Structure of a psoralen derivative of a monosubstituted 18-crown-6 ether

N-[(2,5,9-Trimethyl-7-oxo-7H-furo[3,2-g]-[1] benzopyran-3-yl)methyl]-1,4,7,10,13,16-hexaoxacyclooctadecane- 2,3-dicarboximide, C29H35NO11, Mr = 573.60, monoclinic, P21, alpha = 18.877 (9), b = 6.888 (6), c = 24.488 (10) angstrom, beta = 119.90 (4) degrees, V = 2760.2 angstrom3, Z = 4, Dx = 1.380 Mg m-3, lambda (Cu K a) = 1.54178 angstrom, mu = 0.85 mm-1, F(000) = 1216, T = 170 K, R = 0.065, wR = 0.057 for 3720 observed reflections. There are two molecules (I and II) in the asymmetric unit and the 18-crown-6 part of molecule II is disordered. The psoralen moieties of the two molecules are nearly centrosymmetrically related.