optical isomerism

more then one compound has the same molecular formula (number of atoms of each element) but different arrangement of atoms in space

when molecules have the same molecular formula but different structural formula position chain length functional group

molecules have the same molecular unstructural formula but the 3D orientations of the atoms in space is different geometric (c=c bonds so restricted rotation and each c in the bond has two different groups bonded to them) and optical

a type of stereoisomerism where the molecules have the same molecular and structural formula but different spatial arrangement of atoms in space, occurring when there is an asymmetrical carbon within a molecule known as a chiral centre

c atom with four different groups bonded to it

there is no line of symmetry in the molecule. this means the mirror image of the molecule is non-superimposable and therefore a different molecule molecules with a chiral carbon and a non-suprimposable mirror image are described as optically active. They have the ability to rotate the plane of polarised light

the different forms (isomers) of the same molecule produced by optical isomerism distinguished by +/-

mixture whrein the ratio of enantiomers is 1:1 50/50

• their effect on plane polarised light • their reactions with other chiral carbons so you can test for them by doing these things

light is an electromagnetic wave. made up of vibrations. the electronic vibrations and magnetic vibrations are perpendicular to eachother when light is passed through a material where the vibrations apart from those in one plane (direction) is stilled, this produces plain polarized light

you can determine which an enantiomer it is because the plane of polarization rotates from vertical in an anti-clockwise position so - enantiomer if the plane of polarization rotates from vertical in a clockwise position then + enantiomer each enantiomer rotates to the same amount in the opposite direction

no overall effect on the plane of polarisation therefore they are considered optically inactive

enantiomers of molecules in biological systems usually aren’t both there. only one is used and synthesised. this is because to be complementary to a receptor, the other enantiomer probably has way less compatibility if any sugar and amino acids are chiral molecules as well as proteins and nucleic acids. crazy their shape is important when left handedness and right handedness makes a difference: one optical isomerism will facilitate a biochemical reaction and the other won’t, or will have a different effect chirality is important in drug action. the pharmacology of a drug is influenced by the binding affinity between it and the target, which is affected by chirality