Antibiotic Exposure and Risk of New-Onset Inflammatory Bowel Disease: A Systematic Review and Dose-Response Meta-Analysis.

BACKGROUND & AIMS: The association between antibiotic exposure and inflammatory bowel disease (IBD) remains controversial, especially whether there is a dose-response relationship. We aimed to conduct a systematic review and meta-analysis to thoroughly evaluate the risk of new-onset IBD associated with antibiotic exposure. METHODS: Four databases were searched from their inception to September 30, 2023 for all relevant studies. The risk estimates were pooled together using random-effects models, and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated, stratified by IBD subtype, age, exposure period, study type, and antibiotic classes. Dose-response relationship between the number of antibiotic prescriptions and IBD risk was assessed using generalized least squares regression analysis. RESULTS: Twenty-eight studies involving 153,027 patients with IBD were included. Antibiotic exposure was significantly associated with an increased risk of new-onset IBD for prescription-based studies (pooled OR, 1.41; 95% CI, 1.29-1.53) and for questionnaire-based studies (pooled OR, 1.35; 95% CI, 1.08-1.68). This association existed for both Crohn's disease and ulcerative colitis, as well as in children and adults for prescription-based studies. The majority of antibiotic classes were associated with an increased IBD risk, with metronidazole (OR, 1.70; 95% CI, 1.38-2.10) and quinolones (OR, 1.56; 95% CI, 1.37-1.77) having relatively higher risk estimates. A positive nonlinear dose-response association was observed between the number of antibiotic prescriptions and IBD risk. CONCLUSIONS: Antibiotic exposure was significantly associated with an increased risk of new-onset IBD, and a positive nonlinear dose-response relationship was observed. Antibiotic stewardship may be important for reducing IBD risk.

Synthesis and Properties of two CuI Complexes Involving Tetrathia-fulvalene-Fused Phenanthroline Ligand.

Two CuI complexes based on the π-conjugated tetrathiafulvalene-annulated phenanthroline ligands (TTF-Phen, L1 and L2), [CuI(Xantphos)(L1)]BF4 (1, Xantphos = 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene) and [CuI(Binap)(L2)]BF4 (2, Binap = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl), have been synthesized. They have been fully characterized, and their photophysical and electrochemical properties are reported together with those of L1 and L2 for comparison. Both CuI complexes show metal-to-ligand charge transfer (MLCT) absorption bands, whereas the 3MLCT luminescence is strongly quenched.

Synthesis, Characterization, Properties and DFT Calculations of 2-(Benzo[b]thiophen-2-yl)pyridine-based Iridium(III) Complexes with Different Ancillary Ligands.

A series of new cyclometalated btp-based iridium(III) complexes with three different ancillary ligands, Ir(btp)2(bozp) (3a), Ir(btp)2(btzp) (3b) and Ir(btp)2(izp) (3c) (btp = 2-(benzo[b]thiophen-2-yl)pyridine, bozp =2-(benzo[d]oxazol-2-yl)phenol, btzp =2-(benzo[d]thiazol-2-yl)phenol, izp = 2-(2 H-indazol-2-yl)phenol), have been synthesized and fully characterized. The crystal structure of 3b has been determined by single crystal X-ray diffraction analysis. A comparative study has been carried out for complexes 3a - 3c by UV-vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry and DFT calculations. This observation illustrates that the substitution of N or S in ancillary ligand can lead to a marked bathochromic shift of absorption and emission wavelengths. The spectroscopic characterisation of these complexes has been complemented by DFT and TD-DFT calculations, supporting the assignment of (3)MLCT/(3)LC to the lowest energy excited state.

Bioactive Phenanthrene and Bibenzyl Derivatives from the Stems of Dendrobium nobile.

A new enantiomeric pair of spirodiketones, (+)- and (-)-denobilone A (1 and 2), three new phenanthrene derivatives (3-5), and three new biphenanthrenes (22-24), along with 11 known phenanthrene derivatives (6-16), five known bibenzyl derivatives (17-21), and four known biphenanthrenes (25-28), were isolated from Dendrobium nobile. The structures of 1-5 and 22-24 were elucidated using comprehensive spectroscopic methods. (+)-Denobilone and (-)-denobilone A (1 and 2) were isolated as a pair of enantiomers by chiral HPLC. The absolute configurations of (+)- and (-)-denobilone A (1 and 2) were determined by comparing their experimental and calculated electronic circular dichroism spectra. The absolute configuration of denobilone B (3) was determined by X-ray crystallographic analysis. The inhibitory activities of all compounds against nine phytopathogenic fungi and three cancer cell lines were evaluated.

Deep-red phosphorescent iridium(III) complexes containing 1-(benzo[b] thiophen-2-yl) isoquinoline ligand: synthesis, photophysical and electrochemical properties and DFT calculations.

