19872-91-4Relevant articles and documents
The herringbone helix: A noncanonical folding in aromatic-aliphatic peptides
Delsuc, Nicolas,Godde, Frederic,Kauffmann, Brice,Leger, Jean-Michel,Huc, Ivan
, p. 11348 - 11349 (2007)
Hybrid oligomeric sequences derived from both aliphatic and aromatic units are shown to adopt a folded conformation with an unprecedented architecture. Specifically, a δ-amino acid bearing an aliphatic amine-6-aminomethyl-2-pyridinecarboxylic (P)-was designed and synthesized as a flexible analogue of 6-amino-2-quinolinecarboxylic acid (Q). Oligomers Pn (n = 2, 4, 8) were first synthesized but show no sign of folding in solution in organic solvents, unlike the Qn oligomers from which they are derived, which adopt particularly stable helical conformations. Hybrid oligomers (PQ)n (n = 1, 2, 4) were also prepared and were shown to adopt a novel folded conformation in the solid state where PQ units arrange into two stacks at a 90° angle from each other. Comprehensive NMR studies demonstrate that in solution this peculiar organization coexists with a helical conformation resembling that of Qn oligomers. Copyright
Catenane-based mechanically-linked block copolymers
Ahamed, B. Nisar,Duchêne, Roland,Robeyns, Koen,Fustin, Charles-André
, p. 2149 - 2152 (2016)
An original strategy for the synthesis of diblock copolymers where the blocks are linked by a catenane junction is described. Starting from a functionalized catenane precursor, our strategy enables the preparation of a variety of copolymers by different techniques such as ROP, ATRP and CuAAC click reaction.
Pyridine-based lanthanide complexes: Towards bimodal agents operating as near infrared luminescent and MRI reporters
Pellegatti, Laurent,Zhang, Jian,Drahos, Bohuslav,Villette, Sandrine,Suzenet, Franck,Guillaumet, Gerald,Petoud, Stephane,Toth, Eva
, p. 6591 - 6593 (2008)
We report two prototype Ln3+ complexes that address requirements for both MRI and luminescence imaging and we demonstrate that the presence of two H2O molecules bound to the Ln3+, beneficial for MRI applications of the Gd3+ analogue, is not a major limitation for the development of NIR luminescent agents. The Royal Society of Chemistry 2008.
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Fibel,Spoerri
, p. 3908,3910 (1948)
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Synthesis and evaluation of a rationally designed click-based library for G-Quadruplex selective DNA photocleavage
McBrayer, Dominic,Kerwin, Sean M.
, p. 16446 - 16465 (2015)
DNA containing repeating G-rich sequences can adopt higher-order structures known as G-quadruplexes (G4). These structures are believed to form within telomeres and the promoter regions of some genes, particularly in a number of proto-oncogenes, where they may play a role in regulating transcription. Alternatively, G4 DNA may act as a barrier to replication. To investigate these potential biological roles, probes that combine highly selective G4 DNA targeting with photocleavage activity can allow temporal detection of G4 DNA, providing opportunities to obtain novel insights about the biological roles of G4 DNA. We have designed, synthesized, and screened a small library of potential selective G-quadruplex DNA photocleavage agents incorporating the G-quadruplex targeting moiety of 360A with known photocleavage groups linked via "click" chemistry.
