Surface coordination induced a quasi p-n junction for efficient visible light driven degradation of tetracycline over hydroxyapatite.

The removal of antibiotics from aquatic solutions remains a global environmental challenge. In this work, the photocatalytic removal of a typical antibiotic-tetracycline (TC) using hydroxyapatite (HAp) as a catalyst was investigated. It was impressive that TC could be efficiently degraded by HAp under visible light irradiation, even though both HAp and TC exhibited poor harvesting in visible light region. The experimental and theoretical explorations were undertaken to thoroughly investigate the underlying mechanism of visible light degradation of TC over HAp. The results indicated that the formed TC-HAp complexes via surface coordination played an important role as photosensitizers for the visible light response. Together with the formation of a quasi p-n junction via band alignment, the photogenerated electrons in the highest unoccupied molecular orbital (HOMO) of TC-HAp were excited to the lowest unoccupied molecular orbital (LUMO) and subsequently migrated to the conduction band of HAp to achieve the efficient charge separation. Superoxide radicals and holes were found to be the major active species for TC degradation. The toxicity evaluation showed that TC could be transferred to the lower toxic intermediates, and deep oxidation with prolonged reaction time was necessary to eliminate the toxicity of TC. This work demonstrates the surface coordination with subsequent quasi p-n junction mechanism of TC degradation over HAp under visible light, which will stimulate us to explore new efficient photocatalytic systems for the degradation of various contaminants.

Moisture-Electric-Moisture-Sensitive Heterostructure Triggered Proton Hopping for Quality-Enhancing Moist-Electric Generator.

Moisture-enabled electricity (ME) is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can be directly applied to energy harvesting and signal expression. However, ME can be unreliable in numerous applications due to its sluggish response to moisture, thus sacrificing the value of fast energy harvesting and highly accurate information representation. Here, by constructing a moisture-electric-moisture-sensitive (ME-MS) heterostructure, we develop an efficient ME generator with ultra-fast electric response to moisture achieved by triggering Grotthuss protons hopping in the sensitized ZnO, which modulates the heterostructure built-in interfacial potential, enables quick response (0.435 s), an unprecedented ultra-fast response rate of 972.4 mV s-1, and a durable electrical signal output for 8 h without any attenuation. Our research provides an efficient way to generate electricity and important insight for a deeper understanding of the mechanisms of moisture-generated carrier migration in ME generator, which has a more comprehensive working scene and can serve as a typical model for human health monitoring and smart medical electronics design.

Hepatic transcriptome analysis reveals that elovl5 deletion promotes PUFA biosynthesis and deposition.

The safe and low-cost acquisition of polyunsaturated fatty acids (PUFAs) has become a research hotspot. Fatty acyl elongase 5 (Elovl5), a rate-limiting enzyme for fatty acid elongation, is principally in charge of extending C18 and C20 PUFA substrates. However, the role of elovl5 in regulating pathways and genes involved in PUFA synthesis remain largely unknown. Here, hepatic transcriptome analysis of wild-type and elovl5 knockout (elovl5-/-) zebrafish was performed to identify the potential regulatory targets related to PUFA deposition and synthesis. There were 1579 differentially expressed genes (DEGs), of which 787 had their expression levels increased while 792 had the opposite effect. Peroxisome proliferators-activated receptors (PPAR) signaling pathway was considerably enriched in DEGs, according to the KEGG analysis, in which fatp2, fabp7, and pparδ were engaged in PUFA absorption and deposition. Additionally, transcriptome analysis also revealed that cyp46a1 and cyp2r1 were implicated in the synthesis of bile acids and the metabolism of vitamin D, thus indirectly participating in PUFA biosynthesis and deposition. Finally, the DEGs, which improve PUFA level following elovl5 deletion, were verified through feeding experiment with two prepared diets soybean oil diet and linolenic acid oil diet. This study revealed potential regulatory targets that improve PUFA level after elovl5 deletion in teleosts.

scd knockout activates ß-oxidation of fatty acids via accumulating stearic acid (18:0) and induces anorexia in zebrafish.

