Theoretical infrared spectra of biphenyl, terphenyls and tetraphenyls for astrophysical purposes

► We have calculated the IR spectra of selected polyphenyls. ► We show that polyphenyls have infrared bands that can distinguish them from PAHs. ► Thanks to these bands the search for polyphenyls in space should be possible. ► Their observation could bring a clue to the formation of large PAHs in space.