multiple charge
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2021 ◽  
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.


2021 ◽  
Vol 119 (16) ◽  
pp. 163101
Author(s):  
Zishen Wang ◽  
Jun Zhou ◽  
Kian Ping Loh ◽  
Yuan Ping Feng

2021 ◽  
Vol 127 (2) ◽  
Author(s):  
Sangjun Lee ◽  
John Collini ◽  
Stella X.-L. Sun ◽  
Matteo Mitrano ◽  
Xuefei Guo ◽  
...  

Nano Letters ◽  
2021 ◽  
Author(s):  
Shaobo Cheng ◽  
Xing Li ◽  
Changsong Xu ◽  
Yu Liu ◽  
Marco Beleggia ◽  
...  

2021 ◽  
Vol 9 ◽  
Author(s):  
Divya Kaur ◽  
Umesh Khaniya ◽  
Yingying Zhang ◽  
M. R. Gunner

Biological membranes are barriers to polar molecules, so membrane embedded proteins control the transfers between cellular compartments. Protein controlled transport moves substrates and activates cellular signaling cascades. In addition, the electrochemical gradient across mitochondrial, bacterial and chloroplast membranes, is a key source of stored cellular energy. This is generated by electron, proton and ion transfers through proteins. The gradient is used to fuel ATP synthesis and to drive active transport. Here the mechanisms by which protons move into the buried active sites of Photosystem II (PSII), bacterial RCs (bRCs) and through the proton pumps, Bacteriorhodopsin (bR), Complex I and Cytochrome c oxidase (CcO), are reviewed. These proteins all use water filled proton transfer paths. The proton pumps, that move protons uphill from low to high concentration compartments, also utilize Proton Loading Sites (PLS), that transiently load and unload protons and gates, which block backflow of protons. PLS and gates should be synchronized so PLS proton affinity is high when the gate opens to the side with few protons and low when the path is open to the high concentration side. Proton transfer paths in the proteins we describe have different design features. Linear paths are seen with a unique entry and exit and a relatively straight path between them. Alternatively, paths can be complex with a tangle of possible routes. Likewise, PLS can be a single residue that changes protonation state or a cluster of residues with multiple charge and tautomer states.


2021 ◽  
Author(s):  
Ganbat Duvjir ◽  
Byoung Ki Choi ◽  
Trinh Thi Ly ◽  
Nguyen Huu Lam ◽  
Kyuha Jang ◽  
...  

2021 ◽  
Author(s):  
Jian Gou ◽  
Bingyu Xia ◽  
Xuguang Wang ◽  
Peng Cheng ◽  
Andrew Thye Shen Wee ◽  
...  

Abstract Creating and manipulating multiple charge states of solitary defects in semiconductors is of essential importance for solitary defect electronics, but is fundamentally limited by Coulomb's law. Achieving this objective is challenging, due to the conflicting requirements of the localization necessary for the sizable band gap and delocalization necessary for a low charging energy. Here, using scanning tunneling microscopy/spectroscopy experiments and first-principles calculations, we realized exotic quinary charge states of solitary defects in two-dimensional intermetallic semiconductor Sn2Bi. We also observed an ultralow defect charging energy that increases sublinearly with charge number rather than displaying the usual quadratic behavior. Our work suggests a promising route for constructing multiple defect-charge states by designing intermetallic semiconductors, and opens new opportunities for developing quantum devices with charge-based quantum states.


2021 ◽  
Vol 126 (11) ◽  
Author(s):  
P. N. Ostroumov ◽  
K. Fukushima ◽  
T. Maruta ◽  
A. S. Plastun ◽  
J. Wei ◽  
...  

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