Stearoyl-CoA desaturase (scd) is the rate-limiting enzyme for the biosynthesis of monounsaturated fatty acids (MUFA), and it plays a critical role in regulating hepatic lipogenesis and lipid oxidation. However, its role in teleosts remains unclear. In this study, we generated scd knockout zebrafish (scd-/-) to explore the role of Scd in regulating growth and metabolism in teleosts. The results showed that scd knockout reduces hepatic lipid deposition by down-regulating the expression of lipogenesis-related genes and up-regulating the expression of lipolysis-related genes. In addition, the knockout of scd suppressed food intake and reduced body weight. Further analysis confirmed that scd knockout suppressed the feeding behavior by decreasing expression of orexigenic peptide genes and increasing expression of anorexigenic peptide genes. The high-level stearic acid (18:0) feeding experiment results showed that the accumulation of 18:0 inhibited feeding behavior, reduced food intake, decreased body weight, and increased lipid ß-oxidation, which was essentially consistent with the phenotypes of scd deficiency. Taken together, our results indicate that the knockout of scd inhibited the food intake through the accumulation of 18:0. This study preliminarily reveals the role of Scd in regulating food intake of teleosts, which provides theoretical basis for the functional study of Scd.

All-pH-Tolerant In-Plane Heterostructures for Efficient Hydrogen Evolution Reaction.

Generally, electrocatalytic hydrogen evolution reaction (HER) by water splitting is a pH-dependent reaction, which limits the widespread harvesting of hydrogen energy. Herein, we present a simple way for chemical bonding of MoS2 (002) planes and α-MoC {111} planes to form in-plane heterostructures capable of efficient pH-universal HER. Due to the lattice strain from mismatched lattice parameters between α-MoC and MoS2, this catalyst changes the electronic configuration of the MoS2 and thus acquires the favorable proton adsorption and desorption activity, suggested by the platinum (Pt)-like free Gibbs energy. Consequently, only a low 78 mV overpotential is needed to achieve the current density of 10 mA cm-2 in acidic solution along with a favorable Tafel kinetic process with a Tafel slope of 38.7 mV dec-1. Owing to the synergistic interaction between MoS2 (002) planes and α-MoC {111} planes with strong water dissociation activities, this catalyst also exhibits high HER performances beyond that of Pt in neutral and alkaline. This work proves the advances of in-plane heterostructures and illustrates the production of low-cost but highly efficient pH-universal HER catalytic materials, promising for future sustainable hydrogen energy.

Theoretical Design of Near-Infrared Al3+ Fluorescent Probes Based on Salicylaldehyde Acylhydrazone Schiff Base Derivatives.

The aim of this paper is to design near-infrared (NIR) Al3+ fluorescent probes based on a Schiff base to extend their applications in biological systems. By combining benzo[h]quinoline unit and salicylaldehyde acylhydrazone, we designed two new Schiff base derivatives. According to theoretical simulations on previous experimental Al3+ probes, we obtained the appropriate theoretical approaches to describe the properties of these fluorescent probes. By employing such approaches on our newly designed molecules, it is found that the new molecules have high selectivity toward Al3+ and that their corresponding Al3+ complexes can emit NIR fluorescence. As a result, they are expected to be potential NIR Al3+ fluorescent probes.

Rational design of D-π-A organic dyes to prevent "trade off" effect in dye-sensitized solar cells.

It is an easy task to simulate the spectrum properties for the organic dyes applied in dye-sensitized solar cells (DSSCs) if the suitable method is chosen. However, it is still difficult to quantitatively determine the overall performance for them. In this work, the short-circuit photocurrent density (JSC) and open circuit photovoltage (VOC) are quantitatively calculated by combination of the density functional theory and first principle for DSSCs based on four different organic dyes, 2-((4'-((4-(bis(4-methoxyphenyl)amino)phenyl)diazenyl)biphenyl-4-yl)methylene)but-3-ynoic acid (1), 2-((5-(4-((4-(bis(4-methoxyphenyl)amino)phenyl)diazenyl)phenyl)thiophen-2-yl)methylene)but-3-ynoic acid (2), 3-(7-(4-((4-(bis(4-methoxyphenyl)amino)phenyl)diazenyl)-4H-cyclopenta[2,1-b:3,4-b']-dithiophene)-2-cyanoacrylic acid (3), and 3-(7-(4-((4-(bis(4-methoxyphenyl)amino)phenyl)diazenyl)phenyl)-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-cyanoacrylic acid (4), in which the triarylamine is donor and the cyanoacrylic acid is acceptor along with variable π group. The 3 and 4 are new theoretically designed organic dyes on the basis of 1 and 2 with different electron-rich group as π group. Both JSC and VOC of 3 and 4 are improved as compared with those of 1 and 2, which breaks the normal "trade-off" rule. As a result, the power conversion efficiency (PCE) of 3 and 4 is improved, especially for 3. The aggregation effect is also considered to evaluate the overall performance, which is favorable to further enhance the reliability of theoretical design.

