Iodine Pentoxide Research Articles

Iodine Clusters in the Atmosphere I: Computational Benchmark and Dimer Formation of Oxyacids and Oxides.

The contribution of iodine-containing compounds to atmospheric new particle formation is still not fully understood, but iodic acid and iodous acid are thought to be significant contributors. While several quantum chemical studies have been carried out on clusters containing iodine, there is no comprehensive benchmark study quantifying the accuracy of the applied methods. Here, we present the first study in a series that investigate the role of iodine species in atmospheric cluster formation. In this work, we have studied the iodic acid, iodous acid, iodine tetroxide, and iodine pentoxide monomers and their dimers formed with common atmospheric precursors. We have tested the accuracy of commonly applied methods for calculating the geometry of the monomers, thermal corrections of monomers and dimers, the contribution of spin-orbit coupling to monomers and dimers, and finally, the accuracy of the electronic energy correction calculated at different levels of theory. We find that optimizing the structures either at the ωB97X-D3BJ/aug-cc-pVTZ-PP or the M06-2X/aug-cc-pVTZ-PP level achieves the best thermal contribution to the binding free energy. The electronic energy correction can then be calculated at the ZORA-DLPNO-CCSD(T0) level with the SARC-ZORA-TZVPP basis for iodine and ma-ZORA-def2-TZVPP for non-iodine atoms. We applied this methodology to calculate the binding free energies of iodine-containing dimer clusters, where we confirm the qualitative trends observed in previous studies. However, we identify that previous studies overestimate the stability of the clusters by several kcal/mol due to the neglect of relativistic effects. This means that their contributions to the currently studied nucleation pathways of new particle formation are likely overestimated.

Structural, optical, and electrical characteristics of HPMC/PVA-I2O5 composites: Fabrication and performance analysis for energy storage applications

Polymer composites (PCs) are increasingly utilized in energy storage applications, notably in dielectric capacitors, due to their distinct properties and advantages over conventional liquid electrolytes. In this study, we investigate the structural, optical, electrical, and dielectric properties of hydroxypropyl methylcellulose (HPMC)/polyvinyl alcohol (PVA) composite films filled with varying concentrations of iodine pentoxide (I2O5), prepared via a solution casting method. Incorporating I2O5 into the polymer matrix significantly impacted the composite's properties. FTIR and XRD analyses revealed disturbances in molecular structure, crystallization order, and the presence of I2O5 crystal phases in the composite films. Calculations of crystallinity percentage indicated a reduction with I2O5 addition, leading to increased amorphous phase content suitable for enhancing electrical conductivity (σ). UV/vis spectroscopy studies demonstrated decreased optical energy gaps, suggesting improved charge storage capability. The σ analysis revealed enhanced values with I2O5 addition, indicative of improved charge mobility within the composite films. Frequency-dependent behaviors in complex permittivity (ε′ and ε″) highlighted the potential of these composites for efficient charge storage across different frequency ranges. Impedance analysis provided insights into space charges and conductive paths within the composites, influencing their electrical characteristics. Capacitors fabricated from the HPMC/PVA-I2O5 composites exhibited enhanced energy storage capacity and controlled conductance characteristics, demonstrating promising performance for energy storage applications. Our findings demonstrate that the HPMC/PVA-I2O5 composites are potential dielectric materials for capacitor technology.

Spiro-OMeTAD doped with iodine pentoxide to enhance planar perovskite solar cell performance

Due to its enormous development potential, research on perovskite solar cells (PSCs) is progressing rapidly worldwide. Among numerous hole transport materials (HTMs), an organic molecule spiro-OMeTAD emerged victorious. Spiro's application in PSCs is constrained to its weak hole mobility and low conductivity. Here, an inexpensive, ecologically friendly inorganic oxidant iodine pentoxide (I2O5) is used to aid in quick and manageable oxidation of Spiro. I2O5-modified Spiro as HTM improves the charge carrier transportation. Meanwhile, trap-states density and trap-assisted recombination are decreased. Additionally, the modification adjusts the HTM's energy level to match the perovskite layer properly. As a result, the I2O5-modified PSC achieves a champion power conversion efficiency of 22.80%, while the pristine device gets an efficiency of 20.65%.

