Low-power UV Research Articles

Efficient photocatalytic decomposition of PFOA over BiOI1-x with low power LED light

In recent years, the academic community has shown significant interest in per- or polyfluoroalkyl compounds (PFAS) due to their challenging degradation and potential health risks. Photocatalysis has been investigated for PFAS decomposition due to its environmentally friendly nature. In this study, BiOI with abundant iodine vacancies was synthesized through solvothermal and calcination methods (referred to as BiOI1-x), and was used for PFAS degradation with a low power UV light source. Compared to pure BiOI, BIOI1-x showed higher photocatalytic activity towards PFOA (perfluorooctanoic acid). Within 5 h under 5 W LED light irradiation, the degradation rate of PFOA reached 51.9 % with BiOI1-x calcined at 440 °C (No significant degradation of PFAS was observed with pure BiOI). Capture experiments, electron paramagnetic resonance spectroscopy, and electrochemical experiments revealed that the main active species in the system were photogenerated holes, followed by hydroxyl radicals. Furthermore, the presence of iodine vacancies significantly improved the efficiency of charge carrier separation and enhanced the photocatalytic performance. Finally, a hypothetical degradation pathway for PFOA in this system was suggested. This study achieved efficient degradation of PFAS under low power LED light (5 W), emphasizing its significant practical importance in terms of energy conservation.

High-performance and low-power consumption deep UV photodetectors based on MOCVD-grown ZnGa2O4epilayers with high temperature functionality

This work reports on the fabrication of excellent quality deep ultraviolet photodetectors (DUV PDs) based on metalorganic chemical vapor deposition (MOCVD) grown spinel ZnGa2O4 thin films on c-plane sapphire. Herein, The DUV PDs by exhibiting an ultra-low dark current of 6.69 fA and a high photo-to-dark-current ratio (PDCR) of >108 at a low-power operation of 0.2 V. While PDCR reached more than 109 on applied bias of 10 V having extremely low dark current of 37 fA. The detector revealed an ultra-high responsivity of 185 and 3.53 A/W under the exposure of 107 μW/cm2 of 245 nm wavelength at room temperature (RT) and applied bias of 10 and 0.2 V, respectively, and exhibited the record-high detectivity of the order of 1017 Jones. The temperature-dependent operation remained stable across a wide temperature range, from 27 °C to 125 °C, maintaining ultra-low dark current. The nearly constant growth and decay time of DUV PDs throughout the temperature range emphasizes the robustness and reliability of PD. The ideality factor in both DUV and dark conditions nearing unity proves the dominance of the thermionic emission mechanism. Also shows the stable and slight improved performance after a year. Therefore, these findings suggest that ZnGa2O4 is a strong contender for deep UV detection that shows robustness even at high temperatures.

Floating MIL-88A(Fe)@expanded perlites catalyst for continuous photo-Fenton degradation toward tetracyclines under artificial light and real solar light

In this work, MIL-88A(Fe) was immobilized onto the expanded perlites to fabricate the floating MIL-88A(Fe)@expanded perlites (M@EP) catalyst via high throughput batch synthesis method under room temperature. The as-prepared M@EP could efficiently activate H2O2 to achieve 100% tetracycline antibiotics (TCs) removal under both artificial low power UV light (UVL) and real sunlight (SL) irradiation. The toxicological evaluation, growth experiment of mung beans and antimicrobial estimation revealed the decreasing aquatic toxicity of the TCs intermediates compared to those of the pristine TCs. A self-designed continuous bed reactor was employed to investigate the long-term operation of the M@EP. The findings demonstrated that the antibiotics mixture can be continuously degraded up to 7 days under UVL and 5 daytimes under SL irradiation, respectively. More importantly, ca. 76.9% and 81.6% of total organic carbon (TOC) removal efficiencies were accomplished in continuous bed reactor under UVL and SL irradiation, respectively. This work advances the immobilized MOFs on floating supports for their practical application in large-scale wastewater purification through advanced oxidation processes. Environmental implicationThis work presented the high throughput production and photo-Fenton degradation application of floating MIL-88A(Fe)@expanded perlites (M@EP). Three tetracycline antibiotics (TCs) were selected as model pollutants to test the degradation ability of M@EP in batch experiment and continuous operation under artificial light and solar light. The complete TCs degradation could be accomplished in self-designed device up to 7 d under UV light and 5 d under real solar light. This work tapped a new door to push MOFs-based functional materials in the real water purification.

