The degradation of p-nitrophenol (p-NP) based on OH radicals (HO∙), HO2 radicals (HO2∙) and O2 in aqueous solution was investigated using theoretical computational methods. The complete degradation mechanisms of reaction between p-NP and HO∙ were explored by density functional theory (DFT) methods. The 4-nitrophenoxy radicals and 1,2-dihydroxy-4-nitrocylohexadienyl radicals are confirmed to be major intermediates of the HO∙-initiated reactions in aqueous phase, which consistent with experimental results. The chemical structures of some products (2,4-dihydroxycyclohexa-2,4-dien-1-one and 4-nitrocyclohexa-3,5-diene-1,2-dione) which were not identified in the experiment are determined. New favorable formation channels for some intermediates were found. The primary reactions initiated by HO∙ or HO2∙ with p-NP reveals that HO∙-initiated degradation is the dominant reaction. HO2∙ and O2 can enhance the degradation extent of p-NP in further reactions. Rate constants of the elementary reactions and overall rate constants were calculated. In addition, the HO∙-initiated primary reactions in a water box of 500 water molecules were studied using Monte Carlo simulation. All the OH-addition reactions are barrierless and highly feasible. The observed dynamic reaction process is similar to the DFT calculation prediction. Furthermore, the eco-toxicity evaluation shows that important products are harmless or harmful to aquatic organisms, and are much less toxic than p-NP.

The Cl-initiated oxidation reactions of methyl vinyl ether (MVE) are analyzed by using the high-level composite method CBS-QB3. Detailed chemistry for the reactions of MVE with chlorine atoms is proposed according to the calculated thermodynamic data. The primary eight channels, including two Cl-addition reactions and six H-abstraction reactions, are discussed. In accordance with the further investigation of the two dominant additional routes, formyl chloride and formaldehyde are the major products. Over the temperature range of 200-400 K and the pressure range of 100-2000 Torr, the rate constants of primary reactions are calculated by employing the MESMER program. H-abstraction channels are negligible according to the value of rate constants. During the studied temperature range, the Arrhenius equation is obtained as ktot = 5.64 × 10(-11) exp(215.1/T). The total rate coefficient is ktot = 1.25 × 10(-10) cm(3) molecule(-1) s(-1) at 298 K and 760 Torr. Finally, the atmospheric lifetime of MVE with respect to Cl is estimated to be 2.23 h.

This study investigates the decomposition of 2,2',4,4',5-pentabrominated diphenyl ether (BDE99), a commonly detected pollutant in the environment. Debromination channels yielding tetrabrominated diphenyl ethers and hydrogen abstracting aromatic bromine atom formations play significant roles in the reaction of BDE99 + H, in which the former absolutely predominates bimolecular reactions. Polybrominated dibenzo-p-dioxins (PBDDs) and polybrominated dibenzofurans (PBDFs) can be produced during BDE99 pyrolysis, especially for PBDFs under inert conditions. The expected dominant pathways in a closed system are debromination products and PBDF formations. The bimolecular reaction with hydroxyl radical mainly leads to hydroxylated BDE99s rather than hydroxylated tetrabrominated diphenyl ethers. PBDDs are then generated from ortho-hydroxylated PBDEs. HO2 radical reactions rarely proceed. The total rate constants for the BDE99 reaction with hydrogen atoms and hydroxyl radicals exhibit positive dependence on temperature with values of 1.86 × 10(-14) and 5.24 × 10(-14) cm(3) molecule(-1) s(-1) at 298.15 K, respectively.