The Competition between Hydrogen, Halogen, and Covalent Bonding in Atmospherically Relevant Ammonium Iodate Clusters.

Iodine-containing clusters are expected to be central to new particle formation (NPF) events in polar and midlatitude coastal regions. Iodine oxoacids and iodine oxides are observed in newly formed clusters, and in more polluted midlatitude settings, theoretical studies suggest ammonia may increase growth rates. Structural information was obtained via infrared (IR) spectroscopy and quantum chemical calculations for a series of clusters containing ammonia, iodic acid, and iodine pentoxide. Structures for five of the smallest cationic clusters present in the mass spectrum were identified, and four of the structures were found to preferentially form halogen and/or covalent bonds over hydrogen bonds. Ammonia is important in proton transfer from iodic acid components and also provides a scaffold to template the formation of a halogen and covalent bonded backbone. The calculations executed for the two largest clusters studied suggested the formation of a covalent I3 anion within the clusters.

Insights into the Chemistry of Iodine New Particle Formation: The Role of Iodine Oxides and the Source of Iodic Acid.

Iodine chemistry is an important driver of new particle formation in the marine and polar boundary layers. There are, however, conflicting views about how iodine gas-to-particle conversion proceeds. Laboratory studies indicate that the photooxidation of iodine produces iodine oxides (IxOy), which are well-known particle precursors. By contrast, nitrate anion chemical ionization mass spectrometry (CIMS) observations in field and environmental chamber studies have been interpreted as evidence of a dominant role of iodic acid (HIO3) in iodine-driven particle formation. Here, we report flow tube laboratory experiments that solve these discrepancies by showing that both IxOy and HIO3 are involved in atmospheric new particle formation. I2Oy molecules (y = 2, 3, and 4) react with nitrate core ions to generate mass spectra similar to those obtained by CIMS, including the iodate anion. Iodine pentoxide (I2O5) produced by photolysis of higher-order IxOy is hydrolyzed, likely by the water dimer, to yield HIO3, which also contributes to the iodate anion signal. We estimate that ∼50% of the iodate anion signals observed by nitrate CIMS under atmospheric water vapor concentrations originate from I2Oy. Under such conditions, iodine-containing clusters and particles are formed by aggregation of I2Oy and HIO3, while under dry laboratory conditions, particle formation is driven exclusively by I2Oy. An updated mechanism for iodine gas-to-particle conversion is provided. Furthermore, we propose that a key iodine reservoir species such as iodine nitrate, which we observe as a product of the reaction between iodine oxides and the nitrate anion, can also be detected by CIMS in the atmosphere.

Gas-phase catalytic hydration of I2O5 in the polluted coastal regions: Reaction mechanisms and atmospheric implications

Marine aerosols play an important role in the global aerosol system. In polluted coastal regions, ultra-fine particles have been recognized to be related to iodine-containing species and is more serious due to the impact of atmospheric pollutants. Many previous studies have identified iodine pentoxide (I2O5, IP) to be the key species in new particles formation (NPF) in marine regions, but the role of IP in the polluted coastal atmosphere is far to be fully understood. Considering the high humidity and concentrations of pollutants in the polluted coastal regions, the gas-phase hydration of IP catalyzed by sulfuric acid (SA), nitric acid (NA), dimethylamine (DMA), and ammonia (A) have been investigated at DLPNO-CCSD(T)//ωB97X-D/aug-cc-pVTZ + aug-cc-pVTZ-PP with ECP28MDF (for iodine) level of theory. The results show that the hydration of IP involves a significant energy barrier of 22.33 kcal/mol, while the pollutants SA, NA, DMA, and A all could catalyze the hydration of IP. Especially, with SA and DMA as catalysts, the hydration reactions of IP present extremely low barriers and high rate constants. It is suggested that IP is unstable under the catalysis of SA and DMA to generate iodic acid, which is the key component in NPF in marine regions. Thus, the catalytic hydration of IP is very likely to trigger the formation of iodine-containing particles. Our research provides a clear picture of the catalytic hydration of IP as well as theoretical guidance for NPF in the polluted coastal atmosphere.

