Ian Carmichael University of Glasgow, Scotland, B.Sc.Hons ('71) Ph.D. ('74) Director - Notre Dame Radiation Laboratory Tel. (574) 631-4502 e-mail: carmichael.1@nd.edu Theoretical Studies of Reactive Intermediates

Scientific Interests

Quantum chemistry of reactive intermediates — structure and properties of radicals, radical ions and excited states in solution and on surfaces

Magnetic interactions in molecular species — EPR splittings; NMR spin-coupling constants and chemical shifts; nuclear quadroplar couplings

Theory of radiation and photochemical transformations — photophysical processes; transient absorption spectroscopy

Recent Accomplishments | Top |

Water on alumina — The first molecular water on dry alumina (0001) is calculated by Density Functional Theory (DFT) methods to sit roughly parallel to the surface, O atop Al. Physisorption is predicted to proceed via competitive O–Al and H–O interactions terminating in a hexagonal, ice-like layer at a coverage of two waters per surface Al. However, dissociative adsorption to produce a hydroxylated surface appears energetically favorable.

Radiation damage in MX — Intensity loss from radiation damage during room-temperature X-ray characterization of lysozyme unexpectedly showed that the dose tolerated by a crystal is dependent on the dose rate according to a positive linear relationship (99% correlation coefficient); a 60% increase in dose rate gave a 4-fold increase in crystal lifetime over the range (6-10 Gy s⁻¹) studied.

NMR spin couplings in biomolecules — Internal electronegative substituents (IES) effects are calculated to phase shift ³J_COCC Karplus curves (~15°) suggesting that the two types of inter-residue C-O-C-C coupling pathways observed in many oligosaccharides cannot be treated using the same generalized ³J_COCC Karplus equation. DFT calculations of ³J_HCOH, ³J_CCOH, and ²J_COH values involving exchangeable hydroxyl protons support the use of a generalized Karplus equation to treat ³J_HCOH involving the non-anomeric OH groups. IES effects in ³J_H1,O1H again mandate a separate treatment of this coupling. ³J_CCOH values are shown to depend not only on the C-C-O-H torsion angle but also on the orientation of terminal substituents on the coupled carbon, necessitating three distinct Karplus equations for non-anomeric ³J_CCOH coupling. IES effects on ³J_C2,O1H also require a separate parameterization. ²J_COH values showed no systematic dependence on C–O torsions and are thus not structurally useful.

Selected Publications | Top |

E. de la Mora, I. Carmichael and E.F. Garman

Effective scavenging at cryotemperatures: further increasing the dose tolerance of protein crystals

J. Synchrotron Radiat. 2011 18, 346-57 link

A. Lewansowska, I. Carmichael, G. Hörner, G.L. Hug and B. Marciniak

Steric effects on intramolecular reactivity in cyclic dipeptides: Conformational analysis validated by a combined MD/DFT approach

Chem. Phys. Lett. 2011 512, 123-28 link

X. Hu, W. Zhang, I. Carmichael and A.S. Serianni

Amide cis-trans isomerization in aqueous solutions of N-formyl-D-glucosamine

and N-acetyl-D-glucosamine:  Chemical equilibria and exchange kinetics

J. Amer. Chem. Soc. 2010 132, 4641-52 link

X. Hu, I. Carmichael and A.S. Serianni
N-Acetyl side-chains in saccharides:  New NMR J-coupling equations sensitive to CH-NH and NH-CO bond conformations in 2-acetamido-2-deoxy-aldohexopyranosyl rings chemical equilibria and exchange kinetics
J. Org. Chem. 2010 75, 4899-910 link

A.I. Barker, R.J. Southworth-Davies, K.S. Paithankar, I. Carmichael and E.F. Garman
Room temperature scavengers for macromolecular crystallography: increased lifetimes and modified dose dependence of the intensity decay
J. Synchr. Radiat. 2009 16, 205-16 link

A. Lewandowska, G.L. Hug, G. Hörner, I. Carmichael, F. Kazmierczak and B. Marciniak
Chiral discrimination in the hydrogen-atom transfer between tyrosine and
benzophenone in rigid peptides
Chem. Phys. Lett. 2009 473, 348–53 link

Supported by the Division of
Chemical Sciences
Office of
Basic Energy Sciences
at the
U.S. Department of Energy

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Last Modified: 09/08/2011