Electron Spin Resonance Measurements Research Articles

AIE active fluorescent organic nanoparticles based optical detection of Cu2+ ions in pure water: a case of aggregation-disaggregation reversibility.

An AIE-active pyrene-terpyridine derivative, (4'-(pyren-1-yl)-2,2':6',2''-terpyridine) (1) was found to form nanoaggregate in an aqueous medium. The probe involved hydrogen bonding with solvent molecules that modulated the charge transfer behavior and consequently resulted in different spectroscopic behavior due to the formation of fluorescent organic nanoparticles (FONs). In the presence of Cu2+ ions, FONs displayed a ratiometric red shift of the absorption band (360 to 420 nm) accompanied by a prominent naked-eye color change from colorless to light yellow. With a gradual increase in water content, 1 displayed a huge red shift of the emission band (430 to 475 nm) denoting its switching from monomer to FONs. In the presence of Cu2+, the 475 nm emission band of FONs gradually diminished, facilitating the micromolar scale detection of Cu2+ (LOD = 8.57 μM) in a 100% aqueous medium with a fluorogenic color change from cyan to dark. The SEM and DLS data indicated the cation-induced disaggregation of FONs, which was further confirmed by mass spectral analysis and electron paramagnetic resonance measurement. In addition, the high selectivity of FONs towards Cu2+ ions over other potential cations and the 2 : 1 (1-Cu2+) binding stoichiometry were also determined. Moreover, the spectroscopic behavior of the monomeric amphiphilic probe was well supported by extensive DFT study. Such detection of Cu2+ ions in pure aqueous medium denoting an aggregation-disaggregation event is very rare in the literature.

Nano silver oxide-modified activated carbon as a novel catalyst for efficient removal of bacteria and micropollutants in aquatic environment.

Heterogeneous Fenton process is a promising water treatment technology for sterilization and degradation of organic pollutants, due to the strong oxidation of hydroxyl radicals (OH˙) generated. However, the low H2O2 activation efficiency and the instability of catalyst leading to low OH˙ production restricted development of this technology. Herein, we synthesized a novel porous activated carbon-loaded nano silver oxide (nAg2O/AC) catalyst to enhance the activation of H2O2 for removing bacteria (E. coli) and micropollutants (Tetracycline, TC) from water. In the nAg2O/AC Fenton system, reductive hydroxyl groups on AC accelerated Ag(i)/Ag cycle through mediated electron transfer, which markedly increased H2O2 activation efficiency to 73.7% (About 2.9 times that of traditional Fenton). Hence, nAg2O/AC Fenton achieved up to 6.0 log and 100% removal efficiency for E. coli and TC, respectively. The OH˙ as the major oxidizing species in nAg2O/AC Fenton system was detected and verified by radical scavenging tests and electron spin resonance (ESR) measurement. After 4 and 5 cycles of experiments, the removal of E. coli and TC still reached 5.2 log and 96%, respectively, confirming good stability of nAg2O/AC for considerable application prospects. This study concluded that nAg2O/AC is a promising H2O2 catalyst for simultaneous removal of bacteria and micropollutants in aqueous environment.

How the spin state tunes the slow magnetic relaxation field dependence in spin crossover cobalt(II) complexes.

A novel family of cobalt(II) compounds with tridentate pyridine-2,6-diiminephenyl type ligands featuring electron-withdrawing substituents of general formula [Co(n-XPhPDI)2](ClO4)2·S [n-XPhPDI = 2,6-bis(N-n-halophenylformimidoyl)pyridine with n = 4 (1-3) and 3 (4); X = I (1), Br (2 and 4) and Cl (3); S = MeCN (1 and 2) and EtOAc (3)] has been synthesised and characterised by single-crystal X-ray diffraction, electron paramagnetic resonance, and static (dc) and dynamic (ac) magnetic measurements combined with theoretical calculations. The structures of 1-4 consist of mononuclear bis(chelating) cobalt(II) complex cations, [CoII(n-XPhPDI)2]2+, perchlorate anions, and acetonitrile (1 and 2) or ethyl acetate (3) molecules of crystallisation. This unique series of mononuclear six-coordinate octahedral cobalt(II) complexes displays both thermally-induced low-spin (LS)/high-spin (HS) transition and field-induced slow magnetic relaxation in both LS and HS states. A complete LS ↔ HS transition occurs for 1 and 2, while it is incomplete for 4, one-third of the complexes being HS at low temperatures. In contrast, 3 remains HS in all the temperature range. 1 and 2 show dual spin relaxation dynamics under the presence of an applied dc magnetic field (Hdc), with the occurrence of faster- (FR) and slower-relaxing (SR) processes at lower (Hdc = 1.0 kOe) and higher fields (Hdc = 2.5 kOe), respectively. On the contrary, 3 and 4 exhibit only SR and FR relaxations, regardless of Hdc. Overall, the distinct field-dependence of the single-molecule magnet (SMM) behaviour along with this family of spin-crossover (SCO) cobalt(II)-n-XPhPDI complexes is dominated by Raman mechanisms and, occasionally, with additional temperature-independent Intra-Kramer [LS or HS (D > 0)] or Quantum Tunneling of Magnetisation mechanisms [HS (D < 0)] also contributing.

