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A novel molecule tetra-N-alkylation of cyclen (1,4,7,10-tetraazacyclododecane), 1,4,7,10-tetrakis(2-((4-hydroxy)phenoxy)ethyl)-1,4,7,10-tetraazacyclododecane 2, was synthesized and structurally characterized by single-crystal X-ray diffraction. The molecule turned into chiral helical compound crystals grown from EtOH by slow diffusion at room temperature and three of the four hydroquinone groups of the benzene ring formed a g-electron-rich cavity by C-H…π stacking interaction. The crystal belongs to the monoclinic system, space group P21/C with a = 13.9192(9), b = 13.2871(6), c = 22.1894(15)A^°, β = 91.4600(10)°, V = 4102.5(4)A^°3, Z = 4, Dc = 1.219 g/cm^3, C40H52N4O8, Mr = 752.89, F(000) = 1616,μ = 0.088 mm^-1, MoKa radiation (λ = 0.71073), R = 0.0578 and wR = 0.1389 for 5588 observed reflections with I 〉 2σ(I). Moreover, compound 2 was characterized with ^1H NMR, ^13C NMR, IR spectra and MS. 相似文献
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Toxic metal complexes of macrocyclic cyclen molecule – synthesis,structure and complexing properties
M. Litecká R. Gyepes M. Vilková M. Almáši M. Walko 《Journal of Coordination Chemistry》2017,70(10):1698-1712
Toxic metal (Cd2+, Hg2+, Pb2+, and Ag+) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN4, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ4N1,4,7,10)(NO3)2)] (1), [Hg([12]ane-κ4N1,4,7,10)(NO3-κ2O,O`)]NO3 (2), [Pb2([12]ane-κ4N1,4,7,10)2][Pb(NO3)6] (3) and one polymeric structure {[Ag2([12]ane-κ3N1,4,7)(μ2-[12]aneN10)](NO3)2?2H2O)}n (4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s2 lone pair was suggested in 3 and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd2+ and Pb2+ ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by 1H NMR. Both methods confirm similar cyclen complexing properties toward Zn2+ biometal and Cd2+, Pb2+ toxic metals. 相似文献
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A Bis(pyridine N‐oxide) Analogue of DOTA: Relaxometric Properties of the GdIII Complex and Efficient Sensitization of Visible and NIR‐Emitting Lanthanide(III) Cations Including PrIII and HoIII 下载免费PDF全文
Henrique F. Carvalho Dr. João M. C. Teixeira Carlos T. B. Paula Prof. Petr Hermann Dr. Carlos Platas‐Iglesias Prof. Stephane Petoud Prof. Éva Tóth Prof. Carlos F. G. C. Geraldes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14834-14845
We report the synthesis of a cyclen‐based ligand (4,10‐bis[(1‐oxidopyridin‐2‐yl)methyl]‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid= L1 ) containing two acetate and two 2‐methylpyridine N‐oxide arms anchored on the nitrogen atoms of the cyclen platform, which has been designed for stable complexation of lanthanide(III) ions in aqueous solution. Relaxometric studies suggest that the thermodynamic stability and kinetic inertness of the GdIII complex may be sufficient for biological applications. A detailed structural study of the complexes by 1H NMR spectroscopy and DFT calculations indicates that they adopt an anti‐Δ(λλλλ) conformation in aqueous solution, that is, an anti‐square antiprismatic (anti‐SAP) isomeric form, as demonstrated by analysis of the 1H NMR paramagnetic shifts induced by YbIII. The water‐exchange rate of the GdIII complex is ${k{{298\hfill \atop {\rm ex}\hfill}}}$ =6.7×106 s?1, about a quarter of that for the mono‐oxidopyridine analogue, but still about 50 % higher than the ${k{{298\hfill \atop {\rm ex}\hfill}}}$ of GdDOTA (DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). The 2‐methylpyridine N‐oxide chromophores can be used to sensitize a wide range of LnIII ions emitting in both the visible (EuIII and TbIII) and NIR (PrIII, NdIII, HoIII, YbIII) spectral regions. The emission quantum yield determined for the YbIII complex (${Q{{{\rm L}\hfill \atop {\rm Yb}\hfill}}}$ =7.3(1)×10?3) is among the highest ever reported for complexes of this metal ion in aqueous solution. The sensitization ability of the ligand, together with the spectroscopic and relaxometric properties of its complexes, constitute a useful step forward on the way to efficient dual probes for optical imaging (OI) and MRI. 相似文献
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Dr. Csongor Szíjjártó Elias Pershagen Nadia O. Ilchenko Dr. K. Eszter Borbas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3099-3109
