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Search Results (18)

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Keywords = photo induced electron transfer (PET)

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40 pages, 12301 KiB  
Review
Luminescent Pyrene-Derivatives for Hg2+ and Explosive Detection
by Muthaiah Shellaiah, Kien-Wen Sun, K. Anandan, Arumugam Murugan, Vijayaraj Venkatachalam, Mayank Bhushan, Mani Sivakumar, E. Manikandan, Kumaravel Kaliaperumal and Wen-Tai Li
Chemosensors 2025, 13(4), 145; https://doi.org/10.3390/chemosensors13040145 - 14 Apr 2025
Cited by 2 | Viewed by 1144
Abstract
Mercury and explosives are well-known hazards that affect the environment and threaten society. Mercury generally exists as inorganic mercuric (Hg2+) salts, and its detection via fluorometric response is highly notable. Likewise, mainstream explosives contains a nitro (−NO2) moiety as [...] Read more.
Mercury and explosives are well-known hazards that affect the environment and threaten society. Mercury generally exists as inorganic mercuric (Hg2+) salts, and its detection via fluorometric response is highly notable. Likewise, mainstream explosives contains a nitro (−NO2) moiety as a functional unit, and numerous reports have quantified them using fluorescence quenching. Among the available literature, there are still noticeable concerns about the environmental and biological applicability of luminescent pyrene derivaives-tunedfluorometric detection of Hg2+ and explosives. In the presence of Hg2+ ions, pyrene derivatives tend to form excimers, which can be tuned to the chelation-enhanced fluorescence (CHEF), photo-induced electron transfer (PET), or fluorescence resonance energy transfer (FRET), etc., to exhibit “Turn-On” or “Turn-Off” fluorescence responses. On the other hand, π-π stacking of emissive pyrene-derivatives may lead to J- or H-type aggregation via self-excimers (Py-Py*), which has been found to be quenched/enhanced by explosive hazards. In fact, −NO2-containing explosives interact with pyrene derivatives, leading to exceptional fluorescence quenching or enhancement. This review details the use of pyrene derivatives toward the sensing of Hg2+ and explosives with demonstrated applications. Further, the design requirements, sensory mechanisms, advantages, limitations, and the future scope of using the reported pyrene derivatives in Hg2+ and explosives sensing are discussed. Full article
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14 pages, 4941 KiB  
Article
The Construction of Carbazole-Based Metal–Organic Frameworks as Fluorescent Probes for Picric Acid Detection
by Yichang Jia, Xin Wang, Hechuan Li and Cheng He
Chemosensors 2025, 13(3), 105; https://doi.org/10.3390/chemosensors13030105 - 13 Mar 2025
Viewed by 997
Abstract
Nitroaromatic-explosives (NEs) not only threaten global security but are also recognized as a highly toxic pollutant. Metal–organic framework Zn-Ms (Zn-M1, Zn-M2) were synthesized in this study via the coordination-driven self-assembly of Zn ions and a carbazole-based ligand [...] Read more.
Nitroaromatic-explosives (NEs) not only threaten global security but are also recognized as a highly toxic pollutant. Metal–organic framework Zn-Ms (Zn-M1, Zn-M2) were synthesized in this study via the coordination-driven self-assembly of Zn ions and a carbazole-based ligand L containing an aldehyde group. They inherited the excellent fluorescence performance of ligand L and could work as a fluorescent sensor for detecting picric acid (PA) at low concentrations. Zn-Ms showed an emission at 450 nm and exhibited a higher fluorescence quenching efficiency toward PA than other related NEs. The results suggest that the fluorescent response might be attributed to the inner filter effect (IFE); Förster resonance energy transfer (FRET); and possibly, photo-induced electron transfer (PET). In addition, the critical role of the aldehyde group as a recognition site was corroborated using a post-modification strategy. Full article
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13 pages, 3504 KiB  
Article
The Effect of the Position of a Phenyl Group on the Luminescent and TNP-Sensing Properties of Cationic Iridium(III) Complexes
by Xiaoran Yang, Jiahao Du, Rui Cai and Chun Liu
Sensors 2025, 25(3), 839; https://doi.org/10.3390/s25030839 - 30 Jan 2025
Viewed by 793
Abstract
Three cationic Ir(III) complexes, 1, 2, and 3, were successfully synthesized and characterized by tuning the position of a phenyl group at the pyridyl moiety in 2-phenylpyridine. All three complexes exhibited typical aggregation-induced phosphorescence emission (AIPE) properties in CH3 [...] Read more.
