Additional Molecules Research Articles

Activating the Intrinsic Zincophilicity of PAM Hydrogel to Stabilize the Metal-Electrolyte Dynamic Interface for Stable and Long-Life Zinc Metal Batteries.

As a potential material to solve rampant dendrites and hydrogen evolution reaction (HER) problem of aqueous zinc metal batteries (AZMB), hydrogel electrolytes usually require additional additives or multi-molecular network strategies to solve existing problems of ionic conductivity, mechanical properties and interface stability. However, the intrinsic zincophilic properties of the gel itself are widely neglected leading to the addition of additional molecules and the complexity of the preparation process. In this work, we innovatively utilize the characteristics of acrylamide's high zincophilic group density, activating the intrinsic zincophilic properties of PAM gel through a simple concentration control strategy which reconstructs a novel zinc-electrolyte interface different from conventional PAM electrolyte. The activated novel gel electrolyte with intrinsic zincophilic properties has high ionic conductivity and effectively suppresses water activity, thereby inhibiting HER corrosion. Meanwhile, it induces uniform deposition of (002) crystal planes, leading to excellent deposition kinetics and long cycle life, thereby ensuring high interfacial stability. Compared with conventional PAM gel electrolytes, the activated zincophilic group-rich hydrogel maintained excellent cycling stability (1 mA/cm2, 1 mAh/cm2) over 2250 hours; The Zn//MnO₂ coin cell using novel zincophilic group -rich hydrogel still retains a high specific capacity of more than 170 mAh/g at 0.5 A/g after 1000 cycles.

Reactivity of Thiolate and Hydrosulfide with a Mononuclear {FeNO}7 Complex Featuring a Very High N-O Stretching Frequency.

Synthesis, characterization, electronic structure, and redox reactions of a mononuclear {FeNO}7 complex with a very high N-O stretching frequency in solution are presented. Nitrosylation of [(LKP)Fe(DMF)]2+ (1) (LKP = tris((1-methyl-4,5-diphenyl-1H-imidazol-2-yl)methyl)amine) produced a five-coordinate {FeNO}7 complex, [(LKP)Fe(NO)]2+ (2). While complex 2 could accommodate an additional water molecule to generate a six-coordinate {FeNO}7 complex, [(LKP)Fe(NO)(H2O)]2+ (3), the coordinated H2O in 3 dissociates to generate 2 in solution. The molecular structure of 2 features a nearly linear Fe-N-O unit with an Fe-N distance of 1.744(4) Å, N-O distance of 1.162(5) Å, and <Fe-N-O angle of 178.3°, while that of 3 features a slightly bent Fe-N-O unit with an Fe-N distance of 1.750(5) Å, N-O distance of 1.157(6) Å, and <Fe-N-O angle of 173.3°. Complex 2 displays a very high N-O stretching frequency of 1844 cm-1 in dichloromethane and readily dissociates NO when dissolved in coordinating solvents such as acetonitrile or N,N-dimethylformamide. Investigation of the reduction of 2 by FTIR-SEC and EPR spectroscopy shows the generation of a {Fe(NO)2}9 species, and the results have been corroborated by electronic structure calculations. Furthermore, the reaction of 2 with bezenethiolate (PhS-) and hydrosulfide (HS-) allowed the unambiguous characterization of a dinitrosyl iron complex (DNIC), [Fe(SPh)2(NO)2]1-, and an unprecedented complex, [{(LKP)Fe(DMF)}2{Fe6S6(NO)6}]2+, featuring an iron-sulfur prismane dianion.

Bulk Trapping Organic Semiconductor with Amino-Additive Enabling Ultrasensitive NO2 Sensors.

Organic semiconductor (OSC) gas sensors have garnered considerable attention due to their promising selectivity and inherent flexibility. Introducing a functional group or modification layer is an important route to modulate the doping/trapping state of the active layer and the gas absorption/desorption process. However, the majority of the functionalization lies in the surface/interface assembling process, which is difficult to control the functional group density. This in turn brings challenges for precise modulation of the charge transport and the doping/trapping density, which will affect the repeatability and reproducibility of sensing performance. Herein, we propose a facile bulk trapping strategy incorporating amino-terminated additive molecules via the vacuum deposition process, achieving ultrahigh sensitivity of ∼2000%/ppm at room temperature to NO2 gas and approaching ∼3000%/ppm at 50 °C. Additionally, the device exhibits commendable reproducibility, stability, and low concentration detection ability, reaching down to several ppb, indicating promising potential for future applications. Comprehensive analysis of electrical properties and density functional theory calculations reveals that these exceptional properties arise from the favorable electrical characteristics of the bulk trapping structure, the high mobility of C8-BTBT, and the elevated adsorption energy of NO2. This approach enables the construction of stable and reproducible sensitive sensors and helps to understand the sensing mechanism in OSC gas sensors.