APPLICATION OF HYPERVALENT IODINE COMPOUNDS IN ADVANCED GREEN TECHNOLOGIES

This review summarizes industrial applications of inorganic and organic polyvalent (hypervalent) iodine compounds. Inorganic iodate salts have found some application as a dietary supplements and food additives. Iodine pentafluoride is used as industrial fluorinating reagent, and iodine pentoxide is a powerful and selective oxidant that is particularly useful in analytical chemistry. Common organic hypervalent iodine reagents such as (dichloroiodo)benzene and (diacetoxyiodo)benzene are occasionally used in chemical industry as the reagents for production of important pharmaceutical intermediates. Iodonium salts have found industrial application as photoinitiators for cationic photopolymerizations. Various iodonium compounds are widely used as precursors to [18F]-fluorinated radiotracers in the Positron Emission Tomography (PET).

APPLICATION OF HYPERVALENT IODINE COMPOUNDS IN ADVANCED GREEN TECHNOLOGIES (IN PRESS)

This review summarizes industrial applications of inorganic and organic polyvalent (hypervalent) iodine compounds. Inorganic iodate salts have found some application as a dietary supplements and food additives. Iodine pentafluoride is used as industrial fluorinating reagent, and iodine pentoxide is a powerful and selective oxidant that is particularly useful in analytical chemistry. Common organic hypervalent iodine reagents such as (dichloroiodo)benzene and (diacetoxyiodo)benzene are occasionally used in chemical industry as the reagents for production of important pharmaceutical intermediates. Iodonium salts have found industrial application as photoinitiators for cationic photopolymerizations. Various iodonium compounds are widely used as precursors to [18F]-fluorinated radiotracers in the Positron Emission Tomography (PET).

Tuning the reactivity and energy release rate of I2O5 based ternary thermite systems

Iodine pentoxide (I2O5) based nanothermites are one of the most promising candidates for biocidal energetic materials due to superior reactivity and high iodine content. However, the tunability of nanothermites, which is important for biocidal performance, has not been fully exploited for I2O5 based nanothermites. In this work, I2O5 with various fuels (Al, Ti, Si) and their mixtures (i.e., a ternary system) have been investigated. The reactivity and flame temperature were evaluated by a pressure cell coupled with a spectrometer. Temperature-Jump time-of-flight mass spectrometry (T-Jump TOFMS) was used to probe the reaction mechanism and iodine release behavior, along with a high-speed camera to capture the ignition event. I2O5 showed distinct reactivity with different fuels. As a result, by varying the fuel composition of ternary systems, the combustion properties can be tuned. Rapid heating experiments revealed that the reaction initiation was shifted from gas phase dominated to condensed phase dominated mechanism after introducing Ti or Si into Al/I2O5 system. Further analysis of the ternary systems found that the energy release rate correlates with burn time instead of flame temperature. This study shows an approach to tune the reactivity and energy release rate of I2O5 based nanothermites without compromising the energy density.

Experimental observation of the heat transfer mechanisms that drive propagation in additively manufactured energetic materials

The rise of additive manufacturing has led to the development of new architectures and allowed researchers to 3D-print a variety of energetic composites with different formulations. However, reactive sintering within the composites can negatively impact overall performance of nanoenergetic or reactive materials via the loss of nanostructure. It has been previously proposed that the addition of a gas generator could reduce the impact of reactive sintering while enhancing reactivity. Iodine pentoxide (I2O5) is an extremely powerful oxidizer and a strong gas generator which has been proposed as an efficient source of molecular iodine for biocidal applications. However, fabricated Al/I2O5 nanocomposite propellants are unable to propagate. In this study, we demonstrate that the addition of small quantities of CuO enables consistent propagation. Employing high-speed pyrometry and microscopy, we estimate advective heat transfer in the system and demonstrate that the addition of CuO offers a pathway for enhanced energy-transfer by metal condensation that is not available when I2O5 is the sole oxidizer. Elimination of condensing metal vapor as a participant in energy transfer increased the reliance of the system on particle advection. Small additions of CuO yield a condensable product vapor which can effectively eliminate the reliance on heat transfer via advection, enabling consistent propagation in reactive solid materials. We conclude with a general comment that where reliable propagation is critical, such as a stable burn of a solid propellant or delivery of a biocide, small additions of an oxidizer with a condensable metal vapor could be the difference between guaranteed performance and critical failure.