Three cationic Ir(III) complexes, 1, 2, and 3, were successfully synthesized and characterized by tuning the position of a phenyl group at the pyridyl moiety in 2-phenylpyridine. All three complexes exhibited typical aggregation-induced phosphorescence emission (AIPE) properties in CH3CN/H2O. The AIPE property was further utilized to achieve the highly sensitive detection of 2,4,6-trinitrophenol (TNP) in aqueous media with low limit of detection (LOD) values of 164, 176, and 331 nM, respectively. This suggests that the different positions of the phenyl group influence the effectiveness of 1, 2, and 3 in the detection of TNP. In addition, 1, 2, and 3 showed superior selectivity and anti-interference properties for the detection of TNP and were observed to have the potential to be used to detect TNP in practical applications. The changes in the luminescence lifetime and UV-Vis absorption spectra of 1, 2, and 3 before and after the addition of TNP indicate that the corresponding quenching process is a combination of static and dynamic quenching. Additionally, the proton nuclear magnetic resonance spectra and results of spectral studies show that the detection mechanism is photo-induced electron transfer (PET). Full article
(This article belongs to the Special Issue Recent Advances in Photo(electro)chemical Sensing and Sensors)
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17 pages, 6065 KiB  
Article
AIPE-Active Neutral Ir(III) Complexes as Bi-Responsive Luminescent Chemosensors for Sensing Picric Acid and Fe3+ in Aqueous Media
by Qinglong Zhang, Jiangchao Xu, Qiang Xu and Chun Liu
Chemosensors 2025, 13(1), 10; https://doi.org/10.3390/chemosensors13010010 - 8 Jan 2025
Viewed by 961
Abstract
Three neutral iridium complexes Ir1Ir3 were synthesized using diphenylphosphoryl-substituted 2-phenylpyridine derivatives as the cyclometalating ligand and picolinic acid as the auxiliary ligand. They exhibited significant aggregation-induced phosphorescent emission (AIPE) properties in H2O/THF and were successfully used as bi-responsive luminescent [...] Read more.
Three neutral iridium complexes Ir1Ir3 were synthesized using diphenylphosphoryl-substituted 2-phenylpyridine derivatives as the cyclometalating ligand and picolinic acid as the auxiliary ligand. They exhibited significant aggregation-induced phosphorescent emission (AIPE) properties in H2O/THF and were successfully used as bi-responsive luminescent sensors for the detection of picric acid (PA) and Fe3+ in aqueous media. Ir1Ir3 possesses high efficiency and high selectivity for detecting PA and Fe3+, with the lowest limit of detection at 59 nM for PA and 390 nM for Fe3+. Additionally, the complexes can achieve naked-eye detection of Fe3+ in aqueous media. Ir1Ir3 exhibit excellent potential for practical applications in complicated environments. The detection mechanism for PA is attributed to photo-induced electron transfer (PET) and Förster resonance energy transfer (FRET), and the detection mechanism for Fe3+ may be explained by PET and the strong interactions between Fe3+ and the complexes. Full article
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12 pages, 969 KiB  
Article
Asymptomatic Malaria Reservoirs in Honduras: A Challenge for Elimination
by Sharon Banegas, Denis Escobar, Alejandra Pinto, Marcela Moncada, Gabriela Matamoros, Hugo O. Valdivia, Allan Reyes and Gustavo Fontecha
Pathogens 2024, 13(7), 541; https://doi.org/10.3390/pathogens13070541 - 27 Jun 2024
Cited by 1 | Viewed by 2180
Abstract
Background: Efforts on a global scale for combating malaria have achieved substantial progress over the past twenty years. Two Central American nations have accomplished their goal of eliminating malaria: El Salvador and Belize. Honduras has decreased the incidence of malaria and now reports [...] Read more.
