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High-quality seeding is the key to ensure the preparation of high-quality sapphire single crystals. The strength and direction of the melt flow control the crystal seeding shape and bubble movement and will directly affect the quality of crystal seeding. To improve the crystal seeding quality under complex convection, based on the lattice Boltzmann method, an optimization method of seed crystal rotation was proposed before crystal seeding, and the unsteady melt flow rate, internal temperature of the melt and crystal rotation speed were calculated and analyzed. The coupling relationship between the Grashof number and the Reynolds number is analyzed. The results show that the optimization method of crystal rotation can effectively restrain the convection of the melt and improve the temperature distribution on the surface of the melt. Compared with the multi-frame intercomparison visual inspection detection method and artificial seeding method, the method proposed in this paper is helpful to improve the quality of sapphire seeding. [ABSTRACT FROM AUTHOR]

Melt crystallization has been considered as a green separation technique and widely applied in industry and manufacture due to several attractive features, including no need for a solvent, achieving specific product properties, and several process merits. This paper systematically reviews process intensification approaches in melt crystallization. Firstly, process models are discussed based on the crystallization and sweating processes, and process models and parameters are summarized to describe the process efficiency, separation performance and inclusion migration rules. Secondly, the process intensification approaches are summarized based on technique innovation and device optimization. Lastly, the recent advanced applications of melt crystallization in pharmaceutical and ultrapure product preparation fields are also included. Furthermore, the critical concerns for further research and perspectives are proposed. [ABSTRACT FROM AUTHOR]

In this paper, the growth and promotion of 2 inch AlN single crystals are carried out via the homogeneous physical vapor transport (PVT) method on AlN seeds. It is found that the large-size AlN crystal homo-PVT process is distinguished by the growth of prismatic grains in a macroscopic 3-dimensional mode, and overgrowth plays a key role in the merging of grains under a lateral overgrown c-plane surface. To realize efficient overgrowth, we study the control law of growth conditions through a combination of experiments and computational fluid dynamics (CFD) simulations, and clarify that the effect of overgrowth depends on growth rate and its matching relation with temperature and pressure. Our results show that overgrowth can obviously improve the coherence of c-plane orientations and crystal quality, which provides a foundation for quality promotion through iterative homo-PVT growth on large-size AlN seeds. [ABSTRACT FROM AUTHOR]

A correlation between ferroelectricity and grain sizes in atomic layer deposition (ALD)-derived Hf0.5Zr0.5O2 (HZO) thin films has been demonstrated through controlling process conditions. The influence of annealing temperature, annealing time and film thickness on the structural properties, ferroelectric performance and grain sizes was systematically investigated. A correlation diagram was constructed according to the different values of remnant polarization (Pr) and coercive field (Ec) in the different ranges of grain sizes. The Pr values displayed a continuous declining trend, and the Ec values firstly decreased and then increased with the increase of grain sizes. A strong size effect of ferroelectricity in the HZO thin films was proved through providing a simple annealing process or controlling the film thickness. The results showed that excellent ferroelectricity (∼15 μC cm−2) could be obtained with grain sizes in the range of 15–35 nm, which corresponded to the appropriate annealing conditions of 450 °C for 60 s with a film thickness of 10 nm. This paper can provide guidance for designing ferroelectric HfO2-based films with high performance through controlling grain sizes. [ABSTRACT FROM AUTHOR]

Advances and limitations in the field of growing large, high optical quality single crystals of AgGaS2 (AGS), AgGaGeS4 (AGGS), ZnGeP2 (ZGP), LiInS2 (LIS), LiGaS2 (LGS), LiInSe2 (LISe), LiGaSe2 (LGSe) and LiGaTe2 (LGT) compounds are considered in this contribution. With attendant good optical quality, all as-grown crystals of these compounds contain always some amount of native defects which adversely affect the optical and electrical properties. With the aim of overcoming this limitation, attention in this review is focused on concepts that provide a better insight into origins of non-stoichiometry and mechanism of native point defect occurrence. Among these concepts, preference is given to effective ways of determining the scale of the non-stoichiometry through the study of T–X and P–T diagrams, to promising techniques characterizing precisely phase purity, spatial chemical inhomogeneity, and amount of microstructural inclusions in grown crystals, and to measuring thermodynamic and thermochemical properties of the compounds. Utility of physicochemical characteristics for optimizing the growing process is considered. A combination of chemical information and physical properties of crystals is obligatory for clarifying the origins of defects. Attention is given to clarifying specificity of growing Li-containing crystals caused by high chemical activity of the Li component. With such content, this review paper presents status of current knowledge of non-stoichiometry and defects of crystals demanded in practice for non-linear optics. [ABSTRACT FROM AUTHOR]

Materials are often functionalised using diverse molecular designs. This is in stark contrast to inorganic materials, whose properties are diversified by designing a blend of atoms/ions in a solid solution (mixed crystal or alloy). The miscibility of the molecules is dependent not only on the size but also on the symmetry of the molecule and lattice. Thus, it is difficult for molecular crystals to have high miscibility compared to inorganic materials. The current paper focuses on the recent research and important pioneering works on functional molecular solid solutions. In addition to solid solutions in which molecules and lattices are similar (homeomorphic), the development of materials in which geometrically dissimilar (heteromorphic) molecules are dissolved has also been highlighted. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid materials show structural diversity and flexibility. The introduction of Sb(III) metal ions into the inorganic parts of these materials can endow them with semiconductor properties. In the work described in this paper, we successfully adjusted the band gap of such a material, namely of (C 10 H 16 N) 3 SB 2 CL 9 , from 2.933 eV to 2.788 eV via substituting a halogen for the third hydrogen atom of the benzene ring in its organic cation. This change in the band gap may have been caused by the influence of organic cations on the anions that gradually reduced the Cl–Sb–Cl bond angle. It is hoped that this research can provide inspiration for the design of tunable bandgap semiconductor materials. [ABSTRACT FROM AUTHOR]

The paper reports new results that compare the group of performance figures of merit of piezo-active 2–2-type composites based on [011]-poled domain-engineered (1 − x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 single crystals, where the main crystallographic axes in the crystal layers are rotated to tailor effective electromechanical properties and related parameters. Examples of the orientation and volume-fraction dependences of the figures of merit are analysed for the first time for the system of 2–2 single crystal/polymer composites and 2–0–2 single crystal/corundum ceramic/polymer composites at x = 0.0475–0.09. The connections between the piezoelectric coefficients , energy-harvesting figures of merit and modified figures of merit (j = 1, 2 and 3) are highlighted during rotation of the main X and Y crystallographic axes around the Z axis of the crystal layers. A similar orientation behaviour of , and and their large anisotropy are studied at specific volume fractions of the single-crystal component and for a variety of microgeometric architectures of a corundum ceramic/polymer layer with 0–3 connectivity. Maxima of the longitudinal parameters , and at x = 0.0475–0.09 and constant volume fraction of the single-crystal component of the 2–2-type composites are observed in a relatively narrow orientation range. A new performance diagram is built to show regions of a large anisotropy of and in a 2–0–2 composite and, as a result of the large piezoelectric coefficients and figures of merit, the composites show significant potential in the field of piezoelectric energy-harvesting and sensor applications. [ABSTRACT FROM AUTHOR]