A simple and economic method to modify large organic surfaces for enhancing adhesion and transparent Au/PMMA with high electromagnetic shielding efficiency

This study introduces a simple and cost-effective approach for modifying large organic surfaces, facilitating robust adhesion between Au films and polymethyl methacrylate (PMMA) while retaining transparency to visible light and effectively shielding against electromagnetic interference (EMI). The proposed surface modification method employs a cheap low-power conventional UV lamp to illuminate organic surfaces in an open environment, rending it convenient and applicable for surfaces ranging from small to massive, irrespective of size, shape and location. By subjecting transparent PMMA glass to a brief 20–30 min exposure to a 36 W UV lamp positioned 5 cm away from the sample surface, the PMMA surface is dramatically modified and the surface is turned from hydrophobic to hydrophilic, establishing a strong adhesion between PMMA and Au films. The resulting Au/PMMA glass exhibits remarkable transparency about 70% within the visible light spectrum, coupled with an impressive EMI shielding efficiency that surpasses 20 dB across a broad range of electromagnetic wavebands, encompassing the S, C, X and Ku bands that correspond to the wave frequencies of major electromagnetic pollution and crucial applications of 5G communication, credit card validation, radar systems, traffic control, etc. Various characterizations have been conducted, elucidating the underlying mechanisms. This study presents an important advancement, and the accessible and scalable nature of the large-scalable surface modification method has far-reaching implications across numerous industrial sectors and applications, in addition to transparent EMI shielding Au/PMMA glasses.

Methods for the destruction of oxalic acid decontamination effluents

Oxalic acid is encountered within industrial processes, spanning from the nuclear sector to various chemical applications. The persistence and potential environmental risks associated with this compound underscore the need for effective management strategies. This article presents an overview of different approaches for the destruction of oxalic acid. The study explores an array of degradation methodologies and delves into the mechanistic insights of these techniques. Significant attention is channeled towards the nuclear industry, wherein oxalic acid arises as a byproduct of decontamination and waste management activities. An integral aspect of decommissioning efforts involves addressing this secondary waste-form of oxalic acid. This becomes imperative due to the potential release of oxalic acid into waste streams, where its accommodation is problematic, and its capacity to solubilize and transport heavy metals like Pu is a concern. To address this, a two-tiered classification is introduced: high concentration and low concentration scenarios. The study investigates various parameters, including the addition of nitric acid or hydrogen peroxide, in the presence of metallic ions, notably Mn2+ and Fe2+. These metallic ions are common components of effluents from metallic waste treatment. Additionally, the impact of UV light on degradation is explored. Investigations reveal that at high concentrations and with the influence of hydrogen peroxide, the presence of metallic cations accelerates the rate of destruction, demonstrating a direct correlation. This acceleration is further enhanced by exposure to UV light. At low concentrations, similar effects of metallic cations are observed upon heating the solution to 80°C. The rate of destruction increases proportionally with hydrogen peroxide concentration, with an optimal oxalic acid to hydrogen peroxide ratio of 1:100. Interestingly, a low-power UV light exerted no discernible effects on the destruction rate; heating alone proved sufficient. In essence, regardless of concentration, the degradation of oxalic acid with hydrogen peroxide experiences acceleration in the presence of metallic ions such as Mn2+ and Fe2+.

