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1.
Single‐Crystal to Single‐Crystal Linker Substitution,Linker Place Exchange,and Transmetalation Reactions in Interpenetrated Pillared–Bilayer Zinc(II) Metal–Organic Frameworks 下载免费PDF全文
Dinesh De Dr. Subhadip Neogi Prof. E. Carolina Sañudo Prof. Parimal K. Bharadwaj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17422-17429
A twofold interpenetrated pillared–bilayer framework, {[Zn3( L )2( L2 )(DMF)] ? (18DMF)(6H2O)}n ( 1 ), has been synthesized from the ligands tris(4′‐carboxybiphenyl)amine ( H3L ) and 1,2‐bis(4‐pyridyl)ethylene ( L2 ). The structure contains [Zn3(COO)6] secondary building units (SBUs), in which three ZnII ions are almost linear with carboxylate bridging. This framework undergoes reversible pillar linker substitution reactions at the terminal ZnII centers with three different dipyridyl linkers of different lengths to afford three daughter frameworks, 2 – 4 . Frameworks 2 – 4 are interconvertible through reversible linker substitution reactions. Also, competitive linker‐exchange experiments show preferential incorporation of linker L3 in the parent framework 1 . The larger linker L5 does not undergo such substitution reactions and framework 5 , which contains this linker, can be synthesized solvothermally as a twofold interpenetrated structure. Interestingly, when framework 5 is dipped in a solution of L3 in DMF, linker substitution takes place as before, but linker L5 now moves and diagonally binds two ZnII centers to afford 6 as a nonpenetrated single framework. This linker place exchange reaction is unprecedented. All of these reactions take place in a single‐crystal to single‐crystal (SC‐SC) manner, and have been observed directly through X‐ray crystallography. In addition, each 3D framework undergoes complete copper(II) transmetalation. 相似文献
2.
Single Crystal‐to‐Single Crystal Site‐Selective Postsynthetic Metal Exchange in a Zn–MOF Based on Semi‐Rigid Tricarboxylic Acid and Access to Bimetallic MOFs 下载免费PDF全文
Dr. Alankriti Bajpai Pujari Chandrasekhar Dr. Savitha Govardhan Dr. Rahul Banerjee Prof. Dr. Jarugu Narasimha Moorthy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2759-2765
The metal ions in a neutral Zn–MOF constructed from tritopic triacid H3L with inherent concave features, rigid core, and peripheral flexibility are found to exist in two distinct SBUs, that is, 0D and 1D. This has allowed site‐selective postsynthetic metal exchange (PSME) to be investigated and reactivities of the metal ions in two different environments in coordination polymers to be contrasted for the first time. Site‐selective transmetalation of Zn ions in the discrete environment is shown to occur in a single crystal‐to‐single crystal (SCSC) fashion, with metal ions such as Fe3+, Ru3+, Cu2+, Co2+, etc., whereas those that are part of 1D SBU sustain structural integrity, leading to novel bimetallic MOFs, which are inaccessible by conventional approaches. To the best of our knowledge, site‐selective postsynthetic exchange of an intraframework metal ion in a MOF that contains metal ions in discrete as well as polymeric SBUs is heretofore unprecedented. 相似文献
3.
New Mechanistic Insight into Stepwise Metal‐Center Exchange in a Metal–Organic Framework Based on Asymmetric Zn4 Clusters 下载免费PDF全文
Wei Meng Huijun Li Zhouqing Xu Shanshan Du Yunxia Li Yanyan Zhu Dr. Yi Han Prof. Hongwei Hou Prof. Yaoting Fan Prof. Mingsheng Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(10):2945-2952
Herein, a mechanism of stepwise metal‐center exchange for a specific metal–organic framework, namely, [Zn4(dcpp)2(DMF)3(H2O)2]n (H4dcpp=4,5‐bis(4′‐carboxylphenyl)phthalic acid), is disclosed for the first time. The coordination stabilities between the central metal atoms and the ligands as well as the coordination geometry are considered to be dominant factors in this stepwise exchange mechanism. A new magnetic analytical method and a theoretical model confirmed that the exchange mechanism is reasonable. When the metathesis reaction occurs between CuII ions and framework ZnII ions, the magnetic exchange interaction of each pair of CuII centers gradually strengthens with increasing amount of framework CuII ions. By analyzing the changes of coupling constants in the Cu‐exchanged products, it was deduced that Zn4 and Zn3 are initially replaced, and then Zn1 and Zn2 are replaced later. The theoretical calculation further verified that Zn4 is replaced first, Zn3 next, then Zn1 and Zn2 last, and the coordination stability dominates the Cu/Zn exchange process. For the Ni/Zn and Co/Zn exchange processes, besides the coordination stability, the preferred coordination geometry was also considered in the stepwise‐exchange behavior. As NiII and CoII ions especially favor octahedral coordination geometry in oxygen‐ligand fields, NiII ions and CoII ions could only selectively exchange with the octahedral ZnII ions, as was also confirmed by the experimental results. The stepwise metal‐exchange process occurs in a single crystal‐to‐single crystal fashion. 相似文献
4.
