查找使用阿拉丁产品的科研文献

Efficient fluorescent probe with dual acrylate sites via TD-DFT and addition-cyclization engineering for highly sensitive discrimination of Cys from GSH and Hcy

Xiumin Liu,Hengwei Zhang,Fengting Hu,Yi Wang,Xu Fei,Jing Tian

In this paper, an efficient and novel 1,3-bis(2-pyridylimino)-4,7-dihydroxyisoinndole scaffold-based two-site fluorescent probe 1,3-bis(2-pyridylimino)-4,7-phenylene diacrylate isoindole (BPI-AC) for the sensing of cysteine (Cys) has been designed and synthesized. We have studied the chemical structure and its fluorescent properties for the novel fluorescent probe with double recognition group by means of theoretical calculations and experimental measurements, which were carried out using density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations and experiments on organic chemical synthesis. Firstly, geometries have been recorded for the fluorescent probe. Theoretical research parameters including spectroscopic parameters, molecular orbitals , reaction sites and energy barrier Δ were obtained by fitting the electron density in a multiparticle system. Additionally, the spectral characteristics , selectivity and anti-interference performance of the probe were systematically investigated and verified by in vitro experiments. The experimental results showed that by using this probe, it was possible to quantitatively detect Cys in 1% dimethyl sulfoxide-containing water solution (pH 7.4). Super large Stokes shift (265 nm) endowed the probe low background signal. Finally, according to our theoretical calculations and the available experimental data, the probe BPI-AC with dual recognition sites could distinguish the biothiols with similar structure through series recognition reaction, and the Stokes shift was large, realizing the efficient detection of Cys specificity.

Synthesis and properties of ionic photoproduction of acid generators based on iodonium salts

Rihong Liu,Baicheng Feng,Fanuan Yu,Huifen Xin,Rong Qu,Yan Jin

This paper presents the design and synthesis of nine ionic photogenerating acid generators (PAGs) based on iodonium salts. The compounds were characterized using 1H NMR, 13C NMR, 19F NMR and UV, the structures and properties of 9 PAGs molecules were determined. The maximum ultraviolet absorption wavelength of each PAGs is in the range of 200-250nm, with a wide absorption domain, making it highly applicable. In addition, Using the uneven discoloration of Rhodamine B (RB) in the presence of acid, the acid production efficiency of 9 PAGs under 254nm ultraviolet irradiation was quantitatively measured in acetonitrile. It was found that all 9 PAGs underwent I-C cleavage and generated specific acids and other photolysis products. The mechanism for the heteroclitic cleavage of the I-C bond to generate acid was backed by calculations using time-dependent density functional theory (TD-DFT).

Manipulation and Theoretical Modeling of the Luminescence Performance of Silver Clusters in LTA Zeolites by Adjusting Extra-framework Cations

Ling Pan,Song Ye,Ruihao Huang,Meiyan Wang,Tianning Zheng,Haoran Zhang,Deping Wang

Luminescent silver clusters that are confined inside porous zeolites have attracted great research interest due to the combined advantages of high quantum yield, tunable emission, excellent chemical stability, and desirable adoption ability of this micronano-composite. In this research, a series of Ag-exchanged R-LTA/Ag (R = Li, Na, K) zeolites were synthesized, in which the silver clusters showed blue-shifted excitation in the UV region, red-shifted emission in the visible region, and decreased emission intensity when taking Li+, Na+, and K+ as the extra-framework cations, respectively. The [Ag4(H2O)xR4-sod]6– (x = 2, 4; R = Li, Na, K) structures were constructed, and the TD-DFT method was further carried out to study the influence of extra-framework cations on the luminescence performance of [Ag4]2+ clusters, in which the substitution of Al for Si and the reasonable hydrate levels were both taken into consideration. It is estimated that the S1 and S3 levels for the [Ag4(H2O)4Li4-sod]6– cluster, the S4 level for the [Ag4(H2O)4Na4-sod]6– cluster, and the S5 level for the [Ag4(H2O)2K4-sod]6– cluster can be effectively populated through direct excitation, and the S1 → S0 transition is assumed to be responsible for the radiative emission in the visible region for the [Ag4]2+ pseudo-tetrahedrons. This calculated energy level diagram and simulated absorption spectra of [Ag4(H2O)xR4-sod]6– (x = 2, 4; R = Li, Na, K) clusters explained the modified luminescence property of silver clusters in R-LTA/Ag (R = Li, Na, K) zeolites studied in this research and reported literature.

