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Spectrophotometric and cyclic voltammetric study of interaction of Fe(iii) with vitamin B3 and vitamin B6
摘要： The interaction of Fe(III) with niacin and pyridoxine was investigated by UV-Vis. spectrophotometry. The metal to ligand ratio for Fe(III)- niacin system was found to be approximately 1 : 3 and for Fe(III)-pyridoxine system it was 1 : 1. The redox properties of uncoordinated Fe(III)/Fe(II) system is reversible at platinum electrode and in presence of the ligands the system was found to be quasi-reversible in nature. It was also found that in every case the system was diffusion controlled.
关键词： Cyclic voltammetry,Redox reaction,Slope ratio method,Continuous variation method,Vitamin B3
更新于2025-09-04 15:30:14
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Discrete Dimers of Redox-Active and Fluorescent Perylene Diimide-Based Rigid Isosceles Triangles in the Solid State
摘要： The development of rigid covalent chiroptical organic materials, with multiple, readily available redox states, which exhibit high photoluminescence is of particular importance in relation to both organic electronics and photonics. The chemically stable, thermally robust and redox-active perylene diimide (PDI) fluorophores have received ever-increasing attention owing to their excellent fluorescence quantum yields in solution. Planar PDI derivatives, however, generally suffer from aggregation-caused emission quenching in the solid state. Herein, we report on the design and synthesis of two chiral isosceles triangles wherein one PDI fluorophore and two pyromellitic diimide (PMDI) or naphthalene diimide (NDI) units are arranged in a rigid cyclic triangular geometry. The optical, electronic and magnetic properties of the rigid isosceles triangles are fully characterized by a combination of optical spectroscopies, X-ray diffraction, cyclic voltammetry, and computational modeling techniques. Single-crystal X-ray diffraction analysis shows that both isosceles triangles form discrete, nearly cofacial PDI-PDI π-dimers in the solid state. While the triangles exhibit fluorescence quantum yields of almost unity in solution, the dimers in the solid state exhibit very weak — yet at least an order of magnitude higher — excimer fluorescence yield in comparison with the almost completely quenched fluorescence of a reference PDI. The triangle containing both NDI and PDI subunits shows superior intramolecular energy transfer from the lowest excited singlet state of the NDI to that of the PDI subunit. Cyclic voltammetry suggests that both isosceles triangles exhibit multiple, easily accessible and reversible redox states. Applications beckon in arenas related to molecular optoelectronic devices.
关键词： intramolecular energy transfer,isosceles triangles,rigid covalent chiroptical organic materials,naphthalene diimide,excimer fluorescence,redox-active,π-dimers,photoluminescence,perylene diimide,pyromellitic diimide,cyclic voltammetry
更新于2025-09-04 15:30:14
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Voltammetric immunoassay of human IgG based on the release of cadmium(II) from CdS nanocrystals deposited on mesoporous silica nanospheres
摘要： The authors describe a nanocomposite that was obtained by in-situ deposition of CdS nanocrystals on mesoporous silica nanospheres (MSNs), and its use in an electrochemical immunoassay of human immunoglobulin G (HIgG). The MCN/CdS nanocomposite was covalently modified with the antibodies against HIgG and then employed in a voltammetric immunoassay at antibody-functionalized magnetic beads. Through sandwich immunoreaction, the MCN/CdS nanoprobes are quantitatively captured onto the magnetic beads where numerous Cd(II) ions are released in an acidic solution. The Cd(II) can be detected by anodic stripping voltammetry at a typical working potential of ?0.78 V (vs. Ag/AgCl). In combination with the high loading of CdS on MSNs, the use of the stripping voltammetric analysis renders the method high sensitivity. A wide linear range varying from 0.01 to 100 ng mL?1 is obtained for HIgG detection with a lower detection limit at 2.9 pg mL?1. In addition, the preparation of the nanoprobe is inexpensive. The magnetic bead-based assay does not require complex manipulations. Therefore, this method is deemed to possess a wide scope in that it may be applied to other immunoassays.
关键词： Magnetic beads,Anodic stripping voltammetry,Immunosensor,Nanoprobe,Signal amplification
更新于2025-09-04 15:30:14