More Than Just Light: Clinical Relevance of Light Perception in the Nosocomial Pathogen Acinetobacter baumannii and Other Members of the Genus Acinetobacter

A summary of the major findings concerning light modulation in Acinetobacter baumannii, which governs aspects related to the success of this microorganism as a nosocomial pathogen, is presented. Particularly, the evidence shows that light modulates the ability of the bacteria to persist in the environment, its virulence against eukaryotic hosts and even susceptibility to certain antibiotics. The light signal is sensed through different mechanisms, in some cases involving specialized photoreceptors of the BLUF‐type, whereas in others, directly by a photosensitizer molecule. We also provide new data concerning the genomic context of BLUF‐domain containing proteins within the genus Acinetobacter, as well as further insights into the mechanism of light‐mediated reduction in susceptibility to antibiotics. The overall information points toward light being a crucial stimulus in the lifestyle of members of the genus Acinetobacter as well as in other clinically relevant species, such as members of the ESKAPE group, playing therefore an important role in the clinical settings.     

A Stable and High‐Efficiency Blue‐Light Emitting Terphenyl‐Bridged Ladder Polysiloxane

A novel blue‐light emitting terphenyl‐bridged ladder polysiloxane ( TBLP) was prepared by the condensation of a tetrasilanol monomer via a ladder supramolecular structure. TBLPs emit narrow blue light (420 nm) with high quantum yields (0.96) in diluted solution and shows no evident fluorophore aggregation in the solid state, indicating that the terphenyls are well isolated due to confinement of the ladder‐rungs. In addition, it has excellent emission stability at high temperature based on TGA, DSC and annealing experiments. Overall, TBLPs can be considered as a potential material for fabricating stable and high‐efficiency blue‐light emitting optoelectronic devices.

     

Pure Blue‐Light Emissive Poly(oligofluorenes) with Bifunctional POSS in the Main Chain

Emission of conjugated polymers is known to undergo bathochromic shift from solution to film formation due to π–π stacking in the solid state. In this report, a series of pearl‐necklace‐like hybrid polymers is designed via the hydrosilylation condensation between bifunctional polyhedral oligomeric silsesquioxanes ( B‐POSS ) and oligofluorene segments. Optoelectronic analyses unequivocally show that the presence of these interconnecting B‐POSS can effectively reduce red‐shift in photoluminescence and electroluminescence during film formation. These hybrid poly(oligofluorenes) display stable blue emission with high color purity. Thermal analyses also indicate that they are vitrified polymers with high glass transition temperature (up to 125 °C). We believe that this strategy can be extended to other conjugated systems to control color purity in electroactive materials and holds promise as new emissive materials for various applications.

     

Quadrupolar Chromophores for Voltage Sensing and White‐Light Generation

A few‐state model predicts that spectral properties of some quadrupolar chromophores are affected by the application of static electric fields. These dyes can monitor neuronal activity (action potential), as a sensitive and versatile alternative to classical dipolar dyes and can also be used in organic LEDs: color‐tunable and/or white‐light emission is obtained by varying the working voltage (see chromaticity diagram).

     

Quantum Mechanics/Molecular Mechanics Study on the Photoreactions of Dark‐ and Light‐Adapted States of a Blue‐Light YtvA LOV Photoreceptor

The dark‐ and light‐adapted states of YtvA LOV domains exhibit distinct excited‐state behavior. We have employed high‐level QM(MS‐CASPT2)/MM calculations to study the photochemical reactions of the dark‐ and light‐adapted states. The photoreaction from the dark‐adapted state starts with an S₁→T₁ intersystem crossing followed by a triplet‐state hydrogen transfer from the thiol to the flavin moiety that produces a diradical intermediate, and a subsequent internal conversion that triggers a barrierless C−S bond formation in the S₀ state. The energy profiles for these transformations are different for the four conformers of the dark‐adapted state considered. The photochemistry of the light‐adapted state does not involve the triplet state: photoexcitation to the S₁ state triggers C−S bond cleavage followed by recombination in the S₀ state; both these processes are essentially barrierless and thus ultrafast. The present work offers new mechanistic insights into the photoresponse of flavin‐containing blue‐light photoreceptors.     

Blue‐Light‐Induced Carbene‐Transfer Reactions of Diazoalkanes

Carbenes are very important reactive intermediates to access a variety of complex molecules and are applied widely in organic synthesis and drug discovery. Typically, their chemistry is accessed by the use of transition metal catalysts. Herein, we describe the application of low‐energy blue light for the photochemical generation of carbenes from donor–acceptor diazoalkanes. This catalyst‐free and operationally simple approach enables highly efficient cyclopropenation reactions with alkynes and the rearrangement of sulfides under mild reaction conditions, which can be utilized for both batch and continuous‐flow processes.     

