Highly Luminescent Lanthanide Metal-Organic Frameworks with Tunable Color for Nanomolar Detection of Iron(III), Ofloxacin and Gossypol and Anti-counterfeiting Applications

Solvothermal reaction of 5,5′-(pyridine-2,6-diylbis(oxy))diisophthalic acid (H₄L) with europium(III) or terbium(III) nitrates in acetonitrile-water (1 : 1) at 120 °C gave rise to isostructural 2D coordination polymers, [Ln(HL)(H₂O)₃]_∞ ( NIIC-1-Eu and NIIC-1-Tb ), the layers of which are composed by eight-coordinated lanthanide(III) ions interconnected by triply deprotonated ligands HL³⁻. The layers are packed in the crystal without any specific intermolecular interactions between them, allowing the facile preparation of stable water suspensions, in which NIIC-1-Tb exhibited top-performing sensing properties through luminescence quenching effect with exceptionally low detection limits towards Fe³⁺ (LOD 8.62 nM), ofloxacin (OFX) antibiotic (LOD 3.91 nM) and cotton phytotoxicant gossypol (LOD 2.27 nM). In addition to low detection limit and high selectivity, NIIC-1-Tb features fast sensing response (within 60–90 seconds), making it superior to other MOF-based sensors for metal cations and organic toxicants. The photoluminescence quantum yield of NIIC-1-Tb was 93 %, one of the highest among lanthanide MOFs. Mixed-metal coordination polymers NIIC-1-Eu_xTb_1−x demonstrated efficient photoluminescence, the color of which could be modulated by the excitation wavelength and time delay for emission monitoring (within 1 millisecond). Furthermore, an original 2D QR-coding scheme was designed for anti-counterfeiting labeling of goods based on unique and tunable emission spectra of NIIC-1-Ln coordination polymers.     

Chemical Synthesis of an Octasaccharide Derivative Related to Group B Streptococcus Cell-Wall Polysaccharide

Group B Streptococcus (GBS) is the major pathogen that causes invasive infectious diseases in neonates and infants. The development of preventive and therapeutic strategies against GBS infection has been becoming the most pressing subject worldwide. Group B carbohydrate (GBC), the group B-specific polysaccharide that distinguishes GBS with other streptococci species, has been identified as an attractive antigen for diagnosis and vaccine development because of its highly conservative tetra-antennary structure. In this paper, a highly convergent [3 + 5] glycosylation strategy for efficient synthesis of an octasaccharide derivative related to GBC oligosaccharide unit II has been developed. In this synthesis, each glycosylation reaction was efficiently constructed with glycosyl imidates, especially trifluoroacetimidate, as donors, and each glycosidic bond was stereoselectively controlled via the neighboring group participation effect of acyl group on the 2-O-position of imidate donors or the solvent effect of Et₂O. Furthermore, the aminoethylphosphate group was smoothly installed on the 6-O-position of d -glucitol residue using the phosphoramidite method. After global deprotection, the target octasaccharide was successfully obtained from d -glucitol in 29 steps with an overall yield of 1.37%. The free amino group installed on the aminoethylphosphate spacer of the target molecule enables its modification with functionalized biomolecules for further biological studies.      

Construction of ion-conductive dual-channels by P(EA-co-AALi)-based gel electrolytes for high-performance lithium metal batteries

Journal of Solid State Electrochemistry - As people possess more safety conscious, the issue of electrolytes is attracting concern. The gel polymer electrolyte offers high ionic conductivity,...     

Naphthyl Substituted Impurities Induce Efficient Room Temperature Phosphorescence

Accidentally, it was found that triphenylamine (TPA) from commercial sources shows ultralong yellow-green room temperature phosphorescence (RTP) like commercial carbazole, which however disappears for lab-synthesized TPA with high purity. Herein, we for the first time identify the impurity types that cause RTP of commercial TPA, which are two N, N-diphenyl-naphthylamine isomers. Due to similar molecular polarity and very trace amount (≈0.8 ‰, molar ratio), these naphthyl substituted impurities can be easily overlooked. We further show that even at an extremely low amount (1000000 : 1, mass ratio) of impurities, RTP emission is still generated, attributed to the triplet-to-triplet energy transfer mechanism. Notably, this doping strategy is also applicable to the triphenylphosphine and benzophenone host systems, of which strong RTP emission can be activated by simply doping the corresponding naphthyl substituted analogues into them. This work therefore provides a general and efficient host/guest strategy toward high performance and diverse organic RTP materials.     

Concurrent Solution‐Like Decoloration Rate and High Mechanical Strength from Polymer‐Dispersed Photochromic Organogel

To achieve a fast photochromic response in solid matrix, photochromic molecules/segments have been either dispersed into elastomers via physical doping or linked to glassy polymers by soft units through covalent bonding. However, the former is lack of high mechanical strength and the latter owes the drawback of time‐consumption of synthesis. Here, we propose a facile strategy of co‐solvent evaporation to prepare polymer‐dispersed photochromic organogel where both high mechanical strength of the glassy polymer matrix and solution‐like fast photochromism of the photochromic molecule within organogel can be retained concurrently. Glassy PVA matrix and dispersed organogel of 1,3:2,4‐di‐O‐benzylidene‐d ‐sorbitol/poly(propylene glycol) (DBS/PPG) provide high mechanical strength and sufficient free volume for intramolecular rotation of photochromic spiropyran (SP), respectively. Interestingly, these thin films behave a solution‐like decoloration the decay rate of which is 65–70 fold faster than that in the SP‐directly doped PVA film and only slightly slower than those in their corresponding PPG solutions.

     

LixCoO2及其与LiPF6/EC+DEC电解液的热稳定性研究

使用C80微量量热仪对不同充电状态下LixCoO2的热稳定性、LixCoO2与1.0molLLiPF6EC DEC(质量比=11)电解液的热稳定性进行了研究。结果表明,LixCoO2的放热量和主放热峰温度随x值减小而增加,Li0.05CoO2在271.8℃达到放热峰,总放热量高达1575.5Jg。LixCoO2与电解液反应时,LixCoO2首先分解出的氧气使电解液氧化,同时电解液也发生分解等反应,放热峰温度随x的增大呈增大趋势,放热量随x的增大呈减少的趋势。此外,LixCoO2与电解液反应产生大量的CO2、HF等气体。