Related Experiment Video
Updated: Aug 6, 2025

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Controlling the Conformation of 2-Dimethylaminobiphenyls by Transient Intramolecular Hydrogen Bonding
Daniele Del Giudice1, Matteo Valentini1, Carla Sappino1
1Dipartimento di Chimica, Università di Roma La Sapienza and ISB-CNR Sede Secondaria di Roma - Meccanismi di Reazione, P.le A. Moro 5, I-00185 Roma, Italy.
Abstract:
Temporal control of molecular motions is receiving increasing attention because it is central to the development of molecular switches and motors and nanoscopic materials with life-like properties. Inspired by previous studies, here, we report that acid 12 can be used to temporally control the conformational freedom around the C-C bond connecting the two aromatic rings of the ditopic bases 4 and 5. Consistent with NMR measurements and DFT calculations, before fuel addition, the conformational motion of the two aromatic rings of both 4 and 5 mainly consists of a large amplitude torsional oscillation spanning about 260° and passing for the anti conformation (the two nitrogen atoms at opposite sides). Immediately after the addition of 12, due to the protonation of one nitrogen and consequent formation of an N-H···N intramolecular hydrogen bond, the torsional oscillation in both 4H+ and 5H+ is not only restricted to a smaller range (about 100°) but explores the previously forbidden conformational space around the syn conformation (the two nitrogen atoms at the same side). However, the new state is an out-of-equilibrium state since decarboxylation of the conjugate base of 12 takes place and, at the end of the process, the system reverts to the more conformationally mobile state.
More Related Videos
09:22Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
06:35Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Related Concept Videos
Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
Newman Projections
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as...
Stability of Conjugated Dienes
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR