**Catenanes and roaxanes differ from all other organic compounds synthesized to this date in a way that molecular subunits are linked mechanically.
**Catenane is a compound consisting of two or more rings that are interlocked mechanically without there being necessarily any chemical interaction/bond between the two.
**Rotaxanes consist of a long, fairly linear molecule threaded through a macrocyclic ring, like cotton through the eye of a needle. ** Chemical topology deals with the structure and the property differences of compounds which are identical with regard to the aforementioned first three points and which in spite of that cannot be interconverted by conformational changes, such as rotation about an axis or modification of bond angles. In this module we have classified catenanes and rotaxanes according to their chemical topology.
** Stereochemistry of catenanes and rotaxanes is not a very highly explored topic except for discussion on simple structures of catenanes in particular. Rotaxanes have been very minimally dealt with in this area of study. In this module, we have discussed all possible cases of stereochemistry of catenanes and rotaxanes.
** Catenanes have been synthesized by incorporation of many functional units, including redox-active groups (e.g, viologen, TTF tetrathiafulvalene), photoisomerizable groups (e.g, azobenzene), fluorescent groups and chiral groups. Many of these units have been used to create mnolecular switches as described above, as well as for the fabrication of molecular electronic devices and molecular sensors.
** Rotaxane-based molecular machines have been of particular interest for their potential uses in molecular electronies as logical molecular switching elements and also as molecular shuttles.
ORGANIC CHEMISTRY- I (NATURE OF BONDING AND STEREOCHEMISTRY)- CATENANES AND ROTAXANES