A new water-stable three-dimensional (3D) Eu(III) metal–organic framework with the formula of {[Eu3(BTDC)4(HCOO)(H2O)2]·solvents}n (JXUST-9) was successfully obtained by the solvothermal reaction of 2,1,3-benzothiadiazole-4,7-dicarboxylic acid (H2BTDC) and Eu(NO3)3·6H2O. The PXRD patterns indicate that JXUST-9 exhibits good stability when soaked in boiling water for at least 24 h. The fluorescence experiments indicate that JXUST-9 could be considered as a good multi-responsive sensing material for detecting Fe3+, MnO4− and Cr2O72− in aqueous solutions via the turn-off effect, and the detection limits are 0.94 μM, 1.23 μM and 1.23 μM, respectively. JXUST-9 can also be regenerated at least five times for sensing Fe3+, MnO4− and Cr2O72−. Moreover, a rapid detection test paper incorporated with JXUST-9 has been produced, which is helpful for carrying out visual detection of Fe3+, MnO4− and Cr2O72− in daily applications. [ABSTRACT FROM AUTHOR]

Semiconductor–metal heterostructures are attractive surface-enhanced Raman scattering (SERS)-active materials, which can boost the performance effectively because of the synergistic contribution of the electromagnetic (EM) and charge transfer (CT) enhancement effects. In this paper, a photo-responsive Si/TiO2/Ag heterostructure is prepared and its SERS is explored. The interfacial energy level alignment promotes its CT, resulting in charge separation and favors the measurement of adsorbed molecules on the Ag domains, leading to the increase of SERS activity. The enhancement factor (EF) of the Si/TiO2/Ag heterostructure with rhodamine 6G (R6G) as a probe molecule is estimated to be 1.23 × 1012, possessing excellent repeatability, and the relative standard deviation (RSD) is about 2.09%. Moreover, it can be used to detect glyphosate (Gly) very easily at concentrations as low as 0.1 ppb, which is far lower than the national maximum pesticide residue limit in food. Notably, the Si/TiO2/Ag SERS substrate possesses UV cleaning performance and can serve as a promising recyclable SERS-active substrate in practical trace detection applications at very low cost. [ABSTRACT FROM AUTHOR]

The hot electrons produced by the surface plasmon resonance (SPR) effect of plasmonic metals offer an efficient and sustainable strategy for traditional catalysis. However, the low generation rate and easy recombination property of hot carriers limit their application in plasmonic reactions. In this paper, Au@Ag nanoparticles are first constructed result from SPR coupling effect of the Au and Ag components, then they are further assembled on TiO2 microspheres to form Au@Ag/TiO2, in which the Au@Ag assemblies produce a strong SPR effect caused by the collective plasmonic excitation originating from the formation of hot spots between neighboring NPs. All of these endow Au@Ag/TiO2 with efficient hot electron generation capability. Furthermore, Au@Ag/TiO2 was modified by Ti3C2 to prepare the Au@Ag/TiO2/Ti3C2 photocatalyst in consideration of the excellent electron conduction ability of the MXene. As a result, Au@Ag/TiO2/Ti3C2 possesses efficient hot carrier production and separation abilities at the same time, which exhibits outstanding photocatalytic activity in the photoreduction of nitrobenzene to aniline. Under visible light, 100% conversion and aniline selectivity are achieved in 5 min at 0 °C. Moreover, Au@Ag/TiO2/Ti3C2 displays excellent reusability. [ABSTRACT FROM AUTHOR]

An acetonitrile solvate of a Schiff base molecule (HL) with acetonitrile (HL·2CH3CN) and its Cd(II) complex (Cd(HL)2Cl2, 1) was designed and synthesized. The different conformation of HL in HL·2CH3CN is adjusted by the hydrogen bonding O–H⋯O between HL molecules, together with N–H⋯N between HL molecules and acetonitrile molecules. Meanwhile, the conformation of HL in complex 1 is adjusted by coordination interactions between Zn ions and atoms O and N, together with hydrogen bonding N–H⋯Cl. The presence of the triphenylamine group makes HL·2CH3CN and complex 1 loosely packed. Upon grinding, HL·2CH3CN and complex 1 both showed high-contrast mechanochromic luminescence (MCL) change from blue to green and cyan to yellow, respectively. These changes can be eliminated by fumigation with organic vapor. The results of powder X-ray diffraction (PXRD) show that their MCL is due to the phase transformation from a crystalline state to an amorphous state. In addition, HL·2CH3CN and complex 1 also exhibited high-contrast acidochromism upon exposure to HCl and NH3 vapor. X-ray photoelectron spectroscopy (XPS) and PXRD studies show that the protonation of the –NH– group together with phase transformation from a crystalline state to an amorphous state is attributed to the fluorescence switching. For HL·2CH3CN, the protonation process was accompanied by the departure of acetonitrile molecules. The emission of HL was restored to the amorphous state rather than the original crystalline state emission after further exposure to NH3 vapor, while 1-HCl could revert to the original crystalline state emission. In addition, HL·2CH3CN and complex 1 have been successfully used to produce writable and acid-responsive test papers. [ABSTRACT FROM AUTHOR]

Explaining the intensification of upconversion luminescence (UCL) from a single phase NIR-upconverting (UC) crystal due to non-lanthanide dopant insertion appears challenging in the absence of proper mechanistic investigation. In this paper, through extensive synchrotron based X-ray probing, we made an attempt to understand the variations in the structural attributes of UC crystals generated through non-lanthanide ion doping. The structures of the NaYF4/Yb3+/M3+ (M3+ = Er3+/Tm3+) UC crystals doped with different Li+ concentrations were primarily investigated using Rietveld refinement analysis from synchrotron X-ray diffraction (SXRD) and supported with absorption data (XAFS), where necessary. The structural investigation was also supported by TEM, HRTEM, XANES, FT-IR and Raman spectroscopy. Rietveld analysis revealed that all the generated Li+ doped NaYF4 crystals belong to the P6 space group. Most of the Li+ ions were found to be localized in octahedral voids and lattice positions, simultaneously, in the P6 crystal structures. The overall study showed that the change in the UCL intensity behavior with Li+ incorporation could not be predicted from the lattice parameters, morphology or the particle size variation. A detailed XAFS study rather suggested the possible existence of local lattice disorder, which was found to be reflected in terms of lattice strain obtained from Williamson--Hall analysis, irrespective of the activator ions. The remarkable coherence between the variation trends of UCL intensity and lattice strain indicated that the perturbation of the local symmetry field is in some way connected with the local disorder that may not always manifest through average structural attributes like lattice parameters. [ABSTRACT FROM AUTHOR]

