Search

Employing the flexible tetrapodal ligand 1,2,3,4-tetra-(4-pyridyl)-butane (TPB) along with fumaric acid (H2FMA) as the bridges, a metal-organic framework of [Zn(TPB)(FMA)·(2H2O)] (1) was obtained and characterized by elemental analysis, spectral method (IR), single crystal X-ray diffraction, thermal gravimetric analysis (TGA) and fluorescent property. This polymer exhibits a three dimensional (3D) dense network with an interesting (4,4)-connected PtS topology. It also displays good thermal stability and strong photoluminescence in the blue region band. Thus it may serve as a candidate of thermally stable blue-light-emitting photoluminescent material.

Employing the tetrapodal compound 1,2,3,4-tetra(4-pyridyl)thiophene (TPT) as a bridging ligand, a new metal–organic framework was obtained and characterized by single crystal X-ray diffraction, [Cd(TPT)(N3)2·(H2O)] (1). This polymer exhibits a 2D layer network and an unprecedented 3,4-connected topology, which is constructed from the three-connector TPT and EE azido bridges. It also displays good thermal stability and strong photoluminescence in the blue regionband thus may serve as a candidate of thermally stable blue-light-emitting electroluminescence material. The nature of electronic transitions in the photoluminescent process has also been investigated by means of time-dependent density functional theory (TDDFT) calculations and molecular orbital analyses, which shows that the luminescent property is ligand-based.

Employing the symmetrical ligand 1,2,3,4-tetra-(4-pyridyl)-butane (TPB) as bridges, two novel Zn(II) coordination polymers were obtained and characterized by single crystal X-ray diffraction: [Zn(TPB)0.5(NCS)2] (1) and [Zn(TPB)(N3)2] (2). Polymer 1 features a 2D network with herringbone structural motif constructed by TPB, while polymer 2 shows a dense 3D network connected by TPB and μ1,3-N3- bridges. In the former, the TPB ligand acts as a four-connector, while in the latter it acts as four-connector and linear bridge. Both 1 and 2 exhibit strong fluorescent emissions in the solid state, which may be of significance in the field of photoactive materials.

The structures of two ion-pair complexes, which consist of 1-(4′-R-benzyl)pyridinium (R = NO2 (1), Br (2)) and bis(maleonitriledithiolato)cuprate(II), have been determined by X-ray single crystal analyses, and the results show the stacking patterns in 1 and 2 are different from each other although the difference between the molecular structures of these complexes is only the substituent of the benzene ring, which may arise from the difference of interactions between cations and anions in these two complexes. Complex 1 crystallizes in the non-centrosymmetric space group P1, and dielectric measurements shows ferroelectric behavior with a small hysteresis loop. Quantum chemistry calculation further indicate the electric dipole in a unit cell is 56.5509 Debye, and DSC analysis reveal a Tc of 377 K, from the paraelectric to the ferroelectric phase. The magnetic susceptibilities of these two complexes measured in the temperature range 1.8–260 K show an antiferromagnetic coupling feature between neighboring Cu(II) ions with θ = −0.580 K for 1 and −2.167 K for 2. The polycrystalline EPR spectra of the two complexes at room temperature are different from each other, characterized axial g tensors are g‖ of 2.09, g⊥ of 2.02 for 1, and g‖ = 2.05, g⊥ = 2.03, A‖ = 40.6 × 10−4 cm−1 for 2.

Ion-pair complexes consisting of the [Fe(mnt)2]− anion and [RBzPy]+ cations [R = NO2(1) or Cl (2)] have been prepared and characterized by elemental analysis and i.r. spectroscopy. The single crystal structure of (1) shows that the [Fe(mnt)2]− anions are dimeric, and that the coordination geometry of each Fe atom is square pyramidal. The most significant structural feature of (1) is that anions and cations form completely separate columns and π–π interactions occur within the cation columns. Thermal variations of χmT for the complexes indicated antiferromagnetic coupling within the dimer.