Enhanced photocatalytic degradation of organic pollutants in water using copper oxide (CuO) nanosheets for environmental application

Rapid, inexpensive, and low-power/solar light-driven photocatalytic degradation of organic pollutants to deal with annually produced trillion tons of synthetic dye wastewater to prevent water scarcity issues, ecotoxicological risks, and human health has always been challenging. To overcome this limitation, the present study synthesized earth-abundant, inexpensive copper oxide nanosheets using a simple single-step hydrothermal route. The structural, physicochemical, and functional properties of the nanosheets have been characterized using several characterization techniques. The photocatalytic activity was studied for two commonly industrially used organic dyes, Methylene Blue (MB) and Rhodamine B (RhB). The importance of this work is the usage of a cheap commercially available Phillips UV light (11 W) as well as direct sunlight. With several optimized conditions, almost complete degradation of both dyes was achieved within 35 minutes under low-power UV light and within 70 minutes by the direct illumination of natural sunlight. The enhanced photocatalytic performance can be correlated to the synergetic effect of a higher charge transfer mechanism, good catalytic ‘active surface area’ availability (13.2 m2/g), and several optimized parameters that affect the reaction efficacy. Additionally, five repeated uses of nanosheets without sacrificing performance confirmed their stability and sustainability as a promising candidate for large-scale industrial textile wastewater remedies.

β-Cyclodextrin and cucurbit[7]uril as protective encapsulation agents of the CO-releasing molecule [CpMo(CO)3Me

The CO releasing ability of the complex [CpMo(CO)3Me] (1) (Cp = η5-C5H5) has been assessed using a deoxymyoglobin-carbonmonoxymyoglobin assay. In the dark, CO release was shown to be promoted by the reducing agent sodium dithionite in a concentration-dependent manner. At lower dithionite concentrations, where dithionite-induced CO release was minimised, irradiation at 365 nm with a low-power UV lamp resulted in a strongly enhanced release of CO (half-life (t1/2) = 6.3 min), thus establishing complex 1 as a photochemically activated CO-releasing molecule. To modify the CO release behaviour of the tricarbonyl complex, the possibility of obtaining inclusion complexes between 1 and β-cyclodextrin (βCD) or cucurbit[7]uril (CB7) by liquid-liquid interfacial precipitation (1@βCD(IP)), liquid antisolvent precipitation (1@CB7), and mechanochemical ball-milling (1@βCD(BM)) was evaluated. All these methods led to the isolation of a true inclusion compound (albeit mixed with nonincluded 1 for 1@βCD(BM)), as evidenced by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), FT-IR and FT-Raman spectroscopies, and 13C{1H} magic angle spinning (MAS) NMR. PXRD showed that 1@βCD(IP) was microcrystalline with a channel-type crystal packing structure. High resolution mass spectrometry studies revealed the formation of aqueous phase 1 : 1 complexes between 1 and CB7. For 1@βCD(IP) and 1@CB7, the protective effects of the hosts led to a decrease in the CO release rates with respect to nonincluded 1. βCD had the strongest effect, with a ca. 10-fold increase in t1/4 for dithionite-induced CO release, and a ca. 2-fold increase in t1/2 for photoinduced CO release.

The superior mineralization potential of a graphitic carbon nitride/titanium dioxide composite and its application in the construction of a portable photocatalytic air purification system against gaseous formaldehyde

This study highlights the superiority of g-C3N4/TiO2 as an S-scheme photocatalyst with the enhanced intrinsic redox capabilities to actively mineralize gaseous formaldehyde (FA) across varying humidity levels at low-power UV light irradiation (1 W).

Nitric oxide/PDT combination therapy by the fluorescent self-reporting Co-delivery platforms