Four new bis-cyclometalated iridium(III) complexes, [Ir(btq) 2phen] [PF6] (3a), [Ir(btq) 2bpy] [PF6] (3b), [Ir(btq) 2dtbipy] [PF6] (3c) and [Ir(btq) 2pic] (3d) (btq = 1-(benzo[b] thiophen-2-yl) isoquinoline, phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine, dtbipy = 4,4'-di-tert-butyl-2,2'-bipyridine, pic = picolinic acid) have been synthesized and fully characterized. The crystal structure of 3a has been determined by X-ray analysis. The photophysical and electrochemical properties of these new complexes 3a - 3d have been studied. The photoluminescence spectra of all Ir(III) complexes exhibit deep-red emission maxima at 682, 682, 683 and 698 nm, respectively. The most representative molecular orbital energy-level diagrams and the lowest energy electronic transitions of 3a - 3d have been calculated with density functional theory (DFT) and time-dependent DFT (TD - DFT). The results show that the pic ancillary ligand of complex 3d influences the absorption and emission energies with a further red-shift relative to other three complexes 3a - 3c.

Bioactive anthraquinone derivatives from the mangrove-derived fungus Stemphylium sp. 33231.

Four new anthraquinone derivatives (1-4) and four new alterporriol-type anthranoid dimers (14-17), along with 17 analogues, were isolated from the solid rice fermentation of the fungus Stemphylium sp. 33231 obtained from the mangrove Bruguiera sexangula var. rhynchopetala collected from the South China Sea. Their structures were elucidated using comprehensive spectroscopic methods. The absolute configurations of 1, 3, and 4 were determined by single-crystal X-ray diffraction of their derivatives (1a, 3b, and 4a). The absolute configurations of the chiral 17-19 were determined by comparing their CD spectra with 21. The inhibitory activities of most of the compounds against seven terrestrial pathogenic bacteria and two cancer cell lines were evaluated.

Synthesis, characterization and DFT studies of two new pi-conjugated-conjugated pyridine-based tetrathiafulvalene derivatives.

Two new pi-conjugated pyridine-based tetrathiafulvalene derivatives, 2-(2- (4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-6-phenyl-[1,3]dithiolo[4,5-b][1,4]dithiin-5-yl)pyridine (2a) and 3-(2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-6-(pyridin-2-yl) -[1,3]dithiolo[4,5-b][1,4]dithiin-5-yl)quinoline (2b), have been synthesized and characterized by 1H NMR, elemental analysis and mass spectroscopies. The compound 2a has also been studied by X-ray crystallography and theoretical calculations using density functional theory (DFT) framework with B3LYP/6-311+G(d,p) level of theory. Its crystal structure is triclinic system, space group P1-. The unit cell dimensions are: a = 8.813(3) Å, b = 11.082(3) Å, c = 12.620(4) Å, alfa = 88.805(5)°, beta = 80.440(5)°, gama = 75.680(5)°, V = 1177.3(6) Å3, Z = 2. The molecule exhibits one classical C-H···N intermolecular hydrogen bonds, two kinds of short intermolecular S···S interactions and two types of C-H···pi supramolecular interactions.

2-[Anilino(diphenylphosphoryl)methyl]phenol from a three-component Kabachnik-Fields reaction.

The title compound, C25H22NO2P, was synthesized in high yield by a three-component Kabachnik-Fields reaction of diphenylphosphine oxide, salicylaldehyde and aniline in dry toluene at room temperature. It precipitates as racemic crystals, in which strong hydrogen bonds between the hydroxy group and the P=O group of a neighbouring molecule form one-dimensional heterochiral chains along the crystallographic a axis, with an O···O separation of 2.568 (2) Å. The pseudo-tetrahedral environment of the P atom is distorted, with O-P-C bond angles significantly larger than the C-P-C angles.

N,N'-[2,2'-(Phenyl-aza-nedi-yl)bis-(ethane-2,1-di-yl)]dipicolinamide.

The asymmetric unit of the title compound, C22H23N5O2, contains two independent mol-ecules with similar conformations; the terminal pyridine rings are oriented at dihedral angles of 23.99 (8) and 18.07 (8)° with respect to the central benzene ring in one mol-ecule and 28.99 (8) and 23.22 (8)° in the other. In the crystal, N-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular structure. Weak inter-molecular C-H⋯π inter-actions are also observed in the crystal.

Cyclometalated Iridium(III) Complexes Containing 2-Phenylbenzo[d]oxazole Ligand: Synthesis, X-ray Crystal Structures, Properties and DFT Calculations.

Two new iridium(III) complexes were synthesized and fully characterized, [(bo)2Ir(pzpy)] (2a) and [(bo)2Ir(pzpyz)] (2b) (where bo = 2-phenylbenzo[d]oxazole, pzpy = 2-(1H-pyrazol-3-yl)pyridine, pzpyz = 2-(1H-pyrazol-3-yl)pyrazine). The single crystal structures of 2a-2b have been determined. Considering the relationship between their structures and photophysical properties, DFT calculations have been used to further support this inference. These Ir(III) complexes emit from the excited state of 3MLCT/3LLCT in the green and yellow region, and the quantum yields in the degassed CH2Cl2 solution at room temperature are 35.2% and 46.1%. Theoretical and experimental results show that iridium(III) complexes 2a-2b are promising phosphorescent material.

1,3-Bis[5-(2-pyrid-yl)-1H-tetra-zol-1-yl]propane.