Titanium enhanced ignition and combustion of Al/I2O5 mesoparticle composites

Aluminum (Al) is widely used in thermites, and iodine pentoxide (I2O5) is a strong oxidizer that can release gas phase iodine. The result is a potentially very powerful and effective energetic composite with biocidal properties. However, the alumina coating on the Al presents a diffusion barrier that increases the ignition temperature. In this paper, nano titanium powders (nTi) were added at various mass ratios to Al/I2O5 and a composite mesoparticle was assembled by electrospray. Combustion studies showed that nano Ti can enhance the reactivity of Al/I2O5 thermites significantly with increases in pressure, pressurization rate and dramatic decreases in burn time. Part of this behavior can likely be attributed to less sintering enhancing the completeness of reaction in the Ti added cases. Addition of titanium to aluminum was found to have a significant impact on ignition and when Al is replaced with Ti, the ignition temperature was ∼300 °C below that of the corresponding aluminum thermite. These results show that titanium can be used as a fuel to tune energetic behavior and iodine release temperature and in some ways superior to aluminum.

Diode laser monitoring of atomic iodine in explosive fireballs

The work presented here summarizes the design, development, and evaluation of an applied spectroscopic diagnostic targeted at monitoring iodine producing reactions utilized in counter-biological warheads. The technique employs tunable diode laser absorption spectroscopy (TDLAS) to scan over the F′ = 3 triplet in the hyperfine absorption structure of atomic iodine at 1315 nm. The diagnostic is quantitatively based on statistical mechanics and therefore calibration free for simplified fieldability. The technique was established in a benchtop, milligram-scale study probing thermitic reactions of aluminum and iodine pentoxide initiated with an electrical discharge. It was then extended to investigate the same reactive material in an explosively driven system, closer replicating the intended application space.

Ion Mobility-Mass Spectrometry of Iodine Pentoxide-Iodic Acid Hybrid Cluster Anions in Dry and Humidified Atmospheres.

Nanometer-scale clusters form from vapor-phase precursors and can subsequently grow into nanoparticles during atmospheric nucleation events. A particularly interesting set of clusters relevant to nucleation is hybrid iodine pentoxide-iodic acid clusters of the form (I2O5) x(HIO3) y as these clusters have been observed in coastal region nucleation events in anomalously high concentrations. To better understand their properties, we utilized ion mobility-mass spectrometry to probe the structures of cluster anions of the form (I2O5) x(HIO3) y(IOα)- ( x = 0-7, y = 0-1, α = 1-3), similar to those observed in coastal nucleation events. We show that (I2O5) x(HIO3) y(IOα)- clusters are relatively stable against dissociation during mass spectrometric measurement, as compared to other clusters observed in nucleation events over continental sites, and that at atmospherically relevant relative humidity levels (65% and less) clusters can become sufficiently hydrated to facilitate complete conversion of iodine pentoxide to iodic acid but that water sorption beyond this level is limited, indicating that the clusters do not persist as nanometer-scale droplets in the ambient.

Direct Iodosulfonylation of Alkylynones with Sulfonylhydrazides and Iodine Pentoxide Leading to Multisubstituted α,β-Enones

A facile and efficient method has been developed for the construction of multisubstituted α,β-enones through the direct selective iodosulfonylation of alkylynones with sulfonylhydrazides and iodine pentoxide. The present methodology offers a simple and attractive approach to various multisubstituted α,β-enones in moderate to good yields with excellent stereo- and regioselectivities under the metal- and peroxide-free conditions.