Dr. Sabina Rodríguez‐Hermida Dr. Min Ying Tsang Claudia Vignatti Dr. Kyriakos C. Stylianou Dr. Vincent Guillerm Dr. Javier Pérez‐Carvajal Prof. Francesc Teixidor Prof. Clara Viñas Dr. Duane Choquesillo‐Lazarte Dr. Cristóbal Verdugo‐Escamilla Dr. Inmaculada Peral Dr. Jordi Juanhuix Dr. Albert Verdaguer Dr. Inhar Imaz Prof. Daniel Maspoch Dr. José Giner Planas 《Angewandte Chemie (International ed. in English)》2016,55(52):16049-16053
Materials with surfaces that can be switched from high/superhydrophobicity to superhydrophilicity are useful for myriad applications. Herein, we report a metal–organic framework (MOF) assembled from ZnII ions, 1,4‐benzenedicarboxylate, and a hydrophobic carborane‐based linker. The MOF crystal‐surface can be switched between hydrophobic and superhydrophilic through a chemical treatment to remove some of the building blocks. 相似文献
5.
Hye Jeong Park Young Eun Cheon Prof. Myunghyun Paik Suh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(38):11662-11669
The porous metal–organic framework (MOF) {[Zn2(TCPBDA)(H2O)2]?30 DMF?6 H2O}n ( SNU‐30 ; DMF=N,N‐dimethylformamide) has been prepared by the solvothermal reaction of N,N,N′,N′‐tetrakis(4‐carboxyphenyl)biphenyl‐4,4′‐diamine (H4TCPBDA) and Zn(NO3)2?6 H2O in DMF/tBuOH. The post‐synthetic modification of SNU‐30 by the insertion of 3,6‐di(4‐pyridyl)‐1,2,4,5‐tetrazine (bpta) affords single‐crystalline {[Zn2(TCPBDA)(bpta)]?23 DMF?4 H2O}n ( SNU‐31 SC ), in which channels are divided by the bpta linkers. Interestingly, unlike its pristine form, the bridging bpta ligand in the MOF is bent due to steric constraints. SNU‐31 can be also prepared through a one‐pot solvothermal synthesis from ZnII, TCPBDA4?, and bpta. The bpta linker can be liberated from this MOF by immersion in N,N‐diethylformamide (DEF) to afford the single‐crystalline SNU‐30 SC , which is structurally similar to SNU‐30 . This phenomenon of reversible insertion and removal of the bridging ligand while preserving the single crystallinity is unprecedented in MOFs. Desolvated solid SNU‐30′ adsorbs N2, O2, H2, CO2, and CH4 gases, whereas desolvated SNU‐31′ exhibits selective adsorption of CO2 over N2, O2, H2, and CH4, thus demonstrating that the gas adsorption properties of MOF can be modified by post‐synthetic insertion/removal of a bridging ligand. 相似文献
6.