Spectroscopic and DFT Characterization of a Highly Reactive Nonheme FeV-Oxo Intermediate
Fan, Ruixi,Serrano-Plana, Joan,Oloo, Williamson N.,Draksharapu, Apparao,Delgado-Pinar, Estefanía,Company, Anna,Martin-Diaconescu, Vlad,Borrell, Margarida,Lloret-Fillol, Julio,García-Espa?a, Enrique,Guo, Yisong,Bominaar, Emile L.,Que, Lawrence,Costas, Miquel,Münck, Eckard
, p. 3916 - 3928 (2018)
The reaction of [(PyNMe3)FeII(CF3SO3)2], 1, with excess peracetic acid at -40 °C generates a highly reactive intermediate, 2b(PAA), that has the fastest rate to date for oxidizing cyclohexane by a nonheme iron species. It exhibits an intense 490 nm chromophore associated with an S = 1/2 EPR signal having g-values at 2.07, 2.01, and 1.94. This species was shown to be in a fast equilibrium with a second S = 1/2 species, 2a(PAA), assigned to a low-spin acylperoxoiron(III) center. Unfortunately, contaminants accompanying the 2(PAA) samples prevented determination of the iron oxidation state by M?ssbauer spectroscopy. Use of MeO-PyNMe3 (an electron-enriched version of PyNMe3) and cyclohexyl peroxycarboxylic acid as oxidant affords intermediate 3b(CPCA) with a M?ssbauer isomer shift δ = -0.08 mm/s that indicates an iron(V) oxidation state. Analysis of the M?ssbauer and EPR spectra, combined with DFT studies, demonstrates that the electronic ground state of 3b(CPCA) is best described as a quantum mechanical mixture of [(MeO-PyNMe3)FeV(O)(OC(O)R)]2+ (～75%) with some FeIV(O)(?OC(O)R) and FeIII(OOC(O)R) character. DFT studies of 3b(CPCA) reveal that the unbound oxygen of the carboxylate ligand, O2, is only 2.04 ? away from the oxo group, O1, corresponding to a Wiberg bond order for the O1-O2 bond of 0.35. This unusual geometry facilitates reversible O1-O2 bond formation and cleavage and accounts for the high reactivity of the intermediate when compared to the rates of hydrogen atom transfer and oxygen atom transfer reactions of FeIII(OC(O)R) ferric acyl peroxides and FeIV(O) complexes. The interaction of O2 with O1 leads to a significant downshift of the Fe-O1 Raman frequency (815 cm-1) relative to the 903 cm-1 value predicted for the hypothetical [(MeO-PyNMe3)FeV(O)(NCMe)]3+ complex.
Molecular imaging of biothiols and: In vitro diagnostics based on an organic chromophore bearing a terbium hybrid probe
Zhou, Zhan,Wang, Qianming,Zhang, Cheng Cheng,Gao, Jinwei
, p. 7435 - 7442 (2016)
In this research, a novel terbium-based luminescent hybrid inorganic/organic probe was designed and synthesized. Mesoporous silica nanospheres dispersed in water were used as the appropriate host for the covalently linked lanthanide-containing organic structures. The lanthanide structure was linked to a sulfonate ester unit, which, in the presence of biothiols, was cleaved to result in terbium emission. The hybrid probe exhibited the capabilities of quantitative determination and detection limits for biothiols were presented (36.8 nM for Cys, 32.5 nM for GSH, and 34.7 nM for Hcy). Evaluation of luminescence changes in cell culture demonstrated that this smart probe is cell membrane permeable and selectively lights up in the presence of cysteine and glutathione in human embryonic kidney cells and human lung adenocarcinoma cells. This variation in the presence of biothiols can be controlled by the treatment with N-methylmaleimide. The narrow line-like bands and long-lived excited states of this terbium luminescent sensor allows the discrimination of scattering signals and interfering fluorescence derived from biological tissues.
