个人简介

B.S., 1972, City College of New York Ph.D., 1976, Harvard University Postdoctoral, 1976-78, Ohio State University

研究领域

Computational Chemistry

This research program uses modern methods of electronic structure theory to understand the fundamental nature of interactions between molecules. Chief among the concerns are hydrogen bonds which are so important to structure and function of biomolecules like proteins. Also of interest are a new class of noncovalent bonds involving pairs of electronegative atoms. When considering a H-bond, the thoughts of most would ordinarily turn to OH··O or OH··N interactions that pair electronegative atoms like O and N. Indeed, such bonds are quite common in proteins and act as a strong glue, cementing one part of the molecule to another. On the other hand, clues have turned up over the years that even less electronegative atoms like C can participate in H-bonds, albeit weaker ones. Most of these clues have been of the structural variety, wherein a CH group might lie in close proximity to an O atom, and the geometry of the contact might be reminiscent of a H-bond, i.e. the putative bridging H could lie along the direction of one of the lone electron pairs of the oxygen acceptor. Yet structural information of this sort is incapable of distinguishing a "coincidental" contact, where the two groups happen to lie close together for the sake of the structure of the entire molecule, from a true CH··O H-bond. The latter would be accompanied by an attractive interaction, a "fingerprint" electron redistribution pattern, and a number of characteristic spectroscopic features. Our group makes use of state-of-the-art ab initio quantum chemical methods to probe the underlying nature of the CH··O interaction, paying particular attention to the above properties, extracting information that is inaccessible to experimental measurements. We have learned that under certain conditions, the CH··O interaction is indeed a true H-bond, with an attractive force that can rival the more conventional OH··O bond. And even though the C-H stretching frequency may shift to the blue rather than to lower frequencies, this property is typical of certain weak H-bonds. Calculations have revealed the presence of a hitherto unknown noncovalent bond. A pnicogen atom (N, P, As, etc) can form an attractive interaction with an electronegative atom, for example another N atom. This bond is rooted in the charge transfer that takes place from the latter N lone pair into a σ* antibond of the pnicogen. Computations have shown that this bond can be quite strong, exceeding even a H-bond, and can play an important role in the structure of certain molecules and crystals.

近期论文

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The Pnicogen Bond: Its Relation to Hydrogen, Halogen, and Other Noncovalent Bonds, S. Scheiner, Acc. Chem. Res. 2013 46 280-288 Intramolecular S??O Chalcogen Bond as Stabilizing Factor in Geometry of Substituted Phenyl-SF3 Molecules, V. de P. N. Nziko and S. Scheiner, J. Org. Chem. 2015 80 2356-2363 Anionic CH??X- Hydrogen Bonds. Origin of their Strength, Geometry, and Other Properties. B. Nepal, S. Scheiner, Chem. Eur. J. 2015 21 1474-1481 Conservation and Functional Importance of Carbon-Oxygen Hydrogen Bonding in AdoMet-dependent Methyltransferases, S. Horowitz, L.M.A. Dirk, J. D. Yesselman, J. S. Nimtz, U. Adhikari, R. A. Mehl, S. Scheiner, R. L. Houtz, H. M. Al-Hashimi, R. C. Trievel, J. Am. Chem. Soc. 2013 135 15536-15548 The Magnitude and Mechanism of Charge Enhancement of CH??O H-bonds, U. Adhikari, Steve Scheiner, J. Phys. Chem. A 2013 117 10551-10562