High-performance fluorescence sensors combining convenience, low cost and high sensitivity are prospective for water pollution and human health. Luminescent metal–organic frameworks (LMOFs) as sensors can meet these criteria for high efficient detection of toxic metal ions. Herein, a new LMOF LCU-109 has been fabricated by Sharpless in situ tetrazole synthesis system assisted by polycarboxylic O-donor ligand. It showed a 2D binodal (3,6)-connected kgd structure with multiple N and O dual-functional sites for detecting guest metal ions. As expected, LCU-109 can be highly sensitive and selectively detect trace amounts of Fe3+ and Cu2+ ions in an aqueous solution by the luminescence quenching mechanism. Notably, the detection limits (LODs) of Fe3+ and Cu2+ ions are 0.0043 and 0.0028 ppm, respectively, in water, which are significantly lower than the minimum standards stipulated for drinking water by the World Health Organization (WHO) (0.3/2.0 ppm) and U.S. Environmental Protection Agency (USEPA) (0.3/1.2 ppm). Moreover, LCU-109 also shows excellent luminescent sensing activities for Fe3+ and Cu2+ ions in simulated HEPES biological system and actual river water with low LODs of 0.034/0.019 ppm and 0.0756/0.107 ppm, respectively, which is also lower than the standard of WHO and USEPA. Moreover, convenient and real-time naked eye detection effects are provided by the exquisitely made LCU-109 fluorescent test papers. Importantly, combining density functional theory (DFT) calculations with a variety of experiments, the fluorescence quenching mechanism for energy competitive absorption and weak interaction is further revealed. [ABSTRACT FROM AUTHOR]

In this paper, we focused on the influence of common serum cations on monosodium urate monohydrate (MSUM) crystal nucleation determined from cumulative probability distributions (CPDs) of solute crystal nucleation events as a function of time. Surprisingly, with an increase in the concentration of additive ions, striking "opposite effects" were observed for cations, enhancing nucleation at first followed by suppressing nucleation at physiological pH and ionic strength. This enhancing nucleation phenomenon cannot be explained based on colloidal theories or simple descriptors, such as ion size, but it is consistent with the cationic efficacy for inducing an increase in the proportion of growth units of MSUM. [ABSTRACT FROM AUTHOR]

In this paper, we study the PL spectra of N-rich B-doped diamond single crystals grown in NiMnCo solvent, before and after HPHT (high pressure and high temperature) annealing. The PL peaks are observed under 325 nm, 488 nm and 532 nm excitation, respectively. The effects of boron impurity and HPHT annealing on optical centers in N-rich B-doped diamonds are discussed. Before HPHT annealing, as boron incorporation increases in the N-rich diamond, the intensity of the NV− center (627 nm) presents a trend of rising first and then falling. After HPHT annealing at 2.5 GPa and 2000 °C, PL spectra show complex luminescence systems. A series of lines related to Ni–N and Co–N complexes are observed at 602.2 nm, 729.4 nm, 748.8 nm and 542.7 nm in PL spectra under 532 nm and 488 nm excitation. The paramagnetic NE8 center with a ZPL at 793.6 nm appears in the PL spectrum of the N-rich diamond without a boron additive. In the 325 nm excitation PL spectrum of the N-rich B-doped diamond, we also observed the blue luminescence band known as "band-A". Boron incorporation significantly influences the PL intensity of Ni–N, Co–N and NV− related optical centers in diamonds. [ABSTRACT FROM AUTHOR]

Disordered crystals have garnered increasing attention as new laser materials because of their broad emission bandwidths. This paper reports a novel Yb-doped strontium yttrium phosphate (Yb:YSr3(PO4)3) crystal with a disordered structure, as well as its crystal growth, structure, spectral properties, and laser performance. The crystal structure (cubic, 4¯3m point group) was refined using the Rietveld method. The absorption cross-section and fluorescence lifetime were determined to be 1.31 × 10−20 cm2 at 976 nm and 1267 μs, respectively. The stimulated emission cross-section was 1.04 × 10−20 cm2 at 1013 nm, with an emission bandwidth of 55 nm. In addition, continuous-wave laser operation was realized using the Yb:YSr3(PO4)3 crystal with different output coupler transmissions, where the obtained maximum output power and slope efficiency were 1.3 W and 61%, respectively. A dual-wavelength regime with wavelengths centered at 1039 nm and 1047 nm (Δν = 2.2 THz) was achieved under certain conditions; thus, this crystal is expected to be employed for developing terahertz sources. In addition, the laser can operate at multiple wavelengths, ranging from 1023 to 1050 nm. The results indicate that the Yb:YSr3(PO4)3 crystal with a disordered structure may be a promising multi-wavelength laser crystal. [ABSTRACT FROM AUTHOR]

Diamond nucleation on iridium (001) substrates was investigated under different bias conditions. High-density epitaxial nucleation can be obtained in a narrow bias window. This paper reports both the typical nucleation and growth behaviors of Ir substrates. The bias current change laws with the bias duration time were directly recorded; further, the surface modification of Ir substrates and nucleation behaviors at the interface were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In high-density epitaxial nucleation, the bias current decreases as the duration time increases when the iridium surface is dramatically modified with the furrows and arrows preferentially aligned along the [110] direction; however, no diamond grains can be observed from the TEM, except for the carbon layer at the interface. In bias-enhanced growth, the bias current initially decreased, then increased. The grains can be detected by SEM after the biasing stage. A competition mechanism between diamond nucleation and growth under a bias voltage is proposed for this phenomenon, in which the surface nucleation and bulk nucleation coexist and compete. [ABSTRACT FROM AUTHOR]