The reaction mechanisms for the atmospheric hydroxylation of n-butyl vinyl ether (n-BVE), iso-butyl vinyl ether (i-BVE), and tert-butyl vinyl ether (t-BVE) were investigated by using quantum chemical method in this paper. The geometry optimizations and frequency calculations were carried out at the MPWB1K/6-31+G(d,p) level, and the accurate energetic parameters were obtained by the MPWB1K/6-311++g(3df,2p) method. The reaction mechanisms for the title reactions have been presented. Ten possible reaction channels were discussed for the primary hydroxylation of n-BVE and t-BVE, while fourteen pathways for i-BVE. Three favorable reaction pathways were chosen for each isomer to undergo further investigation. Major products are n-butyl formate, iso-butyl formate, tert-butyl formate, and HCHO. The rate constants of the primary reactions were calculated over the temperature range of 200–400 K and the pressure range of 100–2,000 Torr by employing MESMER program. At 298 K and 760 Torr, the whole rate constants of n-BVE + OH, i-BVE + OH, and t-BVE + OH are 12.3 × 10−11, 9.32 × 10−11 and 5.75 × 10−11 cm3 molecule−1 s−1, respectively. Additionally, the lifetimes of the three isomers with respect to OH radical are \(\tau\) (n-BVE) = 1.13 h, \(\tau\) (i-BVE) = 1.49 h, and \(\tau\) (t-BVE) = 2.41 h.

This study investigates the nitrate radical oxidation of methyl vinyl ether (CH2=CHOCH3, MVE) by quantum chemical methods. The oxidation initiates with the formation of open-cyclic NO3-adducts, followed by a series of unimolecular decomposition or bimolecular reactions. Kinetic data suggest that pressure and temperature have strong influence on the environmental fate of MVE. Under atmospheric condition, methyl formate, formaldehyde and NO2 are the main products by association with O-2/NO. At low pressure (<50 Torr) 2-methoxyoxirane and NO2 are main products by decomposition. Total rate coefficient of the bimolecular reaction exhibits negative dependence on temperature (200-300 K) and positive dependence on pressure (1-7600 Torr). The calculated rate coefficient (7.09 x 10(-13) cm(3) molecule(-1) s(-1)) is in well agreement with experimental data at 293 K and 760 Torr. (C) 2015 Elsevier B.V. All rights reserved.

The OH-initiated oxidation of p-nitroaniline (p-NA) was studied both in gas phase and aqueous solution. The calculated results show that addition reactions between p-NA and OH radicals are highly feasible in gas phase. OH addition to the ortho C of the amino group is the most favorable. The major products are p-nitrophenol (p-NP), 2-amino-5-nitrophenol, 5-amino-2-nitrophenol and p-aminophenol. The H atom of the amino group is the easiest one to be abstracted by OH radical. The undergoing degradation is investigated in the presence of O-2, which generate oxygen-rich compounds including five-membered heterocycles or six-membered heterocycles and 2-amino-5-nitrophenol or 5-amino-2-nitrophenol. The effect of water solution on the title reactions was considered. The calculated results show that aqueous solution makes the addition reactions between p-NA and OH radical more uniform while H-abstraction reactions are not significant. The total rate constant of OH radicals with p-NA under 298 K, 1 atm is determined to be 6.97 x 10(-11) cm(3) molecule(-1) s(-1). With respect to OH radical, the life time of p-NA in atmosphere is estimated to be 4.1 h. (C) 2015 Elsevier B.V. All rights reserved.

The ozonolysis of isopropenyl acetate (IPA) and propenyl acetate (PA) are investigated by quantum chemical method. The detailed reaction mechanisms are provided, including the formation and decomposition of the primary ozonide (POZ), the formation of the secondary ozonide (SOZ) and further reactions of Criegee intermediates. By means of the CBS-QB3 composite method, the potential energy surfaces (PESs) are obtained and the major products are identified, respectively. Based on the PESs calculations, master equation (ME) calculations are used to examine the rate constants. Finally, the lifetimes of IPA and PA in troposphere are estimated. (C) 2014 Elsevier B.V. All rights reserved.