Density functional theory investigation of the contributions of π-π stacking and hydrogen bonding with water to the supramolecular aggregation interactions of model asphaltene heterocyclic compounds

ContextA complex supramolecular process involving electrostatic and dispersion interactions and asphaltene aggregation is associated with detrimental petroleum deposition and scaling that pose challenges to petroleum recovery, transportation, and upgrading. The homodimers of seven heterocyclic model compounds, representative of moieties commonly found in asphaltene structures, were studied: pyridine, thiophene, furan, isoquinoline, pyrazine, thiazole, and 1,3-oxazole. The contributions of hydrogen bonding involving water bridges spanning between dimers and π-π stacking to the total interaction energy were calculated and analyzed. The distance between the planes of the aromatic rings is correlated with the π-π stacking interaction strength. All the dimerization reactions were exothermic, although not spontaneous. This was mostly modulated by the strength of the hydrogen bond of the water bridge and the π-π stacking interaction. Dimers bridged by two water molecules were more stable than those with additional water molecules or without any water molecule in the bridge. Energy decomposition analysis showed that the electrostatic and polarization components were the main stabilizing terms for the hydrogen bond interaction in the bridge, contributing at least 80% of the interaction energy in all dimers. The non-covalent interaction analysis confirmed the molecular sites that had the strongest (hydrogen bond) and weak (π-π stacking) attractive interactions. They were concentrated in the water bridge and in the plane between the aromatic rings, respectively.MethodsThe density functional ωB97X-D with a dispersion correction and the Def2-SVP basis set were employed to investigate supramolecular aggregates incorporating heterocycles dimers with 0, 1, 2, and 3 water molecules forming a stabilizing bridge connecting the monomers. The non-covalent interactions were analyzed using the NCIplot software and plotted as isosurface maps using Visual Molecular Dynamics.

Promoting effect of polyoxometallic acid modification on the NH3-SCR performance of Mn-based catalysts

The strong oxidation capabilities of Mn sites render Mn-based catalysts showing high activities of selective catalytic reduction (SCR) at temperatures < 250℃, but simultaneously lead to the generation of by-product N2O with strong greenhouse effect. The activity-N2-selectivity trade-off was a prevalent observation in the development of Mn-based SCR catalysts. Here, a polyoxometallic acid enhancement strategy was devised to simultaneously promote the N2 selectivity and low-temperature SCR (LT-SCR) activity of Mn-based metal oxide catalysts, where the introduction of uniformly dispersed phosphomolybdic acid (HPMo) tuned the oxidation capabilities and enhanced NH3 adsorption-storage capability of catalysts. The combination of transient reaction, in-situ DRIFTS analysis and DFT calculations revealed that the main origin of N2O on the Mn-based catalysts was the deep oxidation of NH3, which was inhibited by the interaction between HPMo and Mn sites. Additional NH3 molecules adsorbed by the abundant acid sites supplied by HPMo further facilitated the SCR reaction. This strategy could guide the design of high-activity and high-selectivity LT-SCR catalysts for industrial denitration.

High donor-number and low content electrolyte additive for stabilizing zinc metal anode

The aqueous zinc ion batteries (AZIBs) are thought as promising competitors for electrochemical energy storage, though their wide application is curbed by the uncontrollable dendrite growth and gas evolution side reactions. Herein, to stabilize both zinc anodes and water molecules, we developed a modified electrolyte by adding a trace amount of N,N-diethylformanmide (DEF) into the ZnSO4 electrolyte for the first time in zinc ion batteries. The effectiveness of DEF is predicted by the comparison of donor number and its preferential adsorption behavior on the zinc anode is further demonstrated by several spectroscopy characterizations, electrochemical methods, and molecular dynamics simulation. The modified electrolyte with 5% v.t. DEF content can ensure a stable cycling life longer than 3400 h of Zn||Zn symmetric cells and an ultra-reversible Zn stripping/plating process with a high coulombic efficiency of 99.7%. The Zn||VO2 full cell maintains a capacity retention of 83.5% and a 104 mA h g−1 mass capacity after 1000 cycles. This work provides insights into the role of interfacial adsorption behavior and the donor number of additive molecules in designing low-content and effective aqueous electrolytes.

