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8-Azaguanine

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Antonio Carlos Borin – One of the best experts on this subject based on the ideXlab platform.

  • Photochemical Relaxation Pathways of 9H-8-Azaguanine and 8H-8-Azaguanine
    The journal of physical chemistry. A, 2019
    Co-Authors: Adalberto Vasconcelos Sanches De Araújo, Antonio Carlos Borin
    Abstract:

    The photochemical reaction path approach, the MS-CASPT2 quantum-chemical method, and double-ζ basis sets (cc-pVDZ) were used to study 9H-8-Azaguanine and 8H-8-Azaguanine relaxation pathways. Severa…

  • Photochemical Relaxation Pathways of 9H‑8-Azaguanine and 8H‑8-Azaguanine
    , 2019
    Co-Authors: Adalberto Vasconcelos Sanches De Araújo, Antonio Carlos Borin
    Abstract:

    The photochemical reaction path approach, the MS-CASPT2 quantum-chemical method, and double-ζ basis sets (cc-pVDZ) were used to study 9H-8-Azaguanine and 8H-8-Azaguanine relaxation pathways. Several potential energy hypersurfaces were characterized by means of equilibrium geometries, surface crossings (conical intersections and singlet–triplet intersystem crossings), minimum energy paths, and linear interpolation in internal coordinates. The 9H-8-Azaguanine main photochemical event begins with the direct population of the 1(ππ* La) state, which evolves toward a conical intersection with the ground state after surmounting a small energy barrier, explaining why it is nonfluorescent. For 8H-8-Azaguanine, two relaxation mechanisms are possible, depending on the excitation energy. If the S1 1(ππ*) state is initially populated (lower-energy region), the system evolves barrierless to the S1 1(ππ*)min region, from where the excess energy is released. If the 1(ππ* La) state is populated (higher-energy radiation), the system will encounter conical intersections with the S2 1(nOπ*) and S1 1(ππ*) states before evolving to the 1(ππ* La)min region, from where a conical intersection with the ground state is accessible, favoring radiationless deactivation to the ground state. However, because a fraction of the population can be transferred from 1(ππ* La) to the S1 1(ππ*) state, emission from the S1 1(ππ*)min region is also expected, although weaker than it would be if the S1 1(ππ*) state were populated directly. Irrespective of the excitation energy, the emissive state is the same and a single fluorescence band is observed, with the strongest emission occurring upon excitation in the lower-energy region, as observed experimentally. Therefore, our computational study corroborates experimental results, attributing the emission of the neutral form of 8-Azaguanine in solution to the presence of the minor 8H-8-Azaguanine tautomer, while the 9H-8-Azaguanine major tautomer is nonfluorescent

Lin Gao – One of the best experts on this subject based on the ideXlab platform.

  • Electrochemical oxidation behavior of 8-Azaguanine at graphene-Nafion composite film-modified glassy carbon electrode
    Journal of Solid State Electrochemistry, 2014
    Co-Authors: Shengguo Zhai, Lin Gao
    Abstract:

    A simple but highly sensitive electrochemical sensor for the determination of 8-Azaguanine based on graphene-Nafion nanocomposite film-modified glassy carbon electrode (G-Nafion/GCE) was reported. The electrochemical behaviors of 8-Azaguanine at G-Nafion/GCE were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), chronoamperometry (CA), and chronocoulometry (CC). The results showed that the electrochemical sensor exhibited excellent electrocatalytic activity to 8-Azaguanine. 8-Azaguanine can be effectively accumulated at G-Nafion/GCE and produce a sensitive anodic peak, due to the synergetic functions of graphene and Nafion. Under the selected conditions, the modified electrode in pH 1.98 Britton-Robinson buffer solution showed a linear voltammetric response to 8-Azaguanine within the concentration range of 5.0 × 10−8∼3.0 × 10−5 mol L−1, with the detection limit of 1.0 × 10−8 mol L−1. And, the method was also applied to detect 8-Azaguanine in spiked human urine with wonderful satisfactory results.

  • Electrochemical Behavior of 8‐Azaguanine at DNA Langmuir–Blodgett Modified Glassy Carbon Electrode and Its Analytical Application
    Electroanalysis, 2009
    Co-Authors: Fei Wang, Lin Gao, Tian-lai Xing
    Abstract:

    A highly sensitive electrochemical biosensor for the detection of trace amounts of 8-Azaguanine has been designed. Double stranded (ds)DNA molecules are immobilized onto a glassy carbon electrode surface with Langmuir–Blodgett technique. The adsorptive voltammetric behaviors of 8-Azaguanine at DNA-modified electrode were explored by means of cyclic voltammetry and square wave voltammetry. Compared with bare glassy carbon electrode (GCE), the Langmuir–Blodgett film modified electrode can greatly improve the measuring sensitivity of 8-Azaguanine. Under the optimum experimental conditions, the Langmuir–Blodgett film modified electrode in pH 3.0 Britton–Robinson buffer solutions shows a linear voltammetric response in the range of 5.0×10−8 to 1.0×10−5 mol L−1 with detection limit 9.0×10−9 mol L−1. The method proposed was applied successfully for the determination of 8-Azaguanine in diluted human urine with wonderful satisfactory.

Tian-lai Xing – One of the best experts on this subject based on the ideXlab platform.

  • Electrochemical Behavior of 8‐Azaguanine at DNA Langmuir–Blodgett Modified Glassy Carbon Electrode and Its Analytical Application
    Electroanalysis, 2009
    Co-Authors: Fei Wang, Lin Gao, Tian-lai Xing
    Abstract:

    A highly sensitive electrochemical biosensor for the detection of trace amounts of 8-Azaguanine has been designed. Double stranded (ds)DNA molecules are immobilized onto a glassy carbon electrode surface with Langmuir–Blodgett technique. The adsorptive voltammetric behaviors of 8-Azaguanine at DNA-modified electrode were explored by means of cyclic voltammetry and square wave voltammetry. Compared with bare glassy carbon electrode (GCE), the Langmuir–Blodgett film modified electrode can greatly improve the measuring sensitivity of 8-Azaguanine. Under the optimum experimental conditions, the Langmuir–Blodgett film modified electrode in pH 3.0 Britton–Robinson buffer solutions shows a linear voltammetric response in the range of 5.0×10−8 to 1.0×10−5 mol L−1 with detection limit 9.0×10−9 mol L−1. The method proposed was applied successfully for the determination of 8-Azaguanine in diluted human urine with wonderful satisfactory.