In this paper, we present four Co-MOFs using R-substituted isophthalic acid (R-H2BDC, R = H, OH and COOH) along with trigonal n-TBT (n = 3 or 4) as organic ligands. These Co-MOFs are formulated as {[Co(1,3-BDC)(4-TBT)2/3]·(H2O)(DMF)1.5}n (Co-MOF-1), {[Co(HO-BDC)(4-TBT)]·(EtOH)2(DMF)2}n (Co-MOF-2), {[Co(HO-BDC)(4-TBT)2/3]·(H2O)3(MeOH)3(DMA)}n (Co-MOF-3) and {[Co3(BTC)2(3-TBT)2(H2O)2]·(H2O)2(EtOH)5(DMA)1.5}n (Co-MOF-4), where H2BDC = isophthalic acid, OH–H2BDC = 5-hydroxyisophthalic acid and H3BTC = 1,3,5-tricarboxybenzene, 4-TBT = 1,3,5- tris(4-pyridyl)benzene and 3-TBT = 1,3,5-tris(3-pyridyl)benzene. Co-MOF-1, 2 and 3 are constructed from the dimeric Co2(COO)2 unit and exhibit 3D frameworks. In Co-MOF-4, the dimeric Co2(COO)2 unit and single nuclear CoII center are connected by BTC3− and 3-TBT ligands into a 3D network. The catalytic experiments revealed that four Co-MOFs can catalyze the oxidative coupling reaction of benzyl alcohols and aniline to imines with good to excellent conversions under solvent-free conditions and an air atmosphere. Co-MOF-4 exhibited the best catalytic performance and the catalyst could be reused for at least five cycles without losing its structural integrity and catalytic activity. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenoxyacetic acid (2,4-D) is a kind of plant growth regulator which exhibits hormesis effects at low dosages, while high dosages adversely affect the exposed organisms and act as herbicide. 2,4-D has low solubility, therefore, it is a good candidate for crystal engineering research to improve its solubility. This paper presents the preparation of five new multicomponent crystals of 2,4-D, including three salts with imidazole (IMZ), 2-aminopyridine (AAP), and 3-aminopyridine (BAP), and two cocrystals with isonicotinamide (ISO) and pyrazinamide (PYM) as coformers (CCFs). The five multicomponent crystals were first characterized by single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Molecular interactions, crystal packing, and structure similarity analyses performed using Hirshfeld surface and CrystalCMP confirmed the charge-assisted H-bonding sites and structural similarity among the solved crystal structures. The stability tests show that all five multi-component crystals exhibit excellent stability within 12 weeks under accelerated storage conditions (40 °C and 75% RH). Moreover, all the five multicomponent crystals of 2,4-D exhibit increased solubility, especially (2,4-D)+(IMZ)− that increased the solubility of the resulting salt by 70 times compared to the free acid 2,4-D. From the perspective of single-crystal structure and intermolecular interaction, the reasons for these changes in physical and chemical properties are further clarified. [ABSTRACT FROM AUTHOR]

Determination of the step edge energy, ρ (J m−1), is a very difficult task. For this reason, very few theoretical estimates of the edge energies of crystalline materials exist. Nowadays, ρ is calculated using a method that requires geometry optimization of many systems. In this paper, we propose a new computational approach for calculating ρ, based on the construction of a 2D periodic (hkl) slab, on which a [uvw] step delimited by two relaxed edges (acute and obtuse) is generated; the method has been designed both for empirical and quantum-mechanical calculations. At variance with a previous computational method, our strategy requires the geometry optimization of only a system; then it results to be more accurate and less expensive from a computational point of view. We applied this new methodology to the study of the [4¯41], [42¯1] and [010] steps lying on the flat (10.4) face of calcite. The structure and energy of the different [uvw] edges were determined. We calculated, as the most stable step, the acute [4¯41] edge (ρ = 5.04 × 10−10 J m−1), followed by the Ca-terminated acute-[010] (5.39 × 10−10 J m−1) and Ca-terminated [42¯1] (9.77 × 10−10 J m−1). Finally, by using these edge energies, we draw the equilibrium shape of a relaxed 2D nucleus lying on the (10.4) face. [ABSTRACT FROM AUTHOR]

Low dislocation AlN films are the key to prepare high-quality deep ultraviolet emission devices. So, how to reduce the dislocation of the films under the conditions of low cost and high efficiency has become a challenge in the film epitaxy growth. Therefore, this paper combined the magnetron sputtering and high-temperature annealing (HTA) technology, exploring thermal annealing of high-miscut-angle AlN films along different directions. High-resolution X-ray diffraction (XRD) and an optical microscope (OM) were used to characterize the film qualities. After annealing at 1400–1650 °C, the quality of sputtered AlN films improved significantly. The full width at half maximum (FWHM) of (0002) and (10–12) rocking curves decreased as the miscut angles of sapphire increased. The minimum values were obtained when the sapphire substrate had 4° miscut angles along from (0001) to the (11–20) direction. Raman spectroscopy, scanning electron microscopy (SEM), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) further revealed the mechanism of enhancing the film quality by annealing. The essence of annealing to improve the film quality lies in the elimination of grain boundaries. [ABSTRACT FROM AUTHOR]

Excited state intramolecular proton transfer (ESIPT) process-based organic fluorophores provide an opportunity to develop large Stokes-shifted multifunctional fluorescence systems for light emitting, chemosensing and bioimaging applications. In this manuscript, ESIPT molecules with two thiazole ring fused symmetrical (1) structures and one thiazole and a Schiff base functional unsymmetrical (2) structure were synthesized, and the impact of their extended π-conjugation was investigated on the fluorescence properties in the solid and solution state as well as metal ions sensing. The strong intramolecular H-bonding and multiple intermolecular H-bonds in the crystal lattice of 1 and 2 lead to ESIPT-induced solid state fluorescence (λmax = 549 (1) and 580 nm (2); ΦF = 7.6 (1) and 6.1% (2)). Interestingly, the molecular assembly of 2 in the solid state facilitated mechanical stimuli-induced reversible fluorescence switching, whereas the flat molecular arrangement in 1 did not show recovery of fluorescence. In contrast, 1 showed strong fluorescence in solution (ΦF = 0.59 in DMF compared to quinine sulphate) due to its symmetrical structure, with strong intramolecular H-bonding, but the PET effect contributed to the very weak fluorescence of 2. The strong solution and solid state fluorescence coupled with the metal chelating functionality of 1 and 2 showed highly selective fluorescence sensing of Cu2+ ions in aqueous solution. 1 and 2 revealed detection limits of 130 and 10 nM, respectively, for Cu2+ ions, which are significantly lower compared to the WHO-recommended level (1.3 mg L−1). The strong solid state fluorescence of 1 and 2 was further used for fabricating filter paper-based fluorescence sensors for the selective sensing of Cu2+ ions. [ABSTRACT FROM AUTHOR]

Dapsone, a sulfonamide, is used to treat tuberculosis, leprosy, malaria, Kaposi's sarcoma, dermatoses and AIDS-related pneumonia. The purpose of this paper is to study the new solid forms of dapsone by using the crystal engineering method of cocrystallization. Based on the design concept of supramolecular synthons, the "–NH2⋯Npyridine" supramolecular synthon was used. 1-(4 pyridyl)piperazine (PYR) was selected as the co-former to prepare (1 : 1) and (2 : 1) DAP-PYR cocrystals, and the corresponding crystal structures were obtained by single crystal X-ray diffraction. The resulting cocrystals were fully characterized by a range of analytical techniques, including powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, hot-stage microscopy, etc. It was found that (1 : 1) and (2 : 1) DAP-PYR cocrystals formed mainly depending on the initial feed ratio of raw materials, which could be transformed into each other by adding quantitative DAP or PYR after mechanical grinding. Molecular interaction and structure analyses performed by Hirshfeld surface and 2D fingerprint plot analyses confirmed that the formation of the supramolecular synthon is the contribution of hydrogen bonding. Furthermore, the molecular electrostatic potential surface and intermolecular binding energy were calculated to visually identify the molecular hydrogen bonding sites, and it revealed that the strong hydrogen bonding interaction of "–NH2⋯Npyridine" promoted the formation of DAP-PYR cocrystals. [ABSTRACT FROM AUTHOR]