Achieving Dendrite-Free Zinc Metal Anodes via Molecule Anchoring and lon-Transport pumping.

The potential for scale-up application has been acknowledged by researchers for rechargeable aqueous zinc-ion batteries (ZIBs). Nonetheless, the progress of the development is significantly impeded due to the instability of the interface between the zinc anode and electrolyte. Herein, efficient and environmentally benign valine (Val) were introduced as aqueous electrolyte additive to stabilize the electrode/electrolyte interface (EEI) via functional groups in additive molecules, thus achieving reversible dendrite-free zinc anode. The amino groups present in Val molecules have a strong ability to adsorb on the surface of zinc metal, enabling the construction of anchored molecular layer on the surface of zinc anodes. The strongly polar carboxyl groups in Val molecules can act as ion-transport pumps to capture zinc ions in the electric double layer (EDL) through coordination chemistry. Therefore, this reconstructed EEI could modulate the zinc ion flux and simultaneously suppress side reactions and dendritic growth of Zn. Consequently, a long stable cycling up to 1400 h at a high current density of 20 mA cm-2 is achieved. Additionally, Zn//V2O5 full cell with Val additive exhibit enhanced cyclability, retaining 77 % capacity after 3000 cycles, displaying significant potential in promoting the commercialization of ZIBs.

Crystallization modulation and defect passivation in carbon-based perovskite solar cells using multifunctional group additive

Recently, carbon-based perovskite solar cells have attracted wide attention in academia and industry because of their simple preparation process, low cost, and adaptability to roll-to-roll industrial production. The combination of ternary perovskite composition and carbon electrode configuration is expected to meet the requirements of device performance and stability. However, low grain size, and high density of grain boundary and surface defect states result in serious non-radiative recombination, which is one of the main gaps between the carbon-based perovskite solar cells and metal-electrode-based devices. Based on the consideration of crystal tuning and defect passivation of ternary CsFAMA thin films, the additive molecule 5-(Difluoromethoxy)-2-mercapto-1H-benzimidazole (DMB) with multifunctional groups were introduced into the film. XRD show that the (100) and (200) crystal plane orientation growth directed by the DMB additive lead to the formation of the micro-sized perovskite. XPS suggests that DMB not only modulates the crystallization of the films but also exists at the grain boundaries, and realizes the passivation of undercoordinated Pb2+ defects and inhibits the generation of Pb0. The defect state density is significantly reduced, and the carrier lifetime is greatly improved. The possible mechanism for perovskite crystal growth as well as defect passivation based on Lewis acid-base coordination and hydrogen bond was also proposed. After the introduction of DMB, a power conversion efficiency of 14.40% was achieved, which was 13.4% higher than that of the control device. After nearly 1200 h of environmental stability test, the DMB modified device still retained 95% of the original efficiency. This work emphasizes the feasibility of simultaneously realizing the crystallization modulation and defect passivation of carbon-based perovskite solar cells using the additive with multifunctional groups, and provides a reference for the commercialization of carbon-based perovskite solar cells.

Construction of composite SERS substrate based on black phosphorus/mesoporous ZIF-67 and its selective monitoring of food additives

Semiconductor-based surface-enhanced Raman scattering (SERS) dependent on chemical mechanism has shown favorable selective enhancement and recognition capabilities. However, the limited Raman enhancement capability of conventional semiconductor-based still remains a great challenge in the effective monitoring of trace molecules in a practical complex environment. In this context, a novel two-dimensional composite semiconductor substrate was developed by in-situ growing reticular ZIF-67 mesoporous film upon black phosphorus (BP) nanosheets. An attractive synergistic chemical enhancement was triggered attributed to the efficient continued charge transfer process in the BP/ZIF-67 system. Particularly, a selective SERS enhancement of food additive molecules with different orbital structures was found owing to the coupling degree of intrinsic molecular resonance and photo-induced charge transfer. A sensitive detection of lycopene in beverage samples with a high recovery rate was finally realized by the BP/ZIF-67 composite substrate, which exhibited great potential in practical molecular selective recognition.