Theoretical investigation of the vibronic phosphorescence spectra and quantum yields for iridium(III) complexes with 2-(2,5,2',3',4',5',6'-heptafluoro-biphenyl-4-yl)-pyridine as the primary ligand.

Cyclometalated Ir(III) complexes are widely used as phosphorescent materials in organic light-emitting diodes. In this work, the vibrationally resolved phosphorescence spectra of an experimental reported and four novel designed Ir(III) complexes with 2-(2,5,2',3',4',5',6'-heptafluoro-biphenyl-4-yl)-pyridine (HFYP) as primary ligand are investigated by theoretical calculations. The ancillary ligands are 3-(pentafluorophenyl)-pyridin-2-yl-1,2,4-triazolate (exp3), 3-(trifluoromethyl)-pyridin-2-yl-1,2,4-triazolate (5), 5-methylsulfonyl-2-oxyphenyl-2-oxazole (6), 5-trifluoromethyl-2-oxyphenyl-2-oxazole (7), 2-(3-(trifluoromethyl)-1H-1,2-diazol-5-yl)pyridine (8), respectively. Phosphorescence spectra show that there are mainly two strong peaks, which can be ascribed as low-frequency vibrational modes such as the rotation of ligand plane, and benzene ring/pyridine ring in ligand HFYP1 skeleton vibration coupled with CH in pyridine ring in plane bending vibration. The phosphorescence quantum yields were quantitatively determined by evaluating radiative decay rate constant kr, intersystem crossing rate constatant kISC and temperature-dependent nonradiative decay rate constant knr(T). It shows that the quantum yields of compounds exp3, 5 and 8 are relative higher, while those of compounds 6 and 7 are much smaller. This is mainly caused by larger knr(T) of compounds 6 and 7. It is anticipated that in Ir(III) complex with HFYP primary ligand, pyridin-2-yl-1,2,4-triazolate, 1,2-diazol-5-yl-pyridine are good ancillary ligand, while 2'-oxyphenyl-2-oxazoline is not appropriate to be ancillary ligand.

Preparation of TiO2 microspheres with tunable pore and chamber size for fast gaseous diffusion in photoreduction of CO2 under simulated sunlight.

TiO2 microsphere with tunable pore and chamber size are prepared by a simple solventhermal method and used as catalyst for the photocatalytic CO2 reduction. It is found that the hollow microsphere with relative lower surface area of 73.8 m2 g-1 exhibits increased pore size of 18.1 nm and cavity structure, leading to higher CO2 diffusion coefficient of 5.40 × 10-5 cm2 s-1 compared with the solid and yolk/shell microspheres. Therefore, the hollow microsphere possesses more accessible sites for CO2 adsorption, which finally gives rise to the enhanced CO production rate of 10.9 ±â€¯0.7 µmol g-1 h-1 under simulated sunlight, which is respectively 1.6 and 1.4 times higher than that of solid and yolk/shell microspheres. Electron dynamic study further demonstrates that hollow microsphere shows the highest photocurrent density and the lowest charge recombination among three microspheres structure, which is attributed to the swift CO2 diffusion providing fresh CO2 molecules to rapidly scavenge the photo-generated electrons and finally leading to the excellence catalytic reduction performances. This method could be adopted as a general strategy to prepare high performance TiO2 catalysts with desirable structural qualities for the photocatalytic CO2 reduction under nature sunlight.

Star-Shaped Molecules as Dopant-Free Hole Transporting Materials for Efficient Perovskite Solar Cells: Multiscale Simulation.

On the reported TCP-OH (See Scheme 1), other two star-shaped molecules are theoretically designed by replacement of side group of TCP-OH by N,N-di(4-methoxyphenyl)aniline for TPAP-OH and oxygen-bridged triarylamine for TBOPP-OH. The core group, phenol, is kept in three molecules. Their potential to be hole transport material in perovskite solar cells without dopants is evaluated by multiscale simulations. The properties of isolated molecules are estimated by the frontier molecular orbital, absorption spectrum, and hole mobility. After that, the HTM@CH3 NH3 PbI3 adsorbed system is studied to consider the influence of adsorption on HTM performance. Besides the primary judgment, the glass transition temperature is also simulated to determine the stability of amorphous film. Not only the chemical stability is evaluated but also the amorphous film stability is considered. The latter is almost neglected in previous theoretical studies to evaluate the properties of HTMs. The performance of a designed molecule is evaluated from both the isolated molecules and HTM@CH3 NH3 PbI3 adsorbed system including aforementioned items, which is favorable to build reliable structure-property relationship.

