•A new phase of SiP2 has been grown in Sn flux.•A mineralizer was used for crystal growth.•It is a layered structure semiconductor and its structure is closely related to the known phase.A new orthorhombic phase of silicon diphosphide has been grown in Sn flux by using Gd as a mineralizer. It is a needle-like crystal and its structure has been determined through single crystal X-ray diffraction and elemental analysis. It crystallizes in the orthorhombic space group Pnma (No. 62, Z = 8) with cell parameters: a = 10.0908(19) Å, b = 3.4388(6) Å and c = 13.998(3) Å and the final R value is 0.0294. It has a layered structure that is closely related to the Pbam phase of SiP2. Its optical band gap is 1.45 eV and it decomposes at 1002 K.

A new polymorph of BaTeW2O9 with space group Pnma was identified during the exploration of the BaO-WO3–TeO2 system. Single-crystal X-ray diffraction measurements show that the material exhibits a 3D tunnel structure consisting of W–O6 octahedra connected with Te–O3 tetrahedra. Bulk single crystals of orthorhombic BaTeW2O9 with dimensions of 24 mm × 22 mm × 15 mm were grown by a top-seeded solution growth (TSSG) method using TeO2 as flux. Theoretical morphology of the crystal was obtained using the Bravais–Friedel and Donnay–Harker methods for comparison. The crystal shows a high transmittance from 360 nm to 5 μm as well as large birefringence (with Δn = 0.247 at 404.7 nm). The Raman spectrum shows that there is a Raman shift with high intensity and narrow peak width at 910.93 cm−1. TGA and DSC analysis indicate that the material melts incongruently at 783 °C. The thermal conductivity of the crystal was measured to be 1.23, 2.61 and 0.95 W m−1 K−1 at 50 °C along the a-, b- and c-axes, respectively.

A new pair of 1-[(9-anthracenyl)vinyl]pyrene (AVP) isomers was simultaneously obtained in a ratio of about 10:1. They cannot be separated by chromatography. However, they can be more effectively separated via sublimation. Both isomers display an aggregation-induced enhanced emission character, which is mainly due to a large increase in the radiative decay rate. The vinylene bond geometry brings different packing motifs. The interacting adjacent molecules in trans-AVP crystals can adopt both edge-to-face and face-to-face arrangements. In contrast, in cis-AVP crystals the adjacent molecules are inclined to adopt an edge-to-face arrangement. The molecule packing plays an important role in the solid emission efficiency.Both trans and cis-1-[(9-anthracenyl)vinyl]pyrene isomers display an aggregation-induced enhanced emission behavior. The vinylene bond geometry exerts important effects on the molecule packing and solid emission efficiency.

A noncentrosymmetric (NCS) compound, MgTeMoO6, has been synthesized using the high temperature solution method with TeO2–MoO3 mixture as a flux. MgTeMoO6 crystalizes in the orthorhombic space group P21212 (No. 18) with cell parameters a = 5.03780(10) Å, b = 5.26910(10) Å, c = 8.8985(2) Å, and Z = 2. The compound exhibits a novel neutral layered structure consisting of asymmetric MgO6 octahedra, TeO4 polyhedra and MoO4 tetrahedra. Thermal stability measurements revealed an incongruent melting point of 682.35 °C. The crystal exhibits a very broad transmission range from 360 nm to 5.2 μm. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicates that the crystal exhibits a strong SHG efficiency of ∼1.5 × KTiOPO4. Additional SHG measurements indicate the material is type-I phase-matchable. Furthermore, calculations on the local dipole moment indicates that the strong SHG response of MgTeMoO6 is mainly caused by the three types of NLO-active units (TeO4, MoO4 and MgO6).

Polymorphism is important to study the structure–property relationship with a minimum number of variables. Compound 1-(9-anthryl)-2-(1-naphthyl)ethylene (ANE) can form three polymorphs by controlling the crystallization conditions, which belong to the P212121 space group for ANE-a, P21/c space group for ANE-b and P space group for ANE-c, respectively. Orientational disorder was found in ANE-b and ANE-c polymorphs. The emission maximum of the three polymorphs are 496, 470 and 490 nm, respectively. Each is blue-shifted from that of a concentrated solution. The formation of orientational disorder and the blue-shift behavior in emission are closely related to the degree of conformational twisting. A large dihedral angle between the anthracene and naphthalene rings is helpful to induce orientational disorder and blue-shift in the solid emission maximum. The emission efficiency of ANE solution and polymorphs is 42% (CH2Cl2 solution), 28% (ANE-a), 22% (ANE-b) and 47% (ANE-c), respectively. The ANE-c polymorph emits even more efficiently than the solution. This is attributed to the different packing environments, which produce distinct PL decay dynamics. For the three polymorphs, the decay behaviors are all double-exponential and the fluorescence efficiency is enhanced as the proportion of the short-lived component increases. This study shows that compound ANE is a kind of tunable solid-state fluorescent material and the molecular conformation plays an important role in the orientational disorder, aggregate packing and solid-state emission.

