کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1405257 | 1501712 | 2016 | 8 صفحه PDF | دانلود رایگان |
• Synthesis of new polymorphs of Schiff bases.
• X-ray crystal structure and DFT calculation.
• Spectroscopy properties of prepared polymorphs.
Two new polymorphs of Schiff base, (E)-2-((2,6-dichlorobenzylidene)amino)benzonitrile, were prepared from the condensation of 4-amino-benzonitrile and 2,6-dichlorobenzaldehyde. The two polymorphs crystallize in two different space groups: P21/c for polymorph (I) with volume 1264.23(2) Å3 and Pbca for polymorph (II) with volume 2469.3(2) Å3. The two polymorphs have been characterized by FT-IR and UV-VIS spectroscopy. The crystal structures of both compounds were determined by single X-ray analysis. The difference between the two polymorphs was observed at the angle between the two phenyl rings which is 4.81° for the first one and 82.27° for the second one. Both crystal structures are built on the basis of moderate and weak hydrogen bonds. Theoretical calculations on isolated molecules at the MP2 cc-pVDZ level show that the two polymorphs correspond to two molecular conformations that are within less than 1 kJ mol−1 and DFT periodic calculations indicate that (II) is more stable than (I) by 4.1 kJ mol−1 of formula unit. Additionally, we performed TD-DFT calculation for free ligands to support the experimental data.
Journal: Journal of Molecular Structure - Volume 1105, 5 February 2016, Pages 186–193