Nitric oxide (NO) combined with photodynamic therapy (PDT) is a promising tumor treatment method. Herein, the cationic lipid DPNO(Zn) was developed as co-delivery carrier of NO and photosensitizer Chlorin e6 (Ce6). The target CNO lipid nanoparticles (LNPs) were obtained by solvent exchange method as a NO/PDT combination therapy platform, and biocompatible polymer γPGA could be easily coated to form PCNO for in vivo applications. Fluorescence spectra and confocal imaging experiments showed that the Ce6-loaded LNPs could release NO rapidly under low power UV irradiation with fluorescence self-reporting ability. On the other hand, under the irradiation of 660 nm laser, the LNPs could effectively produce singlet oxygen (1O2). In vitro and in vivo antitumor assays showed that the combination treatment of NO/PDT was more effective in tumor growth inhibition compared with individual NO or PDT treatment. Mechanism studies of NO/PDT combined therapy revealed that 1O2 could increase the level of p53 protein, thus activating the caspase 3 apoptosis pathway. And the rapid release of NO could amplify the effect of this pathway by reducing the level of HIF-1α. The NO and 1O2 released under laser irradiation could not only directly damage DNA and mitochondria, resulting in tumor cell dysfunction, but also induce the upregulation of iNOS to further enhance the gas therapy efficiency. This study proved that the light-triggered NO/1O2 generation system can be used as an effective NO/PDT synergistic therapy platform for cancer treatment.

Pulsed-Laser-Triggered Piezoelectric Photocatalytic CO2 Reduction over Tetragonal BaTiO3 Nanocubes.

The recombination of photoinduced carriers in photocatalysts is considered one of the biggest barriers to the increase of photocatalytic efficiency. Piezoelectric photocatalysts open a new route to realize rapid carrier separation by mechanically distorting the lattice of piezoelectric nanocrystals to form a piezoelectric potential within the nanocrystals, generally requiring external force (e.g., ultrasonic radiation, mechanical stirring, and ball milling). In this study, a low-power UV pulsed laser (PL) (3W, 355nm) as a UV light source can trigger piezoelectric photocatalytic CO2 reduction of tetragonal BaTiO3 (BTO-T) in the absence of an applied force. The tremendous transient light pressure (5.7 × 107 Pa, 2.7W) of 355nm PL not only bends the energy band of BTO-T, thus allowing reactions that cannot theoretically occur to take place, but also induces a pulsed built-in electric field to determine an efficient photoinduced carrier separation. On that basis, the PL-triggered piezoelectric photocatalytic CO2 reduction realizes the highest reported performance, reaching a millimole level CO yield of 52.9mmol g-1 h-1 and achieving efficient photocatalytic CO2 reduction in the continuous catalytic system. The method in this study is promising to contribute to the design of efficient piezoelectric photocatalytic reactions.

Wirelessly Powered Drug-Free and Anti-Infective Smart Bandage for Chronic Wound Care.

We present a wirelessly powered ultraviolet-C (UVC) radiation-based disinfecting bandage for sterilization and treatment in chronic wound care and management. The bandage contains embedded low-power UV light-emitting diodes (LEDs) in the 265 to 285 nm range with the light emission controlled via a microcontroller. An inductive coil is seamlessly concealed in the fabric bandage and coupled with a rectifier circuit to enable 6.78 MHz wireless power transfer (WPT). The maximum WPT efficiency of the coils is 83% in free space and 75% on the body at a coupling distance of 4.5 cm. Measurements show that the UVC LEDs are emitting radiant power of about 0.6 mW and 6.8 mW with and without fabric bandage, respectively, when wirelessly powered. The ability of the bandage to inactivate microorganisms was examined in a laboratory which shows that the system can effectively eradicate Gram-negative bacteria, Pseudoalteromonas sp. D41 strain, on surfaces in six hours. The proposed smart bandage system is low-cost, battery-free, flexible and can be easily mounted on the human body and, therefore, shows great promise for the treatment of persistent infections in chronic wound care.