The title compound, C(15)H(14)N(10), is a multidentate ligand obtained by the reaction of 5-(2-pyrid-yl)tetra-zole with 1,3-dibromo-propane. The mol-ecule consists of two 5-(2-pyrid-yl)-1H-tetra-zol-1-yl units connected by a propyl-ene bridge in a U-like conformation. A twofold rotation axis passes through the central C atom.

Efficient yellow electroluminescence of four iridium(iii) complexes with benzo[d]thiazole derivatives as main ligands.

Four bis-cyclometalated iridium(iii) complexes, (bt)2Ir(tpip), (fbt)2Ir(tpip), (cf3bt)2Ir(tpip) and (dfbt)2Ir(tpip) (bt = 2-phenylbenzo[d]thiazole, fbt = 6-fluoro-2-phenylbenzo[d]thiazole, cf3bt = 2-phenyl-6-(trifluoromethyl)benzo[d]thiazole, dfbt = 5,7-difluoro-2-phenylbenzo[d]thiazole, tpip = tetraphenylimidodiphosphinate) have been synthesized and investigated. All complexes emit yellow light peaks at 564-574 nm with quantum efficiencies (Φem) of 27.1-48.4% and excited state lifetimes of 2.40-2.81 µs in degassed CH2Cl2 solution at room temperature. Correspondingly, organic light-emitting diodes (OLEDs) using these complexes as emitters achieve yellow electrophosphorescence with good device characteristics. Due to its highest photoluminescence quantum yield (48.4%), the device based on (dfbt)2Ir(tpip) displays the best device performance with a maximum current efficiency (ηc, max) of up to 69.8 cd A-1 and a maximum external quantum efficiency (EQEmax) of up to 24.3%. Furthermore, all devices showed low efficiency roll-off ratios. The EQE could still be retained at 17.7%, 16.4%, 18.3% and 20.6% for four devices at a luminance of 1000 cd m-2. These results suggest that these materials have potential application in efficient OLEDs.

New Iridium Complex Coordinated with Tetrathiafulvalene Substituted Triazole-pyridine Ligand: Synthesis, Photophysical and Electrochemical Properties.

A new iridium(III) complex based on the triazole-pyridine ligand with tetrathiafulvalene unit, [Ir(ppy)2(L)]PF6 (1), has been synthesized and structurally characterized. The absorption spectra, luminescent spectra and electrochemical behaviors of L and 1 have been investigated. Complex 1 is found to be emissive at room temperature with maxima at 481 and 510 nm. The broad and structured emission bands are suggested a mixing of 3LC (3π-π*) and 3CT (3MLCT) excited states. The influence of iridium ion coordination on the redox properties of the TTF has also been investigated by cyclic voltammetry.

Synthesis, Crystal Structure, Photophysical Properties and Theoretical Study of a New Iridium(III) Complex Containing 2-phenylbenzothiazole Ligand.

A new bis-cyclometalated iridium(III) complex [Ir(dmabt)(2)(bipy)][PF(6)] (3) (dmabt = 4-(benzo[d]thiazol-2-yl)-N,N-dimethylaniline, bipy = 2,2'-bipyridine) has been synthesized and fully characterized. The complex 3 has been determined by X-ray structure analyses which shows that the central iridium(III) ion assumes distorted octahedral geometry. The photoluminescence spectrum exhibits orange emission maximum at 612 nm with quantum yield of 17% at 298 K. The frontier molecular orbital diagrams and the spin-allowed singlet-singlet electronic transitions of 3 have been calculated with density functional theory (DFT) and time-dependent DFT (TD-DFT), and the UV-Vis spectra are discussed based on the theoretical calculations.

Molecular dynamics simulation of diffusion and structure of some n-alkanes in near critical and supercritical carbon dioxide at infinite dilution.

The diffusion coefficients of n-alkanes (from CH4 to C14H30) in near critical and supercritical carbon dioxide at infinite dilution have been studied by molecular dynamics simulation. The simulation results agree well with experiment, which suggests that the simulation method is a powerful tool to obtain diffusion coefficients of solutes in fluids at high pressures. The local structures of such fluids are further investigated by calculating radial distribution functions and coordination numbers. Meanwhile, the dihedral, end-to-end distance and radius of gyration, which are calculated to characterize the flexibility of n-alkanes, are used to reasonably explain the abnormal trends on radial distribution functions and coordination numbers. Moreover, it is found that the flexibility effects on diffusion in pure n-alkanes and infinitely dilute n-alkane/CO2 system are different. The differences in MD simulation results of molecular diffusion in such systems could be qualitatively explained by the flexibility.

Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes.

A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (ks) as 0.97 s(-1). The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L(-1) with a detection limit of 0.0153 mmol L(-1) (3σ), H2O2 in the concentration range from 0.1 to 516.0 mmol L(-1) with a detection limit of 34.9 nmol/L (3σ) and NaNO2 in the concentration range from 0.5 to 650.0 mmol L(-1) with a detection limit of 0.282 µmol L(-1) (3σ). So the proposed electrode had the potential application in the third-generation electrochemical biosensors without mediator.