The rates of excited-state intramolecular electron transfer in 9-(4-biphenyl)-10-methylacridinium (BPAc(+)), crystal violet lactone (CVL), and bianthryl have been measured in a variety of ionic liquids using time-correlated single-photon counting. All three of these reactions had previously been studied in conventional dipolar solvents and their reaction rates shown to be controlled by solvation dynamics. The main focus of this work is to ask whether the same relationships between reaction and solvation times already established in dipolar solvents also apply in ionic liquids. In BPAc(+), where reaction conforms to a simple two-state kinetic scheme and reaction rates are easily measured, the result is a clear "yes". In the case of bianthryl, whose spectra reflect the more complex kinetics of a barrierless process, the answer is also yes. In contrast to other recent studies of bianthryl, the present results demonstrate that the same equality between (integral) reaction times and solvation times observed in conventional solvents also applies in ionic liquids. Finally, the case of CVL is less clear due to the greater uncertainty associated with the data afforded by this weak fluorophore, combined with a lack of data in conventional solvents having large solvation times. But the CVL reaction can also be reasonably interpreted as exhibiting a common behavior in dipolar and ionic solvents.

A one-dimensional (1D) sp carbon nanomaterial with high lateral packing order, known as carbon nanothreads, has recently been synthesized by slowly compressing and decompressing crystalline solid benzene at high pressure. The atomic structure of an individual nanothread has not yet been determined experimentally. We have calculated the C nuclear magnetic resonance (NMR) chemical shifts, chemical shielding tensors, and anisotropies of several axially ordered and disordered partially saturated and fully saturated nanothreads within density functional theory and systematically compared the results with experimental solid-state NMR data to assist in identifying the structures of the synthesized nanothreads. In the fully saturated threads, every carbon atom in each progenitor benzene molecule has bonded to a neighboring molecule (i.e., 6 bonds per molecule, a so-called "degree-6" nanothread), while the partially saturated threads examined retain a single double bond per benzene ring ("degree-4"). The most-parsimonious theoretical fit to the experimental 1D solid-state NMR spectrum, constrained by the measured chemical shift anisotropies and key features of two-dimensional NMR spectra, suggests a certain combination of degree-4 and degree-6 nanothreads as plausible components of this 1D sp carbon nanomaterial, with intriguing hints of a [4 + 2] cycloaddition pathway toward nanothread formation from benzene columns in the progenitor molecular crystal, based on the presence of nanothreads IV-7, IV-8, and square polymer in the minimal fit.

Evidence from recent Mars missions indicates the presence of perchlorate salts up to 1 wt % level in the near-surface materials. Mixed perchlorates and other oxychlorine species may complicate the detection of organic molecules in bulk martian samples when using pyrolysis techniques. To address this analytical challenge, we report here results of laboratory measurements with laser desorption mass spectrometry, including analyses performed on both commercial and Mars Organic Molecule Analyzer (MOMA) breadboard instruments. We demonstrate that the detection of nonvolatile organics in selected spiked mineral-matrix materials by laser desorption/ionization (LDI) mass spectrometry is not inhibited by the presence of up to 1 wt % perchlorate salt. The organics in the sample are not significantly degraded or combusted in the LDI process, and the parent molecular ion is retained in the mass spectrum. The LDI technique provides distinct potential benefits for the detection of organics in situ on the martian surface and has the potential to aid in the search for signs of life on Mars.

Cooperative diffusion coefficient (Dcoop) describes the dynamics of a polymer network in a gel, and is estimated by three independent methods. We measured three Dcoop's of a model polymer network system (Tetra-PEG gels), and obtained the experimental evidence to fundamentally understand the dynamics of polymer gels.