The anisotropic effect of 4-substituents on the 1H NMR chemical shift of H-5 in phenanthrenes

Chloro-, methoxy- and methyl-substituents in the 4-position of phenanthrenes exert a profound and diagnostic influence on the ¹H chemicalshift of H-5, and from ¹³C measurements it is considered to be dueto an anisotropic effect.