Galvanic replacement synthesis of PtPdAu hollow nanorods as peroxidase mimic with high specific activity for colorimetric detection.

Noble metal nanomaterials have been widely demonstrated to possess intrinsic enzyme-like properties and have been increasingly applied in the fields of analysis and biomedicine. However, current exploration of high-activity noble metal nanozymes is still far from adequate. The construction of hollow structures and adjustment of their elemental composition are effective ways to improve the specific activity (SA) of nanozymes. In this study, trimetallic PtPdAu hollow nanorods (HNRs) were developed using a galvanic replacement reaction and Kirkendall effect. The catalytic experiment showed that the PtPdAu HNRs possessed outstanding peroxidase-like performance and their SA value was up to 563.71 U mg-1, which is remarkable among various previously reported nanozymes and higher than that of monometallic or bimetallic counterparts with similar structure and size prepared in this study. Electron paramagnetic resonance (EPR)measurements showed that the PtPdAu HNRs could contribute to the formation of hydroxyl radicals (˙OH) in catalyzing hydrogen peroxide. When using PtPdAu HNRs as a nanozyme in the colorimetric detection of H2O2 and ascorbic acid (AA), the limits of detection were as low as 1.8 μM and 0.068 μM, respectively. This study demonstrates that PtPdAu HNRs are high-activity nanozymes and have the potential to be applied in the field of analysis.

Origin of the Cr3+ concentration-dependent broadband near-infrared emission in Sc2Si2O7.

The challenge of developing phosphors with tailored near-infrared (NIR) emission ranges to meet the diverse demands of various applications is a paramount concern in the contemporary realm of NIR phosphor research. A strong dependence of NIR emission on Cr3+ concentration has been demonstrated in Sc2-xSi2O7:xCr3+, which exhibits an NIR emission band at 840 nm for low Cr3+ doping concentrations (x = 0.001-0.01) and an anomalous NIR emission band at 1300 nm for high Cr3+ doping concentrations (x = 0.01-0.10). Careful investigation of the crystal structure, excitation and emission spectra, and luminescence decay curves indicates that the two NIR emissions can be attributed to the isolated Cr3+ ions and the Cr3+-Cr3+ pairs, respectively. The strong interaction of exchange-coupled Cr3+-Cr3+ pairs is supported by temperature-dependent emission spectra, luminescence decay curves and electron paramagnetic resonance (EPR) measurements. This work provides a new insight into the study of Cr3+-Cr3+ pairs for broadband NIR emission.

Comprehensive characterization and optoelectronic significance of Ho3+ and Cr3+ Co-doped ZnAl2O4 spinels.

The spinels ZnAl1.99-xHoxCr0.01O4 (with x = 0 and 0.001) were synthesized using a solid-state method, and various techniques were employed for their characterization. X-ray diffraction (XRD) analysis confirmed a cubic spinel structure with the Fd3̄m space group for both spinels. The morphology and homogeneity of the chemical composition were determined using scanning electron microscopy (SEM) and energy dispersive X-ray analysis. Raman and infrared vibrational spectroscopy techniques were also employed for analysis. The optical band gap (Eg) was determined from UV/vis absorption spectra, and the direct transition behavior was confirmed by Tauc's law. The observed large disorder and defect concentration are attributed to the presence of Cr3+ and Ho3+ ions, explaining this behavior. The electron paramagnetic resonance (EPR) measurement presented different types of traps. Room temperature absorption spectra exhibited multiple peaks corresponding to the 3d-3d and 4f-4f transitions of Cr3+ and Ho3+ ions. The results obtained validate the significance of our compounds in optoelectronic device applications.

