Theoretical elucidation of a classic reaction: protonation of the quadruple bond of the octachlorodimolybdate(II,II) [Mo2Cl8]4- anion

The protonation reaction of the unbridged quadruple metal-metal bond of [Mo(2)Cl(8)](4-) anion producing the triply bonded hydride [Mo(2)(μ-H)(μ-Cl)(2)Cl(6)](3-) is studied by accurate Density Functional Theory computations. The reactant, product, stable intermediates, and transition states are located on the potential energy surface. The water solvent is explicitly included in the calculations. Full reaction profiles are calculated and compared to experimental data. The mechanism of the reaction is fully elucidated. This involves two steps. The first is a proton transfer from an oxonium ion to the quadruple bond, being rate determining. The second, involves the internal rearrangement of chlorine atoms and is much faster. Activation energies with a mean value of 19 kcal/mol are calculated, in excellent agreement with experimental values.     

Amphiphilic AxBy mikto-arm star copolymers with PLMA and POEGMA arms: Self-assembly and drug encapsulation

We report on the synthesis and self-assembly of amphiphilic mikto-arm star copolymers of the A_xB_y type with mixed arms of poly(lauryl methacrylate) and poly(oligo ethylene glycol methacrylate). Two star copolymers with different hydrophobic-to-hydrophilic ratios are prepared in order to study their self-assembly in aqueous media. Both stars organize in structures with dimensions in the nanoscale. The star with the lower hydrophobic content forms aggregates of lower size and molar mass and it has a higher critical aggregation concentration. The synthesized mikto-arm stars are able to encapsulate curcumin (CUR) and preserve its fluorescence properties while their self-organization is affected by the incorporation of the hydrophobic drug compound. Interestingly, the more hydrophilic star is more strongly affected by the presence of CUR in terms of aggregate size and mass. In phosphate buffered saline (PBS) and fetal bovine serum-PBS solutions the star with higher hydrophobic content appears to better preserve its monomodal size distribution in comparison to the star with lower hydrophobic content either with or without encapsulated CUR. This work opens possibilities for using the new star copolymers in the solubilization of hydrophobic compounds and the delivery of hydrophobic drugs for pharmaceutical and bioimaging applications.     

Nickel dithiolene complexes encapsulated in biocompatible amphiphilic diblock copolymer nanoparticles

The goal of this study is to prepare novel hybrid nanoparticles, in the form of micellar nanoparticles in aqueous media, which will combine the properties of the amphiphilic diblock copolymers (such as PEO‐b‐PPhOx and PI‐b‐PEO) with the ones of the nickel 1,2‐dithiolene (1,2‐Ni DT) complexes. The structural and morphological analysis of these nanoparticles have revealed that they can be promising for photodynamic therapy and near‐infrared (NIR) optical imaging due to their size and absorption in NIR. The micellar nanoparticles have been studied not only in aqueous solutions but also under other physiological conditions, that is, PBS and PBS‐FBS buffer solutions. Their solutions are characterized by several methods, including UV–vis spectroscopy, light scattering, and FTIR. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2507–2513