Para-terphenyl
= Para-terphenyl
<Para-terphenyl> contains three benzene rings connected in a line through para positions, with formula $\mathrm{C_{18}H_{14}}$. The rings are linked by single bonds rather than fused along shared edges.
Inter-ring torsion affects conjugation and optical behavior, making it distinct from fused polycyclic aromatic hydrocarbons. Specifying para connectivity distinguishes it from the ortho and meta terphenyl isomers.