We have demonstrated that Φ 0 periodic Aharonov–Bohm oscillations measured in a ensemble of rings may survive after ensemble averaging procedure. The central point is the difference between the preparation stage of the ensemble and the subsequent measurement stage. The robustness of the effect under finite temperature and non–zero charging energy of rings is discussed.

The imidazopyridine fused-ring in the title compound, C(20)H(16)BrN(3)O, is planar (r.m.s. deviation = 0.011 Å). The phenyl rings of the benzyl substitutents twist away from the central five-membered ring in opposite directions; the rings are aligned at 61.3 (1) and 71.2 (1)° with respect to this ring.

In the title compound, C(22)H(16)N(2)O(6)S(2), the dihedral angle formed by the mean planes of the two benzene rings of the 4-methyl-phenyl-sulfonate groups is 21.9 (1)° and these rings form dihedral angles of 48.26 (9) and 52.73 (9)° with the central benzene ring.

In the title compound, C(21)H(26)N(2)O(2), the dihedral angle between the two benzene rings is 73.47 (16)°. Strong intra-molecular O-H⋯N hydrogen bonds generate S(6) ring motifs. The substituted benzene rings are twisted around the central quaternary C atom in opposite directions, making a vault geometry.

In the title compound, C(23)H(26)O(3), the three six-membered rings of the xanthene system are non-planar, having total puckering amplitudes, Q(T), of 0.443 (2), 0.202 (2) and 0.449 (2) Å. The central ring adopts a boat conformation and the outer rings adopt sofa conformations. The crystal structure is stabilized by van der Waals inter-actions.

In the title compound, C(20)H(18)N(4), the benzene ring lies about an inversion center. The central benzene-1,4-diamine unit is connected to two pyridine rings by the C=N imine bonds. The dihedral angle between the benzene and pyridine rings is 82.9 (1)°.

In the title compound, C(27)H(23)N(3), the dihedral angles between the central pyridine ring and the two outer benzene rings are 32.6 (1) and 52.0 (1)°. The compound displays inter-molecular π-π inter-actions between adjacent six-membered rings, the shortest centroid-centroid distance being 3.981 (3) Å.

In the title compound, C(21)H(19)N(3)O(4), two intramolecular N-H⋯O hydrogen bonds generate two six-membered rings. The dihedral angles between the central heterocyclic ring and the two pendant rings are 61.5 (2) and 63.5 (1)°.

In the title compound, C(15)H(14)O(3)S, the dihedral angle between the two benzene rings is 59.3 (8)°. The crystal structure is stabilized by weak inter-molecular C-H⋯π inter-actions between the benzene rings and the central ethyl-ene bridge, and a weak non-classical C-H⋯O hydrogen bond occurs in the structure.

In the crystal structure of the title compound, C(24)H(24)N(2)O(4), the dihedral angles between the central and the two outer benzene rings are 48.12 (8) and 21.44 (8)°. Intra-molecular O-H⋯N hydrogen bonding generates S(6) rings.