Exploring spin multiplicity in MoS2.

The study of native point-defect-induced spin centres and the synergy of their origin and dynamics are key factors for developing the next-generation spintronics and quantum technologies using quasi-2D transition-metal dichalcogenides (TMDCs). With the help of low-temperature electron paramagnetic resonance (EPR) measurements and first-principles calculations within density functional theory (DFT), herein we report for the very first time the presence of high-spin paramagnetic centres Mo3+ and Mo2+ in sulfur-deficient hexagonal molybdenum disulfide (2H-MoS2-x) nanocrystals. This in fact opposes the established notion of spin S = 1/2 mediated by Mo5+ centres reported so far. The intrinsic lattice strain generated in the nanostructure was found to play a crucial role for such spin localization in this layered material. By performing spin-echo measurements, we find that molybdenum interstitials (S = 3/2) possess the shortest spin-lattice relaxation time (T1) as compared to the sulfur (S = 3/2) and oxygen vacancies (S = 1/2). Moreover, the temperature-dependent T1 measurements revealed a direct process for the spin-lattice relaxation of interstitial defects and a Raman process for the vacancy sites.

Full optimization of dynamic nuclear polarization on a 1 tesla benchtop polarizer with hyperpolarizing solids.

Hyperpolarization by dissolution dynamic nuclear polarization (dDNP) provides the opportunity to dramatically increase the weak nuclear magnetic resonance (NMR) signal of liquid molecular targets using the high polarization of electron radicals. Unfortunately, the solution-state hyperpolarization can only be accessed once since freezing and melting of the hyperpolarized sample happen in an irreversible fashion. A way to expand the application horizon of dDNP can therefore be to find a recyclable DNP alternative. To pursue this ambitious goal, we recently introduced the concept of recyclable hyperpolarized flow (HypFlow) DNP where hyperpolarization happens in porous hyperpolarizing solids placed in a compact benchtop DNP polarizer at a magnetic field of 1 T and a temperature of 77 K. Here we aim to optimize the radical concentrations immobilized in hyperpolarizing solids with the objective of generating as much polarization as possible in a timeframe (<1 s) compatible with future recyclable DNP applications. To do so, the solid-state DNP enhancement factors, build-up rates and DNP spectra of different hyperpolarizing solids containing various nitroxide radical loadings (20-74 μmol cm-3) are compared against the DNP performance of varying nitroxide concentrations (10-100 mM) solvated in a glassy frozen solution. We demonstrate that in <1 s, polarization enhancement goes up to 56 and 102 with surface-bound and solvated radicals, respectively, under the optimized conditions. For the range of nitroxide concentrations used cross effect DNP seems to be the dominant mechanism under benchtop conditions. This was deduced from the electron paramagnetic resonance (EPR) lineshape of TEMPOL investigated using Q-band EPR measurements.

Probing Decoherence in Molecular 4f Qubits

We probe herein the fundamental factors that induce decoherence in ensembles of molecular magnetic materials. This is done by pulse Electron Paramagnetic Resonance measurements at X-band (9.6 GHz) on single...

Six-coordinated nickel(II) complexes with benzothiadiazole Schiff-base ligands: synthesis, crystal structure, magnetic and HFEPR study.

Two new nickel(II) complexes, namely Ni(L1)2 (1) and Ni(L2)2·CH2Cl2(2) were obtained by reacting nickel(II) acetate tetrahydrate with the benzothiadiazole Schiff base ligands HL1 = 2-[4-(2,1,3-benzothiadiazole)imino]methyl-phenol or HL2 = 2-[(2,1,3-benzothiadiazol-4-ylimino)methyl]-6-methoxyphenol in the presence of Et3N. The tridentate NNO chelate ligands induce a distorted octahedral environment around the nickel(II) ions. Single crystal X-ray diffraction analysis reveals elongated Ni-N bonds with the nitrogen atom of the benzothiadiazole ring in both complexes. Intermolecular hydrogen bonds and π-π stacking interactions create two-dimensional and three-dimensional supramolecular arrays, respectively, for complexes 1 and 2. Magnetic susceptibility and high-field electron paramagnetic resonance measurements show the presence of significant magnetic anisotropy, with an axial distortion parameter D of -8--10 cm-1.