Xiao‐Ying Cheng Ming‐Fang Wang Zheng‐Yin Yang Yong Li Zeng‐Chen Liu Qiao‐Xia Zhou 《无机化学与普通化学杂志》2013,639(5):832-841
The Schiff base ligand, 1‐phenyl‐3‐methyl‐5‐hydroxypyrazole‐4‐methylene‐8′‐quinolineimine, and its CuII, ZnII, and NiII complexes were synthesized and characterized. The crystal structure of the ZnII complex was determined by single‐crystal X‐ray diffraction, indicating that the metal ions and Schiff base ligand can form mononuclear six‐coordination complexes with 1:1 metal‐to‐ligand stoichiometry at the metal ions as centers. The binding mechanism and affinity of the ligand and its metal complexes to calf thymus DNA (CT DNA) were investigated by UV/Vis spectroscopy, fluorescence titration spectroscopy, EB displacement experiments, and viscosity measurements, indicating that the free ligand and its metal complexes can bind to DNA via an intercalation mode with the binding constants at the order of magnitude of 105–106 M –1, and the metal complexes can bind to DNA more strongly than the free ligand alone. In addition, antioxidant activities of the ligand and its metal complexes were investigated through scavenging effects for hydroxyl radical in vitro, indicating that the compounds show stronger antioxidant activities than some standard antioxidants, such as mannitol. The ligand and its metal complexes were subjected to cytotoxic tests, and experimental results indicated that the metal complexes show significant cytotoxic activity against lung cancer A 549 cells. 相似文献
7.
Complete Transmetalation in a Metal–Organic Framework by Metal Ion Metathesis in a Single Crystal for Selective Sensing of Phosphate Ions in Aqueous Media 下载免费PDF全文
K S Asha Rameswar Bhattacharjee Dr. Sukhendu Mandal 《Angewandte Chemie (International ed. in English)》2016,55(38):11528-11532
A complete transmetalation has been achieved on a barium metal–organic framework (MOF), leading to the isolation of a new Tb‐MOF in a single‐crystal (SC) to single‐crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core–shell metal exchange through dissociation of metal–ligand bonds. This Tb‐MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF. 相似文献
8.
Unprecedented Second‐Timescale Blue/Green Emissions and Iodine‐Uptake‐Induced Single‐Crystal‐to‐Single‐Crystal Transformation in ZnII/CdII Metal–Organic Frameworks 下载免费PDF全文
Shuai Yuan Yong‐Kai Deng Dr. Di Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):10093-10098
The long‐persistent phosphorescent metal–organic framework (MOF) is a kind of highly desirable but rare material. Here, two new molecular MOF materials, {[Zn(tipa)Cl] ? NO3 ? 2 DMF}n ( 1 ) and {[Cd2(tipa)2Cl4] ? 6 DMF}n ( 2 ) (tipa=tri(4‐imidazolylphenyl)amine), which have 3D twofold interpenetrated ( utp ) and 2D noninterpenetrated ( kgd ) topologies, respectively, are reported. They exhibit unexpected long‐persistent emissions yet reported: At 77 K, they persist in glowing after stopping the UV irradiation on a timescale up to seconds at 77 K, which can be detected by the naked eye (ca. 2 s). Compounds 1 and 2 also undergo single‐crystal‐to‐single‐crystal (SC‐SC) transformations through different routes; a simple anion‐exchange route for 1 and a complicated replacement of μ1‐Cl? ions by DMF molecules accompanying I3? captured in the void for 2 . 相似文献
9.
Intercalation of Coordinatively Unsaturated FeIII Ion within Interpenetrated Metal–Organic Framework MOF‐5 下载免费PDF全文
Rebecca J. Holmberg Thomas Burns Samuel M. Greer Dr. Libor Kobera Dr. Sebastian A. Stoian Dr. Ilia Korobkov Prof. Stephen Hill Prof. David L. Bryce Prof. Tom K. Woo Prof. Muralee Murugesu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7711-7715
Coordinatively unsaturated FeIII metal sites were successfully incorporated into the iconic MOF‐5 framework. This new structure, FeIII‐iMOF‐5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single‐crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid‐state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed FeIII, whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the FeIII ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate ZnII within the MOF‐5 SBU. This new MOF structure displays the potential for metal‐site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials. 相似文献
10.
Single crystals of the FeII metal‐organic framework (MOF) with 1,3,5‐benzenetricarboxylate (BTC) as a linker were solvothermally obtained under air‐free conditions. X‐ray diffraction analysis of the crystals demonstrated a structure for FeII‐MOF analogous to that of [Cu3(BTC)2] (HKUST‐1). Unlike HKUST‐1, however, the FeII‐MOF did not retain permanent porosity after exchange of guest molecules. The Mössbauer spectrum of the FeII‐MOF was recorded at 80 K in zero field yielding an apparent quadrupole splitting of ΔEQ = 2.43 mm · s–1, and an isomer shift of δ = 1.20 mm · s–1, consistent with high‐spin central iron(II) atoms. Air exposure of the FeII‐MOF was found to result in oxidation of the metal atoms to afford FeIII. These results demonstrate that FeII‐based MOFs can be prepared in similar fashion to the [Cu3(BTC)2], but that they lack permanent porosity when degassed. 相似文献
11.
