financial support from the PalackýUniversity Olomouc project IGA_PrF_2022_006E.Č.was supported by the Slovak Research and Development Agency,contract no.APVV-22-0172 and APVV-18-0197。
文摘This article presents a series of six mononuclear Co(II)complexes 1-6 featuring ligands derived from a hexadentate Schiff base family,originating from the condensation of(2-formylphenoxy)acetic acid with various diamines.Notably,these complexes uniquely prefer a trigonal prism geometry,presenting a novel approach to synthesizing complexes with this distinctive shape.The compounds were characterized by elemental analysis,FT-IR spectroscopy,and single-crystal and powder XRD techniques.Furthermore,the magnetism was investigated by DC and AC magnetic measurements and also complemented by X-band EPR spectroscopy.The results reveal that the prepared complexes behave as field-induced single-molecule magnets,characterized by a substantial negative axial zero-field splitting D-parameter and spin reversal energetic barrier U_(eff) reaching values up to 72 K.The theoretical methods based on CASSCF/NEVPT2 calculations were applied to rationalize their magnetic properties.Moreover,these complexes hold promising potential for further functionalization,offering opportunities to enhance their properties,particularly towards developing zero-field single-molecule magnets as evidenced by the slow relaxation of magnetization in zero static magnetic field observed for the zinc-diluted complex 1Zn.
基金the University of South Florida and the National Science Foundation(DMR-1352065)for financial support of this workWe thank Prof.Randy W.Larsen and Christi L.Whittington for assistance with fluorescence tests and helpful discussions.The single-crystal X-ray diffraction of 1 was carried out at the Advanced Photon Source ChemMatCARS Sector 15,supported by the National Science Foundation/Department of Energy under grant number NSF/CHE-1346572.Use of the Advanced Photon Source,an Office of Science User Facility operated for the U.S.Department of Energy(DOE)Office of Science by Argonne National Laboratory,was supported by the U.S.DOE under Contract no.DE-AC02-06CH11357.
文摘Open metal sites are devised to dangle on cobalt trigonal prismatic secondary building units(SBUs)of a porous MOF,when a rigid octacarboxylate ligand,1,_(3),6,8-tetra(_(3),5-dicarboxylphenyl)pyrene,assembled with Co(NO_(3))_(2)under solvothermal conditions.The functional role of dangled open metal sites is exploited for CO_(2)capture studies.
基金supported by the National Natural Science Foundation of China(no.22173043,22473054)the Shenzhen Science and Technology Program(no.JCYJ20220818100417037)。
文摘The engineering of Cr(Ⅱ) complexes for spin crossover (SCO) phenomena remains poorly understood,primarily due to the limited number of reported examples and the associated challenges in their synthesis.In the context of Cr(Ⅱ) complexes with octahedral geometry,the pronounced Jahn–Teller distortion in the high-spin (HS) state significantly restricts the selection of co-ligands necessary for SCO to occur.In this study,we successfully synthesized a series of air-stable and solvent-free Cr(Ⅱ) complexes,[Cr(Tpm^(R))_(2)]X^(2)(Tpm^(R)= Tpm:X=[BF_(4)]^(−),1;X=[ClO_(4)]^(−),2;Tpm^(R)= Tpm:X=[BF_(4)]^(−),3;X=[ClO_(4)]^(−),4),where the Cr(Ⅱ) ions adopt a trigonal antiprism (aTPR) geometry rather than the conventional octahedral configuration.Notably,the Tpm-based complexes 1 and 2,with Cr(Ⅱ) ions in a nearly ideal aTPR geometry,exhibit complete SCO behavior with transition temperatures (T_(1/2)) of 190 K for 1 and 194 K for 2,respectively.In contrast,the Tpm-based complexes 3 and 4 display considerable axial elongation within the aTPR structure,leading to abrupt but incomplete SCO transition at a much lower temperature for 3 (T_(1/2)= 142 K) while 4 remains predominantly in the HS state.Further structural analysis reveals that substituting [BF_(4)]^(−)with [ClO_(4)]^(−)in 4 results in increased elongation and a denser packing arrangement that disfavour the spin transition.Our findings suggest that the aTPR configuration is advantageous for facilitating spin crossover,while the dynamics of spin transitions in these complexes are closely linked to the structural distortions of the [Cr(Tpm^(R))_(2)]^(2+)cations.Furthermore,all complexes demonstrate remarkable resistance to oxygen and maintain air stability,which can be attributed to their compact space-filling structures that effectively impede the diffusion of oxygen into the interstitial regions of the crystal lattice.