A systematic investigation of the system manganese(II) salt–H2SBA–auxiliary ligand–solvent successfully led to the isolation of six new multidimensional coordination polymers: [Mn5(2-pic)2(DMA)4(SBA)4]·4DMA (1), [Mn3(pyzc)2(DMF)(H2O)(SBA)2]·DMF·H2O (2), [Mn5(pyzc)2(DMA)4(SBA)4]·4DMA (3), [Mn5(mpyzc)2(DMA)4(SBA)4]·4DMA (4), [Mn2(phen)2(H2O)(SBA)2]·2DMA (5) and [Mn3(phen)2(SBA)3]·5DMF (6), where SBA = 4,4′-sulfonyldibenzoate 2-pic = 2-picolinate, pyzc = 2-pyrazinecarboxylate acid, mpyzc = 5-methyl-2-pyrazinecarboxylate and phen = 1,10-phenanthroline. The selected use of N-containing ligands to block the coordination sites of manganese enabled us to understand their influence in controlling the nuclearity and the dimensionality of the extended manganese carboxylate coordination networks. Single crystal X-ray crystallography established that the structures of all the solids were built of homometallic clusters varying from monomeric to pentameric manganese(II) carboxylate units. While the solids 1, 3 and 4 are isostructural, possessing a 2D coordination network containing pentanuclear SBUs of the composition {Mn5N2O3}, the 2D solids 2 and 5 are respectively built from binuclear {Mn2N4O7} and trinuclear {Mn3N2O14} SBUs. The solid 6 is the lone example of a 3D coordination network in this system. Dielectric measurements showed comparable dielectric behavior for the isostructural solids 1, 3 and 4 with ε′ ∼ 17 at room temperature. Relatively lower values observed for 2 and 5 (ε′ ∼ 14) were due to a combined effect of strong manganese carboxylate interaction and the presence of ordered polar guest molecules. Significantly higher values for 6 (∼21) could be attributed to disordered guest molecules. All the six solids exhibited antiferromagnetic behavior at lower temperatures. This paper also discusses the growth of the solids in terms of supramolecular aggregation of manganese carboxylate complex species with or without an auxiliary ligand, proposing a mechanistic pathway to trace the chemical events from molecules to the final solid. [ABSTRACT FROM AUTHOR]

Simple liquid-phase approaches for the synthesis of nanomaterials are attractive because their low costs, reduced nanoparticle aggregation, and compatibility with subsequent liquid processes widen the application scope of the resulting materials. This would be particularly interesting for β-Ga2O3 nanoparticles, which often suffer from aggregation issues during their synthesis processes. In this paper, we report a one-step synthesis of β-Ga2O3 nanoparticles in supercritical isopropanol. By simply heating Ga(NO3)3 in isopropanol at 400 °C for 24 hours, β-Ga2O3 nanoparticles with a size of ∼100 nm are obtained without requiring additional calcination in air. A structural characterization comprising X-ray diffraction, scanning electron microscopy, selected-area electron diffraction with transmission electron microscopy, and X-ray absorption fine structure measurements suggest that the synthesis process involves an initial conversion of Ga(NO3)3 to Ga(Oi-Pr)3 or a related species at 80 °C, which then transforms into γ-Ga2O3 nanoparticles upon increasing the temperature, to eventually produce β-Ga2O3 nanoparticles most likely via a dissolution and recrystallization process. [ABSTRACT FROM AUTHOR]

[2]Pseudorotaxane, [(FcCH2NH2CH2C6H4-4-Me)(DB24C8)][PF6] ([1][PF6]; Fc = ferrocenyl and DB24C8 = dibenzo[24]crown-8-ether), undergoes crystalline phase transition at 128 °C upon heating and at 106 °C upon cooling (α-phase at low temperature; β-phase at high temperature), as shown in our previous reports. This paper presents new results from the detailed studies on the crystal phase transition of pseudorotaxane, the dielectric constant of the crystal, and the formation of a gel from a PhCl solution. The crystalline phase transition has been revealed to accompany the partial rotation of the DB24C8 molecule while maintaining the hydrogen bonds between the axle and macrocyclic component molecules. The ultrasonication of a PhCl suspension of a mixture of the axle and cyclic molecules forms a gel, which is composed of microcrystalline [1][PF6] with a new crystal form (α′-phase). The pseudorotaxane crystals with mixed counter anions, [1][PF6]1−x[Y]x (Y = AsF6 and SbF6), exist in the α- or β-phase, depending on the anion composition. Further, [1][PF6]0.28[AsF6]0.72 and [1][PF6]0.76[SbF6]0.24 are obtained in the α-phase, while [1][PF6]0.65[SbF6]0.35 crystallises in the β-phase. The phase transition temperature of the pseudorotaxane with PF6− and SbF6− counter anions is investigated using differential scanning calorimetry (DSC). [ABSTRACT FROM AUTHOR]

Photomechanical molecular crystals are a family of mechanically responsive materials that have been recognized as a novel type of actuator. The actuation properties of photomechanical crystals should be characterized. However, deflection and force, which are crucial for actuators, are dependent on experimental conditions such as light intensity and crystal size, and thus the number of combinations under different conditions is infinite. This causes difficulty in obtaining the relationship between the experimental conditions and actuation outputs. To solve this problem, this paper presents a machine learning-based regression approach for modeling the deflection and force of a photo-bending crystal. The deflection and force were experimentally measured for various light intensities and crystal sizes. These time-series data of deflection and force were represented by feature values via exponential fitting for bending and unbending processes. The features of the maximum value and speed of deflection and force were analyzed by polynomial regression and variable selection. Through this process, the most fitted models were constructed for deflection and force and most of them were interpreted by material mechanics. This statistical strategy will potentially be applied to control or optimize other functions of stimuli-responsive crystals. [ABSTRACT FROM AUTHOR]

In this paper, a novel metal-free compound, [H2(bpyp)][ClO4]2 (1) (bpyp = 1,3-bis(4-pyridyl)propane), has been successfully synthesized. It undergoes a reversible phase transition at around Tc = 256.19 K (Tc is the Curie temperature). Compound 1 shows a moderate ferroelectric polarization (Ps) of about 0.13 μC cm−2 and a coercive field (Ec) as small as 0.65 kV cm−1. The phase transition behavior of compound 1 is well characterized by differential scanning calorimetry (DSC) and variable temperature single crystal diffraction measurements. The displacement and rotational reorientation motion of H2(bpyp)2+ cations and ClO4− anions induce the phase transition of compound 1 from the non-polar space group P21212 (No. 18) to the polar space group P21 (No. 4). The significant second harmonic generation (SHG) switching response further demonstrates the symmetry breaking from P21212 to P21. In particular, a dielectric study exhibits that the dielectric anomaly of compound 1 increases by 3–6 times at the phase transition temperature, which indicates its potential applications in switchable dielectric elements. Meanwhile, compound 1 shows semiconducting properties with a wide optical bandgap of ∼4.47 eV. This finding suggests that metal-free compounds can be used in environmentally-friendly phase transition materials, contributing to the exploration of ferroelectric–dielectric and nonlinear optical (NLO) switching materials. [ABSTRACT FROM AUTHOR]

