Search

The influence of molecular stacking effect on photophysical property in solid phase was investigated theoretically. We found the out–plane distorted vibration and imidazole ring stretching vibration of triimidazo-[1, 3, 5]triazinethe were obviously suppressed in the aggregated state, which decreased Huang–Rhys factor and the corresponding reorganization energy of photophysical process, as a result, it restricted intramolecular motion and restrained dissipation pathways of the excess energy in the excited state, therefore, aggregation induced enhancement emission (AIEE) was found for the title compound from difluorochloromethane solution to solid state. The simulated emission spectrum by discrete spectral lines indicated the main peak was affected by the vibrational modes with lower frequencies, meanwhile the shoulder peak of the emission spectrum was affected by the middle–frequency modes. Furthermore, the predicted intersystem crossing rate (kiosk) and reverse intersystem crossing rate (krisc) using Marcus theory confirmed that an electron can successfully shift from its S1 state to the T1 state, however, the reverse T1 → S1 process can not come into being duo to very small krisc (10–6 − 10–9 s–1), therefore the phosphorescence can be observed. At last, we explored the influence of charge transfer process on the delayed fluorescence phenomenon of the title compound, the prompt fluorescence and the delayed fluorescence phenomenon from photo-induced charge transfer of both the paths can explain the experimental three-exponential fluorescent spectrum.

Hypochlorous acid (HOCl) is widely used in daily production and life because of its green and strongly oxidizing properties. Additionally, as a vital reactive oxygen species (ROS), it is an innate immune system weapon and performs a critical function in many pathophysiology processes. In this paper, a novel water-soluble fluorescent probe, BMH, with excellent performance is designed and synthesized by simple condensation of benzocoumarin and 2-mercaptoethanol. BMH has specific selectivity, excellent sensitivity, ultra-fast response (3 s), and a wide pH detection range. The fluorescence intensity of BMH has an excellent linear correlation with the concentration of HOCl in the scope of 0-10 μM, and the calculated detection limit (DL) is 2.45 nM. The intramolecular charge transfer (ICT) sensing mechanism of BL has been verified by fluorescence, UV, and MS studies as well as density functional theory (DFT) calculations. Furthermore, BMH can be incorporated into a solid-state visual sensor to detect HOCl conveniently. BMH was applied to detect HOCl-spiked actual water samples and achieved satisfying recovery rates. Also, the low-toxicity BMH can be successfully used to track changes in endogenous/exogenous HOCl in living cells. In short, BL provides a robust and reliable monitoring tool to reveal the biological functions of HOCl and ensure its safe use.

The displaced and distorted harmonic oscillator model, which has been proven to be appropriate in calculating vibronic spectra, is employed to treat the emission spectrum of title molecules in combination with a thermal vibration correlation function. The calculated results indicate that the main peak of the emission spectrum is visibly impacted by the normal modes with lower frequencies and that the shoulder peak is originated from the middle-frequency modes. On the level of time-dependent density functional theory (TDDFT), the calculated fluorescence lifetimes of TTM-3NCz and TTM-3PCz are 22.1 and 26.0 ns, respectively, which happen to coincide with the observed values of TTM-3NCz (17.2 ns) and TTM-3PCz (21.2 ns). The above data indicate that both the calculated radiative decay rates are reasonable at room temperature. Furthermore, we investigate the influence of the Duschinsky effect on the fluorescence quantum efficiency (FQE). When it is considered, the predicted FQE of the TTM-3NCz molecule is only 0.11%, and the observed value (49% in toluene) deviates significantly. If we ignore the Duschinsky effect, the FQE of TTM-3NCz increases dramatically to 41.8%. For the TTM-3PCz molecule (the FQE is 46% in toluene), the calculated FQE is 0.042% with the Duschinsky effect and increases to 45.2% without the Duschinsky effect. This phenomenon might be related to external factors and the nature of the TDDFT only considering a single configuration. In addition, the fluorescent properties of the fluorinated TTM-3NCz molecules are studied predictably. The obtained results show that the perfluorinated TTM-3NCz shows better luminous performance due to larger oscillator strength. Finally, the dimers, which are composed of both single title molecules, are explored theoretically to determine how they impact the fluorescent property; however, the effect can be nearly eliminated because of the small binding energies.

One of the causative agents of pokkah boeng disease (PBD), which affects sugarcane crops globally, is the fungus Fusarium sacchari. These fungal infections reduce sugar quality and yield, resulting in severe economic losses. Effector proteins play important roles in the interactions between pathogenic fungi and plants. Here, we used bioinformatic prediction approaches to identify 316 candidate secreted effector proteins (CSEPs) in the complete genome of F. sacchari. In total, 95 CSEPs contained known conserved structures, representing 40 superfamilies and 18 domains, while an additional 91 CSEPs contained seven known motifs. Of the 130 CSEPs containing no known domains or motifs, 14 contained one of four novel motifs. A heterogeneous expression system in Nicotiana benthamiana was used to investigate the functions of 163 CSEPs. Seven CSEPs suppressed BAX-triggered programmed cell death in N. benthamiana, while four caused cell death in N. benthamiana. The expression profiles of these eleven CSEPs during F. sacchari infection suggested that they may be involved in sugarcane-F. sacchari interaction. Our results establish a basis for further studies of the role of effector molecules in pathogen–sugarcane interactions, and provide a framework for future predictions of pathogen effector molecules.

