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81.
Arlanda Huffer Ben Jeffery Benjamin J. Waller Andreas A. Danopoulos 《Comptes Rendus Chimie》2013,16(6):557-565
A method for the synthesis and isolation of 1,1′-methylene-bis-(3-aryl-imidazol-2-ylidene) ligands, aryl = 2,6-diisopropyl-phenyl (DiPP), LDiPP, mesityl (mes), Lmes, is reported, which provides synthetically useful quantities of high purity. Derivatisation of LDiPP with chalcogenides gave the adducts LDiPPE2, E = S, Se, Te. Reaction of LDiPP with [Pd(tmeda)Me2], [Pt(μ-SMe2)Me2]2, [Ir(1,5-COD)(μ-Cl)]2/KPF6 and [NiBr2(dme)] gave [Pd(LDiPP)Me2] (1), [Pt(LDiPP)Me2] (2), [Ir(LDiPP)(1,5-COD)](PF6) (3) and [Ni(LDiPP)Br2] (4), respectively. The latter was reduced in the presence of CO to [Ni(LDiPP)(CO)2] (5). The structures of Lmes, LDiPPTe2, and 1–5 are also reported. 相似文献
82.
The Claisen rearrangement of α-(thioalkoxy)-esters provided access to substituted trans-1, 6-dimethylbicyclo[4.3.0]non-2-enes characteristic of the CD rings of the cucurbitanes. 相似文献
83.
84.
Preparation of Stereoregular Isotactic Poly(mandelic acid) through Organocatalytic Ring‐Opening Polymerization of a Cyclic O‐Carboxyanhydride
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Dr. Antoine Buchard Dr. David R. Carbery Prof. Matthew G. Davidson Dr. Petya K. Ivanova Dr. Ben J. Jeffery Dr. Gabriele I. Kociok‐Köhn Dr. John P. Lowe 《Angewandte Chemie (International ed. in English)》2014,53(50):13858-13861
Poly(mandelic acid) (PMA) is an aryl analogue of poly(lactic acid) (PLA) and a biodegradable analogue of polystyrene. The preparation of stereoregular PMA was realized using a pyridine/mandelic acid adduct (Py?MA) as an organocatalyst for the ring‐opening polymerization (ROP) of the cyclic O‐carboxyanhydride (manOCA). Polymers with a narrow polydispersity index and excellent molecular‐weight control were prepared at ambient temperature. These highly isotactic chiral polymers exhibit an enhancement of the glass‐transition temperature (Tg) of 15 °C compared to the racemic polymer, suggesting potential future application as high‐performance commodity and biomedical materials. 相似文献
85.
Dr. Jeffery M. Tharp Dr. Omer Ad Dr. Kazuaki Amikura Fred R. Ward Emma M. Garcia Prof. Dr. Jamie H. D. Cate Prof. Dr. Alanna Schepartz Prof. Dr. Dieter Söll 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3146-3150
By transplanting identity elements into E. coli tRNAfMet, we have engineered an orthogonal initiator tRNA (itRNATy2) that is a substrate for Methanocaldococcus jannaschii TyrRS. We demonstrate that itRNATy2 can initiate translation in vivo with aromatic non-canonical amino acids (ncAAs) bearing diverse sidechains. Although the initial system suffered from low yields, deleting redundant copies of tRNAfMet from the genome afforded an E. coli strain in which the efficiency of non-canonical initiation equals elongation. With this improved system we produced a protein containing two distinct ncAAs at the first and second positions, an initial step towards producing completely unnatural polypeptides in vivo. This work provides a valuable tool to synthetic biology and demonstrates remarkable versatility of the E. coli translational machinery for initiation with ncAAs in vivo. 相似文献
86.
