Aqua(nitrilo­triacetato)­(1,10‐phenanthroline)iron(III) monohydrate: a seven‐coordinate iron(III) complex

Reaction of 1,10‐phenanthroline (phen) with iron trichloride in the presence of sodium nitrilo­tri­acetate (NTA) resulted in the formation of red crystals of the title complex, [Fe(C₆H₆NO₆)(C₁₂H₈N₂)(H₂O)]·H₂O. The Fe atom has a distorted capped trigonal prismatic coordination comprised of one tetradentate NTA, one bidentate phen molecule and a water mol­ecule. Intermolecular O—H?O hydrogen bonds link the mol­ecules into infinite chains. The chains are crosslinked by hydrogen bonds involving the solvent water mol­ecule, leading to an infinite ladder packing mode.     

Tetra‐μ‐acetato‐κ2O:O′‐bis[(4‐phenylpyridine‐κN)copper(II)]

The title compound, [Cu₂(C₂H₃O₂)₄(C₁₁H₉N)₂] or [Cu₂(MeCO₂)₄(phpy)₂] (phpy is 4‐phenyl­pyridine), consists of centrosymmetric dimers in which the Cu^II atoms display a square‐pyramidal CuO₄N coordination, with four acetate O atoms in the basal plane [Cu—O 1.975 (3)–1.987 (3) Å] and the phpy N atom in the apical position [Cu—N 2.150 (3) Å]. The Cu atoms are 2.654 (1) Å apart and are bridged by four acetate groups. The discrete dimers are extended into a three‐dimensional supramolecular array through intermolecular π–π‐stacking interactions.     

Arylcarbamoylated allylcarbamido-β-cyclodextrin: synthesis and immobilization on nonfunctionalized silica gel as a chiral stationary phase

Four new chiral stationary phases based on mono-(6^A-allylcarbamido-6^A-deoxy)-arylcarbamoylated β-cyclodextrin were synthesized. The chiral stationary phase of phenylcarbamoylated β-cyclodextrin exhibited excellent separation capability for a variety of chiral compounds. Compared with the previous work, it was found that the spacer remained on the surface of the silica gel and decreased the enantioseparation capability.     

Accurate ab initio predictions of ionization energies and heats of formation for the 2-propyl, phenyl, and benzyl radicals

The ionization energies (IEs) for the 2-propyl (2-C(3)H(7)), phenyl (C(6)H(5)), and benzyl (C(6)H(5)CH(2)) radicals have been calculated by the wave-function-based ab initio CCSD(T)/CBS approach, which involves the approximation to the complete basis set (CBS) limit at the coupled cluster level with single and double excitations plus quasiperturbative triple excitation [CCSD(T)]. The zero-point vibrational energy correction, the core-valence electronic correction, and the scalar relativistic effect correction have been also made in these calculations. Although a precise IE value for the 2-C(3)H(7) radical has not been directly determined before due to the poor Franck-Condon factor for the photoionization transition at the ionization threshold, the experimental value deduced indirectly using other known energetic data is found to be in good accord with the present CCSD(T)/CBS prediction. The comparison between the predicted value through the focal-point analysis and the highly precise experimental value for the IE(C(6)H(5)CH(2)) determined in the previous pulsed field ionization photoelectron (PFI-PE) study shows that the CCSD(T)/CBS method is capable of providing an accurate IE prediction for C(6)H(5)CH(2), achieving an error limit of 35 meV. The benchmarking of the CCSD(T)/CBS IE(C(6)H(5)CH(2)) prediction suggests that the CCSD(T)/CBS IE(C(6)H(5)) prediction obtained here has a similar accuracy of 35 meV. Taking into account this error limit for the CCSD(T)/CBS prediction and the experimental uncertainty, the CCSD(T)/CBS IE(C(6)H(5)) value is also consistent with the IE(C(6)H(5)) reported in the previous HeI photoelectron measurement. Furthermore, the present study provides support for the conclusion that the CCSD(T)/CBS approach with high-level energy corrections can be used to provide reliable IE predictions for C(3)-C(7) hydrocarbon radicals with an uncertainty of +/-35 meV. Employing the atomization scheme, we have also computed the 0 K (298 K) heats of formation in kJ/mol at the CCSD(T)/CBS level for 2-C(3)H(7)/2-C(3)H(7) (+) ,C(6)H(5)/C(6)H(5) (+), and C(6)H(5)CH(2)/C(6)H(5)CH(2) (+) to be 105.2/822.7 (90.0/806.4), 351.4/1148.5 (340.4/1138.8), and 226.2/929.0 (210.3/912.7), respectively. Comparing these values with the available experimental values, we find that the discrepancies for the 0 and 298 K heats of formation values are < or =2.6 kJ/mol for 2-C(3)H(7)/2-C(3)H(7) (+),< or =4.1 kJ/mol for C(6)H(5)/C(6)H(5) (+), and < or =3.2 kJ//mol for C(6)H(5)CH(2)C(6)H(5)CH(2) (+).     