A synergistic radical concentration increase in eumelanin–PEDOT:PSS blends: mammalian pigment-based doping for thermopower improvement

The impact of eumelanin integration into PEDOT:PSS is explored here by means of in-depth electron paramagnetic resonance measurements to shed light on the possible contribution of the mammalian pigment to thermopower improvement of PEDOT:PSS.

Facile synthesis of direct Z-scheme PPy/NH2-UiO-66 heterojunction for enhanced photocatalytic Cr(VI) reduction, industrial electroplating wastewater treatment, and tetracycline degradation

Z-scheme heterojunction photocatalysts generally have excellent redox ability and robust removal efficiency for contaminants in water. Herein, we combined p-type PPy and n-type NH2-UiO-66 by ball milling to prepare a direct Z-scheme PPy/NH2-UiO-66 photocatalyst with ultra-high redox potential. Notably, the optimized efficiency of PPy/NH2-UiO-66 (the mass ratio of PPy to NH2-UiO-66 is 1 wt%, named PPy/NU-1) rapidly reduced Cr(VI) (>95%, 60 min) and TC degradation (>90%, 180 min) at 100 W LED light. Moreover, the PPy/NU-1 has high stability and good anti-interference ability, which can effectively remove Cr(VI) from industrial electroplating wastewater, and the Cr(VI) removal rate is 99%, which meets the industrial wastewater standard and has the potential attraction of actual wastewater treatment. In addition, the techniques of UV-Vis diffuse reflection, electron spin resonance (ESR), photoluminescence (PL), and photoelectrochemical measurement showed that PPy/NH2-UiO-66 composites improved the light capture ability, thereby improving the photocatalytic efficiency. The PPy/NU-1 has a very high redox potential by constructing a Z-scheme heterojunction, enhances the interfacial charge transfer ability, and improves the separation efficiency of photogenerated carriers. Finally, the mechanism of the Z-scheme was systematically by nitroblue tetrazolium (NBT) and p-phthalic acid (TA) transformation, ESR experiments, and density functional theory (DFT) calculations. This work provides a strategy for the preparation of visible photocatalysts with excellent photocatalytic activity and provides new insights for interfacial charge transfer and molecular oxygen activation.

Green rGO/FeNPs nanocomposites activated peroxydisulfate for the removal of mixed 17β-estradiol and estriol

Reduced graphene oxide/iron nanoparticles (rGO/FeNPs) synthesized by the chemical method have been used in Fenton oxidation of organic contaminants, yet little is known about biosynthesized rGO/FeNPs using green tea extract (GT) as how to activate persulfate in sulfate radical-based advanced oxidation processes. In this study, rGO/FeNPs were used to activate peroxydisulfate (PDS) for 17β-estradiol (βE2) and estriol (E3) removal. The rGO/FeNPs-PDS system removed 83.6% of βE2 and 62.5% of E3 within 240 min, which was confirmed by a combination of adsorption and degradation via both radical and non-radical pathways. Four main reactive species in βE2 and E3 degradation were observed, i.e., hydroxyl radical (·OH), sulfate radical (SO4·−), singlet oxygen (1O2) and electron transfer, with the respective contributions of ·OH (32.9 and 34.7%), SO4·− (16.1 and 19.7%), 1O2 (12.2 and 14.1%) and electron transfer (8.0 and 7.2%). Analysis of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Electron Paramagnetic Resonance (EPR) and electrochemical measurements all indicated that beside the well-known role of Fe, CO from rGO through the generation of ·OH, SO4·−, 1O2 and electron transfer, as well as GT through electron transfer also participated in the activation of PDS. Finally, the degradation pathways of βE2/E3 were proposed. Overall, this study provides a new insight into the biosynthesis of rGO/FeNPs to activate PDS for the oxidation of mixed emerging contaminants.

Preparation, structural analysis, efficient photocatalytic degradation mechanism and pathway for p-nitrophenol of Ag-deposited Co-coordination polymer composites

