The syntheses, structures and photoluminescence properties are reported for two new binuclear cyclometalated iridium(III) complexes, [Ir2(ppy)4(L)] (1) and [Ir2(F2-ppy)4(L)] (2) (ppy=2-phenylpyridine, F2-ppy = 2-(2,4-difluorophenyl)pyridine, H2L=N,N′-bis(2-hydroxynaphthyl methylidene)-2-hydroxy-1,3-propanediamine. X-ray crystal diffraction shows that L ligands adopt a tetradentate mode to bridge ir(III) ions to form binuclear structures. There are π-π stacking interactions between the binuclear structures, which results in the formation of 3D supramolecular networks. UV–vis absorption spectra and photoluminescence spectra show that the introduction of F− groups in the benzene rings of ppy ligands causes blue shift.

Micro-scale three-dimensional coordination polymer particles (CPPs) have been synthesized from the surfactant-assisted reaction of Zn(OAc)2·2H2O and 5,10,15,20-tetra(4-pyridyl)porphyrin (H2TPyP) in DMF. The three-dimensional (3D) micro-prisms and micro-octahedra of the CPPs were obtained at different temperatures as found by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and a statistical analysis of the size distribution results. X-Ray diffraction (XRD) analysis revealed a circular hexametric cage structure cross-linked by a Zn–N axial coordination of the pyridyl ligands inside the micro-scale CPPs. Further support for this coordination polymerization mode of the micro-CPPs came from IR spectroscopy. The UV–vis spectra clearly show the formation of J-type aggregates in both the microstructures. The micro-CPPs show a stronger luminescence intensity over the individual porphyrin molecules, which is presumably due to the high surface area of the ZnTPyP-CPPs. Nevertheless, nitrogen adsorption/desorption isotherm measurements were performed to confirm the larger surface area and increased porosity of the micro-prisms and micro-octahedra relative to the self-assembled micro-rods of ZnTPyP, indicating the potential application of the two CPPs microstructures in the field of gas adsorption. The surfactant-assisted synthetic route appears to provide a promising method for the construction of highly organized three-dimensional organic micro-structures of 5,10,15,20-tetra(4-pyridyl)porphyrin derivatives.

Three transition metal coordination polymers [Zn2(H2L)(2,2′-bpy)2(H2O)]n∙2nH2O (1), [Zn2(H2L)(2,2′-bpy)2]n (2), and [Cd2(H2L)(2,2′- bpy)2(H2O)2]n∙2nH2O (3), have been assembled from a semirigid triangular multicarboxylate ligand 3,3′,3″-(1,3,5-phenylenetri(oxy))triphthalic acid (H6L) with the help of 2,2′-bipyridine (2,2′-bpy) ligand. X-ray single crystal diffraction analysis reveals that complex 1 crystallizes in the space group of Pī and displays a one-dimensional (1D) ladder chain structure constructed from 2,2′-bpy ligand and H2L ligand, which stacks together in an -ABCABC- motif, featuring a mutually embedded chained structure. In complex 2, the H2L ligands bridge the adjacent Zn(II) atoms into a complicated ribbon chain along the b axis. There is π–π stacking interaction between the chains, which results in the formation of a 2D supramolecular structure. Complex 3 also exhibits a 1D ladder-like chain. The different molecular structures for complexes 1 and 2 formed from the same H6L and Zn(NO3)2∙6H2O in different metal-to-ligand ratios in the presence of NaOH, reveals the influence of metal–ligand ratio on the structure of the coordination polymer. In contrast, a series of same reaction using Cd(NO3)2∙4H2O as a starting material instead of Zn(NO3)2∙6H2O only led to the formation of 3, illustrating the fact organic ligands display different coordination preferences at different metal ions. In addition, the thermal and luminescent properties of complexes 1–3 were also investigated.

Density functional theory calculations have been carried out on the subtriazaporphyrin skeletons, an excellent prototype for investigating the dipolar/octupolar contribution to the second-order nonlinear optical (second-order NLO) activity, revealing the size effect and clarifying the nature of the limit when expanding the conjugated system is employed to improve the hyper-Rayleigh scattering response coefficient (βHRS). The octupolar and dipolar contributions are theoretically separated, rendering it possible to control the dipolar/octupolar second-order NLO contribution ratio by changing the number and orientation of the peripheral fused benzene moieties. In addition, both the dispersion and solvent effect were also revealed to lead to the enhancement of βHRS.

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were carried out to simulate the molecular and electronic structures together with the electronic absorption spectra of a series of peripheral methyloxy/methoxycarbonyl substituented phthalocyanines M[Pc(β-OMe)2n(β-COOMe)8−2n] (M = 2H, Zn; n = 0, 1, 2, 3, and 4). Fragment charge distribution and electrostatic potential analysis indicate that the presence of electron-withdrawing and -donation groups leads to the redistribution of charges and obvious polarization effects to the unsymmetrical phthalocyanine series. Peripheral methyloxy/methoxycarbonyl groups introduced onto phthalocyanine ring were revealed to destroy the degeneracy of LUMOs, resulting in significant Q-band splitting for the unsymmetrical phthalocyanine compounds. In addition, metal-free and zinc phthalocyanine compounds display similar electronic structures and absorptions due to the almost none contribution of the zinc atom or inner hydrogens to the frontier molecular orbitals. The microscopic mechanism of the UV–Vis spectra has been clarified on the basis of multi-band photon-induced electron transference. These theoretical studies would be helpful for the molecular design of novel unsymmetrical phthalocyanines.Graphical abstractThe structure–property relationships of a series of peripheral methyloxy/methoxycarbonyl substituented phthalocyanines are calculated using DFT and TDDFT theory. The molecular and electronic structures, fragment charge distribution and electrostatic potentials, and photon-induced electron transference and microscopic mechanism of UV–Vis spectra are studied. The substituent effects change with the number and position of the substituents.Highlights► The presence of peripheral electron-withdrawing and donation groups results in the charge redistribution and obvious polarization effects. ► Metal-free and zinc phthalocyanine compounds display similar electronic structures and absorptions. ► The unsymmetrical phthalocyanines display significant Q-band splitting. ► The substituent effects change with the number and position of the substituents.