Dr. Holger Stephan Dr. Martin Walther Dr. Silke Fähnemann Prof. Paola Ceroni Dr. Jennifer K. Molloy Dr. Giacomo Bergamini Dr. Fabian Heisig Prof. Christa E. Müller Werner Kraus Prof. Peter Comba 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17011-17018
The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields functional bispidines enabling convenient functionalization for targeted imaging. The BODIPY‐substituted bispidine 3 combines a coordination site for metal ions, such as radioactive 64CuII, with a fluorescent unit. Product 3 was thoroughly characterized by standard analytical methods, single crystal X‐ray diffraction, radiolabeling, and photophysical analysis. The luminescence of ligand 3 was found to be strongly dependent on metal ion coordination: CuII quenches the BODIPY fluorescence, whereas NiII and ZnII ions do not affect it. It follows that, in imaging applications with the positron emitter 64CuII, residues of its origin from enriched 64Ni and the decay products 64NiII and 64ZnII, efficiently restore the fluorescence of the ligand. This allows for monitoring of the emitted radiation as well as the fluorescence signal. The stability of the 64CuII? 3 complex is investigated by transmetalation experiments with ZnII and NiII, using fluorescence and radioactivity detection, and the results confirm the high stability of 64CuII? 3 . In addition, metal complexes of ligand 3 with the lanthanide ions TbIII, EuIII, and NdIII are shown to exhibit emission of the BODIPY ligand and the lanthanide ion, thus enabling dual emission detection. 相似文献
12.
Ligand Symmetry Modulation for Designing a Mesoporous Metal–Organic Framework: Dual Reactivity to Transition and Lanthanide Metals for Enhanced Functionalization 下载免费PDF全文
Prof. Miao Du Xi Wang Dr. Min Chen Dr. Cheng‐Peng Li Jia‐Yue Tian Zhuo‐Wei Wang Prof. Chun‐Sen Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9713-9719
A promising alternative strategy for designing mesoporous metal–organic frameworks (MOFs) has been proposed, by modifying the symmetry rather than expanding the length of organic linkers. By means of this approach, a unique MOF material based on the target [Zn8(ad)4] (ad=adeninate) clusters and C3‐symmetric organic linkers can be obtained, with trigonal microporous (ca., 0.8 nm) and hexagonal mesoporous (ca., 3.0 nm) 1D channels. Moreover, the resulting 446‐MOF shows distinct reactivity to transition and lanthanide metal ions. Significantly, the transmetalation of CoII or NiII on the ZnII centers in 446‐MOF can enhance the sorption capacities of CO2 and CH4 (16–21 %), whereas the impregnation of EuIII and TbIII in the channels of 446‐MOF will result in adjustable light‐emitting behaviors. 相似文献
13.
Theoretical Insights into the Tuning of Metal Binding Sites of Paddlewheels in rht‐Metal–Organic Frameworks 下载免费PDF全文
Theoretical investigations of CO2 sorption are performed in four members of the highly tunable rht‐metal–organic framework (MOF) platform. rht‐MOFs contain two Cu2+ ions that comprise the metal paddlewheels and both are in chemically distinct environments. Indeed, one type of Cu2+ ion faces toward the center of the linker whereas the other type faces away from the center of the linker. Electronic structure calculations on the series of rht‐MOFs demonstrate that one of the Cu2+ ions has a consistently higher charge magnitude relative to the other. As a consequence, the Cu2+ ion with the higher partial positive charge acts as the favored sorbate binding site at initial loading as revealed by grand canonical Monte Carlo (GCMC) simulations that include many‐body polarization. It was found that the charge distribution about the copper paddlewheels is dependent on the type of functional groups present on the linker. This study demonstrates how the binding site about the metal paddlewheels in the rht‐MOF platform can be controlled by changing the functionality on the organic ligand. 相似文献
14.
Saier Wang Rong Bi Jiadi Liu Ying Shi Kuaibing Wang Feifei Mao Hua Wu 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):10-16
With the rapid development of metal–organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen‐containing ligands are employed to construct MOFs with fascinating structures. 4,4′,4′′‐(1,3,5‐Triazine‐2,4,6‐triyl)tribenzoic acid (H3TATB) and the bidentate nitrogen‐containing ligand 1,3‐bis[(imidazol‐1‐yl)methyl]benzene (bib) were selected to prepare a novel ZnII‐MOF under solvothermal conditions, namely poly[[tris{μ‐1,3‐bis[(imidazol‐1‐yl)methyl]benzene}bis[μ3‐4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn3(C24H12N3O6)2(C14H14N4)3]·2C3H7NO·3H2O}n ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction, IR spectroscopy and powder X‐ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single‐crystal X‐ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent ZnII centres, two 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoate (TATB3?) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each ZnII centre is four‐coordinated and displays a distorted tetrahedral coordination geometry. The ZnII centres are connected by TATB3? anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link ZnII centres to give a helical Zn–bib–Zn chain. Furthermore, adjacent ladders are bridged by Zn–bib–Zn chains to form a fascinating three‐dimensional self‐penetrated framework with the short Schläfli symbol 65·7·813·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr4+ and Cu2+ ions. 相似文献
15.
Dr. Yasuo Tanaka Dr. Tomoki Yoneda Prof. Dr. Ko Furukawa Dr. Taro Koide Hirotaka Mori Dr. Takayuki Tanaka Prof. Dr. Hiroshi Shinokubo Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(37):10908-10911
A ZnII‐CuI‐ZnII heterotrimetal complex of decaphyrin was synthesized by stepwise metalations: metalation of a [46]decaphyrin with ZnII ions to produce a 46π decaphyrin bis(ZnII) complex and its subsequent metalation with CuII ion. In the second metalation step, it has been shown that CuII ion is reduced to a CuI ion in the complex and a dianionic bis(ZnII) containing [46]decaphyrin ligand is oxidized to the corresponding monoanionic [45]decaphyrin ligand, indicating a non‐innocent nature of the decaphyrin ligand. Despite the radical nature, the heterotrimetal complex is fairly stable under ambient conditions and exhibits almost no intermolecular magnetic interaction, owing to extensive delocalization of an unpaired electron in the large π‐conjugated circuit of decaphyrin moiety. 相似文献
16.
Single Crystal to Single Crystal (SC‐to‐SC) Transformation from a Nonporous to Porous Metal–Organic Framework and Its Application Potential in Gas Adsorption and Suzuki Coupling Reaction through Postmodification 下载免费PDF全文
Dr. Rupam Sen Debraj Saha Dr. Subratanath Koner Dr. Paula Brandão Dr. Zhi Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5962-5971
A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH2 groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m2 g?1. The material also possesses good CO2 (8 wt %) and H2 (1.87 wt %) adsorption capabilities. 相似文献
17.
Jian-Jun Liu Li-Zhi Li Chun-Ping Chen Jin-Zhong Wei Fei-Xiang Cheng 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(3):372-377
2,4,6‐Tris(pyridin‐4‐yl)‐1,3,5‐triazine (tpt), as an organic molecule with an electron‐deficient nature, has attracted considerable interest because of its photoinduced electron transfer from neutral organic molecules to form stable anionic radicals. This makes it an excellent candidate as an organic linker in the construction of photochromic complexes. Such a photochromic three‐dimensional (3D) metal–organic framework (MOF) has been prepared using this ligand. Crystallization of tpt with Cd(NO3)2·4H2O in an N,N‐dimethylacetamide–methanol mixed‐solvent system under solvothermal conditions afforded the 3D MOF poly[[bis(nitrato‐κ2O,O′)cadmium(II)]‐μ3‐2,4,6‐tris(pyridin‐4‐yl)‐1,3,5‐triazine‐κ3N2:N4:N6], [Cd(NO3)2(C18H12N6)]n, which was characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis and single‐crystal X‐ray diffraction. The X‐ray diffraction crystal structure analysis reveals that the asymmetric unit contains one independent CdII cation, one tpt ligand and two coordinated NO3? anions. The CdII cations are connected by tpt ligands to generate a 3D framework. The single framework leaves voids that are filled by mutual interpenetration of three independent equivalent frameworks in a fourfold interpenetrating architecture. The compound shows a good thermal stability and exhibits a reversible photochromic behaviour, which may originate from the photoinduced electron‐transfer generation of radicals in the tpt ligand. 相似文献
18.
