A new supramolecular compound of chrome(III): Synthesis, spectroscopic characterization, X-ray crystal structure, DFT, and solution studies Hossein Eshtiagh-Hosseini a, * , Zakieh Yousefi a , Masoud Mirzaei a , Ya-Guang Chen b , S. Ali Beyramabadi c , Ardeshir Shokrollahi d , Roghayyeh Aghaei d a Department of Chemistry, School of Sciences, Ferdowsi University of Mashhad, Mashhad 917791436, Iran b Faculty of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun 130024, PR China c Department of Chemistry, Faculty of Science, Islamic Azad University, Neyshabur Branch, Neyshabur, Iran d Department of Chemistry, Yasouj University, Yasouj, Iran article info Article history: Received 7 December 2009 Received in revised form 18 February 2010 Accepted 18 February 2010 Available online 4 March 2010 Keywords: Chrome Pyridine-2,6-dicarboxylic acid 2-Aminopyrimidine Crystal structure Solution studies DFT abstract A new supramolecular compound of Cr(III) atom was synthesized and characterized by using elemental analysis, FTIR spectroscopy, UV–vis, and single crystal X-ray diffraction method. The chemical formula and space group of the resulting compound is (2-apymH)[Cr(pydc) 2 ]Á2H 2 O(1) (pydc = 2,6-pyridinedicar- boxylate, 2-apym = 2-aminopyrimidine) and P2 1 /c where the final R value is 0.0157 for 3896 reflections collected. The [Cr(pydc) 2 ] À anions and the (2-apymH) + moiety form a three-dimensional solid state struc- ture by a variety of noncovalent interactions such as ion pairing and hydrogen bonds interactions. On the basis of crystallographic data, it can be seen that Cr(III) atom is six-coordinated by two (pydc) 2À groups. With respect to bond lengths and angles, it is observed that coordination sphere around Cr(III) atom is a distorted octahedral. Furthermore, DFT calculation and solution study have been completely performed on 1 where corresponding data showed that obtained results from DFT and solution studies have good agreement with X-ray crystallography results. The optimized geometry confirms that the C–O (bonded) bond length of (pydc) 2À ligand in its complex form has been increased compared with the free ligand. The evidence shows that C–O (bonded) is weakened upon formation of complex, while C@O (free) converted to double bond. Anionic complex possesses 90 occupied molecular orbitals and 3 half-occupied ones (91– 93). A comparison between the stoichiometry of the crystalline complex in pydcH 2 –2-apym–Cr system and the results obtained from solution studies clearly revealed that the CrL 2 QH is the most abundant spe- cies existing in aqueous solution possesses a stoichiometry similar to that of the complex which was obtained in the solid state. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction Pyrimidines have attracted much attention because of their applications in some areas due to biodynamic properties and bio- logical activities such as bactericides, fungicides, vermicides, insec- ticides, and medicines [1]. Among pyrimidine derivatives, aminopyrimidines are very important because they are part of the nucleic bases, i.e. cystosine, adenine, and guanine are responsi- ble for molecular recognition and replication of DNA, through the formation and breakage of NÀHÁÁÁN hydrogen bonds. This type of hydrogen bond is chargable for the formation of new nanomateri- als, such as molecular containers, supramolecular tubes, and artifi- cial ion channels [2]. In this paper the two hydrogen atoms in the amine group were used as H-bond donors whereas the two nitro- gen atoms were used as H-bond acceptors, which is particularly attractive as a very simple self-complementary prototype for chain formation with other organic molecules. Metallic compounds with 2-apym as the only organic ligand, or present as a complementary organic ligand, have been increasingly used [3]. There are many cases in which 2-apym is used as a monodentated or bidentated li- gand in complexes. It should be noted that coordination modes of 2-apym depend on the nature of used anions in related metallic salts. The Cu(II) complexes with halides as anions, mononuclear and polymeric compounds have been obtained in which 2-apym acts as a monodentate or a bidentate ligand. With other anions like sulphate, triflate, nitrate, and dicyanamide, mononuclear or poly- nuclear Cu(II) compounds are obtained, in all of them 2-apym act- ing as a monodentate ligand [3]. It was found that 2-apym is a good candidate for synthesis of proton transfer compounds (for short PTCs) and cocrystals also novel metal–organic coordination com- pounds because of its ability to making hydrogen bonds and accepting proton as a base. Reactions of 2-apym with acids such as 2-aminobenzoic acid, 4-aminobenzoic acid, (+)-camphoric acid, 0022-2860/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2010.02.054 * Corresponding author. Tel.: +98 511 8797022; fax: +98 511 8796416. E-mail address: heshtiagh@ferdowsi.um.ac.ir (H. Eshtiagh-Hosseini). Journal of Molecular Structure 973 (2010) 1–8 Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc