Bis(trifluoromethyl)dicarbonate, CF3OC(O)OC(O)OCF3

The synthesis of the new compound, bis(trifluoromethyl)dicarbonate, CF₃OC(O)OC(O)OCF₃, is carried out by reduction of bis(trifluoromethyl)trioxidicarbonate with excess of CO at 0 °C. The product is characterized by IR, Raman, ¹³C and ¹⁹F NMR spectroscopy and its properties are compared with those of the other members of the series CF₃OC(O)O_xC(O)OCF₃, x = 0-3. Single crystals are grown at −25 °C and the X-ray diffraction analysis shows the packing of syn-syn rotamers exhibiting C₂ symmetry. DFT calculations predict this rotamer as the most stable one and also structural and vibrational data are predicted reasonably well.     

Unexpected photo-initiated oxidation of antimony in (tetra-tert-butyl)phthalocyaninatoantimony(III) complex in the presence of singlet oxygen acceptors

The title complex cation, [Sb(tbpc)]⁺ (where tbpc denotes tetra(tert-butyl)phthalocyaninate, C₄₈H₄₈N₈²⁻), was gradually bleached under irradiation with visible light (900 > λ/nm > 600) in aerated nonaqueous solvents, such as CH₂Cl₂, CHCl₃, benzene, chlorobenzene. On the other hand, irradiation under the same conditions but in the presence of 1,3-diphenylisobenzofuran (DPBF) caused slow oxidation of [Sb(tbpc)]⁺ to the corresponding antimony(V) derivatives, [Sb(tbpc)LL′]⁺, (L and L′ denote monoanionic axial ligands containing oxygen as the donor atom), which was monitored by optical absorption and ESI-MS spectra of the photolyzed solutions. Both the photobleaching and oxidation have efficiently been inhibited by preliminary addition of β-carotene in photolyzed solutions, indicating that photosensitization of singlet oxygen (¹O₂) by [Sb(tbpc)]⁺ itself is involved. The use of furans (except dibenzofuran) or oxazoles instead of DPBF gave rise to similar oxidation but not in the case of the other type ¹O₂-acceptors, such as 9,10-diphenylanthracene, tetraphenylcyclopentadienone, or 2,3-dimethyl-2-butene, indicating that formation of ozonide-type endo-peroxide through 1,4-cycloaddition with ¹O₂ is essential. Peroxides, such as EtOOH and H₂O₂, generated through nucleophilic attack to the ozonide by EtOH and H₂O (present in the solvent) respectively, are considered to oxidize [Sb(tbpc)]⁺ to the antimony(V) species. Photochemistry of antimony–phthalocyanine complex has been studied for the first time of pnicogen derivatives of phthalocyanine.     

New Singlet Oxygen Donors Based on Naphthalenes: Synthesis,Physical Chemical Data,and Improved Stability

Singlet oxygen donors are of current interest for medical applications, but suffer from a short half‐life leading to low singlet oxygen yields and problems with storage. We have synthesized more than 25 new singlet oxygen donors based on differently substituted naphthalenes in only a few steps. The influence of functional groups on the reaction rate of the photooxygenations, thermolysis, half‐life, and singlet oxygen yield has been thoroughly studied. We determined various thermodynamic data and compared them with density functional calculations. Interestingly, remarkable stabilities of functional groups during the photooxygenations and stabilizing effects for some endoperoxides during the thermolysis have been found. Furthermore, we give evidence for a partly concerted and partly stepwise thermolysis mechanism leading to singlet and triplet oxygen, respectively. Our results might be interesting for “dark oxygenations” and future applications in medicine.     

Synthesis and Crystal Structures of Antimony(III) Complexes With a Bis(amino)silane Ligand

Bis(amino)silane bearing bulky substituents on nitrogen, LH₂ [L = Me₂Si(NDipp)₂, Dipp = 2, 6‐diisopropylphenyl] was reacted with nBuLi (ratio 1:1 and 1:2) in toluene. The Me₂Si(LiNDipp)₂ was treated with SbCl₃ in a 1:1 ratio to yield the four‐membered SiN₂Sb ring compound of composition [η²(N,N)‐Me₂Si(NDipp)₂SbCl] ( 1 ). The mono lithiated bis(amino)silane was used to synthesize the monodentate heterotetraatomic complex [(η¹‐Me₂SiNDipp)NHDippSbCl₂] ( 2 ) by the reaction with SbCl₃. The complexes were characterized by ¹H and ¹³C NMR, elemental analysis, IR, and single‐crystal X‐ray structural analysis.     

An ESR Study on Singlet Oxygen Photoproduction of the Meso-Tetrakis-(Substituted Phenyl) Porphine Derivatives

The ability of meso-tetrakis- (substituted phenyl) porphine derivatives for photo-generating singlet oxygen (O2) is studied by ESR spectrometry. The results show that the singlet oxygen yields of most of porphine derivatives are higher than that of HPD. It is also exhibited that the nature and structure of the substituent at the meso position are closely related to the photo-sensitizing ability of meso-tetrakis-(substituted phenyl) porphine.     

Porphyrin/Platinum(II) C^N^N Acetylide Complexes: Synthesis,Photophysical Properties,and Singlet Oxygen Generation

A new class of substituted porphyrins has been developed in which a different number of cyclometalated Pt^II C^N^N acetylides and polyethylene glycol (PEG) chains are attached to the meso positions of the porphyrin core, which are meant for photophysical, electrochemical, and in vitro light‐induced singlet oxygen (¹O₂) generation studies. All of these Zn^II porphyrin–Pt^II C^N^N acetylide conjugates show moderate to high (Φ_Δ=0.55 to 0.63) singlet oxygen generation efficiency. The complexes are soluble in organic solvents but, despite the PEG substituents, slowly aggregate in aqueous solvent systems. These conjugates also exhibit interesting photophysical properties, including near‐complete photoinduced energy transfer (PEnT) through the rigid acetylenic bond(s) from the Pt^II C^N^N antenna units to the Zn^II porphyrin core, which shows sensitized luminescence, as shown by quenching of Pt^II C^N^N‐based luminescence. Electrochemical measurements show a set of redox processes that are approximately the sum of what is observed for the Pt^II C^N^N acetylide and Zn^II porphyrin units. UV/Vis spectroscopic properties are supported by DFT calculations.     

meso—四—（取代苯基）卟吩衍生物产生单线态氧的ESR研究

随着肿瘤光动力疗法(Photodynamic Therapy,PDT)的不断发展,出现了一系列新光敏剂,其中,meso-四-(取代苯基)卟吩衍生物是一类肿瘤选择性摄入率高、理化性质稳定的光动力敏化剂,近年来,作者设计并合成了一组meso-四-(取代苯基)卟吩衍生物,并初步观察了它们对细胞及小鼠移植瘤的光动力学效应,为了进一步比较不同卟吩衍生物的光敏化     

Speciation of Antimony(III) and Antimony(V) in Bottled Water by Hydride Generation-Inductively Coupled Plasma Optical Emission Spectrometry

Speciation of Sb(III) and Sb(V) was investigated using hydride generation with the selective formation of stibine from Sb(III). A continuous flow system using a homemade gas-liquid separator with inductively coupled plasma optical emission spectrometry was employed. The conditions and concentrations of NaBH₄, HCl, citric acid, and KI were optimized to obtain limits of detection of 0.05 for Sb(III) and 0.11 µg L^?1 for total Sb without preconcentration. An attractive sampling rate of 26 analyses h^?1 was obtained, suggesting application for routine analysis. The method was employed for the determination of Sb(III) and total Sb in bottled drinking water, and recovery values between 82.0 and 98.8% with relative standard deviation lower than 6.2% were observed, demonstrating appropriate accuracy and precision.     

Synthesis,Characterization, Crystal Structure,and hybrid DFT Computation of Antimony(III) Chloride Diazide,SbCl(N3)2

SbCl(N₃)₂ was synthesized by the reaction of two equivalents of sodium azide with SbCl₃ in CH₂Cl₂. The structure of the compound was determined by X‐ray structure determination. SbCl(N₃)₂ crystallizes in the monoclinic space group C2/c with a = 11.694(4), b = 7.751(4) and c = 12.241(5) Å, β = 100.45(1)°, with 8 formula units per unit cell. The SbCl(N₃)₂ molecules show interactions to form chains. The frequencies obtained by Raman and infrared spectroscopy were assigned to the normal modes of the SbCl(N₃)₂ molecules in comparison with computational results.     

反式双氧锰(V)咔咯配合物的稳定性

采用密度泛函理论(DFT)的B3LYP方法对反式双氧锰(V)咔咯配合物阴离子的稳定性及其质子化物种进行了理论计算. 结果表明: 反式双氧锰(V)咔咯配合物阴离子构型稳定, 其反式双氧锰键O=Mn=O由锰原子的d轨道与两个氧原子的p轨道分别构成一个σ轨道和两个π轨道; 随着外围取代基吸电性增强, O=Mn=O键长缩短, 拉曼伸缩振动频率增大; 其质子化过程中得到两个质子的轴向氧原子与锰原子的距离超出正常化学键的范围, 从而形成水分子并脱离原来分子, 导致质子化行为是不可逆过程, 而形成单氧的咔咯锰(V)-氧配合物.     

咪唑与单线态氧(1O2)1,2-环加成反应的理论研究

采用较新的半经验分子轨道方法Austin Model 1(简称AM1方法), 辅以Berny梯度优化方法, 对单线态氧(~1O_2)与咪唑的1,2-环加成反应,进行了理论研究。计算获得实验尚未检测到的4,5-二氧环丁烷(4,5-dioxetane)的结构, 并在反应势能面上找到单重态双自由基中间体及通过该中间体的两步反应的过渡态。通过对过渡态的结构特征、虚振动方向以及对反应过程的电荷分布情况、轨道相互作用等的分析, 说明该反应是经由单重态双自由基中间体的分步反应。两步反应的活化势垒分别为39.2 kJ·mol~(-1)和150.5 kJ·mol~(-1)。     

Reactions of Distibanes with [Fe2(CO)9]: Synthesis,Structure and DFT Calculations of [(Et2Sb)4Fe4(CO)14], [(nPr2Sb)4Fe3(CO)10], [{(Me3SiCH2)2Sb}4Fe2(CO)6], and [2‐(Me2NCH2)C6H4SbFe2(CO)8]

The iron complexes [(Et₂Sb)₄Fe₄(CO)₁₄] ( 1 ), [(nPr₂Sb)₄Fe₃(CO)₁₀] ( 2 ), [{(Me₃SiCH₂)₂Sb}₄Fe₂(CO)₆] ( 3 ), and [2‐(Me₂NCH₂)C₆H₄SbFe₂(CO)₈] ( 4 ) were prepared by reactions of distibanes with Fe₂(CO)₉. Compounds 1 – 4 were characterized by X‐ray diffraction, ¹H NMR and IR spectroscopy as well as mass spectrometry; complex 1 was additionally characterized by density functional calculations.     

Synthesis and Characterization of Antimony (V) Polyoximes

Antimony (V) polyoximes were synthesized by utilizing the interfacial technique. Reaction occurs only over the limited pH range of 11–13. Yield reaches a plateau after about 180 sec stirring time, with product chain length decreasing with increasing stirring time. The products exhibit low LVN°_w ratios, probably due to a combination of factors including chain stiffness, poor solubility, and presence of the metal atom. Thermal degradation occurs above 300° C through the oxidative route(s) in air. The products exhibit only moderate thermal stability.     

Gadolinium(III) Porpholactones as Efficient and Robust Singlet Oxygen Photosensitizers

Construction of Gd^III photosensitizers is important for designing theranostic agents owing to the unique properties arising from seven unpaired f electrons of the Gd³⁺ ion. Combining these with the advantages of porpholactones with tunable NIR absorption, we herein report the synthesis of Gd^III complexes Gd‐1 – 4 ( 1 , porphyrin; 2 , porpholactone; 3 and 4 , cis‐ and trans‐porphodilactone, respectively) and investigated their function as singlet oxygen (¹O₂) photosensitizers. These Gd complexes displayed ¹O₂ quantum yields (Φ_Δs) from 0.64–0.99 with the order Gd‐1 < Gd‐2 < Gd‐3 < Gd‐4 . The gradually enhanced ¹O₂ sensitization after β‐oxazolone moiety replacement was ascribed to the narrowing of the energy gap (ΔE) between the lowest triplet states (T₁) of the ligand and the energy level of the ¹Δ_g→³Σ_g transition of ¹O₂. In particular, Gd‐4 is capable of excitation in the visible to NIR region (400–700 nm) with a quantum yield near unity. These Gd complexes were first demonstrated as efficient photosensitizers in photocatalysis such as oxidative C?H bond functionalization of secondary or tertiary amines, and the oxygenation of the natural product cholesterol. Finally, after glycosylation, these water‐soluble Gd complexes showed potential applications in photodynamic therapy (PDT) in HeLa cells. This work revealed that Gd^III complexes of “bioinspired” β‐modified porpholactones are efficient NIR photosensitizers and form a chemical basis to construct appealing photocatalysts and theranostic agents based on lanthanides.     

