Molecules, surfaces, crystals: A quantum chemical quest from fundamentals to applications

My research focuses on applying fundamental laws governing the behavior of molecules and materials to predict their real-world performance. Using state-of-the-art quantum chemical approaches as my tool set, I computationally model a wide range of molecular and condensed-matter systems: explosives, pharmaceuticals, porous materials, catalysts, nanomaterials, polymers, soft-matter, films, membranes, surfaces, interfaces, layered materials; hybrid systems: molecules interacting with substrates; and, their properties: structural, energetic, vibrational, electronic, mechanical, adsorption, diffusion. Chemical processes such as reactivity and the change of properties after exposure to external agents (e.g. durability) can also be explored. The results of my investigations can contribute to speeding up, decreasing the cost, and increasing the robustness of the development cycle of new materials and materials-dependent products.https://digitalcommons.mtu.edu/techtalks/1006/thumbnail.jp

Printing 3D Models for Chemistry: A Step-by-Step Open-Source Guide for Hobbyists, Corporate Professionals, and Educators and Students in K-12 and Higher Education

3D-printing is a relatively inexpensive additive manufacturing method used to create tangible objects. As a relatively new technology, the true capability of 3D-printing has not yet been fully exploited, especially in academic and research/teaching settings. Through this work, 3D-printing in a classroom and research environment is employed as a tool for creation of fully customizable, three-dimensional molecular models and for the visualization of theoretical abstract concepts.https://digitalcommons.mtu.edu/oabooks/1001/thumbnail.jp

Detecting Zn(II) Ions in Live Cells with Near-Infrared Fluorescent Probes.

Two near-infrared fluorescent probes (A and B) containing hemicyanine structures appended to dipicolylamine (DPA), and a dipicolylamine derivative where one pyridine was substituted with pyrazine, respectively, were synthesized and tested for the identification of Zn(II) ions in live cells. In both probes, an acetyl group is attached to the phenolic oxygen atom of the hemicyanine platform to decrease the probe fluorescence background. Probe A displays sensitive fluorescence responses and binds preferentially to Zn(II) ions over other metal ions such as Cd2+ ions with a low detection limit of 0.45 nM. In contrast, the emission spectra of probe B is not significantly affected if Zn(II) ions are added. Probe A possesses excellent membrane permeability and low cytotoxicity, allowing for sensitive imaging of both exogenously supplemented Zn(II) ions in live cells, and endogenously releases Zn(II) ions in cells after treatment of 2,2-dithiodipyridin

Detecting Zn(II) Ions in Live Cells with Near-Infrared Fluorescent Probes.

Two near-infrared fluorescent probes (A and B) containing hemicyanine structures appended to dipicolylamine (DPA), and a dipicolylamine derivative where one pyridine was substituted with pyrazine, respectively, were synthesized and tested for the identification of Zn(II) ions in live cells. In both probes, an acetyl group is attached to the phenolic oxygen atom of the hemicyanine platform to decrease the probe fluorescence background. Probe A displays sensitive fluorescence responses and binds preferentially to Zn(II) ions over other metal ions such as Cd2+ ions with a low detection limit of 0.45 nM. In contrast, the emission spectra of probe B is not significantly affected if Zn(II) ions are added. Probe A possesses excellent membrane permeability and low cytotoxicity, allowing for sensitive imaging of both exogenously supplemented Zn(II) ions in live cells, and endogenously releases Zn(II) ions in cells after treatment of 2,2-dithiodipyridin

Calculation of fully non-adiabatic properties of the hydrogen molecular cation and its isotopomers

By using a scattering approach combined with a transformed Hamiltonian theory, fully non-adiabatic properties of the vibration-rotational levels of the ground electronic state of the hydrogen molecular cation H+2 and its isotopomers, D+2 and HD+, are studied.  For low vibrational levels a variational method is also used, providing a check on the methods.  The properties considered include the dissociation energies, the bond lengths and the dipole polarizabilities for all the three cations.  Relativistic corrections are studied just for H+2. While properties such as bond lengths and dipole polarizabilities are studied through analytic integration, a numerical integration approach is developed to study the relativistic correlations, since singular integrands are involved.  In addition, a new calculation method is developed so that the scattering method may be used. Non-adiabatic dissociation energies and bond lengths are also studied for the tritium heteronuclear isotopomers HT+ and DT+.</p

Energetic competition in the complexation affinity of paracetamol with water and oxalic acid

The intermolecular interactions of active pharmaceutical ingredients (APIs) are the driving forces of API molecular activity and stability, in vivo receptor binding, environmental transport, and persistence. In manufacturing, API complexation with another molecule to create stable crystalline structures is pursued, but the formation of more energetically stable complexes can lead to undesired consequences. Density functional theory (DFT) was used to describe the role played by hydrogen bonding in the formation of paracetamol and oxalic acid (PCA-OXA) complexes. PCA-OXA hydrogen bonding sites were investigated to determine strength and overall contribution/competition during the initial stages of the nucleation process. Structural and energetic changes were evaluated for 1:1 PCA-OXA, PCA-Water, and OXA-Water complexes both in vacuum and in water environments via explicit and implicit solvation. Results show significant shortening of the hydrogen bonds within the PCA-OXA complex with large changes in energy in the PCA-OXA complexation mechanism. Two out of the four complexation sites play the largest roles in the initial steps of the nucleation process. In an aqueous environment, little to no energetic competition for PCA hydrogen bonds formation with other molecules is observed. Post Hartree–Fock methods (MP2 and CCSD) were used to calibrate and verify the DFT results

Part I: C \u3c inf\u3e 2 [sbnd]C \u3c inf\u3e 4 hydrocarbons separation addressed via molecular cluster models carved out from periodic MOF-74-Mg/Zn structures

© 2016 Elsevier B.V. Selective sorption of hydrocarbons by tunable sorbents such as metal-organic frameworks is the most promising alternative to traditional cryogenic distillation. Here, density functional theory is used to investigate the selective sorption of C2[sbnd]C4 hydrocarbons by MOF-74-Mg/Zn via periodic and molecular cluster calculations. Both methods agree in showing significant differences in binding energies between olefins and paraffins at the open metal sites of the MOF. The binding energies found using molecular cluster models, however, are significantly smaller than those obtained from the periodic approach, exemplifying the importance of fully accounting for the chemical environment experienced by the adsorbed hydrocarbons