Two Λ-shaped BODIPY dyes based on Tröger's base, 2,8-(6H,12H-5,11-methanodibenzo[b,f]diazocineylene)-di(4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene) (DFTMB) and 2,8-(6H,12H-5,11-methanodibenzo[b,f]diazocineylene)-di(4,4-difluoro-2,6-diethyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene) (DFDEB), were designed and synthesized. Both compounds exhibit intense fluorescence in dilute solution and polycrystalline powder form. From the crystal structure, the impact of the substitutions at the BODIPY core on the crystal packing mode, intermolecular π–π interactions and optical behavior is compared and discussed. The results indicate that the close π–π stacking in the crystalline state has been effectively inhibited by the twisted Λ-shaped Tröger's base.

The crystal structures and optoelectronic properties of the compounds 1,4-bis[2-(1-naphthyl)vinyl]benzene (BNVB), 4,4′-bis[2-(1-naphthyl)vinyl]biphenyl (BNVBP) and 4,4′-bis[2-(9-anthryl)vinyl]biphenyl (BAVBP) were studied and compared. Due to intramolecular H⋯H steric hindrance, BAVBP molecules adopt a twisted conformation and constructed into a three-dimensional C–H⋯π interacting structure. In contrast, the H⋯H steric hindrance is alleviated in compounds BNVB and BNVBP. Both molecules have much better planar character and aggregate into a lamellar structure with a herringbone packing motif. The aggregate structure exerts a dramatic influence on the optoelectronic properties. Compound BAVBP shows an aggregation-induced enhanced emission (AIEE) character. While, both BNVB and BNVBP are AIEE-inactive, BNVBP displays moderate hole-transporting ability.

Photoswitchable azobenzene (AZO) chromophores were introduced to the bay-position of the traditional n-type perylene diimide (PDI). Photocontrolled self-assembly behaviours and the influence of the azobenzene substitution on the assembly structure were investigated by UV/vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). Controlled morphological evolution of the nanostructures from ribbons to spheres was facilely realized by driving the azobenzene switching unit with 365 nm light irradiation. The nanoribbons demonstrated highly ordered structures while the order of the molecular arrangement was destroyed in the nanospheres, as a result of the curved molecular conformation induced by photoisomerization. In addition, the conductivity of the single nanoribbon was investigated. Thanks to the one-dimensional long-range ordered π–π stacking of the PDI cores, the nanoribbon showed good semiconducting properties with a conductance in the range of 2 × 10−5 S m−1 in air. Furthermore, the conductivity decreased with UV light irradiation, mainly due to the increased randomness within the nanostructures, representing the light-induced switching of conductance in the supramolecular systems that is extremely interesting for molecular devices.

A Cs2TeMo3O12 single crystal with dimensions of 17 mm×17 mm×18 mm was grown using the top-seeded solution growth method. Thermal properties, including thermal expansion, specific heat, thermal diffusivity and thermal conductivity, were investigated as a function of temperature. The average linear thermal expansion coefficients along different crystallographic directions were measured to be αa=7.34×10−6 K−1 and αc=32.02×10−6 K−1 over the temperature range of 30–430 °C. The specific heat was measured to be 0.400–0.506 J g−1 K−1 from 22 °C to 440 °C. The thermal conductivity was calculated to be 1.86 and 0.76 W m−1 K−1 at 22 °C along the a and c axes, respectively. With increasing temperature from 22 to 430 °C, the thermal conductivity decreases by 33.0% along the a axis, while it decreases by 18.5% below 200 °C and then remains unchanged along the c axis. The relationship between structure and the thermal properties is also discussed.Graphical AbstractCentimeter-sized crystals of polar Cs2TeMo3O12 were grown using the top-seeded solution growth method. The relative large anisotropy in thermal expansion and thermal conductivity of Cs2TeMo3O12 is attributable to its layered structure.Highlights► Cs2TeMo3O12 single crystals with dimensions of 17×17×18 mm3 were grown. ► Thermal properties of Cs2TeMo3O12 were studied as a function of temperature. ► The thermal expansion anisotropy of Cs2TeMo3O12 is explained using its structure. ► To protect Cs2TeMo3O12 crystal, a small cooling rate should be used during growth. ► A large temperature gradient should be avoided during processing and application.