基金supported by the National Natural Science Foundation of China(21973046,22105089,and 21601070)the Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(20212BCD42018)d the Key R&D Plan of Zhenjiang City(GY2019021).
文摘The mononuclear cobalt(Ⅱ)complexes[Co(LN_(8))](BPh_(4))_(2)·C_(4)H_(10O)(1-BPh_(4))and[Co(LN_(8))](NO_(3))_(2)·CH_(3)CN(2-NO_(3))(LN_(8)=1,4,7,10-tetrakis(2-pyridinemethyl)-1,4,7,10-tetraaza-cyclododecane)have been synthesized and fully characterized.They differ well beyond a formal replacement of the counter anions,with their Co(Ⅱ)centers in significantly different coordination geometries.In 1-BPh_(4),the Co(Ⅱ)ion is not only coordinated by six N atoms from the LN_(8) ligand but also associated with the two remaining N atoms of LN_(8) via weak interactions.In contrast,the Co(Ⅱ)ion in 2-NO_(3) is only six-coordinated in a distorted trigonal prismatic geometry.Magnetic anisotropy and slow magnetic dynamics are drastically affected by these different environments around Co(Ⅱ).The combination of dc magnetic data,high-frequency and-field electron paramagnetic resonance(HFEPR)and theoretical calculations unambiguously reveals large negative zero-field split(ZFS)parameters D for both complexes and a large difference between the D values.Both 1-BPh_(4) and 2-NO_(3) show slow magnetic relaxation at zero field.Magnetic dilution experiments reveal effective energy barriers of 54(4)cm^(-1) for 1-BPh_(4)@Zn and 95(5)cm^(-1) for 2-NO_(3)@Zn and confirm that the slow magnetic relaxation for both complexes originates from single molecule behaviour.Ab initio computational studies explain their electronic structures and the origin of the large negative magnetic anisotropy;they support the corresponding experimental observations.Further magneto-structural analyses reveal that different distortions from the ideal trigonal prismatic geometry exert drastic effects on D values and slow relaxation,and that the additional weak intramolecular interactions between Co and N reduce the axial anisotropy.
基金supported by the National Natural Science Foundation of China(22275192).
文摘Low-symmetry metal-organic cages(MOCs)have received increasing attention due to their complex structures and more advanced functions.Here,we report a new MOC cage with a unique trigonal bipyramidal configuration,[M_(5)L_(6)],constructed via the combination effects of coordination bonds and π…π interactions.A series of structures(BIF-136 to BIF-141)based on this[M_(5)L_(6)]cage were synthesized by the self-assembly of BH(bim)_(3)-ligands and Ni(II)ions under various solvothermal conditions.Each[M_(5)L_(6)]consists of two[M_(4)L_(3)]defective cubic cages sharing three metal nodes,which include two geometric types of flexible Ni(Ⅱ)centers(tetrahedral and octahedral).Benefiting from these modifiable metal centers,these cage-based crystals realized abundant coordination environments and a dimension transition from a 0D cage to a 1D cage-based chain,accompanied by modulations of conjugation degrees,electronic push-pull effects and band gaps.Due to their diverse structural features,we have systematically investigated their third-order nonlinear optical(NLO)properties.To our surprise,these structures show a typical reverse saturated absorption(RSA)response.In particular,BIF-141 achieves excellent optical limiting(OL)performance with a low minimum normalized transmittance(T_(min))of 0.20.This study not only provides a new strategy for constructing low-symmetry cages but also contributes to the understanding of the mechanism of their optical applications.