For the hybrid organic–inorganic perovskites with the general formula of A2MIIX4 (A = methylammonium; MII = Mn, Cu and Co; X = Cl), the arrangement of metal ions and organic ligands leads to a delicate balance of space, spin and charge, which results in diverse properties. In this paper, we reported a group of hybrid organic–inorganic perovskite single crystals of (CH3NH3)2MnCl4, (CH3NH3)2CuCl4 and (CH3NH3)2CoCl4 grown by a simple solution evaporation method. Magnetic measurements show that all the single crystals display magnetic ordering at low temperature. Our results reveal a novel group of hybrid organic–inorganic magnetic perovskites. [ABSTRACT FROM AUTHOR]

In recent years, metal–organic frameworks (MOFs) have been widely used in various fields, especially in the field of electrochemical energy storage and conversion, because of their excellent properties. It is reported that Co-MOFs usually play the role of templates with other active components to improve the overall properties of materials. Pristine Co-MOFs have been widely used for battery applications because of their excellent performance as well as the simple fabrication process, which can eliminate concerns regarding poorly controlled pyrolysis. Herein, for a further specific summary of particular applications of Co-MOFs, we will mainly review the relative applications of Co-MOFs in lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, lithium–sulfur batteries and metal–air batteries. In this paper, the applications of pristine Co-based MOFs are reviewed in detail, which can provide a reference for future work. [ABSTRACT FROM AUTHOR]

Triazine derivatives, a class of electron-deficient π-conjugated molecules with high photochemical activity and excellent luminescent characteristics, have been utilized as a kind of electron-acceptor for the construction of molecular cages, luminescent and photochromic materials. In this paper, a novel and highly stable MOF with cubane-like clusters, [Co4(SO4)3(F)3(tpt)2(tatb)] (1) (tpt = 2,4,6-tris-(4-pyridyl)-1,3,5-triazine, H3tatb = 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid), has been successfully synthesized based on a triazine derivative, and possesses unprecedented sulfate- and fluoride-bridged cubane-type tetranuclear cobalt clusters and a 3D + 3D → 3D open framework. Compound 1 shows a rather high BET surface area and exhibits excellent thermal stability and high chemical stability in common solvents and even in acidic or basic solutions (in a pH range from 4 to 12). Moreover, catalytic measurements show that compound 1 is an excellent heterogeneous catalyst for the selective oxidation of aryl alkenes to aldehydes or ketones with conversions of 97%. [ABSTRACT FROM AUTHOR]

Co-crystallization of the antibacterial agent proflavine (PF) with the inorganic salt ZnCl2 by mechanochemical and solution methods results in the formation of novel compounds ZnCl3(HPF) (1) and [HPF]2[ZnCl4]·H2O (2), both containing the proflavinium cation (HPF)+. Both compounds show a 50–125% enhanced antimicrobial activity with respect to a reference standard of AgNO3, and a 25–50% enhancement to the behaviour of the separate components against pathogen indicator strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. In terms of crystal structure, both compounds ZnCl3(HPF) and [HPF]2[ZnCl4]·H2O are characterized by extensive π-stacking interactions between the proflavine moieties. The same interaction is predominant in the previously unknown crystal structures of neutral proflavine (PF), as well as in that of its dihydrated monochloride salt, [HPF]Cl·2H2O, which are also described in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a series of Eu3+/Tb3+ doped La3Ga5SiO14 (LGS:Eu3+, Tb3+) phosphors with excellent performance have been synthesized by high-temperature solid-phase method. The effects of Eu3+ and Tb3+ doping in LGS on the host lattice were analyzed by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) proved that the Eu3+ and Tb3+ ions were successfully doped into the LGS host. The doped Eu3+/Tb3+ ions only occupy the eight-coordinated La3+ sites. The concentration quenching points of LGS:Eu3+ and LGS:Tb3+ phosphors were determined to be 0.16 and 0.18, respectively. The luminescence performance and fluorescence lifetime of LGS:Eu3+, Tb3+ were studied. LGS:Eu3+, Tb3+ phosphors successfully realized Tb3+ → Eu3+ energy transfer to enhance Eu3+ luminescence. The energy transfer mechanism is speculated on using the experimental results. The energy transfer efficiency from Tb3+ to Eu3+ is about 66.83% in La2.46Tb0.18Eu0.36Ga5SiO14. The LGS:Eu3+, Tb3+ phosphors can achieve tunable luminescence by controlling the doping concentrations of Eu3+ and Tb3+. The ΔE is calculated to be 0.2567 eV for the La2.70Eu0.12Tb0.18Ga5SiO14 phosphor. [ABSTRACT FROM AUTHOR]

In this paper, palygorskite (Pal) and spherical zinc sulfide (ZnS) nanopowders were successfully synthesized by using a simple hydrothermal method. The ZnS nanoparticles were supported on the framework of Pal without agglomeration, thereby increasing the specific surface area of Pal/ZnS nanocomposites (from 36.33 m2 g−1 to 83.85 m2 g−1). The acquired nanocomposites exhibited a significant enhancement in photoactivity for the degradation of rhodamine B under simulated sunlight irradiation. Specifically, when the content of Pal was 40%, the nanocomposite showed optimal photocatalytic activity, with a degradation rate of rhodamine B of 100% in 150 min. The improved photocatalytic performance of the nanocomposites may be attributed to the fact that the incorporation of Pal not only strengthened the adsorption of rhodamine B, but also reduced the band gap energy of the nanocomposites and the recombination rate of electrons and holes. Such inexpensive high-performance Pal/ZnS nanocomposites could find potential applications for the degradation of organic dyes. [ABSTRACT FROM AUTHOR]

The novel single component molecular ferroelectric single crystal of 1,3,5-trimethylnitrobenzene (TMNB) has been investigated in terms of its temperature dependent polar properties. Three phases have been found in the solid state of TMNB: phase I above 161 K, phase II (incommensurate) between 161 and 152 K and phase III below 152 K. The TMNB crystal structures were determined at 100 K (phase III, sp. gr. Pca21) and at 250 K (phase I, sp. gr. Pnma). Ferroelectricity of phase III along the c-axis has been confirmed by the pyroelectric measurements and observations of the hysteresis loops, revealing spontaneous polarization as small as ∼2 × 10−6 C m−2. The crystal is the first example of an origin of spontaneous polarization related to flexibility of the C–H⋯π hydrogen bonds (molecular joints). The TMNB molecules in the dimer can change the mutual orientation of the dipole moments without breaking the C–H⋯π bonds. In this paper, the mechanism of the phase transitions will be discussed, which is governed by the dynamics of the NO2 groups and the flexibility of the C–H⋯π dimer. [ABSTRACT FROM AUTHOR]