This study addressed the problem of photogenerated charge complexation in coordination polymers (CPs), a considerable barrier to stable, high-performance photocatalysts, by hydrothermally preparing a novel cobalt coordination polymer, [Co(DDB)0.5(PTP)(DMA) (H2O)2]·H2O (Co-CP) using the mixed ligands 1,4-di(3,5-dicarboylphenoxy) benzene (H4DDB) and 4′-(4′′-pyridyl)-2,4′,6′,4′′-terpyridine (PTP). Theoretical calculations have demonstrated that the metal-to-ligand charge transfer (MLCT) in Co-CP is crucial in enhancing charge separation efficiency. Additionally, a silver-deposited composite (Ag@Co-CP) was synthesized through photoreduction. With 1.65wt% Ag, the Ag@Co-CP-2 composites exhibited optimal photocatalytic degradation of various organic pollutants, including nitroaromatic, rhodamine B, methylene blue, basic magenta, and methyl orange. Using charge-coupled devices, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, density functional theory, electron spin resonance measurements, and liquid chromatography-mass spectrometry, we extensively examined the morphology, structure, and photoelectric properties of the developed materials. Our exploration of the structural-activity relationship was supported by results from these structural and optoelectronic analyses. Free radical capture tests and analyses of electron spin resonance led us to pinpoint ·O2−, h+, and ·OH as significant contributors to the reaction system. Finally, we outlined the degradation process, reaction mechanism, and potential pathways. This study contributes to the critical task of designing interfaces between noble metals and semiconductors for improved photocatalytic performance.

Selective etching induced Fe3O4 cubes with orderly aligned porous structure for the effective lithium-ion storage and bisphenol A degradation

A novel nitrogen-doped carbon coated Fe3O4 cubes (Fe3O4@N-C) with orderly aligned porous (OA-P) structure was prepared by an acid etching and a carbothermic reduction process. This unique Fe3O4@N-C cubes demonstrated excellent performances in both lithium-ion batteries (LIBs) and bisphenol A (BPA) degradation with PMS activation. As an excellent anode for LIBs, the Fe3O4@N-C with unique OA-P structure could effectively accelerate the Li+ and electron transfer, relieve the volume expansion during Li+ insertion/desertion and enhance the electrical conductivity, which attributed to the reversible capacity of 985.6 mAh g-1 after 200 cycles at the current density of 100 mA g−1. As employed in the PMS activated BPA degradation, the Fe3O4@N-C achieved a degradation rate of 99.8% within 60 min with good stability, which is contributed to the synergistic effects of the increased adsorption and activation sites for PMS and the facilitated mass transport due to the OA-P structures. In addition, the activate-species quench tests and electron paramagnetic resonance measurements revealed that the 1O2-based non-radical path played a dominant role in the BPA degradation.

Wavelength‐Recognizable SbSI:Sb2S3 Photovoltaic Devices: Elucidation of the Mechanism and Modulation of their Characteristics

AbstractThe output of photovoltaic (PV) devices is mostly independent of the wavelength of the incident light, whereas an anomalous wavelength‐dependent photovoltaic effect (WDPE) has recently been observed in antimony chalcohalide‐chalcogenide (SbSI:Sb2S3) PVs. Remarkably, the open‐circuit voltage (VOC) exhibits a reversible change between low VOC for short wavelengths and high VOC for long wavelengths. Herein, this work presents i) insights into the underlying mechanisms of this phenomenon by electron spin resonance (ESR) measurements and ii) the switchable character of WDPE depending on the hole transport material (HTM). Operando ESR measurements with light irradiation revealed that the hole density in the HTM is significantly suppressed when the ultraviolet component is included in the irradiation light. This indicated interfacial charge recombination rather than hole transfer to the HTM under short‐wavelength light irradiation, providing a basis for understanding the mechanism of WDPE. Furthermore, the use of poly(triarylamine) as the HTM unexpectedly exhibit the opposite wavelength‐VOC dependence, where a low VOC is observed with long‐wavelength light. In addition, the introduction of a polar gas accelerated the response speed of these effects. These findings shed light on the expansion of unique wavelength‐responsive single junction devices.

Metal-free catalysts with local fluorination regulation for peroxymonosulfate activation: Nearly 100 % singlet oxygen production for selective degradation of aqueous organic pollutants