Study on the Total Synthesis of Hainanolide(V)-Oxidation of the Tricyclic Alkenes with Singlet Oxygen

Inthepreviouspapers'wereportedthatfromthemotherliquidofrecrystalizingex0cy-cIoadditivelfromintramolecularDiels-Alderreaction(IMDA)'0nexposuret0airforalongperiod,ahydroperoxide2wasisoIated.ThiswasexplainedastoberesuItedfromoxidati0nofthealkeneby'O,withsubsequentrearrangement.Perceivingthehydroperoxidemightserveasavaluableintermediateinthetotalsynthesisofhainan0Iide,ph0tochemicalsinglet0xygenoxidati0n,usingmeso-tetraPhenylporPhyrin(TPP)assensitizingagent',ofsixunsaturatedtricycIicc0mpounds…     

Antimony (III) Sulfate Catalyzed One-Pot Synthesis of 2,3-Disubstitutedindoles

A novel one-pot Fischer indole synthesis approach has been developed by using antimony (III) sulfate as the catalyst. Good yields were obtained after reacting phenylhydrazines hydrochlorides and ketones in refluxing methanol. The exclusive formation of 2,3- disubstituted indoles was observed in the reaction of ethyl methyl ketone with phenylhydrazines. One-pot synthesis of indole-3-propanol using dihydropyran has also been described. The use of reusable antimony (III) sulfate as a catalyst makes this method both economically and environmentally friendly.     

Synthesis and Characterization of Antimony (V)-Polycobalticinium Esters

Antimony (V) polycobalticinium esters, where the anion was PF₆ ^?, Cl^?, Br^? and NO₃ ^?, were synthesized. A number of factors were found to be important in the synthesis, including anion exchange and pH. The products containing PF₆ ^? are oligomeric (DP _w = 7) whereas the other products are di-and trimeric. The products undergo oxidative degradation beginning about 100 to 225°C. They are near semiconductors with resistivities about 10⁵ to 10⁷ ohm-cm.     

Bis(Diethyldithiocarbamato)Antimony(III) Derivatives with Oxygen- and Sulfur-Donor Ligands: Synthesis,Esi-Mass,and Spectral Characterization

Abstract

Replacement reactions of bis(diethyldithiocarbamato)antimony(III) chloride have been carried out with oxygen and sulfur donor ligands such as disodium oxalate, sodium acetate, sodium salicylate, benzoic acid, thioglycolic acid, acetylacetone, thiphenol, ethane-1,2-dithiol, and 2,2-dimethylpropane-1,3-diol to give mixed bis(diethyldithiocarbamato)antimony(III) derivatives of the corresponding ligands. These derivatives have been characterized by the physicochemical [melting point and molecular weight determination, elemental analysis (C, H, N, S, and Sb)], spectral [FT-IR, far-IR, NMR (¹H and ¹³C)], ESI-mass, powder XRD, and SEM studies.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables]     

Reaction Kinetics between Thiobases and Singlet Oxygen Studied by Direct Detection of the 1O2 Luminescence Decay

Thiobase derivatives have received important investigations due to their wide usage as phototherapeutic agents and their potential carcinogenic side effects as immunosuppressants. The substitution of oxygen atom by the sulfur atom makes the ultraviolet absorption of thiobases redshifted and absorbs UVA light (>300 nm), resulting in unusual high quantum yield of triplet state to generate the singlet oxygen (¹O₂) through photosensitization. As a type of reactive oxygen species, ¹O₂ is highly reactive toward thiobases. Herein, we report the measurements of reaction rate constants between di erent thiobases and ¹O₂ in different solvents through the direct detection of ¹O₂ luminescence decay kinetics at 1270 nm. The rate constants of thiouracils with ¹O₂ are five times smaller than that of thioguanine with ¹O₂, which suggests that thiopurines are more reactive than thiopyrimidines and thus less suitable to be a photosensitive drug on the application of photodynamic therapy. Additionally, the rate constants of thiobases and ¹O₂ were found to be obviously influenced by the solvent polarity. With the increase of solvent polarity, the rate constants of thiobases and ¹O₂ decrease.