Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. Although some of the descriptors that appear in our QSPRs were designed to describe chemical reactions, we infer that they serve in this study to quantify interactions between the cation and anion. Melting-point QSPRs were then derived from molecular orbital, thermodynamic, and electrostatic descriptors. Good correlations with the experimental data were found. The correlation coefficients for three-parameter melting-point QSPRs and for one-parameter density QSPRs exceed 0.9. Although some of the descriptors that appear in our QSPRs were designed to describe chemical reactions, we infer that they serve in this study to quantify interactions between the cation and anion.3

In this work, to explain doping behavior of single-layer graphene upon HSSYWYAFNNKT (P1) and HSSAAAAFNNKT (P1-3A) adsorption in field-effect transistors (GFETs), we applied a combined computational approach, whereby peptide adsorption was modeled by molecular dynamics simulations, and the lowest energy configuration was confirmed by density functional theory calculations. On the basis of the resulting structures of the hybrid materials, electronic structure and transport calculations were investigated. We demonstrate that π-π stacking of the aromatic residues and proximate peptide backbone to the graphene surface in P1 have a role in the p-doping. These results are consistent with our experimental observation of the GFET's p-doping even after a 24-h annealing procedure. Upon substitution of three of the aromatic residues to Ala in (P1-3A), a considerable decrease from p-doping is observed experimentally, demonstrating n-doping as compared to the nonadsorbed device, yet not explained based on the atomistic MD simulation structures. To gain a qualitative understanding of P1-3A's adsorption over a longer simulation time, which may differ from aromatic amino acid residues' swift anchoring on the surface, we analyzed equilibrated coarse-grain simulations performed for 500 ns. Desorption of the Ala residues from the surface was shown computationally, which could in turn affect charge transfer, yet a full explanation of the mechanism of n-doping will require elucidation of differences between various aromatic residues as dependent on peptide composition, and inclusion of effects of the substrate and environment, to be considered in future work.

Melting points are important for the specific application of ionic liquids. Although many different ionic liquids are possible, melting points are known only for relatively few. Derivation of melting point QSPRs (Quantitative Structure-Property Relationships) for ionic liquids would therefore greatly aid in the molecular design of new compounds. A new class of ionic liquids, based on 1-substituted-4-amino-1,2,4-triazolium bromide, nitrate, and nitrocyanamide salts were recently synthesized and their melting points measured. After optimizing the molecular geometries of the cations of the ionic liquids using ab initio quantum chemical methods, we derived melting-point QSPRs from molecular orbital and electrostatic descriptors. Good correlations with the experimental data were found. The correlation coefficients for three-parameter melting-point QSPRs exceed 0.8. Although some of the descriptors that appear in our QSPRs were designed to describe chemical reactions, we infer that they serve in this study to quantify interactions between the cation and anion or between the cations.

Molecular dynamics (MD) simulations were carried out to study the conformational rearrangement induced by deprotonation of the fluorescent chromophore in GFP, as well as the associated changes in the hydrogen-bonding network. For both the structures with either a neutral or an anionic chromophore, it was found that the beta-barrel was stable and rigid, and the conformation of the chromophore was consistent with the available x-ray structure. The conformational change in Thr203 due to deprotonation was also found to be consistent with the three-state isomerization model. Although GFP is highly fluorescent, denatured-GFP is nonfluorescent, indicating that the environment of the protein plays an important role in its fluorescence behavior. Our MD simulations, which explore the effect of the protein shell on the conformation of the chromophore, find the flexibility of the central chromophore to be significantly restricted due to the rigid nature of the protein shell. The hydrogen-bonding between the chromophore and neighboring residues was also shown to contribute to the chromophore rigidity. In addition to the MD studies, quantum mechanics/molecular mechanics (QM/MM) ONIOM calculations were carried out to investigate the effect of the beta-barrel on the internal rotation in the chromophore. Along with providing quantitative values for torsional rotation barriers about the bridging bond in the chromophore, the ONIOM calculations also validate our MD force field parameters.