One-dimensional self-assembled microwires of π-conjugated chromophore 1,2,4,5-tetrakis(4-pyridylvinyl)benzene (TKPVB) were successfully fabricated by a simple reprecipitation method. The structure, morphology and photophysical properties of the TKPVB microwires were investigated in details by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy, selected area electron diffraction (SAED), fluorescence microscopy (FM), UV–vis spectroscopy and fluorescence spectroscopy. The crystal structure and FT-IR spectra revealed that the intermolecular hydrogen bonds and the π–π interaction between benzene ring of TKPVB molecules led to the head to tail molecular packing conformation (J-aggregate), which in turn helps forming microwires during the self-assembly process. Compared with isolated molecules in solution, the redshifted emission together with superradiant behavior observed in the microwires was due to the ordered molecular arrangement. Different emission wavelength of these microwires was observed at acidic (such as pH 3.6 and 4.8) and neutral conditions (such as pH 7.0), which made them good candidates for the detection of acidic compartments in living cells.Graphical abstractHighlights► A π-conjugated molecule TKPVB has been employed to fabricate luminescent microwires. ► The hydrogen-bonds and π–π interaction contribute to the self-assembled crystalline microwires. ► Different fluorescence wavelength of the microwires was detected at acidic and neutral conditions. ► The microwires are good candidates of lysosome probes in living cells.

Four hydroxybenzoic acid building blocks, m-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxyterephthalic acid, and 5-hydroxyisophthalic acid, have been synthesized as robust cocrystallizing agents and employed in reactions with piperazine, including [(C4H12N22+)·(C7H5O3−)2] (1), [(C4H12N22+)·(C7H5O4/−)2] (2), [(C4H12N22+)·(C8H5O62−)] (3), and [(C4H12N22+)1/2·(C8H5O5−)]·2H2O (4). Hydrogen-bonded directed assemblies of four salts were validated by single-crystal X-ray diffraction analysis. In compounds 1–4, hydroxybenzoic acids are all deprotonated and piperazine molecules are all protonated to form piperazine dications and keep the chair conformation. Thermal stability of these compounds has been investigated.

Employing 4,4′-trimethylenedipyridine as a template, a new two-dimensional zinc phosphite (4,4′-(C5H4N)2(CH2)3)· [Zn3(HPO3)4] has been prepared at room temperature and characterized by single-crystal X-ray diffraction, FTIR, elemental analysis, powder X-ray diffraction, and thermogravimetric analysis. The compound crystallizes in the monoclinic space group P21/c, with cell parameters, a = 9.3309(19) Å, b = 14.798(3) Å, c = 33.637(7) Å, β = 91.11(3)°, V = 4643.8(16) nm3 and Z = 4. The connectivity of the ZnO4 tetrahedra and HPO3 pseudo pyramids results in infinite corner-sharing 4-membered ring chains as second building units which are further linked by Zn-O-P bonds to form a 2-D layer that with interesting 8-membered ring channels along the [100] direction. The diprotonated 4,4′-trimethylenedipyridine molecules sit in the middle of the layers along the [100] direction and interact with the framework via hydrogen bonds.

Benzotriazole, N,N′-dimethylpiperazine and N-methylpiperazine were applied to crystallize with 5-sulfosalicylic acid (5-H2SSA), affording three new binary molecular cocrystals [(C6H6N3+)·(C7H5O6S−)]·H2O (1), [(C6H16N22+)1/2·(C7H5O6S−)]·H2O (2) and [(C5H14N22+)·(C7H5O6S−)2]·3H2O (3) under general conditions. Proton-transferring occurs from acid to nitrogen of N-donor compounds in all compounds 1, 2 and 3. Analysis of the hydrogen-bonding synthons and their effects on crystal packing were also presented in the context of crystal engineering and host-guest chemistry. In compound 1, 1-D infinite chains are extended to a 2-D layered architecture via strong O-H…O hydrogen bonds and then to a 3-D network by N-H…O interactions. Compou 2 and 3 both have the 1-D chain which is formed by O-H…O bonds and weak C-H…O hydrogen bonds. A common intramolecular S(6) [synthon I] ring is formed by the hydroxyl with the carboxyl group in all three compounds.

