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Tuning the electrochemiluminescent properties of iridium complexes of N-heterocyclic carbene ligands
摘要： A series of five heteroleptic Ir(III) complexes of the general form Ir(dfppy)2(C^C) have been prepared (where dfppy represents 2-(2,4-difluorophenyl)pyridine and C^C represents a bidentate cyclometalated phenyl substituted imidazolylidene ligand). The cyclometalated phenyl ring of the imidazolylidene ligand was either unsubstituted or substituted with electron donating (OMe and Me) or electron withdrawing (Cl and F) groups in the 2 and 4 positions. The synthesised Ir(III) complexes have been characterised by elemental analysis, NMR spectroscopy, cyclic voltammetry and electronic absorption and emission spectroscopy. The molecular structures for four Ir(III) complexes were determined by single crystal X-ray diffraction. Each of the Ir(III) complexes exhibited intense photoluminescence in acetonitrile solution at room temperature with quantum yields (ΦPL) ranging from 58% to 86%. Cyclic voltammetry experiments revealed one oxidation process (formally ascribed to the metal centre), and two ligand-based reductions for each complex. Complexes 1–5 gave moderate to intense annihilation and co-reactant electrochemiluminescence (ECL). Consideration of the electrochemical, spectroscopic and theoretical investigations provide insights into the electrochemiluminescence behaviour.
关键词： iridium complexes,electrochemiluminescence,cyclic voltammetry,photoluminescence,N-heterocyclic carbene ligands
更新于2025-09-19 17:15:36
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Raman Spectroscopy as an Assay to Disentangle Zinc Oxide Carbon Nanotube Composites for Optimized Uric Acid Detection
摘要： Refluxed zinc oxide (ZnO) nanoparticles (NPs) were prepared and attached to carboxylic acid functionalized multi-walled carbon nanotubes (COOH-MWNTs) via sonication. Practical optimization of electrocatalysts using sonication to disentangle a carbon nanotube composite for monitoring uric acid (UA) is shown. Monitoring UA is important for the management of medical disorders. Selection of sonication time is a crucial step in producing the desired composite. We report, for the first time, the practical use of Raman spectroscopy to tune the sonication involved in tethering ZnO NPs to the multi-walled carbon nanotube (MWNT) surface. Maximum current for detecting UA, using chronoamperometry and cyclic voltammetry, correlated with the highest sp2-hybridized carbon signal, as seen in the integrated Raman G band peak areas denoting maximum COOH-MWNT disentanglement. An array of ZnO/COOH-MWNT composites were prepared ranging from 60 to 240 min sonication times. Optimum sonication (150 min) corresponded with both maximum measured current and MWNT disentanglement. The sensor was able to quantitatively and selectively measure UA at clinically relevant concentrations (100–900 μM) with rapid current response time (< 5 s).
关键词： chronoamperometry,zinc oxide nanoparticles,Raman spectroscopy,cyclic voltammetry,multi-walled carbon nanotubes,electrochemical sensing
更新于2025-09-19 17:15:36
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Hexaarylbutadiene: a versatile scaffold with tunable redox properties towards organic neara??infrared electrochromic material
摘要： When 1,1,4,4-tetraanilinobutadiene skeleton is attached with two halogenated aryl units at 2,3-position, they undergo facile two-electron oxidation to give stable dicationic dyes which exhibit a near-infrared (NIR) absorption whereas the neutral dienes show only pale color. Therefore, a distinct electrochromic response with an absorption change in the NIR region is achieved, which are attracting considerable recent attention from the viewpoint of bioimaging. Herein, we demonstrate that the redox potentials of the 1,1,4,4-tetraanilinobutadiene can be precisely controlled by the donating properties of the amino group on the aniline unit as well as the number of halogen atoms on the aryl units at 2,3-positions on the butadiene. In contrast, the NIR absorption bands mainly depend on the number of halogen atoms irrespective to the donating properties of aniline unit. Thus, the hexaarylbutadiene skeleton is proven to be a versatile scaffold to develop less-explored organic electrochromic materials, whose redox and spectroscopic properties can be finely tuned by modifying/attaching the proper substituents.
关键词： Redox chemistry,Absorption,Cations,Cyclic voltammetry
更新于2025-09-19 17:13:59
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Modeling Equilibrium Binding at Quantum Dot Surfaces Using Cyclic Voltammetry
摘要： Cyclic voltammetry is demonstrated as a useful method to measure equilibrium binding between quantum dots and redox active small molecules. Specifically, the interaction of a library of ferrocene derivatives with CdSe interfaces is examined. For the strongly interacting systems, ferrocene carboxylic acid (FcCOOH) and ferrocene hexane thiol (Fc-hexSH), the binding equilibria can be quantitatively deduced from modeling the cyclic voltammetry data. This modeling allows extraction of the diffusion coefficients, equilibrium constants associated with both the reduced and oxidized species, and forward and reverse rates associated with binding for both the reduced and oxidized species. Taken together these data give direct insight into the binding of small molecules to quantum-dot surfaces as a function of oxidation state, critical information for the design of quantum dots as photoredox catalysts and charge transfer mediators.
