The electronic structures of the first-row transition-metal metallocenes, MCp 2 (M ) V, Cr, Mn, Fe, Co, and Ni), have been studied using a broad range of density functional methods with flexible double-ζ plus polarization (DZP) basis sets. Geometrical parameters of the D 5h and D 5d conformations (and structures of lower symmetry for CrCp 2 and CoCp 2 ) were fully optimized. For the ferrocene system, best characterized experimentally, the B3LYP, BLYP, and BP86 methods give structures in good agreement with experiment. For the D 5h -D 5d energy difference, the same three methods predict 0.75 kcal/mol (B3LYP), 0.99 kcal/mol (BLYP), and 1.13 kcal/mol (BP86). The cyclopentadienyl rings are very nearly planar; the angles of the C-H bond out of the Cp ring are less than 1°for all metallocenes except ferrocene. The C-H bonds are bent slightly away from the metal for V and Mn, slightly toward the metal for Fe and Ni, and virtually not at all from chromocene. According to the energetic and vibrational analyses, the D 5h conformations are found to be the global minima, leaving open the possibility that the D 5d conformations may exist under certain conditions. However, MnCp 2 probably exists as a mixture of both D 5h and D 5d conformations, because both are genuine minima with only a small energy difference. The predicted B3LYP energy differences (D 5h -D 5d ) for the six metallocenes are 0.29 (V), 0.28 (Cr), 0.13 (Mn), 0.75 (Fe), 0.38 (Co), and 0.23 kcal/mol (Ni). A number of reassignments of experimental vibrational bands are suggested. The molecular orbital energy level diagrams and the electron configurations for the metallocenes are compared. This information, obtained in a consistent manner across the first transition metal series, is helpful for discussion of the bonding characters and the chemical reactivities of these metallocenes.

The use of pesticides has made great contributions to agriculture, which ensures the high yield of crop. However, the low efficiency and overuse of pesticide has caused severe problems to the environment. Therefore, the construction of an efficient and environmentally friendly nanopesticide delivery system is of urgent need. In this work, we report PEGylated-graphene oxide (PEG-GO) as a nanocarrier for water-insoluble pesticides (e.g., emamectin benzoate, EB) delivery and investigate its antipest activity. In our strategy, through the simple physical adsorption approach, the hydrophobic EB molecule can be effectively loaded on the PEG-GO nanocarrier, forming a stable EB@PEG-GO nanoformulation. As a high performance carrier, PEG-GO exhibits ultrahigh adsorption capacity for EB (1647.2 mg/g). The as-prepared EB@PEG-GO shows excellent stability during the 2-year storage period, which is a benefit for its practical application. Compared with free EB, the advantages of EB@PEG-GO are (1) greatly improved water solubility (30 mg/mL), (2) pH-response and sustained pesticide release performance, (3) prolonged half-life under UV light irradiation (521.16 h), and (4) sustainable antipest activity. In consideration of its industrialization potential, our current results clearly demonstrate the brilliant future of GO-based nanomaterials in plant protection and agriculture.

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serious infections including tuberculosis, endocarditis, osteomyelitis, necrotizing pneumonia, and sepsis. [1] Treatment often requires long-term and intensive antibiotics administration; however, treatment failure and relapse are unfortunately common. [2] As we currently understand it, the major reasons for the failure of clinical therapy to eradicate intracellular bacteria include: i) poor cellular membrane penetration, suboptimal intracellular accumulation, and short retention of antibiotics; [3] ii) diminished antibacterial activity of antibiotics because of the harsh acidic and hydrolytic environment within phagolysosomes; [4] iii) intracellular bacteria being in a dormant state and tolerance of otherwise lethal concentration of antibiotics; [5] and iv) bacteria escape from phagolysosomes and hide in privileged intracellular compartments that evade the bactericidal actions of antibiotics. [6] At later timepoints, potentially after the cessation of therapy, the bacteria may then proliferate resulting in the apoptosis and autophagy of the cells. The evasive bacteria re-enter the circulation or re-infect local tissues. [7] As such, the infected cells have been likened to "Trojan horses" that protect bacteria with later dissemination of the infection into deeper tissues. [8] Drug delivery systems (DDSs) have shown increasing potential for the treatment of intracellular bacterial infection. [9] The Intracellular bacteria in latent or dormant states tolerate high-dose antibiotics. Fighting against these opportunistic bacteria has been a long-standing challenge. Herein, the design of a cascade-targeting drug delivery system (DDS) that can sequentially target macrophages and intracellular bacteria, exhibiting on-site drug delivery, is reported. The DDS is fabricated by encapsulating rifampicin (Rif ) into mannose-decorated poly(α-N-acryloylphenylalanine)-block-poly(β-N-acryloyl-d-aminoalanine) nanoparticles, denoted as Rif@FAM NPs. The mannose units on Rif@FAM NPs guide the initial macrophage-specific uptake and intracellular accumulation. After the uptake, the detachment of mannose in acidic phagolysosome via Schiff base cleavage exposes the d-aminoalanine moieties, which subsequently steer the NPs to escape from lysosomes and target intracellular bacteria through peptidoglycan-specific binding, as evidenced by the in situ/ex situ co-localization using confocal, flow cytometry, and transmission electron microscopy. Through the on-site Rif delivery, Rif@FAM NPs show superior in vitro and in vivo elimination efficiency than the control groups of free Rif or the DDSs lacking the macrophages-or bacteria-targeting moieties. Furthermore, Rif@FAM NPs remodel the innate immune response of the infected macrophages by upregulating M1/M2 polarization, resulting in a reinforced antibacterial capacity. Therefore, this biocompatible DDS enabling macrophages and bacteria targeting in a cascade manner provides a new outlook for the therapy of intracellular pathogen infection.