In this paper, the growth of semi-polar GaN thick films was investigated on an m-plane sapphire by hydride vapor phase epitaxy (HVPE). By optimizing parameters of the HVPE process, both (11−22) and (10−13) semi-polar GaN films have been successfully obtained with a mirror surface and excellent crystal quality on different GaN templates grown by metal organic chemical vapor deposition (MOCVD), respectively. The influence of MO-GaN templates on the HVPE growth was further studied. The results revealed that the same plane of a semi-polar HVPE-GaN thick layer was grown on a single-phase template, such as GaN (11−22)HVPE on (11−22)MO-template and GaN (10−13)HVPE on (10−13)MO-template. However, on mixed-phase MO-templates, a single-phase (11−22) GaN thick layer was found to grow even if the original templates contain both (11−22) and (10−13) plane components. Meanwhile, in contrast with the difficult growth of GaN (10−13) with a smooth surface, it is easier to acquire GaN (11−22) thick layers by a HVPE method. A wider window for the growth of the (11−22) plane could partly explain the reason why the pure GaN (11−22) plane could be grown on mixed-phase ((11−22) & (10−13)) MO-templates. In order to explain this phenomenon, both formation energy (Ef) and migration barrier (Em) of these semi-polar faces were calculated. Our results indicated that the Ef of GaN (10−13) (−0.56 eV) is higher than that of (11−22) (−10.73 eV), and the Em of (10−13) (0.30 eV) is lower than that of (11−22) (1.89 eV). So the (11−22)-plane growth was more likely to be prevalent in competition between two phases. [ABSTRACT FROM AUTHOR]

Over the past several decades, halogen bonding has become a standard 'tool' in supramolecular chemistry and particularly in crystal engineering. Traditionally, the study of halogen bonding has primarily been focused on organic materials, but lately there has been a constant increase in interest for halogen-bonded metal–organic materials. Numerous reports and reviews dealing with halogen bonding in single-component metal–organic solids and metallate salts have been published to date. In contrast, the design of multi-component crystals involving neutral metal–organic complexes and/or neutral halogen bond donors as building blocks has been much less explored. The purpose of this paper is to give an overview of the current advances in the preparation of halogen-bonded metal–organic multi-component solids, including salts, cocrystals comprising neutral constituents as well as cocrystals comprising ionic constituents. In doing so, we shall outline the general design strategies which can be employed in the design of such materials, and suggest possible directions for further research in this fascinating field. [ABSTRACT FROM AUTHOR]

Nickel sulfide (Ni3S2) has been widely known in the energy storage field, owing to the high theoretical capacitance, low cost, and environmental friendliness. We reported simple, low-cost hydrothermal synthesis of Ni3S2 nanoparticles as a remarkable electrode material for symmetric supercapacitor (SSC) in this paper. The structural characterization confirms the successful formation of the sample with a nanoparticle-like morphology with good crystallinity. The unique structure is composed of plenty of ion mobilization channels that exhibits superb electrochemical performance. When employed as an electrode material for supercapacitors, the fabricated Ni3S2 nanoparticles displayed the typical features of battery-type faradic electrodes showing an ultra-high specific capacitance of 2495 F g−1 at 1 A g−1 and excellent cycling stability (92.2% capacitance retention after 5000 consecutive CV cycles) within the potential frame of −0.2 to 0.6 V in a three-electrode system, which surpasses many previous literature reports. In the end, a SSC device was assembled exhibiting an optimized and stable potential window of 1.8 V with a high specific capacitance of 116.6 F g−1 at 5 A g−1. Moreover, the Ragone plot shows a high energy density of 52.4 W h kg−1 and an ultra-high power density of 13 500.0 W kg−1, indicating excellent cycling stability (95% retention after 7000 cycles). Additionally, we demonstrated a coin-type SSC that provides sufficient energy to turn on the red LED, which emits light over a certain period to open up possible realistic applications. These results show the great potential of Ni3S2 nanoparticles in the development of high-performance electrode materials for energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

Studying the influence of oxygen on the growth and properties of diamond has research significance. In this paper, we created an oxygen-rich environment by adding Ni2O3 to the Fe–Ni–C system. Large single crystals of oxygen-containing diamond were successfully synthesized using the temperature gradient method (TGM) in a China-type large volume cubic high-pressure apparatus (CHPA) at 5.5–6.0 GPa and 1360–1600 °C. The results show that with the increase of the Ni2O3 content in the Fe–Ni–C system, the rate of diamond growth decreased while the conditions for diamond growth were enhanced. The morphology of the diamonds changed from {111}, {110} and {113} mixed faces to {111} dominant face. The IR results show that the presence of Ni2O3 increased the nitrogen content in diamonds from 237 ppm to 543 ppm. When 3.5 wt% Ni2O3 was added, A-centre nitrogen began to appear in the diamonds. The XPS results confirmed that oxygen successfully entered the diamond lattice in the form of C–O, C＝O, O–C＝O and N–O with a high concentration of Ni2O3 additives. Meanwhile, there were no obvious impurity inclusions and cracks in the diamond crystals. In addition, the Raman peak position of the diamond appeared to red shift, and the FWHM increased from 4.93 cm−1 to 5.52 cm−1. [ABSTRACT FROM AUTHOR]

All-inorganic materials, mixed halide perovskite (MHP) nanocrystals (NCs), have attracted considerable attention recently because of their excellent luminescence efficiencies and extraordinary physical properties, making them a promising material for next-generation lighting and full-color display. On the other hand, an essential development of blue-emitting devices rather than other color emitters has been hindered by their defect tolerance and quantum efficiency which are relatively lower than those of green-emitting NCs. Moreover, few studies have examined the synthesis and properties of blue-emitting MHP NCs or their applications to light-emitting diodes (LEDs). To solve these problems, this paper reports a facile and controllable way of producing emission wavelength tunable CsPb(Br1−xClx)3 NCs using a fast and straightforward chemical treatment with the trimethylsilyl chloride (TMSC) additive. Structural and chemical analysis showed that the Cl content in the CsPb(Br1−xClx)3 NCs could be modulated by TMSC addition without changing the morphologies. The photoluminescence emission peak wavelength of the CsPb(Br1−xClx)3 NCs could be modulated from 515 to 416 nm by increasing the TMSC content. To this end, blue and green LEDs were successfully demonstrated by using the TMSC-treated CsPb(Br1−xClx)3 NCs as an emissive layer, showing a controllable emission wavelength from 473 to 511 nm. [ABSTRACT FROM AUTHOR]

The demand for proteins with high purity, high activity and high stability is increasing, especially in the biopharmaceutical industry. Traditional industrial protein production technologies include chromatography, which is expensive, and salting out and traditional crystallization methods, which require large amounts of salt and have an adverse effect on the environment. In recent years, a new method—solvent freeze-out (SFO) technology for protein crystallization—has been developed. Compared with traditional methods, SFO requires less salt, and can be carried out at low temperatures, resulting in more stable and active proteins. In addition, SFO can control the nucleation and crystal growth process under different supersaturation levels by setting appropriate operating temperatures, which can ensure industrial application of this technology. This paper reviews important advances in SFO technology for the crystallization of proteins. [ABSTRACT FROM AUTHOR]

