- Optimization of pentadentate bispidines as bifunctional chelators for 64Cu positron emission tomography (PET)
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Pentadentate bispidine ligands (3,7-diazabicyclo[3.3.1]nonanes) are optimized for maximum complex stability and facile functionalization with respect to their coupling to biological vector molecules and/or fluorescence markers for PET (positron emission t
- Comba, Peter,Hunoldt, Sebastian,Morgen, Michael,Pietzsch, Jens,Stephan, Holger,Wadepohl, Hubert
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- Unimolecular Anion-Binding Catalysts for Selective Ring-Opening Polymerization of O-carboxyanhydrides
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Anion-binding can regulate anion transport in chloride channels through dynamic non-covalent interactions, which gives insights into the designing of new organocatalytic transformations but is surprisingly unexplored in polymerization catalysis. Herein, we describe an effective unimolecular anion-binding organocatalysis where 4-(dimethylamino)pyridine is anchored to a thiourea for ring-opening polymerization of O-carboxyanhydrides (OCAs) to furnish highly isotactic poly(phenyllactic acid) (Ph-PLA) with molecular weight (MW) up to 150.0 kDa, which well addresses the formidable challenge of synthesizing high MW stereoregular polyesters. Calculations and experimental studies indicate a dynamic cooperative anion-binding mechanism, where the dynamic anion-binding interaction of thiourea moiety to propagating species facilitates efficient chain propagation and the synergetic decarboxylation retains high selectivity for OCA ring-opening over side reactions (such as cyclization, epimerization, and transesterification).
- Li, Maosheng,Zhang, Shuai,Zhang, Xiaoyong,Wang, Yanchao,Chen, Jinlong,Tao, Youhua,Wang, Xianhong
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- DMAP-thiourea catalyst and preparation method thereof, and high-molecular-weight biodegradable polyester and preparation method thereof
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The invention relates to a DMAP-thiourea catalyst and a preparation method thereof as well as high-molecular-weight biodegradable polyester and a preparation method thereof. The DMAP-thiourea catalyst disclosed by the invention has the characteristic of living polymerization when being used for catalyzing ring opening polymerization of O-carboxyl anhydride monomers (OCAs). According to the DMAP-thiourea catalyst disclosed by the invention, a thiourea group is used as Lewis acid, a monomer is activated through a hydrogen bond, DMAP is used as Lewis alkali and a nucleophilic addition monomer, and ring opening polymerization of an OCAs monomer is commonly catalyzed by utilizing an adjacent synergistic effect. Especially, the increased active species are zwitterions, and no alcohol is needed as an initiator. The polymerization speed is high, the reaction temperature is low, and the obtained polyester is high in molecular weight and narrow in distribution. By adjusting the structure of the catalyst, changing the acidity and alkalinity of the catalyst and the steric hindrance of the catalyst and optimizing parameters such as polymerization temperature, concentration and the like, controllable polymerization of the OCAs monomer is realized, and finally, biodegradable polyester with molecular weight as high as 130,000 is obtained.
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Paragraph 0095-0096; 0099
(2021/07/11)
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- DINUCLEATING LIGAND OR DINUCLEAR METAL COMPLEX
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To provide a dinuclear metal complex that can be synthesized simply and easily and has a proper anticancer action.SOLUTION: The present disclosure provides a dinucleating ligand represented by the following formula (I) and a dinuclear metal complex thereof (where each X may be the same or different to represent H, Cl, OMe, or, Me, Y is H, a phenyl group, a substituted carbamoyl group or the like).SELECTED DRAWING: None
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- Design of coordination interaction of Zn(II) complex with oligo-aspartate peptide to afford a high-affinity tag-probe pair
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A complementary recognition pair consisting of a genetically encodable peptide tag and a small molecular probe isa powerful tool to specifically label and manipulate a protein ofinterest under biological conditions. In this study, we report the redesign of a tag-probe pair comprising an oligo-aspartate peptide tag (such as DDDD) and a binuclear zinc complex. Isothermal-titration calorimetry screening of binding between the series of peptides and zinc complexes revealed that the binding affinity was largely influenced by subtle changes of the ligand structure of the probe. However, the binding was tolerant to differences of the tag peptide sequence. Of those tested, a pair containing a peptide tag (DDAADD) and a binuclear zinc complex possessing 4-chloropyridines (3-2Zn(II)) showed the strongest binding affinity (Ka = 3.88 × 105 M-1), which was about 10-fold larger than the conventional pair of D4-peptide tag (DDDD) and 1-2Zn(II) containing nonsubstituted pyridines (Ka = 3.73 × 104 M-1). The strong binding of this new complementary recognition pair enabled the rapid covalent labeling of a tag-fused maltose binding protein with a fluorescent zinc complex, demonstrating its potential utility in protein analysis.
- Fuchida, Hirokazu,Tabata, Shigekazu,Shindo, Naoya,Takashima, Ippei,Leng, Qiao,Hatsuyama, Yuji,Hamachi, Itaru,Ojida, Akio
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p. 784 - 791
(2015/06/25)
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- ACYLHYDRAZINE DERIVATIVES, PROCESS FOR PREPARING THE SAME AND USE THEREOF
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Novel acylhydrazine derivatives exhibiting an inhibitory activity against activated blood coagulation factor X, which are compounds of general formula (I)or salts thereof, wherein R is an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group; R1and R2are each hydrogen or optionally substituted hydrocarbyl, or alternatively R1and R2or the substituent of X1and R2may be united to form an optionally substituted ring; X1and X2are each free valency, optionally substituted alkylene, or optionally substituted imino; D is oxygen or sulfur; A is -N(R3)-Y- or -N=Y-, R3is hydrogen, optionally substituted hydrocarbyl, or acyl; Y is an optionally substituted chain hydrocarbon group or an optionally substituted cyclic group; and Z is (1) optionally substituted amino, (2) optionally substituted imidoyl, or (3) an optionally substituted nitrogenous heterocycle group.
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- Synthesis of (2R)-1-(4-chloro-2-pyridyl)-2-(2-pyridyl)ethylamine: A selective oxime reduction and crystallization-induced asymmetric transformation
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Reduction of 1-(4-chloro-2-pyridyl)-2-(2-pyridyl)ethanone oxime (3) using zinc in trifluoroacetic acid gave the corresponding racemic pyridylethylamine 4 in excellent yield without reductive removal of the chlorine atom. A subsequent diastereomeric crystallization of the amine 4 with an optically active cis-cyclohexanecarboxylic acid derivative in the presence of a catalytic amount of 3,5-dichlorosalicylaldehyde was found to give the desired R-amine 6 in 42% yield via a 'crystallization-induced asymmetric transformation'.
- Negi, Shigeto,Matsukura, Masayuki,Mizuno, Masanori,Miyake, Kazutoshi,Minami, Norio
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p. 991 - 996
(2007/10/03)
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