Improved physical properties and rotational dynamics in a molecular gyroscope with an asymmetric stator structure.

[structure: see text] A molecular gyroscope consisting of a 1,4-diethynylphenylene rotator linked to trityl and triptycyl groups (3) showed significantly improved physical properties and faster rotational dynamics than analogous symmetric bis(trityl) (1) or bis(triptycyl) (2) structures. An activation energy of 7.9 kcal/mol for 3 was determined by 2H NMR. This is ca. 4-6 kcal/mol lower than that of compound 1. The different dynamics of the three compounds can be qualitatively understood in terms of their different packing coefficients.

[1]  Dominik Horinek,et al.  Artificial molecular rotors. , 2005, Chemical reviews.

[2]  C. Dietrich-Buchecker,et al.  Shuttles and muscles: linear molecular machines based on transition metals. , 2001, Accounts of chemical research.

[3]  M. Garcia‐Garibay,et al.  Crystalline molecular machines: encoding supramolecular dynamics into molecular structure. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[4]  M. Garcia‐Garibay,et al.  Molecular compasses and gyroscopes. II. Synthesis and characterization of molecular rotors with axially substituted bis[2-(9-triptycyl)ethynyl]arenes. , 2002, Journal of the American Chemical Society.

[5]  Hsian-Rong Tseng,et al.  An operational supramolecular nanovalve. , 2004, Journal of the American Chemical Society.

[6]  T R Kelly,et al.  Progress toward a rationally designed molecular motor. , 2001, Accounts of chemical research.

[7]  L. Jelinski,et al.  Aromatic ring flips in a semicrystalline polymer , 1984 .

[8]  Francesco Zerbetto,et al.  Unidirectional rotation in a mechanically interlocked molecular rotor , 2003, Nature.

[9]  H. Scheraga,et al.  Tyrosyl motion in peptides. Deuterium NMR line shapes and spin-lattice relaxation , 1987 .

[10]  M. Garcia‐Garibay,et al.  Molecular compasses and gyroscopes with polar rotors: synthesis and characterization of crystalline forms. , 2003, Journal of the American Chemical Society.

[11]  A. Gavezzotti,et al.  The calculation of molecular volumes and the use of volume analysis in the investigation of structured media and of solid-state organic reactivity , 1983 .

[12]  Michael M. Pollard,et al.  A Reversible, Unidirectional Molecular Rotary Motor Driven by Chemical Energy , 2005, Science.

[13]  Luis Moroder,et al.  Single-Molecule Optomechanical Cycle , 2002, Science.

[14]  H. Scheraga,et al.  Rotational jumps of the tyrosine side chain in crystalline enkephalin. Hydrogen-2 NMR line shapes for aromatic ring motions in solids , 1981 .

[15]  M. Garcia‐Garibay,et al.  Molecular "compasses" and "gyroscopes". I. Expedient synthesis and solid state dynamics of an open rotor with a bis(triarylmethyl) frame. , 2002, Journal of the American Chemical Society.

[16]  Hsian-Rong Tseng,et al.  Molecular-mechanical switch-based solid-state electrochromic devices. , 2004, Angewandte Chemie.

[17]  Takanori Shima,et al.  Molecular gyroscopes: [Fe(CO)(3)] and [Fe(CO)(2)(NO)](+) rotators encased in three-spoke stators; facile assembly by alkene metatheses. , 2004, Angewandte Chemie.

[18]  S. Nishikiori,et al.  In-plane and Out-of-plane Motion of Benzene Trapped in a Cd(py)2{Ag(CN)2}2 Host as Studied by Deuterium NMR , 1997 .

[19]  Ben L. Feringa,et al.  Unidirectional molecular motor on a gold surface , 2005, Nature.

[20]  Jeffrey S. Moore,et al.  Design and Synthesis of a “Molecular Turnstile” , 1995 .

[21]  M. Garcia‐Garibay,et al.  Molecular "compasses" and "gyroscopes." III. Dynamics of a phenylene rotor and clathrated benzene in a slipping-gear crystal lattice. , 2002, Journal of the American Chemical Society.