Chlorine‐Free Pyrotechnics: Copper(I) Iodide as a “Green” Blue‐Light Emitter

The generation of blue‐light‐emitting pyrotechnic formulations without the use of chlorine‐containing compounds is reported. Suitable blue‐light emission has been achieved through the generation of molecular emitting copper(I) iodide. The most optimal copper(I) iodide based blue‐light‐emitting formulation was found to have performances exceeding those of chlorine‐containing compositions, and was found to be insensitive to various ignition stimuli.     

Tactile UV‐ and Solar‐Light Multi‐Sensing Rechargeable Batteries with Smart Self‐Conditioned Charge and Discharge

A tactile, UV‐ and solar‐light multi‐sensing smart rechargeable Zn–air battery (SRZAB) with excellent cell performance, self‐conditioned charge/discharge, and reliable environmental responsivity is made by using multi‐scale conjugated block‐copolymer–carbon nanotube–polyurethane foam assemblies as both a self‐standing air electrode and a sensing unit. Multiscale engineering fully exploits the multi‐synergy among components to endow the newly designed metal‐free multi‐sensing air electrode (MSAE) with bifunctional oxygen reduction and evolution activities, pressure sensitivity, and photothermal and photoelectric conversion functions in a single electrode, enabling effective regulation of interface properties, electronic/ionic transport, or redox reactions in SRZAB upon various stimulations and establishing multiple working principles. MSAE‐driven SRZAB can be used as compressible power sources, self‐powered pressure and optical sensors and light‐to‐electrochemical energy systems.     

Mechanofluorochromic Carbon Nanodots: Controllable Pressure‐Triggered Blue‐ and Red‐Shifted Photoluminescence

Mechanofluorochromic materials, which change their photoluminescence (PL) colors in responding to mechanical stimuli, can be used as mechanosensors, security papers, and photoelectronic devices. However, traditional mechanofluorochromic materials can only be adjusted to a monotone direction upon the external stimuli. Controllable pressure‐triggered blue‐ and red‐shifted PL is reported for C‐dots. The origin of mechanofluorochromism (MFC) in C‐dots is interpreted based on structure–property relationships. The carbonyl group and the π‐conjugated system play key roles in the PL change of C‐dots under high pressure. As the pressure increases, the enhanced π–π stacking of the π‐conjugated system causes the red‐shift of PL, while the conversion of carbonyl groups eventually induces a blue‐shift. Together with their low toxicity, good hydrophilicity, and small size, the tunable MFC property would boost various potential applications of C‐dots.     

Self‐Powered Multimodal Temperature and Force Sensor Based‐On a Liquid Droplet

Herein we report a self‐powered multimodal temperature and force sensor based on the reverse electrowetting effect and the thermogalvanic effect in a liquid droplet. The deformation of the droplet and the temperature difference across the droplet can induce an alternating pulse voltage and a direct voltage, respectively, which is easy to separate/analyze and can be utilized to sense the external force and temperature simultaneously. In addition, an integral display system that can derive information from external temperature/force concurrently is constructed. Combined with advantages of excellent sensing properties and a simple structure, the droplet sensor has promising applications in a wide range of intelligent electronics.     

鲍曼不动杆菌LpxC的同源模建及分子对接

鲍曼不动杆菌已成为最普遍的医院致病菌,且耐药情况严峻.LpxC作为新抗菌药物靶点被大量研究,但鲍曼不动杆菌LpxC晶体尚未解析得到,基于其结构的药物设计等工作无法开展.以铜绿假单胞菌LpxC晶体结构为模板,通过同源模建方法获得鲍曼不动杆菌LpxC结构模型.较好的Ramachandran plot分布和Profile-3D结果验证了模型的合理性.用分子动力学模拟优化鲍曼不动杆菌LpxC模型,修补部分不合理构象.后续分子对接结果显示S构型的苄氧乙酰基羟肟酸类抑制剂比R构型分子能更有效地结合在F191,H237和K238组成的较浅口袋中,这可能是S构型抑制剂活性更高的主要因素,模拟结果与实验数据吻合较好.     

Enhancement of Photostability in Blue‐Light‐Emitting Polymers Doped with Gold Nanoparticles

A dramatic increase in the photostability of a blue‐light‐emitting polymer, poly(9,9‐dioctylfluorene), was achieved by the addition of 5–10 nm gold nanoparticles. The optical absorption band of the gold nanoparticles was tuned to resonate the triplet exciton ground state bandgap energy of the polymer. Photo‐oxidation rate of poly(9,9‐dioctylfluorene) was effectively reduced by doping the polymer with very small amounts (≈10⁻⁶–10⁻⁵ volume fraction) of the gold nanoparticles.