基金The authors are grateful for financial support from the National Natural Science Foundation of China(No.11874143)the Natural Science Foundation of Hubei Province(No.2022CFB402)+1 种基金Science and Technology Major Project of Hubei(No.2022AEA001)the Application Fundamental Research Project of Wuhan Science and Technology Bureau(No.2019010701011396).
文摘Hybrid perovskites have attracted enormous attention in the next generation resistive switching(RS)memristor for the artificial synapses,owing to their ambipolar charge transport,long diffusion length,and tunable visible bandgap.However,the variable switch,limited reproducibility,and poor endurance are the obstacles to the practical application of the perovskite memristors.Herein,we reported a multilevel RS nonvolatile memory based on a 3D trigonal HC(NH_(2))_(2)PbI_(3)(α‐FAPbI_(3))perovskite layer modified by 1‐cyanobutyl‐3‐methylimidazolium chloride([CNBmim]Cl)and sandwiched between ITO and Au electrodes(Au/[CNBmim]Cl/α‐FAPbI_(3)/SnO_(2)/ITO).In contrast to the bare memristor with failure switching from low resistance state(LRS)to high resistance state(HRS),the memristor device based on theα‐FAPbI_(3) modified with[CNBmim]Cl(Target device)shows the retention time over 10^(4) s with On/Off ratio(>10^(2))and endurance up to 550 cycles.The stable RS cycle benefits from the accelerated electrons de‐trapping from the reduced defects and fast charge separation in the interface ofα‐FAPbI_(3)/electrode,leading to the rupture of conductive filaments and transition of LRS to HRS.As a two‐terminal analog synaptic device,the target device can realize random handwritten digit recognition with an impressive accuracy of 89.3%on the condition of low learning phases(500 training cycles).
基金the National Key Research and Development Program of China(Grant No.2019YFA0308404)Science and Technology Commission of Shanghai Municipality(Grant No.20JC1415900)+3 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)support from the National Natural Science Foundation of China(Grants No.12174062)sponsored by Shanghai Pujiang Program No.19PJ1401000National Natural Science Foundation of China(Grant No.12004076).
文摘α-RuCl_(3)is a tantalizing playground to search for the quantum spin liquid states with leading Kitaev term due to the conformation of Jackeli-Khaliullin mechanism.Suppressing the non-Kitaev interaction to approach the Kitaev limit is the major objective in the experimental design of Kitaev-Jackeli-Khaliullin materials,for which the practical feasibility rests on the manipulation of the exact crystalline structure.A tensile strain,leading to the further compressive trigonal field splitting which would alter the spin-orbital entangled character and tune the intrinsic hopping exchanges,has been widely proposed as the promising strategy to enhance the comparative Kitaev interaction.In this work,we preform in-depth Scan Tunneling Microscope study on the electronic patterns of strainedα-RuCl_(3)monolayer on graphite substrate.Based on Chen’s derivative rule,a further trigonal field splitting is identified by analyzing the lateral-gradient imaging effect caused by an anisotropic tip.A spatial variation of the magnitude of trigonal crystal field due to the slight inhomogeneity of strain accords with the orbital polarization near the Mott gap.All evidences point to the facts that the compressive trigonal crystal field in the stretchedα-RuCl_(3)monolayer lifts the degeneracy of t2g states with higher eg and lower a1g orbitals,and the Coulomb interactions of the eg orbitals take the main responsibility for the Mott effect.
