The seminar is sponsored by NYU-ECNU Center for Computational Chemistry at NYU Shanghai
Abstract:
First principles free energy calculations, characterizing polymorphism of self-assembled monolayers (SAMs) of porphyrin molecules formed from solution onto graphite, are performed using efficient methods previously applied only to small-molecule reactivity. SAM structures are typically optimized in the absence of solvent using Density-Functional Theory embodying explicit dispersion corrections. Added then are dispersion-dominated implicit solvation energies and SAM formation entropies derived from both molecular and phonon vibration frequencies. Scanning-Tunnelling Microscopy (STM) images are measured, and polymorph formation free energies approximated. Close parallels between experiment and theory support the hypothesis that the first seconds of SAM formation are under thermodynamic control, despite formed SAMs being kinetically trapped. Polymorphism is associated with large opposing changes to entropy and substrate-molecule and solvent-molecule interaction energies.
Biography:
Jeff Reimers studied organic spectroscopy under Ian Ross and Gad Fischer in 1979 before doing a Ph.D. with Bob Watts on the structure, thermodynamics, and spectroscopy of water and ice (1980-1982). He then studied semiclassical quantum mechanics in USA under Kent Wilson and Rick Heller before returning to Australia to be an ARC Research Fellow from 1985 to 2010 at the University of Sydney. There he collaborated extensively with Noel Hush and Max Crossley on problems involving electron transfer, molecular electronics, porphyrin chemistry, electronic-structure theory, and photosynthesis. In 2014 he moved to a joint appointment at Shanghai University (9 months per year) and The University of Technology Sydney (3 months per year), focusing on new methods for protein crystallography. His work spans a wide range of chemical applications, from mutagenesis to electrical engineering to the origins of consciousness. He has received the Royal Australian Chemical Institute (RACI) Physical Chemistry Division Medal (2014), the RACI H.G. Smith Medal for Chemical Research (2009), and the forthcoming Craig Medal of the Australian Academy of Science (2016); he is a Fellow of the RACI and also the Australian Academy of Science.