Retarded photo‐oxidation in PDOF nanocomposite films with various doped gold nanoparticles.     

Proton‐Activated Amorphous Room‐Temperature Phosphorescence for Humidity Sensing and High‐Level Data Encryption

Supramolecular co‐assembling terpyridine‐derivatives with nanoclay ( LP ) are exploited to acquire efficient amorphous room‐temperature phosphorescence (RTP). Experimental and theoretical investigations reveal that this co‐assembly not only brings about a configuration transformation from the trans‐trans ( a ) to the cis‐trans ( a′′ ) form via the protonating process, significantly narrowing the singlet‐triplet energy gap, thereby effectively facilitating the single‐triplet ISC processes, but also well protects the triplet state and suppresses the nonradiative transitions via restricting molecular rotation and vibration by the hydrogen‐bond interactions between them. Additionally, the flexible and transparent films, through co‐assembling 1 @ LP (or 2 @ LP ) with polyvinyl alcohol (PVA), also display excellent phosphorescence performance. Owing to their distinctive RTP performances, the RH sensing and high‐level data encryption are achieved.     

Blue‐light‐emitting polyfluorene functionalized with triphenylamine and cyanophenylfluorene bipolar side chains

A new bipolar conjugated polyfluorene copolymer with triphenylamine and cyanophenylfluorene as side chains, poly{[9,9‐di(triphenylamine)fluorene]‐[9,9‐dihexyl‐fluorene]‐[2,7‐bis(4′‐cyanophenyl)‐9,9′‐spirobifluorene]} ( PTHCF ), was synthesized for studying the polymer backbone emission. Its absolute weight‐average molecular weight was determined as 4.85 × 10⁴ by using gel permeation chromatography with a multiangle light scattering detector. In contrast to the electronic absorption spectrum in dilute solution, the absorbance of PTHCF in thin film was slightly blue shifted. By comparison of the solution and thin‐film photoluminescence (PL) spectra, a red shift of Δλ = 8–9 nm was observed in the thin‐film PL spectrum. The HOMO and LUMO energy levels of the resulting polymer were electrochemically estimated as ?5.68 and ?2.80 eV, respectively. Under the electric‐field intensity of 4.8 × 10⁵ V cm^?1, the obtained hole and electron mobilities were 2.41 × 10^?4 and 1.40 × 10^?4 cm² V^?1 s^?1, respectively. An electroluminescence device with configuration of ITO/PEDOT:PSS/ PTHCF _70%+PBD_30%/CsF/Ca/Al exhibited a deep‐blue emission as a result of excitons formed by the charges migrating along the full‐fluorene main chain. The incorporation of the bipolar side chains into the polymer structure prevented the intermolecular interaction of the fluorene moieties, balance charge injection/transport, and thereby improve the polymer backbone emission. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Blue‐shifted H‐bond in aromatic sulfines: An ab initio calculation

The intramolecular C? H···O?S H‐bond in the aromatic sulfines, HRC?S?O, was analyzed by NBO and QTAIM methods. The results of QTAIM analysis at the MP2/aug‐cc‐pVDZ level of theory show that the C? H···O?S H‐bond meets all the characteristics of an improper, blue shift hydrogen bond. NBO analysis at the MP2/6–31++G(d,p)//MP2/aug‐cc‐pVDZ level predicts a normal relationship between change of bond length and C? H rehybridization. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Pyrenoimidazole‐Based Deep‐Blue‐Emitting Materials: Optical,Electrochemical, and Electroluminescent Characteristics

A series of pyrenoimidazoles that contained various functional chromophores, such as anthracene, pyrene, triphenylamine, carbazole, and fluorene, were synthesized and characterized by optical, electrochemical, and theoretical studies. The absorption spectra of the dyes are dominated by electronic transitions that arise from the pyrenoimidazole core and the additional chromophore. All of the dyes exhibited blue‐light photoluminescence with moderate‐to‐high quantum efficiencies. They also displayed high thermal stability and their thermal‐decomposition temperatures fell within the range 462–512 °C; the highest decomposition temperature was recorded for a carbazole‐containing dye. The oxidation propensity of the dyes increased on the introduction of electron‐rich chromophores, such as triphenylamine or carbazole. The application of selected dyes that featured additional chromophores such as pyrene, carbazole, and triphenylamine as blue‐emissive dopants into multilayered organic light‐emitting diodes with a 4,4′‐bis(9H‐carbazol‐9‐yl)biphenyl (CBP) host was investigated. Devices that were based on triphenylamine‐ and carbazole‐containing dyes exhibited deep‐blue emission (CIE 0.157, 0.054 and 0.163, 0.041), whereas a device that was based on a pyrene‐containing dye showed a bright‐blue emission (CIE 0.156, 0.135).