A new polar polymorph of BaTeMo2O9, α-BaTeMo2O9, has been synthesized by spontaneous crystallization with molten flux based on the TeO2–MoO3 solvent. The two polymorphous phases of BaTeMo2O9 are referred to as β- and α-BaTeMo2O9 according to their crystallization temperature from high to low. The structure of α-BaTeMo2O9 contains two-dimensional (Te2Mo4O18)4– anionic layers interleaved with Ba2+ cations. Each anionic layer is composed of Mo4O20 tetramers connected to TeOx (x = 3, 4) polyhedra. The Mo6+ and Te4+ are in asymmetric coordination environments attributable to second-order Jahn–Teller (SOJT) effects. Second-harmonic generation (SHG) measurements using 1064 nm radiation show that α-BaTeMo2O9 is phase-matchable. Polarization measurements indicate that α-BaTeMo2O9 is not ferroelectric, i.e., the polarization is not “switchable”. In addition, the powder X-ray patterns of the BaTeMo2O9 samples obtained from solid-state reactions revealed that BaTeMo2O9 undergoes an irreversible phase transition from β-BaTeMo2O9 to α-BaTeMo2O9 at ∼570 °C. BaMoO4 is found to lower the energy barrier and stimulate the transformation. Furthermore, structural distortions of both polymorphs were calculated to gain a better understanding of the structure–property relationships. Crystal data: α-BaTeMo2O9, orthorhombic, space group Pca21 (No. 29), a = 14.8683(2) Å, b = 5.6636(1) Å, c = 17.6849(3) Å, V = 1489.21(4) Å3, and Z = 8.Keywords: noncentrosymmetric (NCS); phase transformation; polar materials; polymorphism; second-order Jahn−Teller (SOJT) effects;

The rectangular shaped hollow polyaniline (PANI) tubes prepared by in situ Acid Red 8 (AR8) crystals as templates provided a sustained release of the entrapped dye and their release behavior was dependent on the environmental pH.

Aggregation-induced emission enhancement (AIEE) phenomenon is observed in the polycyclic aromatic alkaloid derivatives due to the configuration changes in the excited state, which is attributed to intramolecular proton-transfer and the formation of a new structure of enol form.

Bulk single crystals of α-BaTeMo2O9 with dimensions up to 51 × 30 × 20 mm3 were grown successfully by a top-seeded solution growth (TSSG) method using TeO2-MoO3 mixture as a flux. High-resolution X-ray diffraction measurement on the (400)-faced plate indicates that the full-width at half-maximum (FWHM) of the rocking curve is 16.55′′. The as-grown crystal exhibits {010}, {002}, {110}, {111} and {201} facets, which are in good accordance with the predicted growth morphology based upon the Bravais-Friedel and Donnay-Harker (BFDH) method. In addition, thermal properties including thermal expansion, specific heat, thermal diffusivity and thermal conductivity were investigated as a function of temperature. The average linear thermal expansion coefficients along the a-, b-, and c-axis from 30 °C to 500 °C were measured to be αa = 9.10 × 10−6 K−1, αb = 19.58 × 10−6 K−1 and αc = 11.94 × 10−6 K−1, respectively. The specific heat was measured to be 0.433–0.566 J (g K)−1 over the temperature range of 30–540 °C. The thermal conductivity along the a-axis is larger than those along other directions (κa>κb> κc). The transmission spectra and refractive indices were also measured. The α-BaTeMo2O9 crystal exhibits a wide transmission window ranging from 380 nm to 5530 nm. The large birefringence of α-BaTeMo2O9 (Δn = 0.305 for light at 404.7 nm) indicates that it is not only Type I and II phase-matchable, but also a very promising candidate for optical devices.

A series of novel, substituted, pyrido[1,2-a]benzimidazole derivatives were synthesized using a novel tandem annulation reaction between 2-acylbenzimidazole derivatives and 4-bromobut-2-enoic esters under mild conditions. The compounds were characterized using IR, 1H NMR, 13C NMR and HRMS; the crystal structure of 2,7,8-trimethyl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazole was determined as orthorhombic. The absorbance and fluorescence spectra of the pyrido[1,2-a]benzimidazoles were measured in dichloromethane; an intense absorption maxima was observed at 250 nm and emission maxima were noted at 460 nm. The absorption spectra and fluorescence characteristics of the pyrido[1,2-a]benzimidazole derivatives revealed that a phenyl and a methyl group attached to the pyrido[1,2-a]benzimidazole ring markedly influenced maximum emission.