Preparation of novel [Co(SCN)4] hybrid material: crystal structure investigation, DFT mechanistic analysis, antioxidant activity, and molecular docking study for potential inflammatory disorder control

The crystal structure of the title solvated coordination compound, [Co (SCN)4 (BtaH)2]·(BtaH)2.6(H2O), consists of discrete complexes in which the Co2+ cations are sixfold coordinated by four N-bonded thiocyanate anions and two 1-H benzotriazolium molecules to generate distorted trans-CoN6 octahedra. The discrete entities are each connected by three solvate molecules into chains via strong O—H···N hydrogen bonds. These chains are further linked by additional O—H···N, N—H···O, N—H···S, O—H···S and O—H···O hydrogen bonds into a three-dimensional network. Within this network, channels are formed that propagate along the c-axis direction and embed additional acetonitrile solvent molecules that are hydrogen-bonded to the network. In addition, density functional theory (DFT) calculations using the M06-2X/gen method were used to study the system's electronic properties. Interestingly, molecular docking and topological analyses were performed on compounds against various target anti-inflammatory receptors to investigate which targets exhibit the best binding affinities and hydrogen-bonding interactions. Done. As a result, it exhibits excellent anti-inflammatory activity, making it a suitable drug candidate for inflammatory diseases.

Kinetics of direct and water‐mediated tautomerization reactions of five‐membered cyclic amides or lactams

AbstractAs part of a series of studies of hydrogen‐atom transfer or tautomerization reactions of imidic acid–amide species, , we report the rate constants for a set of 24 five‐membered cyclic compounds at low, 50–300 K, and high, 500–1500 K, temperatures. These rate constants are for both the high temperature direct reaction and for that mediated by an additional water molecule which facilitates the hydrogen transfer reaction at low temperatures. In the latter case we show that the rate of reaction from a pre‐reaction complex can be rapid at temperatures down to 50 K on a 1 ms timescale and is dominated by quantum mechanical effects as evaluated by small‐curvature and quantised‐reaction‐states tunnelling. In addition, we present thermochemical data such as enthalpies of formation, entropies, isobaric heat capacities and enthalpy functions for these largely unknown species which span a range of compounds from pyrolidinone to oxo‐tetrazoles.

Abstract 3244: EWS-FLI1-driven upregulation of UGT3A2 unlocks drug sensitivity pathway in Ewing sarcoma

Abstract Ewing sarcoma (ES), an aggressive pediatric bone tumor, presents a clinical challenge, particularly for metastatic or relapsed disease. The hallmark genetic alteration involves the fusion of the FET RNA-binding protein, EWSR1, with an ETS transcription factor, typically FLI1, resulting in the EWS-FLI1 fusion oncoprotein. EWS-FLI1 orchestrates a unique epigenetic program, leading to the aberrant expression of genes crucial for cell-cycle regulation, DNA damage response, and cell migration. Targeting the EWS-FLI1 fusion oncoprotein is a daunting task, which has prompted us to pursue other strategies in parallel. Here, we present an innovative approach harnessing the power of phenotypic drug screens to uncover amenable pathways for targeted medicines in ES. Leveraging data from the Broad Institute’s repurposing dataset encompassing 4,518 drug molecules screened across 578 adherent cancer cell lines using the high-throughput multiplexed screening platform known as PRISM, we identified compounds with selective efficacy against ES. The top-ranking compound identified for selective ES toxicity in the screen was R112, an ATP-competitive inhibitor of Spleen Tyrosine Kinase (SYK). In low-throughput evaluation, R112 induced selective ES cell death when compared to other sarcomas. However, the reported target of R112, SYK, is a dependency in ES based on the Cancer Dependency Map (DepMap) resource. Subsequent validation of compounds identified in the PRISM screen as selectively toxic in ES revealed that while majority of them induced selective ES cell death, their reported targets were diverse and not linked to known dependencies in ES. Notably, one of the emerging compounds, luteolin, a natural compound known for its antioxidative properties, stood out and was selected for further studies alongside R112. Comprehensive genome-wide CRISPR-rescue screens identified UGT3A2, encoding a UDP glycosyltransferase, along with its solute carrier, SLC35B4, as pivotal genes that when deleted rescued both R112 and luteolin-induced cytotoxicity in ES cells. UGT3A2, a direct target gene of EWS-FLI1, demonstrated hyperexpression in EWS-FLI1-positive ES cells and no expression in most cancer and normal cells. While ES cells do not depend on UGT3A2 for survival, this abnormal elevation of UGT3A2 expression emerged as a key determinant driving their hypersensitivity to a subset of additional small molecules identified from the PRISM screen. Despite divergent mechanisms and direct targets, these drugs shared a common phenoxy motif, which UGT3A2 glycosylated. This specific EWS-FLI1-induced UGT3A2 upregulation, thus, unveils a novel biomarker for drug sensitivity,paving the way for precision medicine strategies tailored for Ewing sarcoma. Beyond Ewing sarcoma, this work holds promise in reshaping therapeutic paradigms and offering new avenues for discovering safe and enhanced treatments across a spectrum of cancers. Citation Format: Olasunkanmi Olaoye, Colleen Harrington, Kenneth Ross, Bo Kyung A. Seong, Luk de Waal, Jun Qi, Jennifer Roth, Kimberly Stegmaier. EWS-FLI1-driven upregulation of UGT3A2 unlocks drug sensitivity pathway in Ewing sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3244.