Manipulation and Simulation on the Luminescence Performance of Ag3+ Cluster in Heteroatom Ga-FAU Zeolite

Ruihao Huang,Song Ye,Meiyan Wang,Ling Pan,Tianning Zheng,Deping Wang

The manipulation of silver nanoclusters' luminescence performance in heteroatom zeolite was rarely reported. In this research, the heteroatom Ga-FAU zeolites were synthesized together with the Al FAU zeolite, based on which a series of Ag nanoclusters loaded Al FAUAg and mGa FAUAg zeolites were prepared. The spectroscopy characterization indicated that emission intensity of silver nanoclusters is greatly enhanced in Ga-containing zeolites compared to that in Al FAUAg, and meanwhile, the excitation and emission peak showed redshift and blueshift, respectively, with the introduction and increasing proportion of Ga atoms in mGa FAUAg. The TD-DFT method was carried out on the [Ag 3 Ga x D6r] + (x = 0, 1, 2, 3, 4, 5) clusters to study the effect of framework Ga on the luminescence properties of Ag 3 + in the D6r cavity of FAU zeolite, which suggested that the S 1 → S 0 transition of Ag 3 + is responsible for the radiative visible emission. Moreover, the low-energy shift for S 3 → S 0 transition and high-energy shift for S 1 → S 0 transition were observed with increasing x value in [Ag 3 Ga x D6r] + clusters, which is in accordance with the experimental observation. This research provided an alternative method for the manipulation of silver nanoclusters' luminescence performance by using heteroatom zeolite, which contributed to the design of solid phosphors with desirable emission.

Synthesis, photophysical properties and TD-DFT calculation of fluorescent dyes based on pyrenylthiazoles

Tong Dingyi,Duan Haifeng,Wang Jiajun,Zhang Li,Cao Jungang,Wei Zhonglin,Lin Yingjie

Two families of bis(imido) symmetrical Schiff bases: X-ray crystal structure and optical properties

Xiao-Na Ma,Xue-Jie Tan,Dian-Xiang Xing,Qi-Cheng Sui,Jian-Min Liu,Chen-Xing Xu,Yun Liu

Two families of bis(imido) symmetrical Schiff bases based on 4-methoxybenzaldehyde and thiophene-2-carbaldehyde linked by three lengths of alkyl groups (propane → butane → dodecane) have been prepared and characterized by 1 H and 13 C NMR, Q-TOF mass spectroscopy , IR and elemental analysis . The structures and conformations of four of them have been established by X-ray single-crystal diffraction analysis. It is interesting that different linking groups and different conformations hardly have effect on several properties. For example, they have nearly the same melting points, the same UV–Vis absorption spectra and the same fluorescence emission spectra. Spectral interpretations were guided by time-dependent DFT calculated transition energies and oscillator strengths , which agree well with the experimental UV–Vis spectra. TD-DFT calculations reveal that they share nearly the same transition mechanism, i. e. both bands are largely originated from the π → π* transitions and have little or nothing to do with the alkyl bridge. However, there are also important differences based on the identity of the terminal groups. For example, similar dimers 1 and 2 crystallize in very different space groups P 4 3 2 1 2 (No. 96) and P 2 1 / n (No. 14), and another set of similar dimers 4 and 5 crystallize in P 2 1 / n (No. 14) and P 2 1 2 1 2 1 (No. 16), respectively. This illustrates the flexible nature of these dimers in forming a variety of different packing motifs. The results of this research suggest that the rational design and prediction of crystal structures are more difficult than optical properties , even though similar weak interactions can be controlled in assembling the molecules.

SERS Chemical Enhancement Mechanism of Phenthoate on Gold Nanoparticles Revealed by DFT and TD-DFT

Qi Wang,Chao Song,Zhuang Bo,Haotong Yang,Xun Gao,Jingquan Lin

This study employed density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to investigate the interaction mechanism between Phenthoate and Au20 nanoclusters, and the solvent environment effect was examined under the polarizable continuum model (PCM). By comparing and analyzing theoretical Raman active spectra and experimental Raman spectra, the phenomenon of selective enhancement of specific vibrational modes in surface-enhanced Raman spectroscopy (SERS) was explained. By analyzing the molecular structure, frontier molecular orbitals (FMOs), ultraviolet–visible absorption spectra (UV–vis), noncovalent interactions (NCI), reduced density gradients (RDG), electron localization function (ELF), and localized orbital locator (LOL), the adsorption mechanism and the spectral characteristics induced by interfacial charge transfer were comprehensively revealed at the electronic level. Phenthoate chemically adsorbed onto the Au20 surface through the S atom, forming a stable complex. Meanwhile, this charge transfer mechanism effectively modulated the polarization rate of the molecule. This study provides a theoretical basis for elucidating the adsorption behavior and spectral response mechanism of organophosphorus pesticides on metal nanostructures, offering valuable insights for the design of highly sensitive SERS sensors.

Symmetry-breaking enhanced emission of C60 upon nucleobase binding: Spectroscopic observation combined with TD-DFT mechanism

Rui Feng,Youpeng Lu,Qiang Wang,Rongrong Han,Qi Yao,Yuhua Wu,Jianbo Wu,Hui Zhang,Hongcun Bai

Low-dimensional nanocarbons such as fullerenes are important nano-bio model systems. Their non-covalent interactions with nucleic acid building blocks can enable molecular recognition and alter photophysical behavior, but the structural-activity relationship between nucleobases molecular structure and spectroscopy remains unclear. Here, steady-state photoluminescence (PL) spectroscopy and quantum chemical calculations were used to study C60 adsorption with five nucleobases (A, C, G, T, and U) in dimethyl sulfoxide. C60 shows a visible PL band at ∼409 nm under 301 nm excitation. Equal concentrations of nucleobases markedly enhance C60 emission with minor shifts, following T > U > A > G > C. Density functional theory (DFT) predicts stable π-stacking-like complexes with separations of ∼3.3 Å and binding energies of −0.23 to −0.38 eV. Reduced density gradient analysis reveals dispersion-dominated attraction, consistent with physisorption. Time-dependent DFT indicates that low-energy singlet excitations remain mainly localized on C60, while adsorption-induced symmetry breaking gives these states weak oscillator strength, explaining the enhanced emission. Correlation relationship for the molecular orbital transition was established, and a quantitative assessment and transition contribution were provided based on the orbital transition diagrams. These results clarify fullerene-nucleobase recognition and support adsorption-enhanced fluorescence as a probe of base-dependent interactions.