Generating singlet oxygen (1O2) via activating peroxymonosulfate (PMS) is crucial for the selective removal of organic pollutants in aquatic environments. However, achieving efficient and selective conversion of PMS into 1O2 without consuming energy or metals remains a significant challenge. In this study, graphite phase carbon nitride (g-C3N4) was locally fluorinated via a simple polymerization method. The local fluorinated g-C3N4 (FCN) was used as a metal-free catalyst to activate PMS, enabling highly efficient degradation of 4-chlorophenol (100 %) and detoxification. The FCN/PMS system demonstrates exceptional selectivity for electron-rich pollutants, functions effectively across a broad pH range (2–10), and exhibits remarkable interference resistances to background scavenging ions and natural organic compounds. Furthermore, quenching experiments, probe tests, electron paramagnetic spin resonance measurements, electrochemical characterizations, and theoretical calculations demonstrated that 1O2 was the only reactive species in the catalytic process. Local fluorination regulated the electronic structure of g-C3N4, juxtaposing electron-rich fluorine with electron-deficient carbon dual active sites. This modification alters the electron transfer direction between PMS and g-C3N4, allowing for nearly 100 % selective generation of 1O2via dual electron transfer channels without the need for energy or metals. This study provides a new strategy for designing metal-free heterogeneous catalysts to selectively generate 1O2 in a green way and can facilitate the wider applications of advanced oxidation processes for water purification.

Spin-Polarized Radicals with Extremely Long Spin-Lattice Relaxation Time at Room Temperature in a Metal-Organic Framework.

The generation of spin polarization is key in quantum information science and dynamic nuclear polarization. Polarized electron spins with long spin-lattice relaxation times (T1) at room temperature are important for these applications but have been difficult to achieve. We report the realization of spin-polarized radicals with extremely long T1 at room temperature in a metal-organic framework (MOF) in which azaacene chromophores are densely integrated. Persistent radicals are generated in the MOF by charge separation after photoexcitation. Spin polarization of a triplet generated by photoexcitation is successfully transferred to the persistent radicals. Pulse electron spin resonance measurements reveal that the T1 of the polarized radical in the MOF is as long as 214 μs with a relatively long spin-spin relaxation time T2 of the radicals of up to 0.98 μs at room temperature. The achievement of extremely long spin polarization in MOFs with nanopores accessible to guest molecules will be an important cornerstone for future highly sensitive quantum sensing and efficient dynamic nuclear polarization.

Dynamics of Bioactive Compounds under the Influence of Yellow, Blue, and Violet Light Filters on Hippophae rhamnoides L. (Sea Buckthorn) Fruits

The current study was carried out to monitor the dynamics of phenolic compounds and vitamin C variations in Hippophae rhamnoides L. (sea buckthorn) under the influence of different color filters, as follows: yellow (590 nm), blue (450 nm), and violet (400 nm). The fruits were harvested at maturity from different parts of the canopy (i.e., base, middle, and top), immediately stored at −18 °C, and afterward lyophilized to reduce the loss of compounds for preparing the chemical assays that were carried out. HPLC-DAD-ESI+ was used to determine the phenolic compounds and vitamin C content of the fruits. EPR (electron paramagnetic resonance) measurements were also carried out to confirm the antioxidant character of the berries. This is the first study to examine the effect of different color filters on the accumulation of phenolic compounds and vitamin C content in the fruits of sea buckthorn. Among the three color filters used, the violet filter proved to be the most beneficial for the accumulation of total phenolic compounds (3.326 mg/g) and vitamin C (1.550 mg/g) in the berries. To reach high contents of phenolic compounds and vitamin C, the best setup included using very-high-energy emission LEDs as close as possible to blue and violet (400–450 nm). Therefore, the different light color intensities and temperatures on each level of a canopy play key roles in enhancing the phenolic compound content, antioxidant activity, and vitamin C content of sea buckthorn fruits. This knowledge will help provide insights into the accumulation of secondary metabolites and improve future production strategies in sea buckthorn.

Cation Recognition by Dibenzoarsacrowns

AbstractWe recently reported dibenzoarsacrowns as a novel class of host molecules, and in this work, prepared four dibenzoarsacrowns:12‐dibenzoarsacrown‐4, 15‐dibenzoarsacrown‐5, 18‐dibenzoarsacrown‐6, and 21‐dibenzoarsacrown‐7, and investigated their guest recognition behaviors for alkali metal and ammonium cations (Li+, Na+, K+, and NH4+). It was found that the triphenylarsine moiety of the dibenzoarsacrowns could be electrochemically oxidized and that their oxidation potentials shifted in response to perturbation because of the weak interaction between the arsenic atom and guest cations. Thus, dibenzoarsacrowns could electrochemically detect cations with sizes that fit the host cavity. Electron spin resonance measurements revealed the generation of cation radical species of arsenic under the application of voltage and supported the idea that the interaction between the arsenic atom and guest cations played a crucial role in the detection of cations. In addition, ion chromatography studies showed that size‐selective cation recognition by dibenzoarsacrowns was achievable even in aqueous solutions.