Metal organic framework derived nanostructured ferropericlase for waterborne Pb(II) ion sensing and organic dye removal

Highly crystalline and chemically stable bimetallic MgFe mixed oxide of ferro-periclase crystal structure has been derived for the first time from thermal decomposition of Prussian Blue metal organic framework. Scanning electron microscopy images confirmed formation of nanoflake like morphology. N2 adsorption-desorption isotherms indicated mesoporous nature with high specific surface area, suitable for sensing applications. Mott-Schottky studies suggested that the material is a p-type semiconductor and optical characterisation revealed a band gap (of ∼1.9 eV), well within the visible light absorption range suggesting its potential as a photocatalyst. When the as-synthesized MgFe oxide was tested against some common organic contaminants like Methylene blue and Rhodamine B dissolved in water (generally found in water bodies carrying textiles wastes), it was able to remove almost 90% of the cationic dyes within 3 h under low power UV–visible lamps. Moreover, Differential Pulse Voltammetry studies using the MgFe oxide film as working electrode revealed its potential as an electrochemical sensor for detection of heavy metal ions such as Pb(II) as it detected the presence of Pb(II) even at a very low concentration regime of 4–24 ppb. Therefore, this metal oxide composed of earth abundant elements is proposed as a low cost photocatalyst for organic pollutant removal and voltametric sensor for Pb(II) ions.

Optical gain at 1.55 µm of Er(TMHD)3 complex doped polymer waveguides based on the intramolecular energy transfer effect.

Based on the intramolecular energy transfer mechanism between organic ligand TMHD (2, 2, 6, 6-tetramethyl-3, 5-heptanedione) and central Er3+ ions, optical gains at 1.55 µm were demonstrated in three structures of polymer waveguides using complex Er(TMHD)3-doped polymethylmethacrylate (PMMA) as the active material. With the excitation of two low-power UV light-emitting diodes (LEDs) instead of 980 or 1480 nm lasers, relative gains of 3.5 and 4.1 dB cm-1 were achieved in a 1-cm-long rectangular waveguide with an active core of Er(TMHD)3-doped PMMA polymer. Meanwhile, relative gain of 3.0 dB cm-1 was obtained in an evanescent-field waveguide with cross-section of 4 × 4 µm2 using passive SU-8 polymer as core and a ∼1-µm-thick Er(TMHD)3-doped PMMA as upper cladding. By growing a 100 nm thick aluminum mirror and active lower cladding, the optical gain was doubled to 6.7 dB cm-1 in evanescent-field waveguides because of the stimulated excitation of Er3+ ions in the upper and lower cladding and the improved absorption efficiency.

Optical Amplification at 637 and 1067 nm Based on Organic Molecule AQ(PhDPA)2 and NdIII Complex Codoped Polymer Waveguides.

Based on the molecular energy transfer mechanism, relative gains at 1067 and 637nm wavelengths are achieved in thermally activated delayed fluorescence molecule AQ(PhDPA)2 and Nd complex with chelating phosphine oxide as ligands codoped polymer waveguides, with the excitation of low-power UV light-emitting diodes (LEDs) instead of traditional semiconductor lasers as pump sources. For AQ(PhDPA)2 -Nd(DBTTA)3 (DBFDPO) (DBTTA = dibenzotetrathienoacene, DBFDPO = 4,6-bis (diphenylphosphoryl) dibenzofuran) -codoped polymethylmethacrylate (PMMA), and AQ(PhDPA)2 -Nd(DBTTA)3 (FDPO) (FDPO = 9,9-bis (diphenylphosphorylphenyl) fluorene)-codoped PMMA polymers with a mass ratio of 1:4 respectively, when they are spin-coated as upper claddings, the relative gains of 2.2 and 1.8dB cm-1 at 1067nm are obtained in evanescent-field waveguides with cross-section of 4 × 8µm2 under excitation of 300mW 405nm LED, and the gains of 3.9 and 4.9dB cm-1 at 637nm are achieved with pumping of 530mW 450nm LED respectively. By growing a 100nm-thick aluminum reflector with the waveguides, the optical gain at 1067 and 637nm can be enhanced to 3.5 and 6.1dB cm-1 , corresponding to AQ(PhDPA)2 -Nd(DBTTA)3 (DBFDPO) and AQ(PhDPA)2 -Nd(DBTTA)3 (FDPO)-codoped PMMA polymers, respectively.