In this paper, we employed first-principles methods and the QM/MM technique to study the thermally activated delayed fluorescence (TADF) phenomenon of a near-infrared molecule (PIPAQ) in vacuum, solution, and the aggregation state. Our calculated results show that (1) the cluster can decrease the energy gap between the first singlet excited state (S

The geometry of dimethyl chloronium ion ((CH3)2Cl+) was optimized at the MP2/6-311+g** level, and the structural parameters are in good agreement with experiment. The reaction mechanism about isomerization of (CH3)2Cl+ was also computed and discussed, the result indicated that the activation energy of the rate-determining step in this reaction is 250.6 kJ mol–1, protonated chloroethane (CH3CH2ClH)+ can be obtained by the synergistic effect of C—Cl bond breakage and H migration, and (CH3CH2ClH)+ may lose a proton and produce chloroethane when there exist other anions. In addition, the natural bond orbital (NBO) method was used to deeply analyze the interaction between (CH3)2Cl+ and carborane (CHB11Cl11)– moieties. The stabilization interaction energies between the cation and anion showed that the lone electron pair, which spreads on the chlorine atom attaching to the carborane anion, strongly reacts on anti-bonding C—H of the chloronium ion, consequently the non-planar C—H bond on the onium ion is elongated. The electrostatic potential map confirmed the negative charge distributed on chlorinated carborane and the positive charge on the onium ion. At last the migration mechanism of methyl cation, which transfers from the chloronium ion to the carborane anion, was calculated at B3LYP/6-31G level. The involved potential barrier was only 11.3 kJ mol–1. This indicated it is impossible that dimethyl chloronium ion turned into chloroethane when carborane anion was present, and it can only produce chloroform.

The insertion and abstraction reaction mechanisms of singlet and triplet CCl2 with CH3MH (M=O, S) have been studied by using the DFT, NBO and AIM methods. The geometries of reactions, the transition state and products were completely optimized by B3LYP/6–311G(d, p). All the energy of the species was obtained at the CCSD(T)/6–311G(d, p) level. The calculated results indicated that the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CCl2 can not only trigger the insertion reaction with C-H and M-H in four pathways, by which the products P1 [CH3OCHCl2, reaction I(1)], P3[Cl2HCCH2OH, reaction I(2)], P5[CH3SCHCl2, reaction II(1)] and P7[Cl2HCCH2SH, reaction II(2)] are produced respectively, but also abstract M-H, resulting P4 [CH2O+CH2Cl2, reaction I(3)] and P8[CH2S+CH2Cl2, reaction II(3)]. In addition, the important geometries in domain pathways have been studied by AIM and NBO theories.

The optimized geometries of the complexes between HnY (n=2, 3; Y=O, S, N) and LiNH2 have been calculated at the B3LYP/6-311++G** and MP2/6-311++G** levels. Three stable complexes were obtained. Frequency analysis showed that the enlarged 2N—4Li presents the abnormal blue shift in three complexes. The calculated binding energy with basis set super-position error (BSSE) and zero-point vibrational nergy (ZPE) corrections of complex I–III is −58.65, −31.66 and −69.59 kJ·mol−1 (MP2), respectively. Natural bond orbital theory (NBO) analysis has been performed, and the results revealed that the H2O⋯LiNH2 (complex I) and H3N⋯LiNH2 (complex III) are formed with coexisting σ-s and n-s type lithium bond interactions, complexII is formed with π-s type lithium bond interaction between HnY (n=2,3; Y=O, N) and LiNH2, and H2S⋯LiNH2 (complex II) is formed with n-s type lithium bond interaction between H2S and LiNH2. Natural resonance theory (NRT) and atom in molecule (AIM) theory have also been studied to investigate the bond order and topological properties of the lithium bond structures.

Objective: To investigate the molecular mechanism of Hoxd13-mediated congenital malformations in rat embryos. Methods: SD female rats were mated with male rats in a 1:1 mating scheme. Thirty pregnant female rats were randomly divided into three groups: the control group receiving a normal diet, the model group receiving a vitamin A-deficient diet, and the treatment group receiving a vitamin A-deficient diet supplemented with pcDNA-Hoxd13. The expression of Hoxd13 mRNA and protein in normal embryonic tissue and congenital malformations was determined by RT-PCR and Western blot analysis. At day 20, rats were dissected, and the fetal weight, body and tail length, and the number of live births, absorbed fetus, and stillbirth in each group were recorded. Wnt and Slim1 expression was detected by RT-PCR and Western blot analysis. β-catenin and c-myc expression was also quantified by Western blot analysis. Results: The expression of Hoxd13 mRNA and protein in congenital malformations was significantly lower compared with normal embryonic tissue (P

Density functional theory calculations were carried out to investigate the charge transfer of four tetrathiafulvalene derivatives. Perfluorination of dibenzo-tetrathiafulvalene (DB-TTF) increased the reorganization energy and was considered disadvantageous for the charge-transport process. Fluorination lowered the frontier orbitals of the compound, favoring electron—rather than hole-transport due to the low injection barrier. While intra-ring substitution of carbons of benzene with N atoms did not increase the reorganization energy, it enforced thermodynamic stability and decreased the charge injection barrier due to lowering the frontier orbital. Calculation results also showed that introduction of NH2 to DB-TTF can change the crystal structure and charge mobility, thus providing a method with which to promote ɛ-stacked structures. Calculation of charge transfer integrals using site energy correction methods was found to be more suitable for perfluorinated DB-TTF because it exhibits remarkable polarization effects.