Practice question

UV-VIS spectral shifts describe changes in λmax position and intensity due to solvent polarity, pH, conjugation length or auxochrome substitution. Bathochromic shift, also termed red shift, denotes movement of absorption maximum toward longer wavelength, lower frequency and lower energy. It originates from extension of conjugation, addition of electron-donating groups, or increased polarity stabilizing excited state more than ground state. For example, deprotonation of phenol to phenolate shows bathochromic movement. Recognition of this terminology helps interpret protein chromophore environment changes, drug binding and structural alterations in conjugated biomolecules relevant to biochemistry laboratories.