Similar to the larger members of the cucurbituril family, such as cucurbituril (Q), the smallest member, cucurbituril (Q), can also induce room-temperature phosphorescence (RTP) of α-naphthol (1) and β-naphthol (2). The relationship between the RTP intensity of 1 and 2 and the concentration of Q or Q suggests that the mechanism underlying the Q complex-induced RTP is different from that of the Q-induced RTP for these luminophores. The crystal structures of 1-Q-KI, 2-Q-KI, 1-Q-TlNO(3), and 2-Q-TlNO(3) systems show that in each case Q and the respective metal ions, K(+) or Tl(+), form infinite ···Q-M(+)-Q-M(+)··· chains that surround the luminophores. Although these tube- or wall-like structures are likely destroyed in solution, the key interaction between the convex-shaped outer walls of Q and the plane of the aromatic naphthols, via π···π stacking and C-H···π interactions, is postulated to be essentially maintained leading to a microenvironment that holds the luminophore and the heavy atom perturber together; such a model is supported by the observed Q complex-induced RTP of the above naphthols. With respect to this, a high Q/luminophore concentration was employed in an endeavour to promote the formation of π···π stacking and C-H···π interactions similar to those observed in the crystal structures of the 1- or 2-Q-K(+) and -Tl(+) systems. In keeping with the proposed model, the RTP of each system is quenched when Q is replaced by the alkyl-substituted Q derivatives, decamethylQ and pentacyclohexanoQ. This is in agreement with the substituent groups on the surface of the metal-bond Q obstructing the naphthol molecule from accessing the convex glycouril backbone of Q.