Background: Efforts on a global scale for combating malaria have achieved substantial progress over the past twenty years. Two Central American nations have accomplished their goal of eliminating malaria: El Salvador and Belize. Honduras has decreased the incidence of malaria and now reports fewer than 4000 malaria cases annually, aspiring to reach elimination by 2030. To accomplish this goal, it is essential to assess the existing strategies employed for malaria control and to address the task of incorporating novel intervention strategies to identify asymptomatic reservoirs. Methods: A survey for detecting asymptomatic cases was carried out in the community of Kaukira, in Gracias a Dios, Honduras, focusing on malaria transmission during 2023. Asymptomatic community members were recruited as participants, malaria screening was performed through a rapid diagnostic test in situ, and a blood sample was collected on filter paper. Highly sensitive molecular assays based on photo-induced electron transfer PCR (PET-PCR) were performed to detect the two species of Plasmodium circulating in Honduras: Plasmodium vivax and Plasmodium falciparum. In addition, the identification of the parasite species was verified by amplifying three genetic markers (Pvmsp3α, Pvmsp3ß, and Pfmsp1). Results: A total of 138 participants were recruited, mostly adult women. All individuals tested negative on the rapid diagnostic test. Positive results for malaria were detected by PET-PCR in 17 samples (12.3%). Most samples (12 out of 17) were amplified with a Ct value between 37 and 42, indicating very low parasitemias. Out of the 17 samples, 16 of them also showed amplification in the species assays. There were nine cases of P. falciparum infections and seven cases of P. vivax infections that were further confirmed by nested PCR (nPCR) of Pvmsp3 and Pfmsp1. Parasitemias ranged from 100 p/μL to less than 0.25 p/μL. One sample showed mixed infection. Conclusions: The existence of asymptomatic malaria reservoirs in Honduras can contribute to disease transmission and pose a challenge that may hinder elimination efforts, requiring public health authorities to modify surveillance strategies to identify the disease and treat this population accordingly. Full article
(This article belongs to the Special Issue Current Research on Host–Pathogen Interaction in 2024)
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12 pages, 3767 KiB  
Article
Carbazolyl-Modified Neutral Ir(III) Complexes for Efficient Detection of Picric Acid in Aqueous Media
by Jiangchao Xu, Liyan Zhang, Yusheng Shi and Chun Liu
Sensors 2024, 24(13), 4074; https://doi.org/10.3390/s24134074 - 22 Jun 2024
Cited by 3 | Viewed by 1592
Abstract
Based on the electron-deficient property of picric acid (PA), two neutral Ir(III) complexes 1 and 2 modified with the electron-rich carbazolyl groups were synthesized and characterized. Both 1 and 2 exhibit aggregation-induced phosphorescence emission (AIPE) properties in THF/H2O. Among them, 2 [...] Read more.
Based on the electron-deficient property of picric acid (PA), two neutral Ir(III) complexes 1 and 2 modified with the electron-rich carbazolyl groups were synthesized and characterized. Both 1 and 2 exhibit aggregation-induced phosphorescence emission (AIPE) properties in THF/H2O. Among them, 2 is extremely sensitive for detecting PA with a limit of detection of 0.15 μM in THF/H2O. Furthermore, the selectivity for PA is significantly higher compared to other analytes, enabling the efficient detection of PA in four common water samples. The density functional theory calculations and the spectroscopic results confirm that the sensing mechanism is photo-induced electron transfer (PET). Full article
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13 pages, 3798 KiB  
Article
A Benzil- and BODIPY-Based Turn-On Fluorescent Probe for Detection of Hydrogen Peroxide
by Yunxia Wang, Ye Liu, Bo Liu, Yihua Yuan, Lixia Wei, Mingxiu Wang and Zhe Chen
Molecules 2024, 29(1), 229; https://doi.org/10.3390/molecules29010229 - 31 Dec 2023
Cited by 6 | Viewed by 2201
Abstract
Faced with rising threats of terrorism, environmental and health risks, achieving sensitive and selective detection of peroxide-based explosives (PEs) has become a global focus. In this study, a turn-on fluorescent probe (BOD) based on benzil (H2O2-recognition element) and 4,4-difluoro-4-bora-3 [...] Read more.