Single crystals of the polar hexagonal tungsten oxide (HTO) material Cs2TeMo3O12 with dimensions up to 20 × 20 × 16 mm3 were grown successfully through a top-seeded solution growth (TSSG) method using a TeO2−MoO3 mixture as a self-flux. The Cs2TeMo3O12 crystals grown from a solution with a low concentration exhibit {0002}, {101̅0}, and {101̅1̅} facets, which are in good accordance with the predicted growth morphology based upon the Bravais−Friedel and Donnay−Harker (BFDH) methods. However, the crystals grown from solution with a high concentration show additional {101̅2̅} facets, which are not predicted. Crystals grown by using the [0001]-oriented seed have more regular shapes as compared with those grown by using the [21̅1̅0]-oriented seed. Cs2TeMo3O12 crystallizes in the polar hexagonal space group P63 (no. 173). The result of the high-resolution X-ray diffraction indicates that the full-width at half-maximum (fwhm) of the rocking curve is 18.96′′. Thermal analysis and powder X-ray diffraction demonstrate that Cs2TeMo3O12 melts incongruently at 494.95 °C. Optical measurements indicate that the Cs2TeMo3O12 crystal has a broad transmission window range from 0.43 to 5.38 μm. In addition, polarization measurements indicate that although Cs2TeMo3O12 is polar, the material is not ferroelectric.

Centimeter size crystals of the second-order nonlinear optical and polar oxide Na2TeW2O9 (NTW) have been grown by the top-seeded solution growth method. The specific heat, anisotropic thermal expansion, and thermal diffusivity have been measured. In addition, the average principal thermal expansion coefficients have been calculated on the basis of measurements between 23 and 500 °C. NTW exhibits strongly anisotropic thermal expansion that can be attributed to its low symmetry, monoclinic, in space group Ia. The relationships between the structure and thermal properties are discussed.

Concave gold nanoplates are obtained in hexagonal liquid crystal (LLC) made of SDS (sodium dodecyl sulfate)/glycine/HAuCl4 aqueous solution system where glycine plays the key role. All plates are single-crystals, characterized by {111} facets, with concave centers of regular hexagonal or triangular shapes, and with better electrocatalytic activity than gold nanoplates.

Nonlinear optical (NLO) crystals BaTeMo2O9 (BTM) with large size and good quality have been grown by the flux method. The connections of the Mo−O octahedral group are presented, and the relationship between the structure and the thermal properties has also been discussed. The specific heat, anisotropic thermal expansion and thermal conductivity have been carefully measured. The principal thermal expansion and thermal conductivity coefficients have been determined at different temperatures. Thermal expansion of BTM exhibits weak anisotropy though it belongs to low symmetry system. Interestingly, the thermal conductivity of BTM ascends as the temperature is increased.

Two luminescent materials based on indolo[3,2-b]carbazole have been designed and synthesized. They were highly fluorescent both in solution and in the solid state. High-performance electroluminescent devices with indolo[3,2-b]carbazole luminescent derivatives as the emissive materials were fabricated for the first time with low turn-on voltage of 2.65 V, high luminescence efficiency of 7.92 lm W−1, and high brightness of 68729 cd m−2. The results demonstrated that indolo[3,2-b]carbazole has great potentials as promising building block for highly efficient electroluminescent materials.

The lambda (Λ)-shaped pyridinium salts 2,8-(6H,12H-5,11-methanodibenzo[b,f]diazocineylene)-di(p-ethenyl-N-methylpyridinium) ditosylate (DMDPS), 2,8-(6H,12H-5,11-methanodibenzo[b,f]diazocineylene)-di(p-ethenyl-N-methylpyridinium) diiodide (DMDPI), and 2,8-(6H,12H-5,11-methanodibenzo[b,f]diazocineylene)-di(p-ethenyl-N-methylpyridinium) dinitrate (DMDPN) based on Tröger’s base exhibit a typical aggregation-induced emission (AIE) behavior that it is virtually nonemissive in solution but highly luminescent in the aggregate state. The possibility of utilizing the AIE effect for protein detection and quantification is explored by using bovine serum albumin (BSA) as a model protein. These bioprobes undergo a large spectral change upon binding to BSA, which can be determined by fluorometry. Furthermore, the plots of photoluminescence intensity versus BSA concentration (0−70 μg/mL) display a good linear relationship, indicating quantitative fluorimetric protein detection may be achieved.

