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Theoretical elaboration about the excited state dynamical behaviors for a novel fluorescent sensor
摘要： Using the density functional theory (DFT) and time‐dependent density functional theory (TDDFT) methods, we theoretically explore a novel fluorescent sensor molecule (abbreviated as “2”) (Sensors Actuat B‐Chem. 2018, 263, 585). Because of its symmetry, three stable structures can be located, ie, 2‐enol, 2‐SPT, and 2‐DPT forms in both S0 and S1 states. Via comparing the bond lengths and bond angles involved in the hydrogen bonding moieties, we find the dual intramolecular hydrogen bonds should be strengthened in the S1 state. And based on infrared (IR) vibrational simulations, we further confirm the strengthening dual hydrogen bonds. Upon the photo‐excitation process, the charge redistribution via frontier molecular orbitals (MOs) reveals the tendency of excited state intramolecular proton transfer (ESIPT) reaction. In addition, the constructed S0‐state and S1‐state potential energy curves demonstrate that the excited state single proton transfer (ESSPT) should be the most supported one from 2‐enol to 2‐SPT form. In view of the S1‐state stable 2‐SPT and 2‐DPT structures as well as the fluorescence peaks of them, we can further confirm the ESSPT mechanism for 2 chemosensor. This work not only clarifies the excited state behaviors of 2 system but also successfully explain the previous experimental phenomenon.
关键词： charge redistribution,ESIPT,potential energy curves,intramolecular hydrogen bond
更新于2025-09-23 15:23:52
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Developing cysteamine-modified SERS substrate for detection of acidic pigment with weak surface affinity
摘要： In this paper, we developed cysteamine-modified surface-enhanced Raman scattering (SERS) substrate for detecting detect trace amount of acidic pigment that shows weak affinity with gold nanoparticles (Au NPs). To realize sensitive and reproducible detection of pigment with weak affinity, the SERS substrate was prepared by attaching cysteamine (CA) to the Au NPs, the acidic pigment molecule could rapidly reached to the surface of Au NPs because of the formation of multi-hydrogen-bond and electrostatic interaction between the pigment and CA molecule. The proposed method allowed us to detect five kinds of acidic pigment with a limit of 1.0 ppm, which is below the strictest safety limit. Compared with the previous methods, the advantages of the present substrate were its simple substrate preparation, high reproducibility and good universality. Furthermore, the reliable and enough accurate results had been obtained by using of the proposed substrates in the assay of trace pigment in real samples.
关键词： surface-enhanced Raman scattering,hydrogen bond interaction,cysteamine-modified,acidic pigment,weak affinity
更新于2025-09-23 15:23:52
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Revisited Dual Luminescence of 2,2′-Dipyridylamine Hydrochloride in Solution and Physical Processes behind It
摘要： Reaction of 2,2’-dipyridylamine (dpa) with hydrochloric acid results in formation of dpa hydrochloride (dpa?HCl), leading to substantial changes in its luminescent properties. Luminescence of dpa?HCl in solution has been previously interpreted as aggregation-induced phenomenon. In this work, the emission properties of dpa?HCl in solution were revisited, focusing on the impact of methanol and chloroform solvents. Luminescence, absorption, and 1H NMR spectroscopy were used to study physical state of the solute molecules and photophysical properties associated with them. The results clearly indicate that the concentration and solvent dependencies of luminescence are due to equilibrium between protonated dpaH + and neutral dpa forms, rather than aggregation in solution. In chloroform, strong emission with λem ? 430 nm is associated with the cationic dpaH + form. Polar and hydrogen bonding methanol not only facilitates dissociation of dpaH + cation, but also seems to quench its luminescence through pyridinium hydrogen bond, and the residual weak emission at λem ? 360 nm is associated with the neutral dpa form. The obtained results can be applied in design of new dpa based materials with desirable luminescent properties in both solution and solid state.