Faced with rising threats of terrorism, environmental and health risks, achieving sensitive and selective detection of peroxide-based explosives (PEs) has become a global focus. In this study, a turn-on fluorescent probe (BOD) based on benzil (H2O2-recognition element) and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivative (fluorophore) was developed to sensitively and specifically detect hydrogen peroxide (H2O2). The synthesized BOD had a very weak fluorescence due to intramolecular donor-excited photo-induced electron transfer (d-PET) effect; however, it could emit a strong fluorescence since H2O2 selectively oxidized the benzil moiety and released free BODIPY fluorophore (BOD-COOH). As a result, the proposed BOD detected H2O2 in linear detection ranged from 25 to 125 µM with a detection limit of 4.41 µM. Meanwhile, the proposed BOD showed good selectivity toward H2O2, which is not affected by other common reactive oxygen species (ROS) and ions from explosive residues. In addition, a blue shift from 508 to 498 nm was observed in the absorption spectra upon addition of H2O2. More importantly, the BOD was successfully applied for rapid detection of H2O2 vapor with good sensitivity (down to 7 ppb), which holds great potential for practical use in public safety, forensic analysis and environmental monitoring. Full article
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13 pages, 4511 KiB  
Article
Theoretical Investigation on the “ON-OFF” Mechanism of a Fluorescent Probe for Thiophenols: Photoinduced Electron Transfer and Intramolecular Charge Transfer
by Yuxi Wang, Meng Zhang, Wenzhi Li, Yi Wang and Panwang Zhou
Molecules 2023, 28(19), 6921; https://doi.org/10.3390/molecules28196921 - 3 Oct 2023
Cited by 6 | Viewed by 2339
Abstract
In this study, the sensing mechanism of (2E,4E)-5-(4-(dimethylamino)phenyl)-1-(2-(2,4dinitrophenoxy)phenyl)penta-2,4-dien-1-one (DAPH-DNP) towards thiophenols was investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The DNP group plays an important role in charge transfer excitation. Due to the typical donor-excited photo-induced electron transfer (d-PET) process, [...] Read more.
In this study, the sensing mechanism of (2E,4E)-5-(4-(dimethylamino)phenyl)-1-(2-(2,4dinitrophenoxy)phenyl)penta-2,4-dien-1-one (DAPH-DNP) towards thiophenols was investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The DNP group plays an important role in charge transfer excitation. Due to the typical donor-excited photo-induced electron transfer (d-PET) process, DAPH-DNP has fluorescence quenching behavior. After the thiolysis reaction between DAPH-DNP and thiophenol, the hydroxyl group is released, and DAPH is generated with the reaction showing strong fluorescence. The fluorescence enhancement of DAPH is not caused by an excited-state intramolecular proton transfer (ESIPT) process. The potential energy curves (PECs) show that DAPH-keto is less stable than DAPH-enol. The frontier molecular orbitals (FMOs) of DAPH show that the excitation process is accompanied by intramolecular charger transfer (ICT), and the corresponding character of DAPH was further confirmed by hole-electron and interfragment charge transfer (IFCT) analysis methods. Above all, the sensing mechanism of the turn-on type probe DAPH-DNP towards thiophenol is based on the PET mechanism. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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14 pages, 2646 KiB  
Article
Heterometallic ZnHoMOF as a Dual-Responsive Luminescence Sensor for Efficient Detection of Hippuric Acid Biomarker and Nitrofuran Antibiotics
by Jingrui Yin, Wenqian Li, Wencui Li, Liying Liu, Dongsheng Zhao, Xin Liu, Tuoping Hu and Liming Fan
Molecules 2023, 28(17), 6274; https://doi.org/10.3390/molecules28176274 - 27 Aug 2023
Cited by 48 | Viewed by 2112
Abstract
Developing efficient and sensitive MOF-based luminescence sensors for bioactive molecule detection is of great significance and remains a challenge. Benefiting from favorable chemical and thermal stability, as well as excellent luminescence performance, a porous Zn(II)Ho(III) heterometallic–organic framework (ZnHoMOF) was selected here as a [...] Read more.
