Dual-Valence Characteristics of Be11: Tin/Lead-like Superatom.

To enhance the superatom family, the new superatom analogue Be11 of group IVA elements has been developed. Be11 can exhibit multiple valence states (+2 and +4), similar to carbon-group elements, and is capable of forming stable ionic compounds with other atoms such as carbon, chalcogen, (super)halogen, and hydroxyl. This resembles how tin and lead atoms combine with these elements to form stable molecules. Their special stability can be rationalized from the perspective of a cluster shell model. Sn or Pb could be the nearest atomic analogue to Be11 in group IVA, as the +2 oxidation state is more stable than the +4 oxidation state. This comparative investigation highlights the resemblance between Be11 and carbon-group elements, which encourages additional exploration within the superatom family.

Aggregation Behavior and Application Properties of Novel Glycosylamide Quaternary Ammonium Salts in Aqueous Solution.

Amidation of lactobionic acid with N,N-dimethylaminopropyltriamine was conducted to obtain N-(3'-dimethylaminopropyl)-lactamido-3-aminopropane (DDLPD), which was quaternized with bromoalkanes of different carbon chain lengths to synthesize double-stranded lactosylamide quaternary ammonium salt N-[N'[3-(lactosylamide)]propyl-N'-alkyl] propyl-N,N-dimethyl-N-alkylammonium bromide (CnDDLPB, n = 8, 10, 12, 14, 16). The surface activity and the adsorption and aggregation behaviors of the surfactants were investigated via equilibrium surface tension, dynamic light scattering, and cryo-electron microscopy measurements in an aqueous solution. The application properties of the products in terms of wettability, emulsification, foam properties, antistatic, salt resistance, and bacteriostatic properties were tested. CnDDLPB exhibited a low equilibrium surface tension of 27.82 mN/m. With an increase in the carbon chain length, the critical micellar concentration of CnDDLPBD decreased. Cryo-electron microscopy revealed that all products except C8DDLPB formed stable monolayer, multi-layer, and multi-compartmental vesicle structures in an aqueous solution. C14DDLPB has the best emulsification performance on soybean oil, with a time of 16.6 min; C14DDLPB has good wetting and spreading properties on polytetrafluoroethylene (PTFE) when the length of carbon chain is from 8 to 14, and the contact angle can be lowered to 33°~40°; CnDDLPB has low foam, which is typical of low-foaming products; C8DDLPB and C10DDLPB both show good antistatic properties. C8DDLPB and C14DDLPB have good salt resistance, and C12DDLPB has the best antimicrobial property, with the inhibition rate of 99.29% and 95.28% for E. coli and Gluconococcus aureus, respectively, at a concentration of 350 ppm.

Surface Activity, Wetting, and Aggregation of a Perfluoropolyether Quaternary Ammonium Salt Surfactant with a Hydroxyethyl Group.

This paper reports the synthesis of a novel quaternary surfactant containing a hydroxyethyl group (PFPE-C) and the surface properties of its aqueous solution (investigated by comparisons with two structurally similar chemicals, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC) and PFPE-A). The minimum surface tension (γCMC) and critical micelle concentration (CMC) of the PFPE-C aqueous solution were 17.35 mN/m and 0.024 mmol/L, respectively. This study confirms that surfactants containing hydroxyethyl groups efficiently reduce the surface tension of aqueous solutions, and fluorocarbon surfactants exhibit better surface activity than ordinary hydrocarbon surfactants with similar structures. The micellization, aggregation, air-water interfacial adsorption, and wettability of PFPE-C aqueous solutions have been systematically investigated. Highly concentrated PFPE-C aqueous solutions exhibit good wettability on PTFE and paraffin films. Moreover, the aggregates of PFPE-C in the aqueous solution were clearly seen as vesicles on Cryo-TEM micrographs. Primary biodegradation results indicate that 19% of PFPC-C can be degraded within one week.

Synthesis and Performance of Double-Chain Quaternary Ammonium Salt Glucosamide Surfactants.

A series of double-chain quaternary ammonium salt surfactants N-[N'[3-(gluconamide)] propyl-N'-alkyl]propyl-N,N-dimethyl-N-alkyl ammonium bromide (CnDDGPB, where n represents a hydrocarbon chain length of 8, 10, 12, 14 and 16) were successfully synthesized from D (+)-glucose δ-lactone, N,N-dimethyldipropylenetriamine, and bromoalkane using a two-step method consisting of a proamine-ester reaction and postquaternization. Their surface activity, adsorption, and aggregation behavior in aqueous solution were investigated via measurements of dynamic/static surface tension, contact angle, dynamic light scattering, and transmission electron microscopy. An analysis of their application performance in terms of wettability, emulsifying properties, toxicity, and antibacterial properties was conducted. The results show that with increasing the carbon chain length of the CnDDGPB surfactants, their critical micelle concentration (CMC) increased and the pC20 and efficiency in the interface adsorption of the target product gradually decreased. Moreover, the influence of the hydrophobic carbon chain length on the surface of polytetrafluoroethylene (PTFE) was even greater for the wetting effect, reducing the contact angle to 32° within the length range of C8-C14. The results of the contact angle change and the wettability experiments proved that C10DDGPB exhibited the best wettability. The liquid paraffin and soybean oil emulsification ability of CnDDGPB showed an upward trend followed by a downward trend with the growth of the carbon chain, with C12DDGPB exhibiting the best emulsification performance. The Dlong/Dshort ratio was far lower than 1, which indicates mixed-kinetic adsorption. The surfactants formed spherical micelles and showed a unique aggregation behavior in aqueous solution, which showed an increase-decrease-increase trend with the change in concentration. A cell toxicity and acute oral toxicity experiment showed that the CnDDGPB surfactants were less toxic than the commonly used surfactant dodecyldimethylbenzyl ammonium chloride (1227). In addition, at a concentration of 150 ppm, CnDDGPB exhibited the same bacteriostatic effect as 1227 at a concentration of 100 ppm. The results demonstrate that sugar-based amide cationic surfactants are promising as environmentally friendly disinfection products.