Unveiling the competitive reaction pathways and photophysical evolution of a naphthalene-benzothiazole fluorescent probe for sulfite: A combined experimental and DFT/TD-DFT study

Qiao Li,Dong-Xu Cui,Yanli Leng,Shou-Jun Lai,Tingting Deng,Teng Niu,Shixia Yang,Hongru Dong

A naphthalene-benzothiazole probe (Q) for dual-channel sulfite detection was developed. • DFT calculations confirmed a kinetically dominant Michael addition at the C11 site. • Activation energy for the C11 pathway (16.11kcal/mol) is lower than alternative sites. • Hole-electron analysis revealed an ICT-to-LE transition during fluorescence quenching. The design and synthesis of a D–π–A type fluorescent probe based on a naphthalene-benzothiazole scaffold, for the colorimetric and fluorometric detection of sulfite (SO₃²⁻), are reported. Probe Q exhibits a selective response toward sulfite in DMSO H₂O (7:3, v/v) solution, with a detection limit of 0.42 μM. The reaction mechanism, evaluated through DFT and TD-DFT calculations using a benchmarked PBE0 functional, identifies several potential nucleophilic attack sites (C11, C14, and C16). Transition state and intrinsic reaction coordinate analyses confirm that the Michael addition at the C11 site is the kinetically dominant pathway, with an activation energy of 16.11 kcal/mol. Furthermore, combined hole-electron and excited-state analyses, based on vertical excitation calculations and oscillator strengths, reveal that the fluorescence quenching originates from a transition of the S₁ state from a bright intramolecular charge transfer (ICT) state to a non-radiative state upon sulfite addition. This study provides a molecular-level, synergistic experimental and theoretical framework for the rational design of reaction-based fluorescent probes.

Investigating the features in differential absorbance spectra of NOM associated with metal ion binding: A comparison of experimental data and TD-DFT calculations for model compounds

Mingquan Yan,Xuze Han,Chenyang Zhang

In this study, seven model compounds containing typical functional groups (phenolic and carboxylic groups) present in nature organic matter (NOM) were used to ascertain the nature of the characteristic bands in differential absorbance spectra (DAS) of NOM that are induced by metal ion binding. Some similarities were found between the DAS of the examined model compounds, caffeic acid , ferulic acid , sinapic acid , terephthalic acid , isophthalic acid , esculetin and myricetin and those of NOM. The binding of Cu(II) with carboxylic group might produce two peaks, A1 and A2, while the binding of Cu(II) with phenolic group might produce all four Gaussian peaks, from A1 to A4 displayed in the DAS of NOM. The UV–visible spectra predicted using time-dependent density functional theory (TD-DFT)-based methods met well with the experimental DAS of model compounds at different stages of Cu(II) binding. It demonstrates that the features in absorbance spectra are chiefly caused by HOMO (Highest Occupied Molecular Orbital) - LUMO (Lowest Unoccupied Molecular Orbital) transitions in the molecule and that the appearance of peaks in DAS reflects the changes of the molecular orbitals around reactive functional groups in a molecule before and after metal ion binding. The basis of the DAS features of NOM that are induced by metal ion binding could be identified primarily by the frontier molecular orbital theory .

Synthesis and optical properties of bispyrazolopyridine derivatives

Wei Ma,Yue Wang,Jing Gao,Ru Sun,Jian-Feng Ge

A series of bispyrazolopyridine (BPP) dyes with electron deficient or electron rich aromatic rings were synthesized, and their optical properties were evaluated. Dyes 3a-c connect the BPP unite with electron deficient moieties (pyridine ( 3a ), nitrobenzene ( 3b ), benzonitrile ( 3c )) by a single bond; dyes 3d-e consist of BPP and electron rich moieties (anisole ( 3d ), N,N -diethylaniline ( 3e )). Their optical properties in five organic solvents and water solution were investigated. They show absorption at 310–375 nm and emission at 400–580 nm in organic solvents. Meanwhile, dyes 3a and 3c-d have high fluorescence quantum yield in organic solvents (40%–84%) and aqueous solution (69%–89%), and they also exhibit excellent light stability. The pH-influenced optical properties tests indicate dyes 3a-e show different fluorescence intensities from alkaline (pH = 10.0) to acid condition (pH = 1.0). The protonation of BPP units and aromatic rings was used to explain their emission property, while (TD)DFT calculations were developed to understand the differences in the optical properties.