Pseudopolymorphs of chelidamic acid and its dimethyl ester
Tutughamiarso, Maya,Pisternick, Thorsten,Egert, Ernst
, p. o344-o350 (2012)
Different tautomeric and zwitterionic forms of chelidamic acid (4-hy-droxy-pyridine-2,6-dicarb-oxy-lic acid) are present in the crystal structures of chelidamic acid methanol monosolvate, C7H 5NO5·CH4O, (Ia), dimethyl-ammonium chelidamate (di-methyl-ammonium 6-carb-oxy-4-hy-droxy-pyridine-2-carboxyl-ate), C2H8N+·C7H4NO 5 -, (Ib), and chelidamic acid dimethyl sulfoxide monosolvate, C7H5NO7·C7H 6OS, (Ic). While the zwitterionic pyridinium carboxyl-ate in (Ia) can be explained from the pK a values, a (partially) deprotonated hy-droxy group in the presence of a neutral carb-oxy group, as observed in (Ib) and (Ic), is unexpected. In (Ib), there are two formula units in the asymmetric unit with the chelidamic acid entities connected by a symmetric O - H?O hydrogen bond. Also, crystals of chelidamic acid dimethyl ester (dimethyl 4-hy - droxy-pyridine-2,6-dicarboxyl-ate) were obtained as a monohydrate, C 9H9NO5·H2O, (IIa), and as a solvent-free mod-ifi - cation, in which both ester mol-ecules adopt the hy-droxy-pyridine form. In (IIa), the solvent water mol-ecule stabilizes the synperiplanar conformation of both carbonyl O atoms with respect to the pyridine N atom by two O - H?O hydrogen bonds, whereas an anti-periplanar arrangement is observed in the water-free structure. A database study and ab initio energy calculations help to compare the stabilities of the various ester conformations.
Sensitised lanthanide luminescence using a RuIIpolypyridyl functionalised dipicolinic acid chelate
Chong, Bowie S. K.,Etchells, Isaac M.,Ireland, Alexander R.,Moore, Evan G.,Pfrunder, Michael C.,Rajah, Divya
supporting information, p. 7400 - 7408 (2021/06/12)
A visible light absorbing [RuII(tpy)2]2+-type chromophore appended with a dipicolinic acid LnIIIchelator has been prepared and complexed with several differing lanthanide cations to form the corresponding heterobimetallic d-f assemblies. The subseqent solution speciation analysed by1H NMR spectroscopy revealed an unexpected decrease in the LnIIIchelate complex stability, in particular for the 1?:?3 complex, when compared to the parent dipicolinic acid. As a result, the desired Ln(ML)3complexes could not be isolated, and the 1?:?1 LnIII-ML complexes were instead characterised and investigated using steady state absorption and emission spectroscopy. Sensitised NIR emission from the YbIII, NdIIIand ErIIIcomplexes was observed upon1MLCT excitation of the RuIIbased metalloligand in the visible region atca.485 nm. Investigations using transient absorption spectroscopy revealed essentially quantitative intersystem crossing to form the3MLCT excited state, as expected, which then acts as the energy donor for the metalloligand based antennae effect, facilitating sensitisation efficiencies of 4.8, 17.0 and 37.4% respectively for the YbIII, ErIIIand NdIIIcations.
Study on the structure-activity relationship of dihydroartemisinin derivatives: Discovery, synthesis, and biological evaluation of dihydroartemisinin-bile acid conjugates as potential anticancer agents
Zou, Xiaosu,Liu, Chang,Li, Congcong,Fu, Rong,Xu, Wei,Bian, Hongzhu,Dong, Xun,Zhao, Xiaozhen,Xu, Zhenye,Zhang, Jinghua,Shen, Zhengwu
supporting information, (2021/08/17)
A series of dihydroartemisinin derivatives was synthesized, and their anti-proliferation activity against cancer cells was evaluated. Structure-activity relationship studies led to the discovery of dihydroartemisinin-bile acid conjugates that exhibit broa
Coordination chemistry of [Y(pypa)]-and comparison immuno-PET imaging of [44Sc]Sc- And [86Y]Y-pypa-phenyl-TRC105
Li, Lily,de Guadalupe Jaraquemada-Peláez, María,Aluicio-Sarduy, Eduardo,Wang, Xiaozhu,Barnhart, Todd E.,Cai, Weibo,Radchenko, Valery,Schaffer, Paul,Engle, Jonathan W.,Orvig, Chris
, p. 5547 - 5562 (2020/05/13)
Both scandium-44 and yttrium-86 are popular PET isotopes with appropriate half-lives for immuno-positron emission tomography (immuno-PET) imaging. Herein, a new bifunctional H4pypa ligand, H4pypa-phenyl-NCS, is synthesized, conjugate