Hysteresis-Free and Bias-Stable Organic Transistors Fabricated by Dip-Coating with a Vertical-Phase-Separation Structure.

The morphology of organic films plays a pivotal role in determining the performance of transistor devices. While the dip-coating technique is capable of producing highly oriented organic films, it often encounters challenges such as limited coverage and the presence of defects in gaps between strips, adversely affecting device performance. In this study, we address these challenges by increasing solution viscosity through the incorporation of a substantial proportion of dielectric polymers, thereby enhancing the participation of additional molecules during the film formation process when pulled up. This method produces continuous and oriented organic films with a notable absence of gaps, significantly improving the carrier mobility of transistor devices by more than twofold. Importantly, the fabricated devices exhibit remarkable reliability, showing no hysteresis even after 200 cycles of measurement. Furthermore, the current and threshold voltages of the devices demonstrate exceptional stability, maintaining steady after 10,000 s of bias measurement. This approach provides a solution for the cost-effective and large-scale production of organic transistors, contributing significantly to the advancement of organic electronics.

Influence of incubation period on membrane patch color for insoluble contaminant measurement in degraded hydraulic oils

Insoluble contaminants and varnish, resulting from oil degradation byproducts and sometimes depleted additive molecules, are initiated primarily due to thermal stress on the oil. This poses significant challenges in tribology, particularly for the lubrication systems of modern complex machinery, leading to severe debilitating effects such as loss of operating clearances and impaired heat transfer. Addressing varnish buildup is crucial, and timely oil analysis emerges as a valuable tool, offering essential insights into the oil degradation level and the potential presence of insoluble contaminants. Among the various laboratory testing methods available to assess varnish potential, colorimetric analysis, specifically Membrane Patch Colorimetry (MPC), is widely applied owing to its efficiency and cost-effectiveness. This study extends the application of MPC test principles, commonly utilized for turbine oils, to measure insoluble contaminants generated by degraded hydraulic fluids. Adhering to the ASTM D7843-21 standard, which stipulates the precision of this testing method for turbine oils is contingent upon the sample’s incubation period, our investigation focuses on exploring modifications to the standard 72-hour incubation period. We aim to assess the viability of shortening or extending this duration for conducting MPC tests on used hydraulic fluids, thereby potentially enhancing the precision and relevance of MPC tests in hydraulic fluid analysis.