Developing efficient and sensitive MOF-based luminescence sensors for bioactive molecule detection is of great significance and remains a challenge. Benefiting from favorable chemical and thermal stability, as well as excellent luminescence performance, a porous Zn(II)Ho(III) heterometallic–organic framework (ZnHoMOF) was selected here as a bifunctional luminescence sensor for the early diagnosis of a toluene exposure biomarker of hippuric acid (HA) through “turn-on” luminescence enhancing response and the daily monitoring of NFT/NFZ antibiotics through “turn-off” quenching effects in aqueous media with high sensitivity, acceptable selectivity, good anti-interference, exceptional recyclability performance, and low detection limits (LODs) of 0.7 ppm for HA, 0.04 ppm for NFT, and 0.05 ppm for NFZ. Moreover, the developed sensor was employed to quantify HA in diluted urine samples and NFT/NFZ in natural river water with satisfactory results. In addition, the sensing mechanisms of ZnHoMOF as a dual-response chemosensor in efficient detection of HA and NFT/NFZ antibiotics were conducted from the view of photo-induced electron transfer (PET), as well as inner filter effects (IFEs), with the help of time-dependent density functional theory (TD-DFT) and spectral overlap experiments. Full article
(This article belongs to the Special Issue Metal Organic Frameworks (MOFs) for Sensing Applications)
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17 pages, 6576 KiB  
Article
Self-Associated 1,8-Naphthalimide as a Selective Fluorescent Chemosensor for Detection of High pH in Aqueous Solutions and Their Hg2+ Contamination
by Awad I. Said, Desislava Staneva, Silvia Angelova and Ivo Grabchev
Sensors 2023, 23(1), 399; https://doi.org/10.3390/s23010399 - 30 Dec 2022
Cited by 13 | Viewed by 3096
Abstract
A novel diamino triazine based 1,8-naphthalimide (NI-DAT) has been designed and synthesized. Its photophysical properties have been investigated in different solvents and its sensory capability evaluated. The fluorescence emission of NI-DAT is significantly impacted by the solvent polarity due to its inherent intramolecular [...] Read more.
A novel diamino triazine based 1,8-naphthalimide (NI-DAT) has been designed and synthesized. Its photophysical properties have been investigated in different solvents and its sensory capability evaluated. The fluorescence emission of NI-DAT is significantly impacted by the solvent polarity due to its inherent intramolecular charge transfer character. Moreover, the fluorescence emission quenched at higher pH as a result of photo-induced electron transfer (PET) from triazine moiety to 1,8-naphthalimide after cleaving hydrogen bonds in the self-associated dimers. Furthermore, the new chemosensor exhibited a good selectivity and sensitivity towards Hg2+ among all the used various cations and anions in the aqueous solution of ethanol (5:1, v/v, pH = 7.2, Tampon buffer). NI-DAT emission at 540 nm was quenched remarkably only by Hg2+, even in the presence of other cations or anions as interfering analytes. Job’s plot revealed a 2:1 stoichiometric ratio for NI-DAT/Hg2+ complex, respectively. Full article
(This article belongs to the Special Issue Chemiresistive Sensors: Materials and Applications)
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13 pages, 10691 KiB  
Article
Flexible Heater Fabrication Using Amino Acid-Based Ink and Laser-Direct Writing
by Sangmo Koo
Micromachines 2022, 13(12), 2209; https://doi.org/10.3390/mi13122209 - 13 Dec 2022
Cited by 1 | Viewed by 2145
Abstract
Nature’s systems have evolved over a long period to operate efficiently, and this provides hints for metal nanoparticle synthesis, including the enhancement, efficient generation, and transport of electrons toward metal ions for nanoparticle synthesis. The organic material-based ink composed of the natural materials [...] Read more.
Nature’s systems have evolved over a long period to operate efficiently, and this provides hints for metal nanoparticle synthesis, including the enhancement, efficient generation, and transport of electrons toward metal ions for nanoparticle synthesis. The organic material-based ink composed of the natural materials used in this study requires low laser power for sintering compared to conventional nanoparticle ink sintering. This suggests applicability in various and sophisticated pattern fabrication applications without incurring substrate damage. An efficient electron transfer mechanism between amino acids (e.g., tryptophan) enables silver patterning on flexible polymer substrates (e.g., PET) by laser-direct writing. The reduction of silver ions to nanoparticles was induced and sintered by simultaneous photo/thermalchemical reactions on substrates. Furthermore, it was possible to fabricate a stable, transparent, and flexible heater that operates under mechanical deformation. Full article
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10 pages, 2457 KiB  
Article
Theoretical Investigations on the Sensing Mechanism of Phenanthroimidazole Fluorescent Probes for the Detection of Selenocysteine
by Zhe Tang, Xiaochen Wang, Runze Liu and Panwang Zhou
Molecules 2022, 27(23), 8444; https://doi.org/10.3390/molecules27238444 - 2 Dec 2022
Cited by 5 | Viewed by 2220
Abstract
The level of selenocysteine (Sec) in the human body is closely related to a variety of pathophysiological states, so it is important to study its fluorescence sensing mechanism for designing efficient fluorescent probes. Herein, we used time-dependent density functional theory to investigate the [...] Read more.
