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Construction of CO2‐based amphiphilic block copolymers (ABCs) is an efficient method for providing CO2‐based polycarbonates with self‐assembly properties in aqueous media. It is challenging to construct CO2‐based ABCs by one‐step strategies from mixed monomers because hydrophilic blocks, usually composed of polar monomers, have negative effects on the synthesis of polycarbonates. In this work, we report a one‐step method to construct CO2‐based ABCs obtained by simultaneous ring‐opening copolymerization (ROCOP) of CO2/epoxides and reversible addition‐fragmentation chain transfer (RAFT) polymerization of N‐isopropyl acrylamide (NIPAM). A trithiocarbonate/carboxy compound was used as the bifunctional chain transfer agent, and an aluminum porphyrin complex was used as the catalyst for ROCOP, which proved to be efficient in CO2 copolymerization even in the presence of NIPAM with strong polarity. This strategy allows flexible control over the molecular weight (5–16 kg/mol) and the hydrophilic‐hydrophobic balance (HLB 9–18) of the ABCs, and ensures narrow polydispersity Đ (1.1–1.3) of the polymers. The ABCs can further self‐assemble into micelles in water with controllable diameters and reversible phase transformation behavior with temperature changes from 25 to 40 °C. This simple route to CO2‐based ABCs with multiple functions has large potential in biomedical applications. [ABSTRACT FROM AUTHOR]

The development of degradable polymeric materials such as degradable polyurethane or polyurea has been much highlighted for resource conservation and environmental protection. Herein, a facile strategy of constructing mechanically strong and tough poly(urea‐urethane) (PUU) thermosets that can be degraded under mild conditions by using triple boron‐urethane bonds (TBUB) as cross‐linkers is demonstrated. By tailoring the molecular weight of the soft segment of the prepolymers, the mechanical performance can be finely controlled. Based on the cross‐linking of TBUB units and hydrogen‐binding interactions between TBUB linkages, the as‐prepared PUU thermosets have excellent mechanical strength of ≈40.2 MPa and toughness of ≈304.9 MJ m−3. Typically, the PBUU900 strip can lift a barbell with 60 000 times its own weight, showing excellent load‐bearing capacity. Meanwhile, owing to the covalent cross‐linking of TBUB units, all the PUU thermosets show initial decomposition temperatures over 290 °C, which are comparable to those of the traditional thermosets. Moreover, the TBUB cross‐linked PUU thermosets can be easily degraded in a mild acid solution. The small pieces of the PBUU sample can be fully decomposed in 1 m HCl/THF solution for 3.5 h at room temperature. [ABSTRACT FROM AUTHOR]

The study investigated the effect of water molecule(cluster) and aqueous solvent on S-proline( Pro)divalent copper complex(S-Pro·Cu(II))enantiomerization under the gas phase using the methods of M06 and MN15 based on density functional theory combining with self-consistent reaction field of SMD model. The results showed that gas phase Cu2+ and carbonyl O monodentate ligand is the most stable. The enantiomerization of S-Pro•Cu(II)can be realized in 5 channels a, b, c, d and e. In channel a, b and c α -H transfers directly with O, Cu and N as a bridge respectively. After Cu and carbonyl O are bidentately coordinated α-H transfers with O and O and N unite as a bridge in channel c and d(α-H transfers with Cu as a bridge, it is hydrogen anion migration. The other is hydrogen proton migration). The potential energy surface calculation shows that the dominant pathways of the enantiomerization of isolated S-Pro•Cu(II) are pathways b and c, and the activation energy of the reaction is 153. 4 and 160. 3 kJ·mol, 1 respectively. The dominant pathway is channel c in the water vapor phase environment and the activation energy of the reaction is 143. 7 kJ·mol-1. Channel b is the most disadvantaged, and the enantiomerization in this channel cannot be achieved. The activation energy of channel c drops to 89. 9 kJ·mol-1 under the effect of aqueous solvent. The results show that Pro•Cu) can maintain its chiral characteristics well in the gas phase, and is easy to be enantiomerized in the water vapor phase. [ABSTRACT FROM AUTHOR]

Bacterial infections have posed a grave challenge to public health. Molecular fluorescent probes play increasing important roles in diagnosis and treatment of bacterial infections, but are frequently hindered by the aggregation‐caused quenching and low bacterial specificity as well as reduced bactericidal activity. Herein, metabolism‐driven nanoprobes (HF‐D‐Ala NPs) are reported for bacteria‐activated detection and following visible‐light induced inactivation. The nanoprobes are formed via facile self‐assembly of amphiphilic fluorescent small molecule (HF‐D‐Ala), showing strongly quenched fluorescence and enhanced photostability due to the dense aggregation of hydrophobic structural units. Once encountering with bacteria, HF‐D‐Ala NPs are disassembled into free HF‐D‐Ala, which can be further integrated into cell walls via bacterial metabolism. This progress can readily "turn‐on" the molecular fluorescence, realizing visual bacterial detection and imaging. Subsequently, the labeled bacteria can be effectively inactivated by carbon monoxide released from incorporated HF‐D‐Ala upon visible‐light. With good specificity and biocompatibility, HF‐D‐Ala NPs can selectively detect and inactivate bacteria in biofilms and bacteria co‐existing with mammalian cells, showing great potential for bacterial infection theranostic applications. [ABSTRACT FROM AUTHOR]

Based on its off-diagonal Bethe ansatz solution, we study the thermodynamic limit of the spin- 1 2 XYZ spin chain with the antiperiodic boundary condition. The key point of our method is that there exist some degenerate points of the crossing parameter ηm,l, at which the associated inhomogeneous T − Q relation becomes a homogeneous one. This makes extrapolating the formulae deriving from the homogeneous one to an arbitrary η with O(N−2) corrections for a large N possible. The ground state energy and elementary excitations of the system are obtained. By taking the trigonometric limit, we also give the results of antiperiodic XXZ spin chain within the gapless region in the thermodynamic limit, which does not have any degenerate points. [ABSTRACT FROM AUTHOR]