Relationship between the structure and luminescent properties for two crystal modifications of N -butyl-2-cyano-3-[4-(di
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URE OF ORGANIC COMPOUNDS
Relationship between the Structure and Luminescent Properties for Two Crystal Modifications of NButyl2Cyano3[4 (Dimethylamino)phenyl]2Propenamide Ya. A. Mikhlinaa, B. M. Bolotina, and L. G. Kuz’minab a
Research Institute of Chemical Reagents and High Purity Substances, ul. Bogorodskii Val 3, Moscow, 107076 Russia email: [email protected] b Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia email: [email protected] Received April 3, 2013
Abstract—Two crystal modifications (1o and 1y) of Nbutyl2cyano3[4(dimethylamino)phenyl]2pro penamide, which differ in the color of crystals and the color of luminescence, have been studied by Xray dif fraction and spectralluminescence methods. The corresponding bond lengths and bond angles in the mole cules of two crystal modifications are virtually identical. In both crystal structures, there are two systems of weak intermolecular interactions: πstacking interactions and –CN···H–N hydrogen bonds involving nitrile and NH groups. In the crystal structures, two hydrogen bonds connect pairs of molecules into centrosymmet ric dimers. The N···H distances are 2.21 and 2.41 Å in 1o and 1y, respectively. The interplanar distances in the πstacked systems of 1o and 1y are 3.33 and 3.41 Å, respectively. Both types of weak interactions are stron ger in 1o than in 1y, which accounts for a larger shift of absorption and luminescence bands for the former compound. DOI: 10.1134/S1063774513050076
INTRODUCTION In recent years, supramolecular ensembles have attracted considerable interest due to their possible practical applications in different optical and opto electronic devices [1–3]. These ensembles are poly molecular structures, which are formed by the associ ation of molecules through noncovalent interactions, such as ππ stacking, electrostatic, and van der Waals interactions; hydrogen bonds; etc. The structures and the properties of such associates were studied in [4–7]. The effect of intramolecular hydrogen bonds on the luminescent properties of α(pchlorobenzoyl)4 (diethylamino)cinnamonitrile and αethoxycarbonyl 4dimethylcinnamonitrile was reported in [8]. There are intermolecular hydrogen bonds in the crystals of both compounds, and these bonds influence electron density redistribution and give rise to charge polariza tion, which is reflected in the spectralluminescent properties of crystals compared to dilute solutions. The aim of this study is to reveal the type of inter molecular interactions in the crystals of Nbutyl2 cyano3[4(dimethylamino)phenyl]2propenamide and evaluate the effect of these interactions on the spectralluminescent properties. H3C O
N H3C NC
NH C4H9 н
We isolated this compound as two crystal modifica tions. One modification (1y) exhibits green lumines cence (λmax = 500 nm), whereas the other modifica tion (1o) displays orange luminescence (λmax = 610 nm). It should be noted that only the monomeric modifica tion with
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