Iodine Pentoxide Nano‐rods for High Density Energetic Materials

AbstractThe iodine pentoxide is one of the most advanced oxidizers for nanostructured energetic formulations among the thermites due to the highest energy release per volume 25.7 kJ cm−3. The size and shape of iodine pentoxide particles have a strong impact on the pressurization rates during the reaction. Although micro‐sized iodine pentoxide particles are commercially available, nano‐sized particles, which are desired for various nano‐energetic applications, are not available on the market. Conventional wet chemical methods are unable to produce iodine pentoxide nanoparticles due to high solubility in water. In this study, we demonstrate fabrication of iodine pentoxide nano‐rods by high energy mechanical treatment of micro‐sized I2O5 particles. Tuning the energy dose in high‐energy ball milling is allowing to produce I2O5 nano‐rods with diameter of 50–100 nm and length of 300–600 nm. The produced nano‐rods exhibited 10 % smaller decomposition energy compared to the precursor of micro particles. The experiments showed that the nano‐energetic materials prepared with nano‐sized I2O5 rods have pressure discharge value of 43.4 MPa g−1 which is two times higher than using commercial iodine pentoxide particles.

Reactive characterization of anhydrous iodine (v) oxide (I2O5) with aluminum: amorphous versus crystalline microstructures

Iodine pentoxide (I2O5) is typically synthesized by dehydration of iodic acid such that the produced material inherently includes hydrated iodic acid species that facilitate further water absorption when exposed to ambient environments. This is a detrimental property for I2O5 powder used in energetic systems. A dry-approach for synthesizing I2O5 with either crystalline (nano C I2O5) or amorphous (nano A I2O5) structure was used for this study and compared to the commercially available material. This synthesis approach enabled isolation of the microstructure as a variable to better understand water absorption behavior of I2O5 and associated reactivity. Material characterization included BET, SEM, TEM, and XRD as well as equilibrium analyses using DSC and TGA along with flame speeds. Results show that nano C I2O5 reacts less with atmospheric water and has a more anhydrous behavior than the crystalline I2O5 powder commercially available. The nano A I2O5 also produced a distinct pre-ignition reaction (PIR) and evidence for smaller PIRs are shown for all mixtures of Al with I2O5. These properties along with increased specific surface area of the nano C I2O5 and nano A I2O increased reactivity and enhanced combustion with Al when compared with commercial I2O5.

Trifluoromethylation of thiophenols and thiols with sodium trifluoromethanesulfinate and iodine pentoxide

A selective and facile trifluoromethylation process for a wide range of thiophenols and thiols under metal free conditions has been developed using two simple and safe solids, sodium trifluoro-methanesulfinate and iodine pentoxide, via the radical process.

ChemInform Abstract: Iodotrifluoromethylation of Alkenes and Alkynes with Sodium Trifluoromethanesulfinate and Iodine Pentoxide.

AbstractAn operationally simple procedure for the iodotrifluoromethylation of alkenes and alkynes is developed using two simple solids NaSO2CF3 and I2O5 as reagents in an aqueous medium.

ChemInform Abstract: A Free‐Radical Cascade Trifluoromethylation/Cyclization of N‐Arylmethacrylamides and Enynes with Sodium Trifluoromethanesulfinate and Iodine Pentoxide.

An I2O5-promoted free-radical cascade trifluoromethylation/cyclization of a broad range of N-arylmethacrylamides and enynes with sodium trifluoromethanesulfinate in aqueous medium has been achieved. This strategy allows highly selective access to a variety of CF3-containing oxindoles and pyrrolidines. Electron spin resonance (ESR) studies indicate that atom-transfer processes are involved in this system.

Iodotrifluoromethylation of alkenes and alkynes with sodium trifluoromethanesulfinate and iodine pentoxide.

A scalable, selective, and operationally easy iodotrifluoromethylation of a wide range of alkenes and alkynes by using two simple and safe solids, sodium trifluoromethanesulfinate and iodine pentoxide, in aqueous medium has been developed. Mechanistic studies confirm that free-radical processes are involved in this system since the key radical intermediates such as CF(3) and β-CF(3) alkyl radicals have been clearly detected by spin trapping and electron spin resonance.