Probe-Free Direct Identification of Type I and Type II Photosensitized Oxidation Using Field-Induced Droplet Ionization Mass Spectrometry

While Type I and Type II photosensitizers are often carefully tailored to achieve their respective advantages in treating different cancers, the identifications of the Type I and II mechanisms as such, the key reaction intermediates, and the consequent oxidation products of the substrates have never been easy. Using our unique home-built field-induced droplet ionization mass spectrometry (FIDI-MS) method that selectively samples molecules at the air–water interface, here we show the facile determination of both Type I and II mechanisms of a poster-child photosensitizer, temoporfin, without the addition of any probes. The unstable doublet radical resulting from the hydrogen abstraction by the triplet temoporfin through the Type I mechanism is captured, manifesting the in situ advantage of FIDI-MS. We anticipate that the method developed in this study can be widely utilized in the future designs of novel photosensitizers and the screening of their photosensitization mechanisms.     

Polyhydroxy Fullerene-loaded ZIF-8 Nanocomposites for Better Photodynamic Therapy

Photodynamic therapy (PDT) has been received broad attentions as a cancer treatment, and fullerenes are potential photosensitizer owing to their unique electronic structures. However, fullerenes show insolubility in water for the special structure, which will induce aggregation to hinder the production of reactive oxygen species (ROS). Furthermore, the size of fullerenes is not conducive to reach the tumors through the enhanced permeability and retention (EPR) effect. Herein, a polyhydroxy fullerene-loaded metal-organic framework is designed and prepared to address the mentioned problems encountering with fullerenes as photosensitizers. The nanocomposite PHF@ZIF-8, which is synthesized by a simple one-pot method, displays great biocompatibility and outstanding photodynamic performance under the 448 nm laser irradiation. This work provides strong evidence for PHF@ZIF-8 as a promising photosensitizer candidate.     

Iron-Catalyzed Cleavage Reaction of Keto Acids with Aliphatic Aldehydes for the Synthesis of Ketones and Ketone Esters

The radical–radical coupling reaction is an important synthetic strategy. In this study, the iron-catalyzed radical–radical cross-coupling reaction based on the decarboxylation of keto acids and decarbonylation of aliphatic aldehydes to obtain valuable aryl ketones is reported for the first time. Remarkably, when tertiary aldehydes were used as carbonyl sources, ketone esters were selectively obtained instead of ketones. The gram-scale preparation of aryl ketone through this strategy was easily achieved by using only 3 mol % of the iron catalyst. As a proof-of-concept, the bioactive molecule flurprimidol was synthesized in two steps by using this strategy.     

Multipolar Porphyrin-Triazatruxene Arrays for Two-Photon Fluorescence Cell Imaging

Two-photon excited fluorescent (TPEF) materials are highly desirable for bioimaging applications owing to their unique characteristics of deep-tissue penetration and high spatiotemporal resolution. Herein, by connecting one, two, or three electron-deficient zinc porphyrin units to an electron-rich triazatruxene core via ethynyl π-bridges, conjugated multipolar molecules TAT-(ZnP) _n (n=1–3) were developed as TPEF materials for cell imaging. The three new dyes present high fluorescence quantum yields (0.40–0.47) and rationally improved two-photon absorption (TPA) properties. In particular, the peak TPA cross section of TAT-ZnP (436 GM) is significantly larger than that of the ZnP reference (59 GM). The δ_TPA values of TAT-(ZnP)₂ and TAT-(ZnP)₃ further increase to 1031 and up to 1496 GM, respectively, indicating the effect of incorporated ZnP units on the TPA properties. The substantial improvement of the TPEF properties is attributed to the formation of π-conjugated quadrapole/octupole molecules and the extension of D -π-A-D systems, which has been rationalized by density function theory (DFT) calculations. Moreover, all of the three new dyes display good biocompatibility and preferential targeting ability toward cytomembrane, thus can be superior candidates for TPEF imaging of living cells. Overall, this work demonstrated a promising strategy for the development of porphyrin-based TPEF materials by the construction and extension of D -π-A-D multipolar array.     