关键词： quantum dots,surface chemistry,equilibrium binding,nanoparticles,cyclic voltammetry
更新于2025-09-19 17:13:59
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Direct culture-free electrochemical detection of cells in milk based on quantum dots-modified nanostructured dendrons
摘要： With regard to global food safety and preventing the spread of diseases caused by foodborne pathogens or their toxins, there is an increasing need for simple and rapid methods for the screening of such pathogens. We aimed to develop a fast and efficient biosensor for the screening of milk samples contaminated by Salmonella spp. and provide a quick and cost-effective method as an alternative to the time-consuming conventional cultivation- or PCR-based approaches. We exploited a simple but highly specific technique whereby bacterial cells were separated immunomagnetically, with subsequent reaction with conjugate; i.e. specific IgG molecule labelled with an electrochemically potent indicator. The unique structure of this indicator exploits the benefits of hyperbranched dendron molecules and heavy metal–derived quantum dots (QDs). Square-wave anodic stripping voltammetry (SWASV) using of screen-printed carbon electrodes with in situ formed Bi(III) film (BiSPCE) was used for the detection and quantification of metal ions released from the QDs (CdTe) after their acidic dissolution. The metal ion signals proportionally correlate with the amount of captured bacteria cells. By this method, the presence of Salmonella spp. was proven in 2.5 hours even in minimal number of bacterial cells (4 CFU) in 1 mL of the sample.
关键词： Salmonella spp.,Electrochemical immunosensor,Quantum dots,Stripping voltammetry,Foodborne pathogen,Nanostructured dendrons
更新于2025-09-19 17:13:59
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New Zn(II) Complexes of Substituted bis(Salicylidene)phenyl-1,2-diamino Based Organic Ligands: Synthesis, Photoluminescence, Applications in Forensic Fingerprint and Dye Sensitized Solar Cells
摘要： New azomethine-Zn(II) complexes of bis(salicylidene)phenyl-1,2-diamino organic ligand derivatives were synthesized by the reaction of salicylaldehyde, substituted phenyl-1,2-diamine with zinc acetate. The synthesized complexes were characterized by FTIR, 1H NMR and EDS. Their photophysical and electrochemical properties were studied and their applicability for dye-sensitized solar cells (DSSCs) and forensic finger print developments have been demonstrated. Photoluminescence studies revealed that the emission peaks of the complexes in solution state appeared at 372-406 nm and emitted blue light. Latent fingerprint detection study indicated that the powder compounds show good adhesion and finger ridge details without back ground staining. Based on these results, it was ascertained that these Zn(II) complexes can serve as a suitable non-dopant blue light emitting compound for flat panel display applications and applied to detect fingerprints on all types of smooth surfaces.
关键词： Latent finger print,Dye sensitized solar cells,Photoluminescence,Schiff base,Cyclic voltammetry,Zinc(II),Complexes
更新于2025-09-19 17:13:59
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Biocompatible Palladium Telluride Quantum Dot-Amplified Biosensor for HIV Drug
摘要： Indinavir (IDV) is a potent and well-tolerated protease inhibitor antiretroviral (ARV) drug used as a component of the highly active antiretroviral therapy (HAART) of human immunodeficiency virus (HIV). It undergoes hepatic first-pass metabolism that is catalysed by microsomal cytochrome P450-3A4 enzyme (CYP3A4), which results in pharmacokinetics that may be favourable or adverse. Therapeutic drug monitoring (TDM) of IDV during HIV treatment is therefore critical, in order to prevent the adverse effects of its first-pass metabolism and optimise an individual’s dosage regime. Biosensors are now the preferred diagnostic tools for TDM assessment at point-of-care, due to their high sensitivity and real-time response. An electrochemical biosensor for IDV was prepared by depositing a thin film of CYP3A4 (a thiolate enzyme) and thioglycolic acid-capped palladium telluride quantum dot (TGA-PdTeQD) on a cysteamine-functionalised gold disk electrode (Cyst|Au) using a combination of thiol and carbodiimide covalent bonding chemistries. The electrochemical signatures of the biosensor (CYP3A4|TGA-PdTeQD|Cyst|Au) were determined by cyclic voltammetry (CV) that was performed at a scan rate of 500 mV s?1, and the sensor responses at the characteristic reduction peak potential value of ? 0.26 V were recorded. The sensitivity, linear range (LR) and limit of detection (LOD) values of the indinavir biosensor were 4.45 ± 0.11 μA nM?1 IDV, 0.5–1.0 nM IDV (i.e. 3.6 × 10?4–7.1 × 10?4 mg L?1 IDV) and 4.5 × 10?4 mg L?1 IDV, respectively. The values of the two analytical parameters (LR and LOD) of the biosensor were by up to four orders of magnitude lower than the maximum plasma concentration (Cmax) values of indinavir (0.13–8.6 mg L?1 IDV). The IDV biosensor was successfully used to detect IDV in human serum samples containing dissolved indinavir tablet. This, therefore, indicates the indinavir biosensor’s suitability for TDM applications, using samples obtained within 1–2 h of drug intake at point-of-care, for which very low levels of the drug are expected.