基金supported by the National Natural Science Foundation of China(Grant No.62488201)the National Key Research and Development Projects of China(Grant Nos.2022YFA1204100 and 2023YFA1607400)+1 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘A bulk superconductor hosting intrinsic surface superconductivity provides a unique platform for exploring Majorana bound states.Trigonal γ-PtBi_(2),a superconductor,is a promising candidate,as both surface superconducting gaps and topological surface states have been observed.However,the simultaneous presence of bulk and surface superconductivity has remained unresolved.In this study,we directly visualize coexisting bulk and surface superconducting gaps in trigonal PtBi_(2) using ultra-low-temperature scanning tunneling microscopy/spectroscopy.The bulk gap,Δ,is∼0.053 meV,with a critical temperature(T_(c))of∼0.5K and a critical field below 0.01 T,accompanied by a vortex lattice and vortex bound states and yielding a coherence length of∼200 nm.Remarkably,certain surface regions exhibit a much larger gap(Δ)of∼0.42 meV,persisting up to a T_(c)value of∼3K and surviving magnetic fields of up to 2 T,yet lacking a static vortex lattice.This coexistence of robust surface and bulk superconductivity establishes γ-PtBi_(2)as a unique platform for exploring the interplay between bulk and surface Cooper pairings in topological superconductors.
文摘This article summarizes the nursing experience with a patient who underwent resection of a lateral ventricle trigone meningioma via a contralateral interhemispheric approach.Key nursing measures included preoperative health education and psychological care,baseline neurological assessment,and comprehensive physiological preparation.Postoperative care focused on intensive vital sign monitoring and support,comprehensive neurological evaluation and early rehabilitation,as well as a proactive strategy for preventing secondary epilepsy and controlling intracranial infection.Through active treatment and systematic nursing care,the patient achieved an uncomplicated recovery and was discharged on postoperative day 9.The successful implementation of these structured nursing interventions contributed to favorable postoperative outcomes,offering a valuable reference for the perioperative management of similar complex neurosurgical cases.
基金by the National Natural Science Foundation under Grant No 10374068the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20050610011.
文摘The electron paramagnetic resonance spectra of trigonal Mn^(2+)centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals are studied on the basis of the complete energy matrices for a d5 configuration ion in a trigonal ligand field.It is demonstrated that the local lattice structure around a trigonal Mn2+center has an elongation distortion along the crystalline c3 axis,and when Mn2+is doped in the ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals,there is a similar local distortion.From the EPR calculation,the local lattice structure parameters for trigonal Mn2+centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)are determined.
基金the Natural Science Foundation of Xuzhou Normal University (01BXL009)
文摘The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl36H2O with apoHCl (apo = 2璦mino pyridine N璷xide) in acetonitrile. The result shows that CH3CN has been hydrolysised with the water from FeCl36H2O dissolving, and then the hydrolysised product condenses with apo to give aapo. A single-crystal X璻ay study of Fe(aapo)2Cl3 shows it belongs to the monoclinic system, space group C2/c with a = 15.873(3), b = 10.322(2), c = 11.987(2) ? b = 106.35(1), V = 1884.5(6) 3, Z = 4, Mr = 466.51, Dc = 1.644 g/cm3, m(MoKa) = 1.253 mm-1, F(000) = 948, R = 0.0377 and wR = 0.0749 for 1262 observed reflections with I > 2(I). Fe (Ⅲ) is coordinated by a trigonal bipyramidal geometry with three chlorine atoms lying on the equatorial plane and two oxygen atoms connected with the nitrogen atoms of pyridine rings occupying the axial positions, while the iron and Cl(1) atoms lie on the crystallographic 2-fold axis. The dihedral angle of two pyridine rings is 71.74(9). There exist N(2)H(2)…O(1)?hydrogen bonds in the crystal structure.
文摘The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with Mr = 420. 99, a= 6. 716(1), b=22- 860(8), c= 11. 891 (3) A, V= 1826(1) A3, Z=4,Dx= 1. 53 Mg. m-3,A= 0. 71073A, μ= 1. 684 mm-l, and F(000) =872. The structure was solved by direct methods. The final refinement is converged with unweighted and weighted agreement factors of 0. 047 and 0. 064 for 1610 observed reflections with I≥3δ(I). The results of structure analysis indicate that the framework of this five-coordinated germanium compound is a distorted trigonal bipyramid(TBP).