TiO2 Decorated SiO2 Nanoparticles as Efficient Antibacterial Materials: Enhanced Activity under Low Power UV Light

AbstractTiO2 based photocatalytic materials show effective antibacterial activity typically under a high‐power UV light. However, exposure to high‐intensity radiation may be detrimental to biological as well as non‐biological materials. In this work, we demonstrate a significantly higher antibacterial activity at even low power UV where TiO2 nanoparticles are decorated on silica nanoparticles. The antibacterial activity of the nanoparticles with varying Si : Ti molar compositions were explored against E. coli to obtain effective antibacterial activity with minimal power of UV radiation (8 W). The nanoparticles with a molar ratio of SiO2 : TiO2=2 : 1 (Si2Ti) showed the best antibacterial activity. The minimum inhibitory concentration (MIC) of the Si2Ti catalyst was also determined for varying duration of exposure to 8 W UV radiation. Even at a very low concentration of 5 mg/mL Si2Ti sample, where the active catalyst amount was only 1.66 mg/mL, 100 % killing of E. coli was observed after 90 minutes of UV exposure. For the exposure time of 120 minutes, MIC was reduced even further to 3 mg/mL with an active catalyst amount of 1 mg/mL. The excellent antibacterial activity is attributed to the small crystallite size of TiO2 along with enhanced interaction with bacteria owing to the presence of SiO2. In addition, Si2Ti showed good biocompatibility with more than 87 % cell viability with fibroblast cells for 500 μg/mL of the sample.

Light-initiated 1,3-dipolar cycloaddition between dehydroalanines and tetrazoles: application to late-stage peptide and protein modifications.

As an easily introduced noncoded amino acid with unique electrophilicity distinct from the 20 natural amino acids, dehydroalanine (Dha) is not only a precise protein post-translational modification (PTM) insertion tool, but also a promising multifunctional labelling site for peptides and proteins. However, achieving a balance between the reaction rate and mild reaction conditions has been a major challenge in developing novel Dha-modified strategies. Rapid, efficient, and mild Dha modification strategies are highly desired. Additionally, catalyst-free photocontrollable reactions for Dha-containing peptide and protein modification have yet to be developed. Here, we report a photoinitiated 1,3-dipolar cycloaddition reaction between Dha and 2,5-diaryl tetrazoles. Under low-power UV lamp irradiation, this reaction is completed within minutes without catalysis, resulting in a fluorescent pyrazoline-modified peptide or protein with excellent chemoselectivity for Dha residues. Notably, this reaction exhibits complete site-specificity in the modification of thiostrepton, a natural antimicrobial peptide containing multiple Dha residues (Dha3, Dha16, and Dha17), within 20 minutes in high yields. This is currently the fastest reaction for modifying the Dha residue in thiostrepton with clear site-specificity towards Dha16. This photoinitiated reaction also provides a chemoselective strategy for precise functionalization of proteins. Additionally, the rapidity and efficiency of the reaction minimize UV light damage to the biological reaction system. Combined with fluorogenic properties, this photo-controllable methodology can be applied to live cell imaging, further broadening the application scope of the Dha modification methodology.

Obtaining Reversible, Durable, High-Contrast Photochromism and Antibacterial Properties in a Flexible, Wearable Fiber Using Nanometer-Sized Polyoxotungstate

An approach to preparing a functional fiber has been developed. The method is carried out to link nanometer-sized polyoxometalate and cotton fabric by employing a cationic agent. Interestingly, the composite fabric exhibits a broad absorption peak in the visible range after irradiation, accompanied by obvious color changes from white to blue owing to electron transfer. The W(VI) transforms into a heteropoly blue W(V) rapidly (<5 s) in response to UV irradiation with a low-power UV (5 W), whereas its recovery seems slightly slow (5 h) in the air. Nevertheless, increasing the temperature can accelerate the fading process. Further, the continuous coloring–fading process presents outstanding repetition stability. Additionally, the composite fabric shows a degree of antibacterial property. Meanwhile, the physical properties indicate that multifunctional cotton retains natural features after chemical modification. In a word, the reversible photoresponsive cellulose fabric can be a promising candidate for developing a wearable and flexible sensor to monitor environmental changes.