Theoretical insights into the 1D-charge transport properties in a series of hexaazatrinaphthylene-based discotic molecules.

Discotic liquid crystal (DLC) materials have attracted considerable attention mainly due to their high charge carrier mobilities in quasi-one-dimensional columns. In this article, five hexaazatrinaphthylene-based DLC molecules were investigated theoretically, and their frontier molecular orbital energy levels, crystal structures, and electron/hole drift mobilities were calculated by combination of density functional theory (DFT) and semiclassical Marcus charge transfer theory. The systems studied in this work include three experimentally reported molecules (1, 2, and 3) and two theoretically designed molecules (4 and 5). Compared with the 1-3 compounds, 4 and 5 have three more extended benzene rings in the π-conjugated core. The present results show that the orders of the frontier molecular orbital energy levels and electron drift mobilities agree very well with the experiment. For 4 and 5, the electron/hole reorganization energies are lower than those of compounds 1-3. Furthermore, the calculated electron/hole transfer integral of 5 is the largest among all the five systems, leading to the highest electron and hole mobilities. In addition, the hydrophobicity and solubility were also evaluated by DFT, indicating that compound 5 has good hydrophobicity and good solubility in trichloromethane. As a result, it is expected that compound 5 can be a potential charge transport material in electronic and optoelectronic devices. © 2017 Wiley Periodicals, Inc.

Effect of TiO2 particles on normal and resonance Raman spectra of coumarin 343: a theoretical investigation.

It is well known that interfacial structures and charge transfer in dye-sensitized solar cells are extremely important for the enhancement of cell efficiency. Here, the normal Raman spectra (NRS) and resonance Raman spectra (RRS) of a C343-sensitized TiO2 cluster (Ti9O18) are theoretically predicted from combined electronic structure calculations and a vibrationally-resolved spectral method to reveal the relationship between interfacial geometries and excited-state dynamics. The results show that although the NRS of free C343 and the C343-TiO2 cluster correspond to the vibrational motions of C343 in a high frequency domain, their mode frequencies show obvious differences due to the interaction of the TiO2 cluster on C343, and several new Raman active fingerprint modes, such as bidentate chelating bonding modes, can be used to determine interfacial geometries. However, the resonance Raman activities of low-frequency modes are significantly enhanced and several modes from the TiO2 cluster can be observed, consistent with experimental measurements. Furthermore, the RRS from a locally excited state and a charge transfer state of C343-TiO2 are dramatically different, for instance, new Raman active modes with 1212 cm(-1), 1560 cm(-1) and 1602 cm(-1), corresponding to the motions of CH2 rocking, C=C/C-N/C=O stretching and C=O/C=C stretching, appear from the charge transfer state. The obtained information on mode-specific reorganization energies from these excited states is greatly helpful to understand and control interfacial electron transfer.

Theoretical studies on absorption, emission, and resonance Raman spectra of Coumarin 343 isomers.

The vibrationally resolved spectral method and quantum chemical calculations are employed to reveal the structural and spectral properties of Coumarin 343 (C343), an ideal candidate for organic dye photosensitizers, in vacuum and solution. The results manifest that the ground-state energies are dominantly determined by different placements of hydrogen atom in carboxylic group of C343 conformations. Compared to those in vacuum, the electronic absorption spectra in methanol solvent show a hyperchromic property together with the redshift and blueshift for the neutral C343 isomers and their deprotonated anions, respectively. From the absorption, emission, and resonance Raman spectra, it is found that the maximal absorption and emission come from low-frequency modes whereas the high-frequency modes have high Raman activities. The detailed spectra are further analyzed for the identification of the conformers and understanding the potential charge transfer mechanism in their photovoltaic applications.

rac-3-{4-[(4-Nitro-benzyl-idene)amino]-3-phenyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-yl}-1,3-diphenyl-propan-1-one.

In the title mol-ecule, C(30)H(23)N(5)O(3)S, the 1,2,4-triazole ring is approximately planar (r.m.s. deviation = 0.006 Å), and forms dihedral angles of 66.0 (2), 65.1 (2), 30.1 (2) and 28.1 (2)° with the four phenyl rings. The phenyl ring of the benzyl group directly attached to the triazole ring is almost perpendicular to the nitro-phenyl ring, making a dihedral angle of 84.9 (2)°.

