Gold(I) (Au(I))−thiolate complexes are widely believed as the precursors to Au nanoparticle formations. While the literature suggests that the Au(III)-to-thiol ligand stoichiometric ratio of 1:3 is required to reduce a Au(III) and yield a Au(I)−thiolate, other stoichiometric ratios are also known to produce Au nanoparticles upon reduction. Using the characteristic red luminescence of Au(I)-alkanethiolates, we examined the process of their formations and their implications on the Au nanoparticle synthesis in detail. The onset of the luminescence, correlated with the Au(I)−thiolate formation, as well as the kinetics of the luminophore formation were evaluated in terms of the Au(III)-to-alkanethiol ratios. The onset of the luminescence was affected significantly by the solvent polarity during reaction but not post reaction. We found that the kinetics of the luminophore formation can vary widely, requiring from minutes to 24 h for completion depending on the thiol ligands and molar ratios, as well as solvents. This information could help in designing Au nanoparticle syntheses with the logical choice of Au(III)-to-thiol ratio, solvent, and the timing of reduction.

Using the methods of equilibrium and non-equilibrium molecular dynamics alongside capillary viscometer experiments, we explore differences between united and all-atom models of a series of linear ethers. The models are based on two transferable force fields, and changes in viscosity and diffusion are studied across a wide range of temperatures and shear rates. We analyze diffusivity and viscosity data by means of the rotational relaxation time and Arrhenius equation. Rotational relaxation times are calculated explicitly from the ether chain’s end-to-end vectors, and self-diffusion values are calculated from the mean square displacement. We find an increase in orientational alignment as temperature drops in both models and consistent differences in activation energies across the models and experiment. A clear relationship is observed between viscosity, rotational relaxation time, and diffusion time. These time constants also impact the reliability of the viscosity value determined by the Green–Kubo method. We also study the trends in zero-shear viscosity as chain length increases and force field performance relative to experiment as this length changes.

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