Synthesis of C2-Symmetrical Bis-(β-Enamino-Pyran-2, 4-dione) Derivative Linked via 1, 6-Hexylene Spacer: X-ray Crystal Structures, Hishfeld Studies and DFT Calculations of Mono- and Bis-(Pyran-2, 4-diones) Derivatives. - Ahmed T. A. Boraei; Matti Haukka; Ahmed A. M. Sarhan; Saied M. Soliman; Abdullah Mohammed Al-Majid; Assem Barakat (Symmetry, 2021)