scholarly journals An Easily Synthesized Covalent Nanocage that Hosts Fullerenes in Multiple Charge States and Selectively Binds C70

Author(s):  
Daniel A. Rothschild ◽  
Aaron Tran ◽  
William P. Kopcha ◽  
Jianyuan Zhang ◽  
Mark C. Lipke

Discrete nanocages provide a way to solubilize, separate, and tune the properties of molecular guests, including fullerenes and other aromatics. However, few such nanocages can be synthesized efficiently from inexpensive starting materials, limiting their practical utility. To address this limitation, we developed a new pyridinium-linked cofacial porphyrin nanocage (Cage4+) that can be prepared efficiently on a gram scale. NMR studies in CD3CN reveal that Cage4+ binds C60 and C70 with association constants >108 M-1 and complete selectivity for extracting C70 from mixtures of both fullerenes. The solubility of Cage4+ in polar solvents enabled electrochemical characterization of the host-guest complexes C60@Cage4+ and C70@Cage4+, finding that the redox properties of the encapsulated fullerenes are minimally affected despite the positive charge of the host. Complexes of the −1 and −2 charge states of the fullerenes bound in Cage4+ were subsequently characterized by UV-vis-NIR and NMR spectroscopies. The relatively easy preparation of Cage4+ and its ability to bind fullerenes without substantially affecting their redox properties suggests that C60@Cage4+ and C70@Cage4+ may be directly useful as solubilized fullerene derivatives.

2020 ◽  
Vol 17 (2) ◽  
pp. 85-89
Author(s):  
Francisco J. Hidalgo ◽  
Nathan A.P. Lorentz ◽  
TinTin B. Luu ◽  
Jonathan D. Tran ◽  
Praveen D. Wickremasinghe ◽  
...  

: Maltodextrins have an increasing number of biomedical and industrial applications due to their attractive physicochemical properties such as biodegradability and biocompatibility. Herein, we describe the development of a synthetic pathway and characterization of thiol-responsive maltodextrin conjugates with dithiomaleimide linkages. 19F NMR studies were also conducted to demonstrate the exchange dynamics of the dithiomaleimide-functionalized sugar end groups.


1980 ◽  
Vol 45 (2) ◽  
pp. 335-338 ◽  
Author(s):  
Adéla Kotočová ◽  
Ulrich Mayer

The solvation effect of a number of nonaqueous polar solvents was studied on the oxidation-reduction properties of the [Co(en)3]3+-[Co(en)3]2+ system. Interactions of these ions with the solvent molecules are discussed in terms of their coordination, which is accompanied by a specific interaction of the Lewis acid-base type, namely formation of a hydrogen bond between the interacting particles. This is the main controlling factor of the redox properties of the studied system.


1987 ◽  
Vol 252 (4) ◽  
pp. C441-C449 ◽  
Author(s):  
L. A. Levy ◽  
E. Murphy ◽  
R. E. London

Fluorine 19 nuclear magnetic resonance (NMR) studies of intracellular fluorinated calcium chelators provide a useful strategy for the determination of cytosolic free calcium levels in cells and perfused organs. However, the fluorinated chelator with the highest affinity for calcium ions which has been described to date. 1,2-bis-(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), exhibits a dissociation constant (Kd) value 5- to 10-fold greater than the intracellular calcium concentration levels in most cell types, thus limiting the ability of fluorine NMR to report these concentrations reliably. We have consequently designed and synthesized several fluorinated calcium chelators with higher affinity for calcium. The best of these, 2-(2-amino-4-methyl-5-fluorophenoxy)-methyl-8 aminoquinidine-N,N,N',N'-tetraacetic acid (quinMF), has a Kd value approximately 10 times lower than that of 5FBAPTA. Several of the newly synthesized indicators have different chemical shifts for the calcium complexed and uncomplexed chelators to allow the simultaneous use of two indicators. In addition to providing information about the level of cytosolic free calcium, chelators containing a quinoline ring exhibit considerable sensitivity to magnesium levels and hence have potential application for the determination of cytosolic-magnesium concentrations. Application of these chelators is illustrated by determination of the cytosolic-free calcium level in erythrocytes. Use of quinMF, the chelator with the lowest Kd value, gives a calcium value of 25-30 nM.


Author(s):  
Vijayaraj Anantharaj ◽  
Jayant Bhonsle ◽  
Taizoon Canteenwala ◽  
Long Y. Chiang

2021 ◽  
Author(s):  
Sebastian Ponath ◽  
Chetan Joshi ◽  
Amy T. Merrill ◽  
Volker Schmidts ◽  
Kim Greis ◽  
...  

A comprehensive analysis of the organocatalytic α‐chlorination of aldehydes with N‐chloroimides and differ‐ ent catalysts is presented. For this reaction, alternate mechanisms were proposed that differ in the role of resting state intermediates and the rationalization of the observed enantioselectivity. This manuscript aims at resolving these funda‐ mental questions on the basis of rigorous structural characterization of intermediates (configuration and conformation), NMR studies, ion mobility‐mass spectrometry, concentration profiles, isotope studies, and DFT calculations. <br>


2020 ◽  
Vol 32 (9) ◽  
pp. 1001-1009
Author(s):  
Yi-Sheng Luo ◽  
Qiu-Ying Wang ◽  
Xue-Chun Mao ◽  
Shou-Ri Sheng

A new aromatic diamine, 10,10-bis[4-(4-aminophenoxy)phenyl]-9(10 H)-anthrone (BAPA) has been synthesized from anthrone via three-step procedure. Direct phosphorylation polycondensation of BAPA with various aromatic dicarboxylic acids produced a series of cardo poly(ether amide)s with inherent viscosities of 0.97–1.29 dL g−1. All the polymers were readily soluble in polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide (DMAc), and pyridine at room temperature, and afforded transparent, strong, and flexible films upon casting from DMAc solvent. The resulting poly(ether amide)s had glass transition temperatures of 254–316°C, 10% weight loss temperatures of 495–524°C, and char yields of 55–70% at 800°C in nitrogen. These polymers were amorphous and their films exhibited tensile strengths of 81.6–104.7 MPa, tensile moduli of 1.8–2.4 GPa, and elongations at break of 8–15%.


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