  The chain-like organic compounds with conjugated structure have the potential
to become high temperature superconductors. We examine this idea by choosing
p-quinquephenyl with five phenyl rings connected in para position. The dc
magnetic susceptibility measurements provide solid evidence for the presence of
Meissner effect when the compound is doped by potassium. The real part of the
ac susceptibility shows exactly same transition temperature as that in dc
magnetization, and the imaginary part of nearly zero value after transition
implies the realization of zero-resistivity. All these features support the
existence of superconductivity with a critical temperature of 7.3 K in this
material. The occurrence of bipolarons revealed by Raman spectra guarantees
potassium metal intercalated into p-quinquephenyl and suggests the important
role of this elementary excitation played on superconductivity.