The level of selenocysteine (Sec) in the human body is closely related to a variety of pathophysiological states, so it is important to study its fluorescence sensing mechanism for designing efficient fluorescent probes. Herein, we used time-dependent density functional theory to investigate the fluorescence sensing mechanism of phenanthroimidazole derivates A4 and B4 for the detection of Sec, which are proposed to be designed based on excited state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) mechanisms. The calculation results show that the fluorescence quenching mechanism of A4 and B4 is due to the photo-induced electron transfer (PET) process with the sulfonate group acts as the electron acceptor. Subsequently, A4 and B4 react with Sec, the sulfonate group is substituted by hydroxyl groups, PET is turned off, and significant fluorescence enhancement of the formed A3 and B3 is observed. The theoretical results suggest that the fluorescence enhancement mechanism of B3 is not based on ICT mechanism, and the charge transfer phenomenon was not observed by calculating the frontier molecular orbitals, and proved to be a local excitation mode. The reason for the fluorescence enhancement of A3 based on ESIPT is also explained by the calculated potential energy curves. Full article
(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)
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19 pages, 3782 KiB  
Article
An AIEE Active Anthracene-Based Nanoprobe for Zn2+ and Tyrosine Detection Validated by Bioimaging Studies
by Muthaiah Shellaiah, Natesan Thirumalaivasan, Basheer Aazaad, Kamlesh Awasthi, Kien Wen Sun, Shu-Pao Wu, Ming-Chang Lin and Nobuhiro Ohta
Chemosensors 2022, 10(10), 381; https://doi.org/10.3390/chemosensors10100381 - 22 Sep 2022
Cited by 34 | Viewed by 3687
Abstract
Novel anthracene-based Schiff base derivative (4-(anthracen-9-ylmethylene) amino)-5-phenyl-4H-1,2,4-triazole-3-thiol; AT2) is synthesized and utilized as an aggregation-induced emission-enhancement (AIEE) active probe to detect Zn2+ and Tyrosine. Ultraviolet-visible absorption/photoluminescence (UV-vis/PL) spectroscopy studies on the AIEE property of AT2 (in ethanol) with increasing water fractions [...] Read more.
Novel anthracene-based Schiff base derivative (4-(anthracen-9-ylmethylene) amino)-5-phenyl-4H-1,2,4-triazole-3-thiol; AT2) is synthesized and utilized as an aggregation-induced emission-enhancement (AIEE) active probe to detect Zn2+ and Tyrosine. Ultraviolet-visible absorption/photoluminescence (UV-vis/PL) spectroscopy studies on the AIEE property of AT2 (in ethanol) with increasing water fractions (fw: 0–97.5%) confirm the J-type aggregation. Excellent sensor selectivity of AT2 to Zn2+ and its reversibility with Tyrosine are demonstrated with PL interrogations. 2:1 and 1:1 stoichiometry and binding sites of AT2-Zn2+ and Tyrosine-Zn2+ complexes are elucidated from Job plots, HR-mass, and 1H-NMR results. Nanomolar-level detection limits (LODs) of Zn2+ (179 nM) and Tyrosine (667 nM) and association constants (Kas) of 2.28 × 10−6 M−2 (for AT2-Zn2+) and 1.39 × 10−7 M−1 (for Tyrosine-Zn2+) are determined from standard deviation and linear fittings. Nanofiber formation in AIEE and aggregated/dispersed nanoparticles in the presence of the Zn2+/Tyrosine are supported by scanning-electron microscope (SEM), transmission-electron microscope (TEM), atomic-force microscope (AFM), and dynamic-light scattering (DLS) investigations. Density-functional theory (DFT) studies confirm an “On-Off” twisted intramolecular charge transfer/photo-induced electron transfer (TICT/PET) and “On-Off-On” PET mechanisms for AIEE and sensors, respectively. B16-F10 cellular and zebrafish imaging are conducted to support the applications of AIEE and sensors. Full article
(This article belongs to the Section Applied Chemical Sensors)
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17 pages, 5809 KiB  
Article
A Novel Triphenylamine-Based Flavonoid Fluorescent Probe with High Selectivity for Uranyl in Acid and High Water Systems
by Bing Liu, Wenbin Cui, Jianliang Zhou and Hongqing Wang
Sensors 2022, 22(18), 6987; https://doi.org/10.3390/s22186987 - 15 Sep 2022
Cited by 5 | Viewed by 2800
Abstract
Developing a fluorescent probe for UO22+, which is resistant to interference from other ions such as Cu2+ and can be applied in acidic and high-water systems, has been a major challenge. In this study, a “turn-off” fluorescent probe for [...] Read more.