Two types of metal-loaded visible-light-driven photocatalysts, Mo-BiVO4 and Ag-BiVO4, were synthesized by wet impregnation method. Material poperties were characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy and low temperature nitrogen adsorption-desorption. Photocatalytic activity of the obtained materials was investigated through degrading methylene blue (MB) solution under visible-light irradiation. The results reveal that both metal loaded-BiVO4 catalysts have monoclinic scheelite structure. Mo and Ag exist as oxides on the surface of the particles. The changes of absorption in visible-light region, band gap (Eg) and specific surface area (ABET) caused by loading Ag are more obvious than those caused by loading Mo. But the isoelectric point of Ag-BiVO4 decreases less than that of Mo-BiVO4 does. Both catalysts show higher photocatalytic activity than pure BiVO4, resulting in the significantly improved efficiency of degradation of MB. And the degradation efficiency of these two metal-loaded BiVO4 photocatalysts is similar to each other. However, mechanisms of such enhancement are different. The decrease of isoelectric point helps Mo-BiVO4 improve the degradation efficiency. As for Ag-BiVO4, the augmentation of absorption in visible-light region as well as the abatement of Eg plays more important roles.

A series of transition metal coordination polymers [Co(H3L)2(4,4′- bpy)(H2O)2]n∙n(4,4′-bpy) (1), [Ni(H2L)(4,4′-bpy)(H2O)2]n (2), [Co2(L)(phen)2(H2O)4]n∙(H2O)2n (3), and [Ni2(L)(phen)2(H2O)4]n∙(H2O)2n (4) have been assembled from a semirigid multicarboxylate ligand 3,3′-(1,4-phenylenebis(oxy))diphthalic acid (H4L) with the help of 4,4′-bipyridine (4,4′-bpy) ligand or 1,10-phenanthroline (phen) ligand. X-ray single crystal diffraction analysis reveals that complex 1 crystallizes in the space group of P − 1 and displays a one-dimensional (1D) chain structure constructed from 4,4′-bpy ligand and H3L ligand, which was further interlinked to form a three-dimensional network via hydrogen bonds. In complex 2, Ni(II) atoms are coordinated by L ligand in monodentate fashion to form alternate left- and right-helices, which are further bridged together by the coordination interactions between Ni(II) atoms and 4,4′-bpy, leading to a 2-fold (4, 4)-connected interpenetrating network. Isostructural complexes 3 and 4 belong to the space group P − 1 and display a 1D chain structure constructed from phen and L ligands, which was further interlinked to form a 2D plane via π–π interactions. In addition, their thermal and luminescent properties were also investigated.Highlights► 3,3′-(1,4-phenylenebis(oxy))diphthalic acid (H4L) was synthesized. ► Four transitional metal coordination polymers have been assembled based on H4L. ► Complex 2 exhibits a 2D (4, 4)-connected entangled interpenetrating network.

An alkaline precipitation method was introduced to produce hydrous cerium oxides. The prepared powder was characterized by Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry, and thermal gravimetry (TG) approaches. The adsorbent has a chemical formula of CeO2·nH2O (n < 2) and a cubic fluorite-type structure after high temperature treatment. Adsorption capacity of different temperature treated hydrous cerium oxides does not directly correlate with BET specific surface area. Phosphate adsorption isotherms follow the Langmuir equation below the treatment temperature of 800°C. Phosphate adsorption causes no change on the structure of a hydrous cerium oxides, and no signs of CePO4 precipitates are found. The ion-exchanging structure of hydrous cerium oxide plays a fundamental role in phosphate adsorption. The structure is highly temperature resistant and forms adsorption sites which adsorb both water and some anions. Complete loss of adsorption ability cannot be achieved unless the treatment temperature is higher than 1200°C. Mechanism study shows that the adsorption of phosphates is mainly an anion-exchange process.

One-dimensional strontium hydroxyapatite (Sr-HAp) nanorods were successfully synthesized by a simple solvothermal method. The products were characterized via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), cold field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) excitation and emission spectra. The experimental results indicated that oleic acid as a surfactant played a key role in confining the growth of the Sr-HAp powders. A possible formation mechanism of the one-dimensional nanorod was proposed and elaborated. Moreover, the as-obtained Sr-HAp samples showed an intense and bright emission band centered at 460 nm under long-wavelength UV light excitation and the contents of NaOH used in the synthetic process had an obvious impact on the optical performance of Sr-HAp powders. The possible luminescent mechanism of the Sr-HAp samples was discussed.