Aminophenol-Decorated Gold Nanoparticles for Curing Bacterial Infections. Le Wang, Wenfu Zheng, Sixiang Li, Leni Zhong, Xingyu Jiang.The Journal of Physical Chemistry C 2022, 126 Benchmark Study of Alkane Molecular Chains.
Single Gold Nanostars Achieve Inherent Cascade Catalytic and Near-Infrared Photothermal Activities for Efficient Tumor Therapy. Meijun Zhao, Yuxuan Li, Yian Liu, Lintao Bai, Junjie Ma, Mei Ren, Jiahui Liu, Heyun Shen.This article is cited by 626 publications. Further insight into the binding strengths of these anchoring groups to gold electrodes is obtained by statistically analyzing the stretching length of molecular junctions. For diamine and dicarboxylic-acid groups, the conductance values are sensitive to pH due to protonation and deprotonation of the anchoring groups. These observations are attributed to different electronic couplings between the molecules and the electrodes and alignments of the molecular energy levels relative to the Fermi energy level of the electrodes introduced by different anchoring groups. The prefactor of the exponential decay function, which reflects the contact resistance, is highly sensitive to the anchoring group, and the decay constant is weakly dependent on the anchoring group. The I − V characteristics, temperature independence, and exponential decay of the conductance with the molecular length all indicate tunneling as the conduction mechanism for these molecules. Multiple sets of conductance values were found in each case. We created a large number of molecular junctions mechanically and analyzed the statistical distributions of the conductance values of the molecular junctions. Based on these data, rational selection of the anchor group is critical to achieve high MM conversion and to prepare pure, high MW bottlebrush polymers by ROMP grafting-through.We studied the effect of anchoring groups on the conductance of single molecules using alkanes terminated with dithiol, diamine, and dicarboxylic-acid groups as a model system. The addition of trifluoroacetic acid to the ROMP reaction substantially increased the propagation rate for all anchor groups tested, likely due to scavenging of the pyridine ligands. A chelation mechanism was initially proposed to explain the observed anchor group effect, but experimental and computational studies indicated that the rate differences likely resulted from a combination of varying steric demands and electronic structure among the different anchor groups. The observed >4-fold difference in propagation rate had a dramatic effect on the maximum obtainable backbone degree of polymerization, with slower propagating MMs reducing the maximum bottlebrush MW by an order of magnitude (from ∼10(6) to ∼10(5) Da). This phenomenon was conserved across all MMs tested, regardless of solvent, molecular weight (MW), or repeat unit identity. We observed a variance in the rate of propagation of >4-fold between similar MMs with different anchor groups. We evaluated the effect of anchor group chemistry-the configuration of atoms linking the polymer to a polymerizable norbornene-on the kinetics of ROMP of polystyrene and poly(lactic acid) MMs initiated by (H2IMes)(pyr)2(Cl)2Ru═CHPh (Grubbs third generation catalyst). Control over bottlebrush polymer synthesis by ring-opening metathesis polymerization (ROMP) of macromonomers (MMs) is highly dependent on the competition between the kinetics of the polymerization and the lifetime of the catalyst.
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