在探索生成用于结晶海绵方法的金属有机骨架(MOFs)的结晶条件的过程中,两个离散的金属-有机络合物,即,水[2,4,6-三(吡啶-4-基)-1,3,5-三嗪]溴化锌(II),[Zn(C18H12N6)(H2O)]Br2和水[2,4,6-三(吡啶-4-基)-1,3,5-三嗪]氯化锌(II),遇到[Zn(C18H12N6)(H2O)]Cl2。正交晶系空间群Pnma的结构(编号62)在299K下获得溴化物同源物,在100K下获得氯化物同源物。溴化物同源物在从299冷却到100K时发生相变,产生具有四个结构域的晶体多晶型物,其表现出单斜P21/m空间群对称性(编号11),这源于构象变化。在所有观察到的结构中有助于晶体堆积的主要分子内接触是H。.H,Halide...H/H...Halide,C...H/H...C,N...H/H...N.Zn结合水和非Zn结合吡啶基N原子之间的分子内氢键是三维网络中的突出特征。非Zn结合的吡啶环和涉及卤化物配体的接触之间的芳族π-堆叠进一步稳定了晶体堆积。
During the course of exploring crystallization conditions in generating metal-organic frameworks (MOFs) for use in the crystalline sponge method, two discrete metal-organic complexes, namely, aqua[2,4,6-tris(pyridin-4-yl)-1,3,5-triazine]zinc(II) bromide, [Zn(C18H12N6)(H2O)]Br2, and aqua[2,4,6-tris(pyridin-4-yl)-1,3,5-triazine]zinc(II) chloride, [Zn(C18H12N6)(H2O)]Cl2, were encountered. Structures in the orthorhombic space group Pnma (No. 62) for the bromide congener at 299 K and the chloride congener at 100 K were obtained. A phase transition for the bromide congener occurred upon cooling from 299 to 100 K, yielding a crystal polymorph with four domains that exhibits monoclinic P21/m space-group symmetry (No. 11), which arises from conformational changes. The main intramolecular contacts that contribute to the crystal packing in all observed structures are H...H, Halide...H/H...Halide, C...H/H...C, and N...H/H...N. Intramolecular hydrogen bonding between the Zn-bound water and non-Zn-bound pyridyl N atoms is a prominent feature within the three-dimensional networks. Aromatic π-stacking between the non-Zn-bound pyridine rings and contacts involving the halide ligands further stabilize the crystal packing.