Coumarin‐sensitized, long‐wavelength‐absorbing luminescent EuIII‐complexes have been synthesized and characterized. The lanthanide binding site consists of a cyclen‐based chelating framework that is attached through a short linker to a 7‐hydroxycoumarin, a 7‐B(OH)2‐coumarin, a 7‐O‐(4‐pinacolatoboronbenzyl)‐coumarin or a 7‐O‐(4‐methoxybenzyl)‐coumarin. The syntheses are straightforward, use readily available building blocks, and proceed through a small number of high‐yielding steps. The sensitivity of coumarin photophysics to the 7‐substituent enables modulation of the antenna‐absorption properties, and thus the lanthanide excitation spectrum. Reactions of the boronate‐based functionalities (cages) with H2O2 yielded the corresponding 7‐hydroxycoumarin species. The same species was produced with peroxynitrite in a ×106–107‐fold faster reaction. Both reactions resulted in the emergence of a strong ≈407 nm excitation band, with concomitant decrease of the 366 nm band of the caged probe. In aqueous solution the methoxybenzyl caged Eu‐complex was quenched by ONOO?. We have shown that preliminary screening of simple coumarin‐based antennae through UV/Vis absorption spectroscopy is possible as the changes in absorption profile translate with good fidelity to changes in EuIII‐excitation profile in the fully elaborated complex. Taken together, our results show that the 7‐hydroxycoumarin antenna is a viable scaffold for the construction of turn‐on and ratiometric luminescent probes. 相似文献
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Selective Alkylation of C‐Rich Bulge Motifs in Nucleic Acids by Quinone Methide Derivatives 下载免费PDF全文
Dr. Tuomas Lönnberg Mark Hutchinson Prof. Dr. Steven Rokita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13127-13136
A quinone methide precursor featuring a bis‐cyclen anchoring moiety has been synthesized and its capacity to alkylate oligonucleotide targets quantified in the presence and absence of divalent metal ions (Zn2+, Ni2+ and Cd2+). The oligonucleotides were designed for testing the sequence and secondary structure specificity of the reaction. Gel electrophoretic analysis revealed predominant alkylation of C‐rich bulges, regardless of the presence of divalent metal ions or even the bis‐cyclen anchor. This C‐selectivity appears to be an intrinsic property of the quinone methide electrophile as reflected by its reaction with an equimolar mixture of the 2′‐deoxynucleosides. Only dA‐N1 and dC‐N3 alkylation products were detected initially and only the dC adduct persisted for detection under conditions of the gel electrophoretic analysis. 相似文献
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Gilles Gasser 《Journal of organometallic chemistry》2007,692(17):3835-3840
The attempted coupling of (ferrocenylmethyl)trimethylammonium iodide (1) with 1,4,7-(triformyl)-1,4,7,10-tetraazacyclododecane (2) in water led to the formation of the expected compound 1-(ferrocenemethyl)-4,7,10-(triformyl)-1,4,7,10-tetraazacyclododecane (3). In addition, hydrolysis of the ferrocenyl precursor 1 led to the formation of two other known compounds, hydroxymethylferrocene (4) and bis(ferrocenylmethyl) ether (5). An X-ray crystal structure determination of 4 revealed the presence of H-bonding between the hydroxyl groups of one molecule of 4 and the oxygen atom of an adjacent molecule resulting in a left-handed helical chain of molecules lying along the b-axis direction. The O?O distances are significantly shorter than those found in previously reported structures of hydroxymethylferrocene derivatives indicative of moderate strength H-bonding interactions. In the structure of 5, the orientation of the ferrocenyl groups are staggered relative to a vector comprising the two carbons of the C-O-C linker. 相似文献
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The synthesis of phthalazin-1-ones 6, 7, 8 via the reaction of 3-hydroxyisoindolin-l-ones 3, 4, 5 with hydrazine hydrate is described. Starting compounds 3, 4, 5 were regiospecifically prepared upon the lithiation (n-BuLi) of the benzanilides 1 and subsequently the reaction of the dilithiated anilides 2 with methyl pyridinecarboxylates. 相似文献
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以轮环藤宁为起始原料,依次与溴乙酸叔丁酯,溴乙酸乙酯和水合肼反应合成了一种核磁共振对比剂螯合前体--4,7,10-三(叔丁氧碳酰甲基)-1,4,7,10-四氮杂环十二烷-1-乙酰肼(4),其结构经1H NMR, 13C NMR, FT-IR和MS(ESI)表征。研究了溶剂、水合肼用量、微波功率和反应时间对4收率的影响。结果表明:乙醇为溶剂,水合肼10 eq.,于400 W微波反应10 min, 4(粉末固体)收率90%。 相似文献