Effective Cr(VI) reduction over high throughput Bi-BDC MOF photocatalyst

High throughput Bi-BDC metal-organic framework (BDC = benzene-1,4-dicarboxylic acid) with uniform rod-like morphology was prepared by microwave-assisted method, which could accomplish completely photocatalytic Cr(VI) reduction within 6.0 min under low-power LED UV light with the presence of tartaric acid (TA). The Cr(VI) reduction performance of as-prepared Bi-BDC photocatalyst was slightly influenced by the environmental factors including pH and different inorganic ions. The as-obtained Bi-BDC MOF could be used for five runs’ operation with constant photocatalysis performance. As well, the Cr(VI) reduction mechanism with the presence of TA over the Bi-BDC photocatalyst was clarified.

Yttrium (Y) doped ZnO nanowire/p-Si heterojunction devices for efficient self-powered UV-sensing applications

In the current work, n-type Y-doped ZnO nanowires (n-Y:ZnO) and p-type Si heterojunctions are fabricated by employing two-step chemical bath deposition (CBD) process. The work demonstrates the systematic incorporation of Y in ZnO nanowires for achieving the low power UV response. The crystalline nature, morphology, chemical compositions of doped nanowires are studied extensively by employing XRD, FESEM, HRTEM, elemental mapping, EDS and XPS. The change in defect states due to Y incorporation has been studied in detail by using deconvoluated PL spectra. The results indicate that ZnO nanowires exhibit Zn interstitials dependent huge UV/blue luminescence and oxygen vacancy related lowest green luminescence simultaneously for selective 1% Y-doping. The best self-powered photoresponse has been achieved for 1% Y-doped ZnO nanowires/p-Si heterojunction under relatively low power UV illumination (374 nm @5 mW/cm2). More significantly, at self-powered mode, such heterojunction has been delivered a stable and fast (<1 s) photoresponse with a maximum responsivity of 225 mA/W and high On/Off ratio of ∼104. The work provides an insight into the fabrication of heterojunction UV detectors for next-generation self-powered, large area optoelectronic devices.

Switching on Cytotoxicity of Water-Soluble Diiron Organometallics by UV Irradiation.

The diiron compounds [Fe2Cp2(CO)2(μ-CO)(μ-CSEt)]CF3SO3, [1]CF3SO3, K[Fe2Cp2(CO)3(CNCH2CO2)], K[2], [Fe2Cp2(CO)2(μ-CO)(μ-CNMe2)]NO3, [3]NO3, [Fe2Cp2(CO)2(PTA){μ-CNMe(Xyl)}]CF3SO3, [4]CF3SO3, and [Fe2Cp2(CO)(μ-CO){μ-η:1η3-C(4-C6H4CO2H)CHCNMe2}]CF3SO3, [5]CF3SO3, containing a bridging carbyne, isocyanoacetate, or vinyliminium ligand, were investigated for their photoinduced cytotoxicity. Specifically, the novel water-soluble compounds K[2], [3]NO3, and [4]CF3SO3 were synthesized and characterized by elemental analysis and IR and multinuclear NMR spectroscopy. Stereochemical aspects concerning [4]CF3SO3 were elucidated by 1H NOESY NMR and single-crystal X-ray diffraction. Cell proliferation studies on human skin cancer (A431) and nontumoral embryonic kidney (HEK293) cells, with and without a 10-min exposure to low-power UV light (350 nm), highlighted the performance of the aminocarbyne [3]NO3, nicknamed NIRAC (Nitrate-Iron-Aminocarbyne), which is substantially nontoxic in the dark but shows a marked photoinduced cytotoxicity. Spectroscopic (IR, UV-vis, NMR) measurements and the myoglobin assay indicated that the release of one carbon monoxide ligand represents the first step of the photoactivation process of NIRAC, followed by an extensive disassembly of the organometallic scaffold.