Fan Yang Wenhui Hu Chongqing Yang Margaret Patrick Andrew L. Cooksy Jian Zhang Jeffery A. Aguiar Chengcheng Fang Yinghua Zhou Ying Shirley Meng Jier Huang Jing Gu 《Angewandte Chemie (International ed. in English)》2020,59(11):4572-4580
A gas‐phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor‐phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution‐phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO2 to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element‐specific X‐ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square‐pyramidal geometry with four Zn?N bonds in the equatorial plane and one Zn‐OH2 bond in the axial plane. The fine‐tuned internal strain was further supported by monitoring changes in XRD and UV/Visible absorption spectra across a range of infiltration cycles. The ability to use internal strain to increase catalytic activity of MOFs suggests that applying this strategy will enhance intrinsic catalytic capabilities of a variety of porous materials. 相似文献
87.
Qi‐Zhi Zhong Joseph J. Richardson Shiyao Li Wenjie Zhang Yi Ju Jianhua Li Shuaijun Pan Jingqu Chen Frank Caruso 《Angewandte Chemie (International ed. in English)》2020,59(4):1711-1717
Functional coatings are of considerable interest because of their fundamental implications for interfacial assembly and promise for numerous applications. Universally adherent materials have recently emerged as versatile functional coatings; however, such coatings are generally limited to catechol, (ortho‐diphenol)‐containing molecules, as building blocks. Here, we report a facile, biofriendly enzyme‐mediated strategy for assembling a wide range of molecules (e.g., 14 representative molecules in this study) that do not natively have catechol moieties, including small molecules, peptides, and proteins, on various surfaces, while preserving the molecule's inherent function, such as catalysis (≈80 % retention of enzymatic activity for trypsin). Assembly is achieved by in situ conversion of monophenols into catechols via tyrosinase, where films form on surfaces via covalent and coordination cross‐linking. The resulting coatings are robust, functional (e.g., in protective coatings, biological imaging, and enzymatic catalysis), and versatile for diverse secondary surface‐confined reactions (e.g., biomineralization, metal ion chelation, and N‐hydroxysuccinimide conjugation). 相似文献
88.
Jeffery M. Tharp Omer Ad Kazuaki Amikura Fred R. Ward Emma M. Garcia Jamie H. D. Cate Alanna Schepartz Dieter Sll 《Angewandte Chemie (International ed. in English)》2020,59(8):3122-3126
By transplanting identity elements into E. coli tRNAfMet, we have engineered an orthogonal initiator tRNA (itRNATy2) that is a substrate for Methanocaldococcus jannaschii TyrRS. We demonstrate that itRNATy2 can initiate translation in vivo with aromatic non‐canonical amino acids (ncAAs) bearing diverse sidechains. Although the initial system suffered from low yields, deleting redundant copies of tRNAfMet from the genome afforded an E. coli strain in which the efficiency of non‐canonical initiation equals elongation. With this improved system we produced a protein containing two distinct ncAAs at the first and second positions, an initial step towards producing completely unnatural polypeptides in vivo. This work provides a valuable tool to synthetic biology and demonstrates remarkable versatility of the E. coli translational machinery for initiation with ncAAs in vivo. 相似文献
89.
Yiyuan Han Zhixing Lin Jiajing Zhou Gyeongwon Yun Rui Guo Joseph J. Richardson Frank Caruso 《Angewandte Chemie (International ed. in English)》2020,59(36):15618-15625
Functional materials composed of proteins have attracted much interest owing to the inherent and diverse functionality of proteins. However, establishing general techniques for assembling proteins into nanomaterials is challenging owing to the complex physicochemical nature and potential denaturation of proteins. Here, a simple, versatile strategy is introduced to fabricate functional protein assemblies through the interfacial assembly of proteins and polyphenols (e.g., tannic acid) on various substrates (organic, inorganic, and biological). The dominant interactions (hydrogen‐bonding, hydrophobic, and ionic) between the proteins and tannic acid were elucidated; most proteins undergo multiple noncovalent stabilizing interactions with polyphenols, which can be used to engineer responsiveness into the assemblies. The proteins retain their structure and function within the assemblies, thereby enabling their use in various applications (e.g., catalysis, fluorescence imaging, and cell targeting). 相似文献
90.