A new nonlinear optical crystal BaTeMo2O9 was grown from the TeO2−MoO3 flux system with sufficient size (30 × 23 × 18 mm3) and optical quality that allowed the characterization of its properties. It crystallizes in the noncentrosymmetrical system, space group P21 (no. 4), with a = 5.5346 Å, b = 7.4562 Å, c = 8.8342 Å, and β = 90.897°. The as-grown BaTeMo2O9 crystal has well-developed faces with the major forms {100}, {001}, {011}, and {011̅}. The transmission spectra results suggest that it can transmit well from 0.5 to 5.0 µm. The refractive indices were also measured. The smaller refractive indices nx and ny are in the ac-plane, and the largest refractive index nz polarization direction is parallel to the crystallographic b-axis.

By combining a new, large π-conjugated bidentate ligand, 2,8-bis[2-(2-pyridyl)vinyl]-5,11-di(2-ethylhexyl)-indolo[3,2-b]carbazole (BPVIC) with a [Cd(NCS)2]∞ polymer chain, a novel supramolecular coordination polymer, [Cd2(BPVIC)2(SCN)4]∞, with network structure has been prepared. The crystal structures of the ligand and the coordination polymer were determined by X-ray crystallography. The crystallographic analyses revealed that “drums” formed by the ligands, Cd2+ cations, and SCN− anions are interconnected, leading to the formation of infinite three-dimensional networks. The π−π and C−H···π interactions among the free ligands, acting as energy traps and increasing nonradiative decay, are eliminated effectively in the metal coordination polymer. The metal coordination polymer exhibits strong luminescence in the yellow region and therefore is a potential luminescent material.

We reported an asymmetric phenylenevinylene with a cis double bond 2-(4-(p-tolyl)styryl)-1,4-dip-tolylbenzene (cis-TSDTB) and its use as efficient deep-blue emitter for organic light-emitting diodes (OLEDs) applications. The crystal structure of cis-TSDTB showed torsion configuration and asymmetric geometry, which make it packing in a reduced intermolecular interaction arrangement. And its single crystals showed excellent fluorescence owing to this unique molecular configuration. Typical OLEDs using cis-TSDTB as non-doped emitters exhibited saturated blue light with the CIE 1931 coordinates of (0.15, 0.10), which is quite close to the National Television Standards Committee (NTSC) blue standard. High luminescence efficiency (3.4 cd A−1) and high brightness (9855 cd m−2) have been realized in the device. All of these outstanding results indicated that cis-phenylenevinylene will be a promising candidate as blue light-emitting materials.

Two new Λ-shaped fluorene-based Tröger’s base (TB) analogues with aryl substitutions are successfully synthesized and their photophysical and electroluminescent properties are examined in detail. Both compounds exhibit strong fluorescence emission in dilute solutions and aggregated states. Some abnormal photophysical behaviors have been observed; that is, the amorphous films of the two TB analogues show multiple blue–green emissions similar to the emissions of some polyfluorenes and oligofluorenes, while both the dilute solutions and the polycrystalline powders of two compounds show single blue–violet emission. Furthermore, the emissions of the amorphous film are obviously red-shifted in comparison with the polycrystalline powders. Organic light emitting diodes (OLEDs) using the two compounds as non-doped emitters with device structure of ITO/NPB (30 nm)/TBFB-BP or TBFB-FB (40 nm)/TPBI (40 nm)/LiF (1 nm)/Al (80 nm) were fabricated and high brightness (22047 cd/m2 for TBFB-BP and 13434 cd/m2 for TBFB-FB), high efficiency (2.78 cd/A, 1.82 lm/W for TBFB-BP and 2.76 cd/A, 1.93 lm/W for TBFB-FB) and low turn-on voltage (4.6 V for TBFB-BP and 4.5 V for TBFB-FB) were obtained. Our studies suggest that TB analogues could be excellent light emitting materials for OLED applications.

In this thesis, we will elaborate on the synthesis and characterization of monolithic Gd2O3 aerogel. We conducted the experiment in the following procedure. Use gadolinium nitrate or gadolinium chloride, a kind of inorganic gadolinium salt as raw material, and polymerize it in ethanol with propylene oxide as gelation initiator in the way of sol–gel. After this step, we can obtain the wet gel. Then, dry the wet gel by supercritical CO2, at last we will get aerogel. The product has strong transparency and also shows some thermal stability. XRD characterization shows that it is amorphous. Nitrogen adsorption/desorption analysis tells clearly its surface area (223 m2/g), average pore diameters (42 nm) and large pore volume (1.83 ml/g). It is also characterized by transmission electron microscopy and high-resolution transmission electron microscopy.

