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Roger Lalancette email:
rogerlal@rutgers.edu
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Research Interests
Our research interests include small-molecule structure elucidation by single- crystal X-ray diffraction techniques, medium-size molecules (up to 100 atoms), as well as macromolecules (protein and peptide-chain structural information), and GC/MS of pesticides in soil and water samples at the part- per-trillion level.Our most recent work centers on the prediction of the type of intermolecular hydrogen bonding that exists in cyclic keto carboxylic acids. This prediction is based on the solid-state infrared spectrum (KBr pellet or neat powder) compared to the solid-state Raman spectrum, and subsequent proof of structure by lower-temperature (-30 C) single-crystal X-ray analysis. We have found only one example of intramolecular hydrogen-bonding in this type of molecule; mostly, we have found that hydrogen bonding forms either as a chain (catemer) from the acid proton of one molecule to the carbonyl oxygen of the next molecule, typically along a screw axis, or as an acid dimer leaving the carbonyl oxygen non-hydrogen-bonded.
We have demonstrated that the symmetry-based differences between solid-state IR and solid-state Raman spectra may be used reliably to differentiate those acids with dimeric H-bonding from those with non-centrosymmetric H-bonding patterns.