CRYSTAL STRUCTURE AND POLYMORPHIES OF THE 4-METHOXY-4'-NITRO-DIPHENYL-ACETYLENE (MONA). Chaoguo Wang, College of Chemical Engineering and Materials Science, Beijing Institute of Technology, Beijing 100081

A Novel tolane 4-methoxy-4'-nitro-diphenyl-acetylene (MONA) has been prepared quantitatively by reacting Cuprous p-methoxy phenyl-acetylene with p-iodonitrobenzene. A single crystal of the MONA was grown by solution growth method. The crystal was characterized by X-ray diffraction structure analysis and second-harmonic generation (SHG) investigation. We found polymorphies crystal forms of the MONA grown from different solvents and they have different nonlinear optical properties depending on the different crystal structures[1]. Crystals of the MONA for structure studies were grown from ethyl acetate at room temperature yielding a stable form [[alpha]] -MONA with yellow color(melting point = 122 deg.C ). The structure was solved by direct method (MULTAN 82) from data collected at room temperature on an Enral-Nonius CAD4 diffractometer and refined by least squares to a final R value of 0.077 using 1900 reflections. The [[alpha]] -MONA is a centrosymmetric. Its crystal structure is triclinic, with space group P -1, a=1.1912(3), b=1.2110(3), c=1.4818(4)nm, [[alpha]] =99.53(2), [[beta]] =113.02(2), [[gamma]] =92.81(2)deg. , V=1.92476nm³, Mr=253.26, Z=6, Dx=1.311g/cm³, [[eta]] =0.87 cm-1, F(000)=792. The relationship between the crystal growth and crystal structure is discussed.

1 Stiegman A E. Graham Eva Perry K j. et al. " The Electronic structure and second-order nonlinear optical properties of Donor-Acceptor acetylenes: A detailed investigation of structure-property relationship," J. Am. Chem. Soc. 1991, 113, 7658-7666.