This paper examines the influence of temperature and oxygen on the growth of large-scale silicon carbide nanowires by using a combination of sol–gel impregnation and carbothermal reduction methods. To investigate the growth process of SiC nanowires, the microstructural changes of nanowires at different temperatures from 1050 °C to 1550 °C were observed using SEM. In addition, XRD, TEM and FTIR were also used to analyze the nucleation, crystal structure and chemical phase of the SiC nanowires. XPS revealed the chemical reactions that occur during the growth of SiC nanowires. In this paper, we also evaluated the impacts of temperature and oxygen from SiOC (an intermediate) on the growth of SiC nanowires. The results show that a proper temperature was necessary for the nucleation and growth of SiC nanowires. The findings also indicate that the presence of O2 could contribute to the growth of longer SiC nanowires. [ABSTRACT FROM AUTHOR]

A careful selection of organic and inorganic components enables the production of unusual structure types with promising practical properties by facile syntheses. In this paper, we describe novel supramolecular architectures comprising organic adamantane-like divalent building blocks and iodide or polyiodide anions. Highly acidic conditions facilitated the formation of a doubly protonated organic ligand out of 5,7-dimethyl-1,3-diazaadamantane that generates three different crystal structures with inorganic counterions. In these structures, cationic substructures are constructed by transforming neutral organic ligands into [(C10N2H20)I]+ or [(C10N2H20)(H2O)]2+ cations, which crystallize with charge-compensating iodine-based anions of different complexities. All three crystal structures are characterized by various noncovalent forces, ranging from strong (N)H⋯I, (O)H⋯I, and (N)H⋯O hydrogen bonds to secondary and weak I⋯I interactions. Raman and diffuse reflectance spectroscopy as well as DFT calculations were employed to describe the electronic structures and optical properties of new supramolecular architectures, with particular attention to the role of non-covalent interactions. [ABSTRACT FROM AUTHOR]

A new benzothiadiazole-based MOF {[Zn(BIBT)(oba)]·DMA}n (JXUST-3, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2oba = 4,4′-oxybisbenzoate) has been solvothermally synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and TGA. The fluorescence studies suggest that JXUST-3 could simultaneously selectively sense trivalent metal ions including Al3+, Cr3+ and Fe3+ by a turn-off effect, and the detection limits are 0.055, 0.049 and 0.056 μM, respectively. Moreover, JXUST-3 exhibits relatively good thermal and chemical stabilities and reusability. The fluorescent test paper also displayed an obvious turn-off effect, indicating that JXUST-3 can be used as a potential multi-response fluorescent probe. The possible quenching mechanisms of JXUST-3 for Al3+ and Fe3+ were competitive energy absorption, and for Cr3+ ions, they were competitive energy absorption and weak interactions between Cr3+ and the framework. Therefore, JXUST-3 could be viewed as a transition metal MOF fluorescence sensor for Al3+, Cr3+ and Fe3+ by the turn-off effect, simultaneously. [ABSTRACT FROM AUTHOR]

Recently, π-conjugated polymers (CPs) applied to graphitic carbon nitride (g-C3N4) with high crystallinity have received great attention for removing organic pollutants. Herein, we propose that doping oxygen atoms into the g-C3N4 skeleton can improve photodegradation efficiency due to excellent carrier separation through enhanced polarization promoted by π-conjugated system expansion and high crystallinity. In detail, the higher electronegativity and larger size of oxygen atoms can enhance the crystallinity and conjugated plane of g-C3N4 leading to an increase in electrical conductivity and electron delocalization of O-doped g-C3N4, which extremely enhances the polarization degree. Therefore, the mechanism of the improved photocatalytic performance for diclofenac sodium, bisphenol A, and phenol can be attributed to the rapid photodegradation caused by fast charge separation. We believe that this paper can offer a novel perspective on the relationship between crystallinity, conjugation degree, and polarization in photocatalysts for environmental purification. [ABSTRACT FROM AUTHOR]

Emulsions are typically formed in a mixture of immiscible liquids. However, emulsion particles are also found upon mixing miscible liquids. In this paper, we suggest that emulsion particles are formed by ethanol mixed into toluene, as detected via dynamic light-scattering and small-angle X-ray scattering spectroscopy measurements. Furthermore, the addition of ethanol into a homogeneous fullerene solution (C70/toluene) also forms emulsion particles. The emulsion particles could provide a space in which crystallization of C70 occurs via anti-solvent crystallization (ASC). The size change of the emulsion particles through coalescence and shrinkage processes, which depend on the amount of ethanol, explains the change of crystallization environment until a supersaturation state is reached. It is believed to be the previously undiscovered key indicator of the ASC mechanism prior to nucleation. [ABSTRACT FROM AUTHOR]

Developing dual-state fluorescence materials with high emission efficiency both in solution and solid states is still a challenge. Herein, a functionalized pyrazoline derivative (NF) was designed and synthesized. NF exhibited high blue emission efficiency in both THF solution and solid states with the absolute fluorescence quantum yields of 58% and 43%, respectively. The mechanism of this unique fluorescence behavior was systematically studied with the help of single-crystal structure analysis. The results showed that a close-knit molecular structure existed due to intramolecular C–H⋯π interactions, which can impair the intramolecular rotation to accelerate the radiative transition in the mono-molecule state (in dilute solution). Moreover, the steric hindrance and intermolecular hydrogen-bond interactions of the substituent groups can restrict the close packing and prompt the formation of J-aggregates in the aggregation state, which resulted in high emission performance in the solid state. Meanwhile, the dual-state blue emission property of NF was utilized for the picric acid (PA) detection in the solution state and on a test paper by the synergistic effects of photo-induced electron transfer (PET) and Förster resonance energy transfer (FRET) processes. The limit of detection as low as 6.80 × 10−7 M achieved in the THF–H2O mixture. This work provided a new scope for the design of high dual-state blue emission materials. [ABSTRACT FROM AUTHOR]

A bibliographic and literature-based analysis of the impact of the Cambridge Structural Database (CSD) and the papers associated with crystal structures in the CSD has been undertaken. The analysis shows the broad impact of the CSD in the chemical sciences and also highlights how areas where the CSD has impact have changed over time. In addition, we note the changing nature of crystallography as a science, observing how crystal structures are now impactful. A brief illustration of some more unusual contributions to the CSD and publications using the CSD is also presented. [ABSTRACT FROM AUTHOR]

This paper analyzes the trends in atomic size, coordination number, and relative abundance of metal–oxygen bonds throughout the 6th row of the periodic table, as deduced from the structural data in the CSD. Special emphasis is given to the transition from Ba to the lanthanide series, and from these to the 5d metals. All the data indicate that Lu is closer than La to the behaviour shown by the 5d metals. Besides, a Lu-containing group 3 gives trends down the group that are similar to those of neighboring transition metal groups. [ABSTRACT FROM AUTHOR]