关键词： Human serum,Limit of detection,Indinavir,Palladium telluride quantum dot,Cyclic voltammetry,Electrochemical sensors,Cytochrome P450-3A4
更新于2025-09-16 10:30:52
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Effect of organic dyes and polypyrrole on the efficiency of dye-sensitized solar cells
摘要： Polypyrrole films were coated on conductive glass by electrochemical deposition (alternative current of direct process). They were then used as the dye-synthesized solar cell counter electron electrodes. Scanning electron microscopy revealed that polypyrrole forms a nanoparticle like structure on the conductive glass. In the present study, two new organic dyes based on aniline and substituted 5-Nitrosalicylaldehyde with aniline were prepared and used and sensitizes in dye-sensitized solar cells. These dyes in solution and on a nano-anatase v2o5 substrate were investigated. Additionally, oxidation potential measurement were also carried out. Finally, dye-sensitized solar cells were fabricated to determine and conversion efficiency of each dye.
关键词： FESEM,Cyclic Voltammetry,FT-IR,Dye-sensitized solar cells,UV Spectroscopy,XRD,Nitrosalicylaldehyde-aniline
更新于2025-09-16 10:30:52
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Electrochemical performance of indium-tin-oxide-coated lossy-mode resonance optical fiber sensor
摘要： Analysis of liquids performed in multiple domain, e.g., optical and electrochemical (EC), has recently focus significant attention. Our previous works have shown that a simple device based on indium-tin-oxide (ITO) coated optical fiber core may be used for optical monitoring of EC processes. At satisfying optical properties and thickness of ITO a lossy-mode resonance (LMR) effect can be obtained and used for monitoring of optical properties of an analyte in proximity of the ITO surface. However, EC response of the ITO-LMR device to a redox probe has not been achieved for ITO-LMR sensor whereas it is generally observed for commercially available ITO electrodes. The changes in the response to a redox probe are typically used as a sensing parameter when EC label-free sensing is considered, so it is crucial for further development of combined LMR-EC sensing concept. In this work, we focus on enhancing the EC activity of the device by tuning ITO magnetron sputtering deposition parameters. Influence of the deposition pressure on the ITO properties has been the main consideration. Both optical and EC readouts in 0.1 M KCl containing such redox probes as 1 mM of K3[Fe(CN)6] or 1 mM 1,1′-Ferrocenedimethanol were discussed at different scan rate. The performed studies confirm that for optimized ITO properties the ITO-LMR sensor used as the EC electrode may also show excellent EC performance. The observed EC processes are quasi-reversible and diffusion-controlled. Moreover, for the devices, which offer improved EC response, an optical monitoring of the EC process is also possible. According to our best knowledge, fully functional combined optical and EC sensor, where optical effect is resonance-based and other than well-known surface plasmon resonance, is presented for the first time.
关键词： Electrochemical properties,Cyclic voltammetry,Optical properties,Lossy-mode resonance,Optical fiber sensor,Indium tin oxide,Magnetron sputtering
更新于2025-09-16 10:30:52
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The effect of bis-carboxylic groups of squarylium dyes on the efficiency of dye-sensitized solar cells
摘要： Symmetric squarylium dye (SQIND1) with bi-carboxylic groups has been synthesized and photoelectrochemical properties have been studied in comparison with its non-functionalized analog groups (SQIND2). The experimental results showed that the introduction of anchor carboxylic groups in SQIND1 sensitizer provides a more intimate contact with nanoparticles TiO2 which increases the number of charge carriers transferred from the SQIND1 to the semiconductor. The theoretical calculations and absorbance results show that the electron density of LUMO of SQIND1 is delocalized in the whole chromophore, leading to strong electronic coupling between SQIND1 sensitizer and conducting band of TiO2, resulting in improved dye-sensitized solar cell efficiency compared to SQIND2. Hence, the SQIND1 sensitized exhibit better photovoltaic performance. Although, the absence of any linker groups in the SQIND1, then SQIND1 was perfect efficiently sensitized on porous TiO2 with the long UV–Vis and NIR region up to 800?nm of the spectrum and showed higher remarkable performance of values, such as η of 3.3%, a Jsc of 7.6?mA/cm2, a Voc of 0.59, and FF of 0.73.
关键词： Cyclic voltammetry,Dye-sensitized solar cell,Symmetric squarylium dyes,Photoelectrochemical properties,DFT
更新于2025-09-12 10:27:22