Two novel compounds, 2,5-bis(9-hydroxyfluoren-9-yl)-[2,2′] bithiophene (BHFBT) and 2,5-bis(9-hydroxyfluoren-9-yl)-[2,2′:5′,2″] trithiophene (BHFTT) consisting of thiophene rings and two fluorenyl groups have been synthesized and characterized. The crystal structures were determined by single crystal X-ray diffraction method. The compound BHFBT maintained guest-free crystal structure, but BHFTT only obtained crystal structure with inclusion of guest molecules. The two fluorenyl groups were situated at opposite sides for BHFBT while at the same side for BHFTT. Consequently, the two C–OH bonds directed to the same side to each other for BHFBT but directed to opposite sides for BHFTT. Red shift of their optical absorption and emission spectra has also been observed with the increasing number of thiophene rings.

In this paper we report the growth and characterization of Nd:(LuxGd1−x)3Ga5O12 crystal for the first time. The polycrystalline materials were synthesized by conventional solid-state reaction. Single crystal with good optical quality was successfully obtained and the dimensions of the as-grown crystal were Ø21 × 30 mm3. X-ray powder diffraction studies confirm that the Nd:(LuxGd1−x)3Ga5O12 crystal is isostructural with Gd3Ga5O12 with unit cell parameter of 1.2361 nm which is less than that of Gd3Ga5O12 crystal (1.2376 nm). The absorption and emission spectra of the crystal at room temperature have also been studied. Continuous-wave (CW) laser performance at 1.06 μm has been demonstrated on the crystal.

Three new compounds based on indolo[3,2-b]carbazole,2,8-bis(4-diphenylaminophenyl)-5,11-di-n-octylindolo[3,2-b]carbazole (BTOICZ), 2,8-bis(9,9′-di-n-butylfluorenyl)-5,11-di-n-octylindolo[3,2-b]carbazole (BFOICZ) and 2,8-bis[N-(n-butyl)carbazolyl]-5,11-di-n-octylindolo[3,2-b]carbazole (BCOICZ), as hole-transporting materials have been synthesized by Suzuki coupling reaction. The effects of substituents on the optical, thermal and electrochemical properties of indolo[3,2-b]carbazole derivatives have been studied carefully. Electroluminescent (EL) devices using these compounds as hole-transporting layer in combination with Alq3 as electron-transporting and emitting layer have been fabricated and characterized. The devices based on BTOICZ or BFOICZ showed green emission at 526 nm, while the device based on BCOICZ emitted very weak light. The turn-on voltages are 4.1 and 5.4 V for BTOICZ and BFOICZ, respectively. The maximal luminance efficiencies are 0.738 and 0.767 lm/W for BTOICZ and BFOICZ, respectively. The difference of the EL performances of these compounds reveals that the substituent effects have great effect on the hole-transporting performance of the indolo[3,2-b]carbazole-based compounds.

Two new triphenylamine-substituted indolo[3,2-b]carbazole compounds, 2,8-bis(4-diphenylaminophenyl)-5,11-di-n-octylindolo[3,2- b]carbazole (1) and 6,12-bis(4-diphenylaminophenyl)-5,11-di-n-octylindolo[3,2- b]carbazole (2), have been designed and synthesized. The theoretical and experimental studies show that the different substituted-positions of triphenylamine groups have great effect on the optical and electrochemical properties. EL devices with the configuration of ITO/1(or 2)/Alq3/Mg:Ag/Ag show green emission. The activating voltages (recorded at 1 cd/m2) are 4.1 and 3.7 V, respectively. The maximal luminance efficiencies are 0.738 and 1.464 lm/W, respectively. The difference of EL performances indicates 6,12-disubstituted indolo[3,2-b]carbazole compound possessing better hole-injecting and transporting performance than that of the 2,8-disubstituted compound.Two triphenylamine-substituted indolo[3,2-b]carbazole compounds have been designed and synthesized as hole-transporting materials. The theoretical and experimental studies show that the difference of the substituted-positions has great effects on the optical and electrochemical properties. EL results indicate the indolo[3,2-b]carbazole compound with 6,12-disubstituted by triphenylamine possessing better hole-transporting performance than the 2,8-disubstituted one.