The O3-initiated oxidation of vinyl propionate is studied using quantum chemistry calculations. Detailed and complete reaction mechanisms are presented which involve the formation of the primary ozonide (POZ), the subsequent decomposition of POZ, the secondary reactions of CH3CH2C(O)OCHO2 (IM4) in the presence of H2O or NO as well as the generation of the secondary ozonide (IM6). Based on the above PESs calculations, the Multichannel Rice–Ramsperger–Kassel–Marcus theory is employed to calculate the total and individual rate constants for major product channels. The rate constants and branching ratios of main products are obtained. The total rate constants are temperature dependent over the whole study temperature range (200–2,000 K), but pressure independent over the range of 0.01–10,000 Torr. In addition, the atmospheric lifetime is estimated in accordance with rate constants.

2,4,4'-Tribromodiphenyl ether (BDE-28) was selected as a typical congener of polybrominated diphenyl ethers (PBDEs) to examine its fate both in the atmosphere and in water solution. All the calculations were obtained at the ground state. The mechanism result shows that the oxidations between BDE-28 and OH radicals are highly feasible especially at the less-brominated phenyl ring. Hydroxylated dibrominated diphenyl ethers (OH-PBDEs) are formed through direct bromine-substitution reactions (P1∼P3) or secondary reactions of OH-adducts (P4∼P8). Polybrominated dibenzo-p-dioxins (PBDDs) resulting from o-OH-PBDEs are favored products compared with polybrominated dibenzofurans (PBDFs) generated by bromophenols and their radicals. The complete degradation of OH adducts in the presence of O2/NO, which generates unsaturated ketones and aldehydes, is less feasible compared with the H-abstraction pathways by O2. Aqueous solution reduces the feasibility between BDE-28 and the OH radical. The rate constant of BDE-28 and the OH radical is determined to be 1.79 × 10(-12) cm(3) molecule(-1) s(-1) with an atmospheric lifetime of 6.7 days.

Sensitive vesicle system, which is formed by amphiphiles constructed non-covalently has unique responsiveness to external stimuli. Vesicles prepared from "surpamolecular cyclodextrin amphiphiles" (SCA) are one of the most important types. Here, the development of this kind of vesicular system is reviewed. At first, the preparation and applications in pharmaceutical engineering, new smart materials, biological mimics, etc. of this kind of vesicle system classified by the guest molecules are introduced and described. Then the prospects are pointed out based on the current development of the system.

Supramolecular chemistry is a hot research topic in current chemistry. The photo-switched supramolecular system based on cyclodextrins and azo compounds is a new area which has been developed in supramolecular chemistry recently. Their complexation with good optical properties attracted great interest in the fields of chemical self-assembly, catalysis, molecular machine design and smart materials. Here, the development of photo-switched supramolecular system based on cyclodextrins and azo compounds is reviewed. Firstly, the background and principle of the system are introduced. Then, the different aggregates controlled by the supramolecular system, including vesicles, gels, rotaxanes, catalytic systems and molecule hands, are emphatically described. At last, combined with current development of the system, the prospects are pointed out.

This paper describes the first example of controllable transformation from sensitive and reversible heat-set organogel to stable gel induced by sodium acetate. Upon the addition of proper amount of acetate sodium into the reversible heat-set organogel system composed of β-CD, phenolphthalein (PP) and lithium chloride in N,N-dimethylformamide, the reversible gel could transform to stable gel as the temperature decreased. Further studies showed that other analogous acetates with K+ and Mg2+ do not possess this property. The gel was characterized by SEM, XRD and FT-IR. This work may pave the way for the design of smart materials with multi-responsiveness.

A method based on electrochemiluminescence resonance energy transfer (ECRET) between luminol as the donor and CdSe/ZnS quantum dot (QD) for evaluation of the interactions between DNAs and measurement of the conformational changes of DNAs was developed. When a positive potential was applied to the conjugates consisting luminol, DNA and QD, ECRET between luminol molecules and QDs could be detected in 0.2mol/L Na2CO3–NaHCO3 buffer (pH 10) containing 1.0×10−2mol/L H2O2. In this case, luminol molecules emitted a light with a maximum emission (λm) of 460nm or transferred energy to proximal ground-state QDs. The excited state QDs relaxed to their ground state by emitting a light with a λm of 655nm. The ECRET between luminol and QD was used to evaluate interactions between DNAs and to measure conformational changes of DNAs.

