Conjugation is one of the most important structural factors controlling the electronic absorption of organic compounds in ultraviolet-visible (UV-Visible) spectroscopy. It refers to the continuous overlap of adjacent p-orbitals in a molecule, usually involving alternating single and multiple bonds. This overlap allows π-electrons to become delocalized over several atoms rather than being confined to one particular double bond. The extent of conjugation strongly influences the energy difference between the ground and excited electronic states and, consequently, the wavelength at which a molecule absorbs radiation. In an organic molecule, electrons can undergo several types of electronic transitions when they absorb ultraviolet or visible radiation. The important transitions are σ → σ*, n → σ*, π → π*, and n → π*. Here, σ and π represent bonding molecular orbitals, while σ* and π* represent antibonding molecular orbitals. Non-bonding electrons, represented by n, are generally present on heteroatoms such as oxygen, nitrogen, sulfur, and halogens. Among these transitions, π → π* transitions are particularly important for conjugated organic compounds. In an isolated alkene such as ethene, the π-electrons are localized between the two carbon atoms. On absorption of ultraviolet radiation, an electron can be promoted from the π bonding orbital to the π* antibonding orbital. This requires a relatively large amount of energy, so the absorption occurs at a comparatively short wavelength. The maximum wavelength of absorption, λmax, is the wavelength at which the absorption of radiation is greatest. When two or more double bonds are separated by single bonds in such a way that their p-orbitals can overlap continuously, conjugation occurs. For example, in 1,3-butadiene, CH₂=CH–CH=CH₂, the four carbon atoms possess overlapping p-orbitals. The π-electrons are therefore delocalized over the entire conjugated system. The molecular orbitals formed from these interacting p-orbitals have different energy levels, and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) becomes smaller than that of an isolated double bond. The decrease in the HOMO-LUMO energy gap is the key reason for the effect