2-[(3-Propyl-sulfanyl-5-p-tolyl-4H-1,2,4-triazol-4-yl)imino-meth-yl]phenol.

In the title mol-ecule, C(19)H(20)N(4)OS, the two benzene rings form dihedral angles of 16.2 (1) and 12.0 (1)°, respectively, with the central triazole ring. In the crystal, inter-molecular O-H⋯N hydrogen bonds link mol-ecules into chains in the [010] direction.

3-{4-[(2-Hy-droxy-benzyl-idene)amino]-3-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-yl}-1,3-diphenyl-propan-1-one.

There are two crystallographically independent mol-ecules (A and B) in the asymmetric unit of the title compound, C(25)H(22)N(4)O(2)S, with almost identical mol-ecular conformations. The hy-droxy-phenyl ring plane and the 1,2,4-triazole ring form dihedral angles of 17.1 (2) and 7.4 (2)° in A and B, respectively. The dihedral angles between 1,2,4-triazole ring and the other two phenyl rings are 89.6 (3) and 83.3 (2)° in mol-ecule A, and 89.2 (3) and 82.2 (2)° in mol-ecule B. One intra-molecular O-H⋯N hydrogen bond is present in each mol-ecule. Weak inter-molecular C-H⋯O hydrogen bonds consolidate the crystal packing.

3-[4-(2-Chloro-benzyl-idene-amino)-3-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-yl]-1,3-diphenyl-propan-1-one.

In the title mol-ecule, C(25)H(21)ClN(4)OS, the triazole ring forms dihedral angles of 47.9 (2), 84.5 (2) and 3.9 (2)° with the two phenyl rings and the chloro-phenyl ring, respectively. The chloro-phenyl ring, the triazole ring and the conjugative linker between the two aromatic rings are nearly coplanar with an r.m.s. deviation of 0.0483 (2) Šand a maximum deviation of 0.0911 (2) Å.

rac-3-{4-[(Furan-2-ylmethyl-idene)-amino]-3-methyl-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-yl}-1,3-diphenyl-propan-1-one.

In the title mol-ecule, C(23)H(20)N(4)O(2)S, the triazole ring forms dihedral angles of 150.3 (2), 77.3 (2) and 77.6 (2)°, respectively, with the furan ring and the phenyl rings. The furan ring is almost perpendicular to the central phenyl ring, making a dihedral angle of 86.0 (3)°.

3-[3-Methyl-4-(4-nitro-benzyl-idene-amino)-5-sulfanyl-idene-4,5-dihydro-1H-1,2,4-triazol-1-yl]-1,3-diphenyl-propan-1-one dichloro-methane monosolvate.

In the title compound, C(25)H(21)N(5)O(3)S·CH(2)Cl(2), the dichloro-methane solvent mol-ecule is disordered over four positions, with an occupancy ratio of 0.271 (3):0.3884 (18):0.298 (2):0.0424 (15). The 1,2,4-triazole ring makes dihedral angles of 47.3 (2)/87.3 (2) and 3.6 (2)° with the phenyl and nitro-phenyl rings, respectively. An intra-molecular C-H⋯S hydrogen bond results in the formation of an almost planar six-membered ring [r.m.s. derivation = 0.0051 (2) Å]. Inter-molecular C-H⋯O hydrogen bonding consolidates the structure.

Electronic spectra of linear isoelectronic clusters C2n+1S and C2n+1Cl+ (n = 0-4): an ab initio study.

Structures and stabilities of linear carbon chains C2n+1S and C2n+1Cl+ (n=0-4) in their ground states have been investigated by the CCSD and B3LYP approaches. The CASSCF calculations have been used to determine geometries of selected excited states of both isoelectronic series. Linear C2n+1S cluster has a cumulenic carbon framework, whereas its isoelectronic C2n+1Cl+ has a dominant character of acetylenic structure in the vicinity of terminal Cl. The vertical excitation energies of low-lying excited states have been calculated by the CASPT2 method. Calculations show that the excitation energies have nonlinear size dependence. The 2(1)Sigma+<--X1Sigma+ transition energy in C2n+1S has a limit of 1.78 eV, as the chain size is long enough. The predicted vertical excitation energies for relatively strong 1(1)Pi<--X1Sigma+ and 2(1)Sigma+<--X1Sigma+ transitions are in reasonable agreement with available experimental values. The spin-orbit effect on the spin-forbidden transition in both series is generally small, and the enhancement of the spin-forbidden transition by spin-orbit coupling exhibits geometrical and electronic structural dependence.