关键词： 2,2’-dipyridylamine,protonation,hydrogen bond,absorption,luminescence
更新于2025-09-23 15:21:21
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Investigation on the mechanism of ESIPT of 2-hydroxy-1-naphthaldehyde-(4-pyridinecarboxylic)- hydrazone and detection of Al<sup>3+</sup> ion
摘要： The sensing mechanism of 2-hydroxy-1-naphthaldehyde-(4-pyridinecarboxylic)-hydrazone for Al3+ is investigated based on the excited-state intramolecular proton transfer (ESIPT) and photo-induced electron transfer (PET) processes. Absorption and fluorescence spectra are calculated, which are well consistent with experimental results. By analyzing the major bond parameters, infrared (IR) vibrational spectra as well as frontier molecular orbitals (MOs), it can be concluded that the hydrogen bond is enhanced in the first singlet excited state (S1), which can also be visualized by the reduced density gradient function. Potential energy curves (PECs) are also scanned, which can elucidate that the ESIPT process is more likely to occur in the S1 state. Changes in molecular configuration and intensity of fluorescence emission confirmed that the ESIPT and PET processes are forbidden in the presence of Al3+.
关键词： ESIPT,Hydrogen bond,Reduced density gradient,Potential energy curve,Al3+ sensing
更新于2025-09-23 15:21:01
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Infrared spectroscopic analysis on structural changes around the protonated Schiff base upon retinal isomerization in light-driven sodium pump KR2
摘要： Krokinobacter rhodopsin 2 (KR2) was discovered as the first light-driven sodium pumping rhodopsin (NaR) in 2013, which contains unique amino acid residues on C-helix (N112, D116, and Q123), referred to as an NDQ motif. Based on the recent X-ray crystal structures of KR2, the sodium transport pathway has been investigated by various methods. However, due to complicated structural information around the protonated Schiff base (PRSB) region in the dark state and lack of structural information in the intermediates with sodium bound in KR2, detailed sodium pump mechanism is still unclear. Here we applied comprehensive low-temperature light-induced difference FTIR spectroscopy on isotopically labeled KR2 WT and site-directed mutant proteins (N112A, D116E, R109A, and R109K). We assigned the N-D stretching vibration of the PRSB at 2095 cm?1 and elucidate the hydrogen bonding interaction with D116 (a counter ion for the PRSB). We also assigned strongly hydrogen-bonded water (2333 cm?1) near R109 and D251, and found that presence of a positive charge at the position of R109 is prerequisite for the pumping function of KR2.
关键词： Retinal,Sodium ion pump,Low-temperature FTIR,Protein-bound water,Hydrogen bond
更新于2025-09-23 15:19:57
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Introducing Trifluoromethyl to Strengthen Hydrogen Bond for High Efficiency Organic Solar Cells
摘要： Nowadays, the ternary strategy has become a common way to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). The intermolecular interaction between the third component and donor or acceptor plays a key role in achieving a high performance. However, hydrogen bond as a strong intermolecular interaction is rarely considered in ternary OSCs. In this work, we introduce trifluoromethyl on a newly synthesized small molecular DTBO to strength hydrogen bonds between DTBO and IEICO-4F. Due to the existence of hydrogen bonds has a strong impact on electrostatic potential (ESP) and benefits π-π stacking in the active layer, the ternary OSCs show superior charge extraction and low charge recombination. In DTBO, PTB7-Th and IEICO-4F based ternary devices, the PCE increases from 11.02 to 12.48%, and short-circuit current density (JSC) increases from 24.94 to 26.43 mA/cm2 compared with typical binary devices. Moreover, the addition of DTBO can realize an energy transfer from DTBO to PTB7-Th and broaden the absorption spectrum of blend films. Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns show that the π-π stacking distance of IEICO-4F decreased after adding 10 wt% DTBO. The effect of the hydrogen bond is also achieved in the PM6: Y6 system, showing 16.64% efficiency by comparison to the 15.49% efficiency of binary system. This work demonstrates that introduce trifluoromethyl to enhance hydrogen bond which improve π-π stacking can achieve higher performance in OSCs.
关键词： energy transfer,ternary devices,organic solar cells,hydrogen bond,π-π stacking
更新于2025-09-23 15:19:57
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Eco-friendly sugar-based natural deep eutectic solvents as effective electrolyte solutions for dye-sensitized solar cells
摘要： Dye-sensitized solar cells containing sugar-based Natural Deep Eutectic Solvents (NADESs) as active electrolyte solvents have been studied in their photovoltaic (PV) properties, including main PV characteristics, IPCE, and EIS. Five monosaccharides were selected as NADES H-bond donors and investigated with a phenothiazine-based sensitizer carrying a glucose functionality and a glucose-based co-adsorbent (glucuronic acid) to explore directional intermolecular interactions and improve the PV performance. The highest power conversion efficiencies were recorded for cells containing the glucose-based sensitizer in the presence of glucuronic acid in the sugar-based NADES. When one of these components was omitted, performances were lower suggesting that the best response came from an interplay between the sugar-based units. Not only has the unprecedented use of a NADES as a fully natural and bio-renewable DSSC medium been presented, but for the first time an active role of the electrolyte solvent has been reported and exploited to increase the performance of the solar device.
