By a News Reporter-Staff News Editor at Physics Week -- A new study on Rotaxanes is now available. According to news reporting originating in Stockholm, Sweden, by VerticalNews journalists, research stated, "Motion is an essential and fundamental feature of any living organism. The evolved organisms have developed sophisticated and perfect machineries and highly delicate mechanisms to carry out directional and coordinated movements which eventually lead to motion at the macroscopic length scale."
The news reporters obtained a quote from the research from Stockholm University, "By mimicking these natural machineries, attempts to design and synthesize similar molecular motors are made in relevance to their applications in drug delivery, data storage, and molecular sensing. It is highly desirable to establish the rules for controlling the conformational states of molecular motors by tuning some of the external variables which can be used for the design strategies. We contribute to this subject by looking into the solvent influence on the conformational states of a synthetic molecular rotor, namely, diketopyrrolopyrrole (DPP) based rotaxane, using the force-field molecular dynamics approach. We study this system in three different solvents, and we report a strong solvent dependence in the population of three different translational isomers. In chloroform solvent we report the dominant population of the 2-P isomer which is in excellent agreement with experimental results based on H NMR spectra (Org. Lett. 2013, 15, 1274). However, there is a striking difference seen in the population of translational isomers in DMSO solvent, and we attribute these features to negligence of solvent hydrogen bonding induced upfield and downfield effects in the interpretation of experimental proton NMR spectra. In addition, we also report a solvent-polarity-induced fully unstretched to folded conformational transition in the rotaxane system. On the basis of the molecular mechanics Poisson-Boltzmann (and generalized Born) surface area approach, we identify the driving force for the formation of the supramolecular guest-host rotaxane system."
According to the news reporters, the research concluded: "Finally, we calculate the relative binding free energies for the macrocycle at different binding sites of the DPP skeleton using the molecular dynamics simulations performed for the macrocycle-rotaxane system in water solvent which suggests the increased stability of the 2-O isomer in polar solvent."
For more information on this research see: Solvent-Dependent Conformational States of a Rotaxane-Based Molecular Machine: A Molecular Dynamics Perspective. Journal of Physical Chemistry C, 2013;117(47):25059-25068. Journal of Physical Chemistry C can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Journal of Physical Chemistry C - www.pubs.acs.org/journal/jpccck)
Our news correspondents report that additional information may be obtained by contacting N.K. Jena, Stockholm University, Dept. of Phys, Albanova, SE-10691 Stockholm, Sweden.
Keywords for this news article include: Sweden, Europe, Physics, Stockholm, Rotaxanes, Nanotechnology, Organic Chemicals, Molecular Dynamics, Molecular Machines, Emerging Technologies
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