Molecular Structure of the Zwitter Ionic Form of Sulfonefluorescein

Hashime KANAZAWA, Keitaro SENGA, Zenzo TAMURA, Yoichi IITAKA
1994 Analytical Sciences  
The crystal and molecular structures of sulfonefluorescein have been determined in order to elucidate the structure of the molecular species H2+SF-(zwitter ionic form of sulfonefluorescein, H2SF; Fig. 1 ), which was assumed to exist in an aqueous solution of H2SF in a low-pH region.' Sulfonefluorescein was synthesized according to a method described by Orndorff et al.2, and was purified by dissolving the product in dimethylsulfoxide. After filtration, the compound was crystallized from an
more » ... lized from an ethanol solution. X-Ray diffraction data were obtained by using a four-circle diffractometer with graphitemonochromated Cu Ka radiation. The crystal data, experimental method of obtaining the diffraction data and a summary of the structure determination are given in Table 1 . The crystal structure was solved by using SHELXS3, and the hydrogen atoms were located on a difference electron-density map. Although the peak electron-densities of H03 and H06 were about 0.3 e/A3, they were clearly hydrogen bonded to sulfonate oxygen atoms of the neighboring molecules. Their positions were optimized by setting the 0-H distances at 0.95 A, which were then subjected to a block-diagonal leastsquares refinement with isotropic temperature factors.
doi:10.2116/analsci.10.521 fatcat:6uly2m5ao5gofislg73rihisbi