Chromic shifts in UV-Visible spectroscopy |Bathochromic|Hypsochromic|Hyperchromic|Hypochromic shifts

Chromic effects in UV-Visible absorption spectra video explains the various transitions in UV-Visible spectroscopy, defines chromophore, chromogen, auxochrome and explain them with examples. This also explains the various chromic shifts: Bathochromic shift, Hypsochromic shift, Hyperchromic effect and Hypochromic effect with examples.
Chromophore – Covalently bonded group present in a molecule which is capable of absorbing UV or Visible light and exhibit a characteristic absorption band. eg. ethylenic, acetylenic , carboxylic acids, carbonyl , esters etc.
Chromogen – Compound possessing the chromophore
Bathochromic shift – shifts to longer wavelength (red shift)
Hypsochromic shift – shifts to shorter wavelength (blue shift)
Hyperchromic effect – increase in intensity
Hypochromic effect – decrease in intensity
Bathochromic shift (Red shift) – Absorption band shifts to longer wavelength due to
presence of an auxochrome
change in the polarity of solvent
presence of conjugation
Aniline
lone pair on nitrogen delocalizes the p system of the aromatic ring
Conjugation increases
Low energy gap
Bathochromic shift
Hypsochromic shift– Absorption band shifts to shorter wavelength due to
presence of an auxochrome
change in the polarity of solvent
removal of conjugation
Biphenyl rings are not completely planar (rings at an angle of 45o)
2-methyl biphenyl is pushed further out of coplanarity
Weak orbital overlap
Hyperchromic effect – Intensity of absorption band increases due to
presence of an auxochrome
change in the polarity of solvent
presence of conjugation
Hypochromic effect– Intensity of absorption band decreases due to
presence of an auxochrome
change in the polarity of solvent
removal of conjugation

Видео Chromic shifts in UV-Visible spectroscopy |Bathochromic|Hypsochromic|Hyperchromic|Hypochromic shifts канала Revathi Purushothaman