Vesicular particles based on inclusion complexes between BPB and -HB--CDs were prepared and characterized for the first time. The morphologies and sizes were confirmed by transmission electron microscopy (TEM), scanning electron microscope (SEM), and dynamic light scattering (DLS). Particularly, these vesicular particles exhibiting clearly fluorescent dots observed by laser confocal scanning microscopy (LCSM) could be alternative candidates as fluorescent probes and labels being applied to cellular staining, labeling, bio-mimicking and drug delivery. The ultraviolet, fluorescence, and nuclear magnetic resonance (NMR) measurements confirmed the existence of stable 1:1 BPB--HB--CD complexes in the system. The vesicular particles were assumed to be constructed by orderly self-aggregates of these inclusion complexes.

Novel electrochemiluminescence resonance energy transfer (ECRET) between an emitter electrochemically generated by luminol as the donor and luminescent quantum dots as the acceptor is investigated. The ECRET technique can be used to study the interactions and conformational changes of proteins.

The recent progress in atom transfer radical polymerization (ATRP) based on cyclodextrin has been reviewed. In cyclodextrin synthesis chemistry, ATRP can be applied to covalently modifying the native cyclodextrins and can participate in constructing cyclodextrins assemblies by noncovalent interactions. And these novel cyclodextrins and assemblies obtained by ATRP can be further applied to the fields such as organic synthesis, complicated "smart" supramolecular assemblies, drug delivery and release system, protein recognition and enantiometric separation.

In the title compound, C8H7ClN4S2, the thiazole ring is essentially planar [r.m.s. deviation = 0.0011 (2) Å] and conformation of the thiazolidine ring is twisted on the C—C bond. The C=N bond has a Z configuration.

Ethyl benzoate was found to complex with cyclodextrins in formation of vesicles for the first time. These vesicles were characterized by transmission electron microscopy and dynamic light scattering. The complex stoichiometry, the stability constant and conformations of ethyl benzoate cyclodextrins in aqueous solution were investigated by ultraviolet and nuclear magnetic resonance analyses. The vesicle system was prepared without complicated synthesis. This kind of vesicles prepared by cyclodextrin inclusion complexes could be applied in many fields.

This paper describes a novel heat-set organogel transformation which could be triggered by lithium chloride (LiCl) from precipitate for the first time. The system was prepared with β-cyclodextrin (β-CD) and triphenylphosphine (Ph3P) in N,N-dimethylformamide (DMF). The system as an original transparent solution at room temperature could turn into precipitation by heating. Subsequently, the precipitation turned into organogel instantly based on the injection of LiCl into the system. SEM measurement revealed that the precipitate and gel systems have different microstructures. IR and XRD measurements revealed that the inclusion complexes formed by β-CDs and Ph3P were arranged in cage structures in the precipitate and channel structures in the gel. Molecular dynamics simulations were performed both on the formation of the precipitate and gel models in this system, which were consistent with the test results.

Aggregates assembled by “supramolecular amphiphilies” are more promising in developing responsive materials. First pH-reversible vesicles based on “supramolecular amphiphilies” were prepared from the supramolecular inclusion of cyclodextrins (CDs) and anthraquinone derivate (1-((3-(dimethylamino)propyl)amino)anthracene-9,10-dione, 1). 1, as the guest molecule, was synthesized by the direct reaction of 1-nitroanthraquinone with N1,N1-dimethylpropane-1,3-diamine. The vesicles were characterized in detail by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and epi fluorescence microscope (EFM). 1H NMR, 2D NMR ROESY, UV–vis spectrum, and FT-IR were further employed to study the formation mechanism of the vesicles. The vesicles’ responsive property, especially the pH-responsive property was tested. We also tried to use the vesicle system as a new kind of fluorescence staining material for living cells and mouse prostate carcinoma cells (RM-1) were found to be stained effectively by the vesicles. Our research may provide new references in exploiting novel intelligence materials and biomaterials.