Baojun Li Mengsi Zhang Haotian Lu Hailong Ma Yue Wang Huimin Chen Yun Ding Aiguo Hu 《化学:亚洲杂志》2019,14(23):4352-4357
A maleimide‐based acyclic enediyne with salicylaldiminato substituents at the alkyne termini was synthesized, which was further chelated with three kinds of metal‐ions, CuII, ZnII, and MgII, and form metalloenediynes. The cycloaromatization of this thermally inactive enediyne ligand was greatly accelerated through the coordination with metal ions. Specifically, the CuII‐metalloenediyne showed an extremely low onset temperature of 55 °C and underwent spontaneous cycloaromatization at ambient temperature to produce free radicals, followed by generation of reactive oxygen species in the physiological environment. The metalloenediyne exhibited excellent DNA cleavage ability and high cytotoxicity towards HeLa cells, with half‐maximal inhibitory concentration values comparable to many commercial antitumor agents. The combination of the electron‐withdrawing effect of the maleimide moiety at the ene position and metal coordination at the yne termini provides a new inspiration for designing and synthesizing highly efficient enediyne antitumor agents. 相似文献
19.
Beibei Li Zhanfeng Ju Mi Zhou Kongzhao Su Daqiang Yuan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7769-7773
The exploitation of new and active earth‐abundant metal catalysts is critical for sustainable chemical production. Herein, we demonstrate the design of highly efficient, robust, and reusable ZnII‐bipyridine‐based metal–organic framework (MOF) catalysts for the intramolecular hydroamination of o‐alkynylanilines to indoles. Under similar conditions homogeneous catalytic systems mainly provide hydrolysate. Our results prove that MOFs support unique internal environments that can affect the direction of chemical reactions. The ZnII‐catalyzed hydroamination reaction can be conducted without additional ligands, base, or acid, and is thus a very clean reaction system with regard to its environmental impact. 相似文献
20.
A New 3,5‐Bisporphyrinylpyridine Derivative as a Fluorescent Ratiometric Probe for Zinc Ions 下载免费PDF全文
Dr. Nuno M. M. Moura Dr. Cristina Núñez Dr. Sérgio M. Santos Prof. M. Amparo F. Faustino Prof. José A. S. Cavaleiro Dr. Filipe A. Almeida Paz Prof. M. Graça P. M. S. Neves Prof. José Luis Capelo Prof. Carlos Lodeiro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6684-6692
A new 3,5‐disubstituted pyridine with two porphyrin moieties was prepared through an efficient synthetic approach involving 2‐formyl‐5,10,15,20‐tetraphenylporphyrin ( 1 ), piperidine, and catalytic amounts of [La(OTf)3]. 3,5‐Bis(5,10,15,20‐tetraphenylporphyrin‐2‐ylmethyl)pyridine ( 2 ) was fully characterized and its sensing ability towards Zn2+, Cu2+, Hg2+, Cd2+, and Ag+ was evaluated in solution by absorption and fluorescence spectroscopy and in gas phase by using matrix‐assisted laser desorption/ionization (MALDI)‐TOF mass spectrometry. Strong changes in the ground and excited state were detected in the case of the soft metal ions Zn2+, Cd2+, Hg2+, and Cu2+. A three‐metal‐per‐ligand molar ratio was obtained in all cases and a significant ratiometric behavior was observed in the presence of Zn2+ with the appearance of a new band at 608 nm, which can be assigned to a metal‐to‐ligand charge transfer. The system was able to quantify 79 ppb of Zn2+ and the theoretical calculations are in accordance with the stoichiometry observed in solution. The gas‐phase sensorial ability of compound 2 towards all metal ions was confirmed by using MALDI‐TOF MS and in solid state by using polymeric films of polymethylmethacrylate (PMMA) doped with ligand 2 . The results showed that compound 2 can be analytically used to develop new colorimetric molecular devices that are able to discriminate between Hg2+ and Zn2+ in solid phase. The crystal structure of ZnII complex of 3,5‐bisporphyrinylpyridine was unequivocally elucidated by using single‐crystal X‐ray diffraction studies. 相似文献