Synthesis and Crystal Structure Studies of Three N-Phenylphthalimide Derivatives

Abstract

The three N-phenylphthalimide derivatives, 2-(3,4-dichlorophenyl)isoindoline-1,3-dione (I), 2-(2,4-dichlorophenyl)isoindoline-1,3-dione (II) and 2-(2,4,5-trichlorophenyl)isoindoline-1,3-dione (III), were synthesized by the condensation of equimolar amounts of phthalic anhydride and 3,4-dichloroaniline, 2,4-dichloroaniline, 2,4,5-trichloroaniline, respectively, under acetic acid reflux and their structures determined by a combination of elemental analysis, FT-IR, ¹H & ¹³C-NMR spectroscopy and single crystal X-ray diffraction studies. Compounds I and II crystallize in a monoclinic crystal system (space group P2₁/c) with cell parameters of a = 5.7414(2), b = 8.0917(6), c = 26.077(1) Å and β = 99.4709(12)^o for compound I, and a = 12.7133(9), b = 13.4328(9), c = 7.2603(5) Å and β = 93.210 (2)^o for compound II. On the other hand, compound III crystallizes in a tetragonal crystal system (space group I4₁/a) with a = 13.4607(9) and c = 30.100(2) Å. The phthalimide moieties of these compounds are essentially planar, while the chloro-substituted phenyl ring of each compound shows consistent twist from the phthalimide plane with dihedral angles of 61.02(3), 69.09(3) and 85.78(5)^o, respectively, for I, II and III. In the crystal structures of these compounds, a few weak C–H···O interactions form double-tape structures of centrosymmetric dimers of graph-set notation R ²₂ (10) for I and III, and an inversion dimer of graph-set motif R ²₂ (14) for II. In addition, some short contacts of C···C, C···O and Cl···Cl are observed for I, II and III, respectively.

Graphical Abstract

This paper presents the synthesis, characterization and structural studies of three derivatives of Phthalimides which are well known cytotoxic DNA intercalating agents and potential anti-cancer agents, inhibit the acute inflammatory response and HIV-1 reverse transcriptases and found usefulness in OLEDs. Compounds I and II crystallize in a monoclinic crystal system (space group P2₁/c) while compound III crystallizes in a tetragonal crystal system (space group I4₁/a). The phthalimide moieties of these compounds are essentially planar, while the chloro-substituted phenyl ring of each compound shows consistent twist from the phthalimide plane. A few weak C–H···O interactions form double-tape structures for I and III, and a dimer for II.