Steric Effects Causing Increased or New Electronic Interactions

Steric Effects causing Increased or New Electronic Interactions 

Ortho substituents may also exert noii-steric effects on the absorption spectra. They may increase the conjugation between the two component parts of the molecule and shift the absorption to longer wavelengths (e.g. 2-nitrobiphenyl33). 

When aromatic rings are bent out of the planar configuration, the characteristic fine structure is lost in the electronic absorption spectra5. This effect has been found in the spectra of a number of alkyl substituted condensed ring 

---