Numerical investigations of translocation characteristics of nano-silica lunar dust across pulmonary surfactant monolayer

The interactions between nano-silica lunar dust (NSLD) on the moon surface and pulmonary surfactant (PS) monolayer will pose risks to astronaut health in future manned lunar exploration missions, but the specifics of these interactions are unknown. This study investigates them using the coarse-grained molecular dynamics method considering different sizes (5, 10, and 15 nm) and shapes (sphere, ellipsoid, and cube), with special focus on the unique morphology of NSLDs with bugles. The key findings are as follows: (1) The 10 nm and 15 nm NSLDs embed in the PS monolayer through the major sphere of spherical-type, major ellipsoid of ellipsoidal-type, or one edge of cubic-type NSLDs upon contact the PS monolayer. (2) Adsorbed NSLDs cause a higher Sz value (ASz > 0.84), while embedded NSLDs cause a lower Sz value (0.47 < ASz < 0.83) that decreases with an increase in the number of bulges. (3) The embedding process absorbs 50–342 dipalmitoylphosphatidylcholine (DPPC) molecules, reducing the PS monolayer area by 0.21%–6.05%. NSLDs with bulges absorb approximately 9–126 additional DPPC molecules and cause a 0.05%–3.22% reduction in the PS monolayer area compared to NSLDs without bulges. (4) NSLDs move obliquely or vertically within the PS monolayer, displaying two distinct stages with varying velocities. Their movement direction and speed are influenced by the increasing complexity of NSLD with more bulges on them. In general, larger NSLDs with sharper shapes and increasing complex morphology of more bulges cause more significant damages to the PS monolayer. These findings have implications for safeguarding astronaut health in future manned lunar exploration missions.

Unraveling the Molecular Size Effect on Surface Engineering of Perovskite Solar Cells.

Surface engineering in perovskite solar cells, especially for the upper surface of perovskite, is widely studied. However, most of these studies have primarily focused on the interaction between additive functional groups and perovskite point defects, neglecting the influence of other parts of additive molecules. Herein, additives with -NH3 + functional group are introduced at the perovskite surface to suppress surface defects. The chain lengths of these additives vary to conduct a detailed investigation into the impact of molecular size. The results indicate that the propane-1,3-diamine dihydroiodide (PDAI2 ), which possesses the most suitable size, exhibited obvious optimization effects. Whereas the molecules, methylenediamine dihydroiodide (MDAI2 ) and pentane-1,5-diamine dihydroiodide (PentDAI2 ) with unsuitable size, lead to a deterioration in device performance. The PDAI2 -treated devices achieved a certified power conversion efficiency (PCE) of 25.81% and the unencapsulated devices retained over 80% of their initial PCE after 600h AM1.5 illumination.

Spectroscopic properties, crystal structure, Hirshfeld surface analysis and DFT study of a new Cu(II) complex based on quinazolinone O,N,O-donor ligand

A quinazolinone-based Schiff base ligand 3-[(2‑hydroxy-5-methoxybenzylidene)amino]-2-(2‑hydroxy-5-methoxyphenyl)-2,3-dihydroquinazolin-4-one (L1) and its new mononuclear copper(II) complex [Cu(L1)Cl(H2O)] (1) were synthesised and fully characterised by various spectroscopic techniques (NMR, FTIR, UV–Vis) and single-crystal X-ray diffraction study. The aspherical model of the crystal structure of the ligand L1 as well as of the copper(II) complex 1 was refined by the Hirshfeld Atom Refinement method. The crystal structure of the copper(II) complex shows the existence of a substitution disorder at the position of the water molecule, which represents two different complex molecules [Cu(L1)Cl(H2O)] (1a) and [Cu(L1)Cl] (1b) with different coordination polyhedra around the copper atom. The majority of the mononuclear complex [Cu(L1)Cl(H2O)] (1a) in the crystal structure contains a coordinated water molecule, but the minority in the crystal structure contains a mononuclear complex [Cu(L1)Cl] (1b) and a water molecule is outside the coordination sphere around the copper atom. The crystal structure of complex 1 showed a penta-coordinated (1a) or tetra-coordinated (1b) Cu atom in the shape of a tetragonal pyramid (1a) or square planar (1b) formed by a chloride atom in the equatorial plane, and a Schiff base bound as an O,N,O-tridentate ligand, and an additional water molecule in the axial position (only 1a). A detailed analysis of the intermolecular interactions was investigated using three-dimensional 3D Hirshfeld surfaces and their associated two-dimensional 2D fingerprint plots. Hirshfeld surface analysis was performed for both crystal structures. Furthermore, theoretical DFT analysis has been performed in order to interpret the experimental data. In order to obtain high quality DFT data, we present here a new basis set B1MH, which is an extension of the LanL2DZ basis with incorporated polarisation and diffusion functions for heavy atoms (C, N, O, Cl and Cu) and added ECPs for Cl and Cu atoms. The presented B1MH basis set allowed us to obtain better theoretical results than those previously published.