Preparation and structural characterization of a hexanuclear molybdenum (II) cluster containing carboxylate ligands (Bu4N)2[Mo6(μ3-Cl)8(O2CMe)6]

The hexamolybdenum cluster complex [Mo₆(₃-Cl)₈(O₂CMe)₆]^2–, 1 was isolated as the Bu₄N⁺ salt in 71% yield from the reaction of (Bu₄N)₂[Mo₆(₃-Cl)₈Cl₆] with AgO₂CMe in CH₂Cl₂ solvent. The compound was characterized by single crystal X-ray diffraction analysis. The cluster contains an octahedral arrangement of six molybdenum atoms with eight chloride ligands bridging the eight trianglar faces and six carboxylate ligands terminally coordinated through one oxygen atom to each of the six molybdenum atoms. Crystal data: space group =P2₁/n,a=10.713(3)Å,b=14.43(1)Å,c=21.919(4)Å, =94.37(2)°,Z=2, 1965 reflections,R=0.036.     

穿过液膜的自发电势振荡

An artificial membrane consisting of pricramic acid in nitrobenzene was used as an oil phase imposed between two aqueous phases. The right one contained trimethyl-slearylammonium chloride and aicohol; and the left contained sucrose solution (or H_2O). We found that this system exhibited rhythmic oscillation of electrical potential. The amplitude of the oscillations was between 20—150 mV. The oscillations were observed even when ethyl alcohol was absent in the aqueous of trimethylslearylammonium Chloride, and the increase in amplitude of oscillation with time was found to be less in the presence of sucrose. Some of the expremental results have been explained.     

Preparation and structural characterization of the hexatungsten cluster complex (EDTEH)2[W6(μ3-Cl)8Cl6], (EDTEH=(MeO2CCH2)2N(H)CH2CH2N(CH2CO2Me)2+

The hexanuclear tungsten cluster complex [W₆(₃-Cl)₈Cl₆]^2–,1 was isolated as a salt of the cation (MeO₂CCH₂)₂N(H)CH₂CH₂N(CH₂CO₂Me)₂₊, EDTEH⁺, by crystallization from methanol solvent of the product obtained from the reaction of (H₃O)₂[W₆(₃-Cl)₈Cl₃] with the disodium salt of ethylenediaminetetraacetic acid. The compound was charcterized by single-crystal X-ray diffraction analysis. The cluster anion contains an octahedral arrangement of six tungsten atoms with chloride ligands bridging the eight triangular faces of the cluster and one chloride ligand terminally coordinated to each of the six tungsten atoms. The cation (EDTEH)⁺ achieves its positive charge by protonation of one of the nitrogen atoms. Crystal data: space group = P2₁/a,a=10.689(2) Å,b=22.931(6) Å,c=12.093(3) Å, =98.41(2)°,Z=2, 2476 reflections,R=0.028.     

Photocatalytic Oxidation of Aniline in the Gas Phase Using Porous TiO2 Thin Films

The gas-phase photocatalytic oxidation of aniline on a new kind of porous nano-TiO₂ composite films is investigated. The composite film was prepared on glass fiber with the water glass as binders and dilute H₂SO₄ solution as solidifying reagent. The surface characters were observed by scanning electron microscope. The photocatalytic degradation of aniline on the composite films was carried out in a TiO₂/UV system. Some important factors affecting the photodegradation, such as the concentration of TiO₂, the initial concentration of aniline, and the existing water vapor, are also studied. The product of photocatalytic oxidation was detected by Fourier transform-Infrared. The partial intermediate products were absorbed on TiO₂ surface, which resulted in catalyst deactivation. But when it was irradiated under UV illumination or solar irradiation for some time, the catalyst could be reused without loss of catalytic activity. Translated from the Journal of Wuhan University (Natural Science Edition), 2005, 51(2) (in Chinese)     

Mature homogeneous erythropoietin building blocks by chemical synthesis: the EPO 22-37 glycopeptide domain presenting the full N-linked dodecasaccharide

A synthesis of EPO 22-37 glycopeptide (1), presenting the N-linked dodecasaccharide of erythropoietin, is described.