Functionalized metal-organic frameworks for effective removal of rocephin in aqueous solutions.

The porous metal-organic frameworks, MIL-101, MIL-101-SO3H and MIL-101-NH2 were used for the removal of harmful drug (rocephin) from water via adsorption. The kinetics study suggests that the adsorption onto all the MOFs follows the pseudo-second-order model. The adsorption isotherms results suggest that the adsorption onto MIL-101 and MIL-101-NH2 fits well with Langmuir model and the maximum adsorption capacities are calculated to 204.08 mg g-1 and 277.78 mg g-1, respectively; while the adsorption onto MIL-101-SO3H cannot fit well with both Langmuir and Freundlich models and the maximum adsorption capacity in the experiment is 25 mg g-1. Furthermore, the effect of pH as well as the adsorption mechanism was analysed systematically. It was found that electrostatic interaction as well as hydrogen-bond interaction plays dominant roles in adsorption of rocephin, and MIL-101-NH2 with abundant amino groups can exhibit better adsorption capacity and removal percentage towards rocephin than MIL-101, MIL-101-SO3H, and some other common adsorbents. In addition, co-existed Zn(NO3)2 can induce a large improvement of rocephin adsorption performance of MIL-101-NH2. At last, MIL-101-NH2 demonstrates to be a renewable adsorbent. In conclusion, we suggest MIL-101-NH2 is a promising adsorbent for effective removal of rocephin in water.

A metal-organic framework with large 1-D channels and rich OH sites for high-efficiency chloramphenicol removal from water.

High-efficiency removal of chloramphenicol (CAP) drug from waste water still faces a large challenge up to date. Herein, we report the first metal-organic framework-based adsorbent (PCN-222) for CAP and effective removal was achieved. PCN-222 exhibits a large adsorption capacity of 370 mg g-1, superior to some other MOFs and various reported adsorbents; and more importantly, the adsorption equilibrium can be quickly obtained at only 58 s. Besides, ∼99.0% of CAP can be removed from water in the low concentrations (including the concentrations found in real water). Further investigation indicates that H-bond interaction, electrostatic interaction and the special pore structure of PCN-222 all play important effects on the high-efficiency removal of CAP. Therefore, our work may provide a novel perspective for removing CAP or other antibiotic drugs from contaminated water.

Effects of additives on the thermostability of chloroperoxidase.

The effects of several polyhydroxy compounds (glucose, fructose, gumsugar, galactose, trehalose, dextran, xylose, PEG200, glycerin) and surfactant (dioctyl sulfosuccinate sodium salt, AOT) on the catalytic activity and thermal stability of chloroperoxidase (CPO) in aqueous systems were investigated at various temperatures. A 25% superactivity was found in AOT solutions at 25 degrees C, and it could be maintained during the 882 h. PEG200 and glycerin were proven to be the most efficient stabilizer for CPO in temperatures ranging from 25 to 60 degrees C. Trehalose is more helpful than other sugars for extended storage of CPO. These results are promising in view of industrial applications of this versatile biological catalyst. The protective mechanism of various additives on CPO was discussed.

Deactivation of chloroperoxidase by monosaccharides (D-glucose, D-galactose, and D-xylose).

In this work, it was found that some monosaccharides normally used to stabilize enzymes at high temperatures, however, actually caused a deactivation of chloroperoxidase (CPO). The red native CPO was converted to a stable pale species that lost enzymatic activity. This deactivation was irreversible and was sensitive to temperature. It was different from the general peroxide-mediated deactivation of CPO. Data from measurement of chlorination activity as well as UV-vis, fluorescent, and CD spectral analysis indicated that monosaccharide-induced deactivation can be attributed to precipitation of protein in the presence of monosaccharide and the interaction of the aldehyde group of sugar with amino groups, especially the terminal amino group, on proteins to form Schiff bases which then rearrange to the stable amino ketone. It is further noted that the deactivation efficiency depends on the stereostructure of monosaccharides. D-glucose was the most efficient inactivating agents due to its aptitude for both of the interactions mentioned in the above paragraphs. The deactivation was specific to aldose. No deprivation of the heme iron was involved in this deactivation.