Insights into additional lactone-based signaling circuits in Streptomyces: existence of acyl-homoserine lactones and LuxI/LuxR homologs in six Streptomyces species.

Acyl-homoserine lactones (AHLs), mediating pivotal physiological activities through quorum sensing (QS), have conventionally been considered limited to Gram-negative bacteria. However, few reports on the existence of AHLs in Gram-positive bacteria have questioned this conception. Streptomyces, as Gram-positive bacteria already utilizing a lactone-based QS molecule (i.e., gamma-butyrolactones), are yet to be explored for producing AHLs, considering their metabolic capacity and physiological distinction. In this regard, our study examined the potential production of AHLs within Streptomyces by deploying HPLC-MS/MS methods, which resulted in the discovery of multiple AHL productions by S. griseus, S. lavendulae FRI-5, S. clavuligerus, S. nodosus, S. lividans, and S. coelicolor A3(2). Each of these Streptomyces species possesses a combination of AHLs of different size ranges, possibly due to their distinct properties and regulatory roles. In light of additional lactone molecules, we further confirm that AHL- and GBL-synthases (i.e., LuxI and AfsA enzyme families, respectively) and their receptors (i.e., LuxR and ArpA) are evolutionarily distinct. To this end, we searched for the components of the AHL signaling circuit, i.e., AHL synthases and receptors, in the Streptomyces genus, and we have identified multiple potential LuxI and LuxR homologs in all 2,336 Streptomyces species included in this study. The 6 Streptomyces of interest in this study also had at least 4 LuxI homologs and 97 LuxR homologs. In conclusion, AHLs and associated gene regulatory systems could be more widespread within the prokaryotic realm than previously believed, potentially contributing to the control of secondary metabolites (e.g., antibiotics) and their complex life cycle, which leads to substantial industrial and clinical applications.

Influence of donor or acceptor presence on excitation states in molecular chains: Nonadiabatic polaron approach.

In this paper, we considered a molecular structure that consists of a molecular chain and an additional molecule (donor or acceptor) that can inject (or remove) single excitation (vibron, electron, etc.) onto the molecular chain. We assumed that the excitation forms a self-trapped state due to the interaction with mechanical oscillations of the chain structure elements. We analyzed the energy spectra of the excitation and showed that its state (when it migrates to the molecular chain) has the properties of the nonadiabatic polaron state. The conditions under which the excitation can migrate from one subsystem to another one were considered. It was shown that the presence of a "donor" molecule cannot significantly change the properties of the excitation located on the molecular chain. At the same time, the molecular chain can affect the position of the energy level of the excitation localized on the donor subsystem. Indirectly, this can influence the process of excitation migration from one subsystem to another one. The influence of the basic energy parameters of the system and the environment temperature on this process are discussed. The entire system was assumed to be in thermal equilibrium with the environment.

Switching of Protonation Sites in Hydrated Nicotine via a Grotthuss Mechanism.

The switching of the protonation sites in hydrated nicotine, probed by experimental infrared (IR) spectroscopy and theoretical ab initio calculations, is facilitated via a Grotthuss instead of a bimolecular proton transfer (vehicle) mechanism at the experimental temperature (T = 130 K) as unambiguously confirmed by experiments with deuterated water. In contrast, the bimolecular vehicle mechanism is preferred at higher temperatures (T = 300 K) as determined by theory. The Grotthuss mechanism for the concerted proton transfer results in the production of nicotine's bioactive and addictive pyrrolidine-protonated (Pyrro-H+) protomer with just 5 water molecules. Theoretical analysis suggests that the concerted proton transfer occurs via hydrogen-bonded bridges consisting of a 3 water molecule "core" that connects the pyridine protonated (Pyri-H+) with the pyrrolidine-protonated (Pyrro-H+) protomers. Additional water molecules attached as acceptors to the hydrogen-bonded "core" bridge result in lowering the reaction barrier of the concerted proton transfer down to less than 6 kcal/mol, which is consistent with the experimental observations.