Coupling of CpCr(CO)3 and heterocyclic dithiadiazolyl radicals. synthetic, x-ray diffraction, dynamic NMR, EPR, CV, and DFT studies

The reaction of the 1,2,3,5-dithiadiazolyls (4-R-C(6)H(4)CN(2)S(2))(2) (R = Me, 2a; Cl, 2b; OMe, 2c; and CF3, 2d) and (3-NC-5-tBu-C(6)H(3)CN(2)S(2))(2) (2e) with [CpCr(CO)(3)](2) (Cp = eta(5)-C(5)H(5)) (1) at ambient temperature respectively yielded the complexes CpCr(CO)(2)(eta(2)-S(2)N(2)CC(6)H(4)R) (R = 4-Me, 3a; 4-Cl, 3b; 4-OMe, 3c; and 4-CF(3), 3d) and CpCr(CO)(2)(eta(2)-S(2)N(2)CC(6)H(3)-3-(CN)-5-(tBu)) (3e) in 35-72% yields. The complexes 3c and 3d were also synthesized via a salt metathesis method from the reaction of NaCpCr(CO)(3) (1B) and the 1,2,3,5-dithiadiazolium chlorides 4-R-C(60H(4)CN(2)S(2)Cl (R = OMe, 8c; CF(3), 8d) with much lower yields of 6 and 20%, respectively. The complexes were characterized spectroscopically and also by single-crystal X-ray diffraction analysis. Cyclic voltammetry experiments were conducted on 3a-e, EPR spectra were obtained of one-electron-reduced forms of 3a-e, and variable temperature 1H NMR studies were carried out on complex 3d. Hybrid DFT calculations were performed on the model system [CpCr(CO)(2)S(2)N(2)CH] and comparisons are made with the reported CpCr(CO)(2)(pi-allyl) complexes.     

Hydrophilic interaction liquid chromatography method for measuring the composition of aquatic humic substances

A hydrophilic interaction liquid chromatography (HILIC) method was developed to measure the composition of humic substances from river, reservoir, and treated wastewater based on their physicochemical properties. The current method fractionates the humic substances into four well-defined groups based on parallel analyses with a neutral and a cationic HILIC column, using mobile phases of varied compositions and pH. The results indicate that: (i) the proportion of carboxylic acids in the humic substances from terrestrial origins is less than half of that from treated wastewater (Jeddah, KSA), (ii) a higher content of basic compounds was observed in the humic substances from treated wastewater and Ribou Reservoir (Cholet, France) than in the sample from Loire River (France), (iii) a higher percentage of hydrophobic macromolecules were found in the humic substances from Loire River than in the other samples, and (iv) humic substances of treated wastewater contained less ionic neutral compounds (i.e., pK_a 5–9) than the waters from terrestrial origins. The physicochemical property disparity amongst the compounds in each humic substances sample was also evaluated. The humic substances from the lightly humic Loire river displayed the highest disparity, whereas the highly humic Suwannee river (Georgia, USA) showed the most homogeneous humic substances.     

Ferric Ion Driven Assembly of Catalase-like Supramolecular Photosensitizing Nanozymes for Combating Hypoxic Tumors

A facile approach to assemble catalase-like photosensitizing nanozymes with a self-oxygen-supplying ability was developed. The process involved Fe³⁺-driven self-assembly of fluorenylmethyloxycarbonyl (Fmoc)-protected amino acids. By adding a zinc(II) phthalocyanine-based photosensitizer (ZnPc) and the hypoxia-inducible factor 1 (HIF-1) inhibitor acriflavine (ACF) during the Fe³⁺-promoted self-assembly of Fmoc-protected cysteine (Fmoc-Cys), the nanovesicles Fmoc-Cys/Fe@Pc and Fmoc-Cys/Fe@Pc/ACF were prepared, which could be disassembled intracellularly. The released Fe³⁺ could catalyze the transformation of H₂O₂ enriched in cancer cells to oxygen efficiently, thereby ameliorating the hypoxic condition and promoting the photosensitizing activity of the released ZnPc. With an additional therapeutic component, Fmoc-Cys/Fe@Pc/ACF exhibited higher in vitro and in vivo photodynamic activities than Fmoc-Cys/Fe@Pc, demonstrating the synergistic effect of ZnPc and ACF.     

Analytical application of acetate anion in negative electrospray ionization mass spectrometry for the analysis of triterpenoid saponins--ginsenosides

Ginsenosides containing different numbers of glycosyl groups can be easily differentiated based on the formation of characteristic ginsenoside-acetate adduct anions and deprotonated ginsenosides generated by electrospray ionization (ESI) of methanolic solutions of ginsenosides (M) and ammonium acetate (NH4OAc). Ginsenosides containing two glycosyl groups gave a characteristic mass spectral pattern consisting of [M+2OAc]2-, [M-H+OAc]2- and [M-2H]2- ions with m/z values differing by 30 Th, while this mass spectral pattern was not observed for ginsenosides containing one glycosyl group. Formation of [M+2OAc]2- was influenced by the chain length of glycosyl groups and was used to differentiate the ginsenosides containing different combinations of monosaccharide and disaccharide units in the glycosyl groups. Under identical collisional activation conditions, [M+OAc]-, [M-H+OAc]2- and [M+2OAc]2- underwent proton abstractions predominantly to generate [M-H]-, [M-2H]2- and [M-H+OAc]2- ions, respectively. The ion intensity ratios, I[M-H](-/I) [M+OAc]-, I[M-2H](2-/I) [M-H+2OAc]2- and I[M-H+OAc](2-/I) [M+OAc]2-, being sensitive to the structural differences of ginsenosides, could differentiate the isomeric ginsenosides, including (i) Rf, F11 and Rg1, (ii) Rd and Re, and (iii) Rb2 and Rc. Additionally, NH4OAc was found to enhance the sensitivity of detection of ginsenosides in the form of [M-H]- down to the femtomole level.     

Synthesis of new amphiphilic dendrons bearing aliphatic hydrocarbon surface sectors and a monocarboxylic or dicarboxylic acid focal point

[structure: see text]. A new series of amphiphilic G1-G3 dendrons containing purely aliphatic hydrocarbon dendritic surface sectors and one or two carboxylic acid group(s) at the focal point was synthesized in good yields. The key branching steps involve diallylation reactions of diethyl malonate or Meldrum's acid. These dendrons are highly soluble in hexane despite having highly polar carboxylic acid groups at the focal point.