The title compound, C(35)H(35)ClN(4)O(3), resulted from a spiro-lactam ring closure of rhodamine B dye. The xanthene ring system is approximately planar [r.m.s. deviation = 0.050 (9) Å for the xanthene ring]. The dihedral angles formed by the spiro-lactam and 5-chloro-2-hy-droxy-benzene rings with the xanthene ring system are 87.9 (7) and 79.1 (7)°, respectively.

In the mol-ecule of the title compound, C(24)H(28)O(4), the three six-membered rings of the xanthene system are not planar, having envelope, boat and envelope conformations. In the crystal structure, C-H⋯O hydrogen bonds link the mol-ecules, generating centrosymmetric R(2) (2)(12), R(4) (4)(28) and R(2) (2)(16) ring motifs and forming a three-dimensional network.

Xanthene dyes can be appended to cyclodextrins via an ester or amide bridge in order to switch the fluorescence on or off. This is made possible through the formation of nonfluorescent lactones or lactams as the fluorophore can reversibly cyclize. In this context we report a green approach for the synthesis of switchable xanthene-dye-appended cyclodextrins based on the coupling agent 4-(4,6-dim...

1561 References Cited U.S. PATENT DOCUMENTS 3,792,423 2/1974 Becker et al. ......................... 73/620 3,979,712 9/1976 Ettenhofer et al. . 4,028,934 6/1977 Sollish ................................... 73/620 4,327,576 5/1982 Dickey et al. ................... 73/40.5 A 4,640,121 2/1987 Leuker et al. ................... 73/40.5 A 4,641,526 2/1987 Izumi et al. ........................... 73/5...

In the xanthene ring system of the title compound, C(23)H(25)BrO(4), the 4H-pyran ring is almost planar [maximum deviation = 0.040 (3) Å] and the cyclo-hexene ring adopts a sofa conformation. The cyclo-hexene ring attached to the xanthene system is puckered [Q(T) = 0.427 (3) Å, θ = 55.0 (4) ° and ϕ = 164.4 (6) °]. In the crystal, mol-ecules are linked to each other by O-H⋯O and C-H⋯O hydrogen b...

In the title compound, C(37)H(40)N(4)O(2), the xanthene and spiro-lactam rings are almost planar, with r.m.s. deviations from the mean planes of 0.223 (2) and 0.057 (2) Å, respectively, and form a dihedral angle of 85.76 (3)°. The dihedral angle between the xanthene mean plane and the benzene ring is 87.16 (5)°. One of the two ethyl groups of one of the diethyl-amino groups is disordered over t...