This paper presents of a new, conjugated and symmetric multi-branched two-photon absorption chromophore 1,2,4,5-tetrakis(4-N-methyl-N-hydroxyethylamino)vinylphenyl benzene (TKAVPB) with D-π-D structure. The new dye built on 1,2,4,5-benzene core with four amino-branching units, which allows efficient π-electron delocalization, exhibits moderate two-photon absorption (TPA) value in the femtoseconds regime (TPA cross-section as 97 × 10−50 cm4 s photon−1 molecule−1 with 200 fs laser pulses). Linear absorption, single and two-photon fluorescence spectra were experimentally studied. When pumped with 760 nm laser irradiation, TKAVPB shows strong two-photon up-conversion fluorescence with peak at 527 nm.

We designed and synthesized a three-branched isophorone-based compound, 4,4′,4′′-tri[2-(3-dicyanomethylene-5,5-dimethylcyclohex-1-enyl)vinyl]triphenylamine, as well as its one- and two-branched analogues. Their photophysical, electrochemical and electroluminescent characters showed a regular change with increasing branches. Density functional theory was employed to study their electron density distribution. Using the dyes as light-emitting layers without doping, organic light-emitting diodes showed appropriate red emission at λmax = 647–670 nm and a maximum brightness of 1801 cd m−2. Moreover, the results shows that the device using the single-branched material as a pure emitting layer has higher efficiency and lower turn-on voltage than using multi-branched materials.A family of isophorone-based multi-branched compounds have been designed and synthesized. Because of they have the same electron donor and acceptor, branch number and steric structure have become as the important factors that differentiate their photo-physical characters. This Letter shows that the single-branched dye has better electroluminescent properties than the multi-branched in solid film.

In this work, we report the synthesis of ZnS nanospheres with relatively narrow size distribution using polyvinyl pyrrolidone (PVP) as a capping reagent. The nanocrystallite powers were characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), and UV–vis optical absorption spectra. The synthesized nanocrystallite show typical lattice spacings corresponding to the cubic phase of ZnS, as confirmed from HRTEM, ED, and XRD. The UV–vis spectra shows a blue shift of the first excitonic transition band compared with bulk ZnS, probably due to the quantum size effect.

The ground-state structure and electronic properties of a newly synthesized red fluorescent material, 2-[3-(2-{4-[(2-hydroxy-ethyl)-methyl-amino]-phenyl}-vinyl)-5, 5-dimethyl-cyclohex-2-enylidene]-malononitrile (A31), are investigated using a hybrid density-functional theory (DFT) approach, B3LYP, and the 6-31G* basis set. We have obtained four geometrical isomers. The theoretical infrared (IR) spectrum calculated by B3LYP/6-31G* level of theory is in very good agreement with our experimental measurement. The cation and anion are optimized to clarify the effects of the hole and electron injections and the energies needed by injections are estimated.

Concave gold nanoplates are obtained in hexagonal liquid crystal (LLC) made of SDS (sodium dodecyl sulfate)/glycine/HAuCl4 aqueous solution system where glycine plays the key role. All plates are single-crystals, characterized by {111} facets, with concave centers of regular hexagonal or triangular shapes, and with better electrocatalytic activity than gold nanoplates.

Aggregation-induced emission enhancement (AIEE) phenomenon is observed in the polycyclic aromatic alkaloid derivatives due to the configuration changes in the excited state, which is attributed to intramolecular proton-transfer and the formation of a new structure of enol form.

The rectangular shaped hollow polyaniline (PANI) tubes prepared by in situ Acid Red 8 (AR8) crystals as templates provided a sustained release of the entrapped dye and their release behavior was dependent on the environmental pH.

A noncentrosymmetric (NCS) compound, MgTeMoO6, has been synthesized using the high temperature solution method with TeO2–MoO3 mixture as a flux. MgTeMoO6 crystalizes in the orthorhombic space group P21212 (No. 18) with cell parameters a = 5.03780(10) Å, b = 5.26910(10) Å, c = 8.8985(2) Å, and Z = 2. The compound exhibits a novel neutral layered structure consisting of asymmetric MgO6 octahedra, TeO4 polyhedra and MoO4 tetrahedra. Thermal stability measurements revealed an incongruent melting point of 682.35 °C. The crystal exhibits a very broad transmission range from 360 nm to 5.2 μm. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicates that the crystal exhibits a strong SHG efficiency of ∼1.5 × KTiOPO4. Additional SHG measurements indicate the material is type-I phase-matchable. Furthermore, calculations on the local dipole moment indicates that the strong SHG response of MgTeMoO6 is mainly caused by the three types of NLO-active units (TeO4, MoO4 and MgO6).