TY - JOUR
T1 - Molecular compasses and gyroscopes. II. Synthesis and characterization of molecular rotors with axially substituted bis[2-(9-triptycyl)ethynyl]arenes
AU - Godinez, Carlos E.
AU - Zepeda, Gerardo
AU - Garcia-Garibay, Miguel A.
PY - 2002/5/1
Y1 - 2002/5/1
N2 - We have developed a simple convergent procedure for the synthesis of molecular rotors consisting of a central aromatic group coupled with two axially positioned ethynyltriptycenes. Molecular rotors with 1,4-phenylene (1), 1,4′-1,1′-biphenylene (2), 9, 10-anthracenylene (3), and 2,7-pyrenylene (4) groups were prepared by Pd(0)-catalyzed coupling of ethynyl triptycenes with the corresponding dibromoarenes. Although compounds 1-4 were not expected to have free rotation in the solid state, the rotational potentials of 1 and 3 were analyzed by semiempirical methods and the crystal packing of 1 was analyzed to design the structures most likely to yield a functional rotor in the solid state. Semiempirical PM3 calculations predict compounds 1, 2, and 4 to have frictionless internal rotation even at temperatures as low as 25 K, while compound 3 is expected to have a barrier of ca. 4 kcal/mol.
AB - We have developed a simple convergent procedure for the synthesis of molecular rotors consisting of a central aromatic group coupled with two axially positioned ethynyltriptycenes. Molecular rotors with 1,4-phenylene (1), 1,4′-1,1′-biphenylene (2), 9, 10-anthracenylene (3), and 2,7-pyrenylene (4) groups were prepared by Pd(0)-catalyzed coupling of ethynyl triptycenes with the corresponding dibromoarenes. Although compounds 1-4 were not expected to have free rotation in the solid state, the rotational potentials of 1 and 3 were analyzed by semiempirical methods and the crystal packing of 1 was analyzed to design the structures most likely to yield a functional rotor in the solid state. Semiempirical PM3 calculations predict compounds 1, 2, and 4 to have frictionless internal rotation even at temperatures as low as 25 K, while compound 3 is expected to have a barrier of ca. 4 kcal/mol.
UR - http://www.scopus.com/inward/record.url?scp=0036570048&partnerID=8YFLogxK
U2 - 10.1021/ja012550i
DO - 10.1021/ja012550i
M3 - Artículo
SN - 0002-7863
VL - 124
SP - 4701
EP - 4707
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 17
ER -