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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Frequency analysis of amide-linked rotaxane mimetics
Werner Reckien1, Barbara Kirchner, Sigrid D Peyerimhoff
1Theoretische Chemie, Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany.
The Journal of Physical Chemistry. A
|November 28, 2006
Summary
This study analyzes vibrational shifts in 2-fold hydrogen bonds, revealing distinct red and blue shifts for donor and acceptor groups. These findings offer insights into supramolecular chemistry and hydrogen bonding interactions.
Area of Science:
- Supramolecular Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Hydrogen bonds are crucial in supramolecular chemistry, influencing the structure and function of complex molecular assemblies.
- Isophthalic amide systems serve as valuable models for studying hydrogen bonding in various supramolecular compounds like rotaxanes and anion receptors.
Purpose of the Study:
- To perform a vibrational analysis of 2-fold hydrogen bonds between an isophthalic amide donor and diverse acceptors.
- To correlate observed vibrational shifts with binding energies in these hydrogen-bonded systems.
Main Methods:
- Utilized vibrational spectroscopy to analyze hydrogen bond interactions.
- Employed computational methods to calculate vibrational modes and shifts.
- Investigated both stretching and bending modes of donor (NH2) and acceptor (carbonyl) groups.
Main Results:
- Observed significant red-shifts (up to 65 cm(-1)) in stretching modes of acceptor carbonyl and donor NH2 groups.
- Detected blue shifts in NH2 bending modes and identified a weak C-H---acceptor hydrogen bond.
- Found smaller N-H stretching red-shifts but larger C=O stretching red-shifts in 2-fold compared to single hydrogen bonds.
- Attributed the pronounced C-H blue shift to the proximity of the acceptor in the 2-fold hydrogen bond.
Conclusions:
- Vibrational analysis provides a sensitive probe for characterizing 2-fold hydrogen bonds and their interactions.
- The distinct shifts in vibrational modes offer a method to assess binding energies in supramolecular complexes.
- Understanding these specific vibrational behaviors enhances the design and prediction of supramolecular structures.
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