关键词： deep eutectic solvents,solar energy,glucose,hydrogen bond,photovoltaics
更新于2025-09-23 15:19:57
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Selectivity, Thermodynamic and Anisotropic Properties of Substituted Liquid-Crystal Cyanoazoxybenzenes as Stationary Phases for Gas Chromatography
摘要： Herein we discuss physical properties of 4-(ω-hydroxyalkoxy)-4’-cyanoazoxybenzene homologs. 1D and 2D correlation NMR spectroscopy (in particular, 1Н, 15N-HMBC experiment) have allowed elucidation of structure of the prepared rod-like supramolecular cyanoazoxybenzenes. Mesomorphic properties of the compounds have been studied by means of polarization thermomicroscopy and differential scanning calorimetry. All the studied cyanoazoxybenzenes have revealed enantiotropic nematic mesomorphism over wide temperature range. Nematic mesophase of the eighth homolog has possessed large positive dielectric anisotropy. Introduction of small amounts of the prepared cyanoazoxybenzenes as additive has stabilized the mesophase and has increased the dielectric anisotropy of 4-pentyloxy-4’-cyanobiphenyl. Gas-liquid chromatography studies have shown that sorbents based on 4-(2-hydroxyethyloxy)-4’-cyanoazoxybenzene are highly selective towards various structural isomers; that cannot be achieved using conventional nematic liquid crystals. Thermodynamic evidence of specific interactions between the mesogen and the non-mesomorphic sorbate has been discovered.
关键词： Mesogen,Dielectric anisotropy,Sorbent,Hydrogen bond,Structural selectivity,NMR spectroscopy,Nematic phase,Position isomerism,Azoxybenzene,Double refraction,Supramolecule
更新于2025-09-19 17:15:36
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Hydrogen and Sulfonyl Radical Generation for the Hydrogenation and Arylsulfonylation of Alkenes Driven by Photochemical Activity of Hydrogen Bond Donor-Acceptor Complexes
摘要： An efficient photoinduced strategy for the hydrogenation and arylsulfonylation of alkenes has been developed. The reaction afforded a range of hydrogenated products and sulfonated oxindoles in high yields under external photocatalyst-free, oxidant- and reductant-free conditions. Mechanistic investigations suggested that this transformation is driven by the photochemical activity of hydrogen bond donor-acceptor complex, generated from the substrates of arylsulfinic acids and C6-(vinyl sulfone)phenanthridines or N-arylacrylamides via hydrogen bond interaction.
关键词： arylsulfinic acids,alkenes,photochemistry,radical transformation,hydrogen bond interaction
更新于2025-09-19 17:15:36
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Photoinduced electron transfer within supramolecular hemoprotein co-assemblies and heterodimers containing Fe and Zn porphyrins
摘要： Electron transfer (ET) events occurring within metalloprotein complexes are among the most important classes of reactions in biological systems. This report describes a photoinduced electron transfer between Zn porphyrin and Fe porphyrin within a supramolecular cytochrome b562 (Cyt b562) co-assembly or heterodimer with a well-defined rigid structure formed by a metalloporphyrin–heme pocket interaction and a hydrogen-bond network at the protein interface. The photoinduced charge separation (CS: kCS = 320 – 600 s–1) and subsequent charge recombination (CR: kCR = 580 – 930 s–1) were observed in both the Cyt b562 co-assembly and the heterodimer. In contrast, interestingly, no ET events were observed in a system comprised of a flexible and structurally-undefined co-assembly and heterodimers which lack the key hydrogen-bond interaction at the protein interface. Moreover, analysis of the kinetic constants of CS and CR of the heterodimer using the Marcus equation suggests that a single-step ET reaction occurs in the system. These findings provide strong support that the rigid hemoprotein-assembling system containing an appropriate hydrogen-bond network at the protein interface is essential for monitoring the ET reaction.
关键词： Hydrogen bond network,Photoinduced electron transfer,Cytochrome b562,Marcus theory,Hemoprotein assembly
更新于2025-09-19 17:15:36