First-principles calculations of the structural, electronic, and optical properties of ${\text{TeO}}_2$ polymorphs were performed with the density functional theory plane-wave pseudopotential method. The results reveal that all the three crystalline ${\text{TeO}}_2$ phases are wide-gap semiconductors and the lone electron pairs have contributions near the Fermi energy level. The layer structure of $\beta {\text{-TeO}}_2$ leads to the obvious anisotropy of the complex dielectric function. Considering the lattice contribution of dielectric constants, we predict the static dielectric constants of ${\text{TeO}}_2$ polymorphs. For $\alpha {\text{-TeO}}_2$ , the calculated values of 19.0 for ${\epsilon }_{1\perp }$ and 25.3 for ${\epsilon }_{1\parallel }$ agree well with the experimental value, and the $\beta$ - and $\gamma$ -phases also belong to the high dielectric constant materials. Besides, a special collective plasma resonance for $\gamma {\text{-TeO}}_2$ has been found in lower energy. It corresponds to the small peak in the imaginary part of dielectric function, and reflects the abrupt reduction in the reflectivity spectrum.

BiB ₃ O ₆ crystals possess large piezoelectric coefficients and high-temperature stability of their piezoelectric properties, which is promising for piezoelectric sensor applications.

Solvothermal reactions of aromatic quaterphenyl-2,5,2′,5′-tetracarboxylic acid (H₄qptc) ligand and transitional metal cations of M^II (M = Co, Ni, Mn, Cu, Zn) in the presence of 1,10-phenanthroline (phen) afford five new coordination polymers (CPs), namely, {[M(H₂qptc)(phen)(H₂O)₂]·2H₂O}_n (M = Co (1), Ni (2)), [Mn(qptc)_0.5(phen)(H₂O)]_n (3), [Cu(qptc)_0.5(phen)]_n (4) and [Zn₃(Hqptc)₂(phen)₂(H₂O)₂]_n (5). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Complexes 1 and 2 are isostructures and each displays a one-dimensional (1D) zigzag chain, which further forms a 2D supramolecular architecture via inter-chain π⋯π interactions. Complex 3 possesses a (3,6)-connected CdI₂ layered architecture incorporating left- and right-handed helical chains. Complex 4 exhibits a 3D porous structure with rare (3,6)-connected ant topology. Complex 5 shows a 3D (3,4,5)-connected network with (4².6)₂(4³.6².8)(4⁵.6⁴.8)₂ topology. The results show that the conformations and coordination modes of H₂qptc^{2 −}/qptc⁴⁻ ligand are crucial factors for the formation of the different structures. Moreover, the photoluminescence of 5 has been investigated.

Four new coordination polymers, namely [Co(H₂O₂abtc)(bibp)]_n (1), {[Mn_1.5(Oabtc)(H₂O)₂]·(H₂bmib)_0.5·H₂O}_n (2), {[Cd_1.5(O₂abtc)]·(H₂bmib)_0.5·2H₂O}_n (3), and {[Cd(nip)(bibp)]·0.5H₂O}_n (4),were constructed under solvothermal conditions in the presence of two bis(imidazole) bridging linkers (bimb = 1,4-bis(2-methylimidazol-1-ylmethyl)benzene, bibp = 4,4′-bis(imidazol-1-yl)biphenyl). The unstable azo ligand of 3,3′,5,5′-azobenzenetetracarboxylic acid (H₄abtc) could be oxidized and resulted in three oxidized derivatives of H₄Oabtc (one N atom was oxidized), H₄O₂abtc (two N atoms were oxidized), and H₂nip (one H₄abtc was oxidized to two 5-nitroisophthalic acids). Their structures were determined by single-crystal X-ray diffraction and further characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analysis. Complex 1 exhibited an interestingly 2D + 2D → 3D parallel entangled network based on 4-connected (4⁴·6²)-sql sheets. Complex 2 was found to be a {Mn₃(COO)₆} trinuclear SBU based 2D (3,6)-connected (4³)₂(4⁶·6⁶·8³)-kgd sheet. While complex 3 displays a {Cd₃(COO)₈} trinuclear SBUs based 3D (4,8)-connected (4⁶)₂(4¹²·6¹²·8⁴)-flu network. Complex 4 can be regard as a {Cd₂(COO)₂} binuclear SBUs based 6-connected (4⁴·6¹¹)-6T8 framework. In addition, the magnetic property of complexes 1, 2 and the luminescence properties of complexes 3, 4 were investigated.