Developing a fluorescent probe for UO22+, which is resistant to interference from other ions such as Cu2+ and can be applied in acidic and high-water systems, has been a major challenge. In this study, a “turn-off” fluorescent probe for triamine-modified flavonoid derivatives, 2-triphenylamine-3-hydroxy-4H-chromen-4-one (abbreviated to HTPAF), was synthesized. In the solvent system of dimethyl sulfoxide:H2O (abbreviated to DMSO:H2O) (v/v = 5:95 pH = 4.5), the HTPAF solution was excited with 364 nm light and showed a strong fluorescence emission peak at 474 nm with a Stokes shift of 110 nm. After the addition of UO22+, the fluorescence at 474 nm was quenched. More importantly, there was no interference in the presence of metal ions (Pb2+, Cd2+, Cr3+, Fe3+, Co2+, Th4+, La3+, etc.), especially Cu2+ and Al3+. It is worth noting that the theoretical model for the binding of UO22+ to HTPAF was derived by more detailed density functional theory (DFT) calculations in this study, while the coordination mode was further verified using HRMS, FT-IR and 1HNMR, demonstrating a coordination ratio of 1:2. In addition, the corresponding photo-induced electron transfer (PET) fluorescence quenching mechanism was also proposed. Full article
(This article belongs to the Special Issue Chemical Sensors in Analytical Chemistry)
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17 pages, 3011 KiB  
Article
Mimicking Natural Photosynthesis: Designing Ultrafast Photosensitized Electron Transfer into Multiheme Cytochrome Protein Nanowires
by Daniel R. Marzolf, Aidan M. McKenzie, Matthew C. O’Malley, Nina S. Ponomarenko, Coleman M. Swaim, Tyler J. Brittain, Natalie L. Simmons, Phani Raj Pokkuluri, Karen L. Mulfort, David M. Tiede and Oleksandr Kokhan
Nanomaterials 2020, 10(11), 2143; https://doi.org/10.3390/nano10112143 - 28 Oct 2020
Cited by 4 | Viewed by 3573
Abstract
Efficient nanomaterials for artificial photosynthesis require fast and robust unidirectional electron transfer (ET) from photosensitizers through charge-separation and accumulation units to redox-active catalytic sites. We explored the ultrafast time-scale limits of photo-induced charge transfer between a Ru(II)tris(bipyridine) derivative photosensitizer and PpcA, a 3-heme [...] Read more.
Efficient nanomaterials for artificial photosynthesis require fast and robust unidirectional electron transfer (ET) from photosensitizers through charge-separation and accumulation units to redox-active catalytic sites. We explored the ultrafast time-scale limits of photo-induced charge transfer between a Ru(II)tris(bipyridine) derivative photosensitizer and PpcA, a 3-heme c-type cytochrome serving as a nanoscale biological wire. Four covalent attachment sites (K28C, K29C, K52C, and G53C) were engineered in PpcA enabling site-specific covalent labeling with expected donor-acceptor (DA) distances of 4–8 Å. X-ray scattering results demonstrated that mutations and chemical labeling did not disrupt the structure of the proteins. Time-resolved spectroscopy revealed three orders of magnitude difference in charge transfer rates for the systems with otherwise similar DA distances and the same number of covalent bonds separating donors and acceptors. All-atom molecular dynamics simulations provided additional insight into the structure-function requirements for ultrafast charge transfer and the requirement of van der Waals contact between aromatic atoms of photosensitizers and hemes in order to observe sub-nanosecond ET. This work demonstrates opportunities to utilize multi-heme c-cytochromes as frameworks for designing ultrafast light-driven ET into charge-accumulating biohybrid model systems, and ultimately for mimicking the photosynthetic paradigm of efficiently coupling ultrafast, light-driven electron transfer chemistry to multi-step catalysis within small, experimentally versatile photosynthetic biohybrid assemblies. Full article
(This article belongs to the Special Issue Hybrid Nanosystems for Artificial Photosynthesis)
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