Selective Iodination Research Articles

Highly sensitive, responsive, and selective iodine gas sensor fabricated using AgI-functionalized graphene

Radioactive molecular iodine (I2) is a critical volatile pollutant generated in nuclear energy applications, necessitating sensors that rapidly and selectively detect low concentrations of I2 vapor to protect human health and the environment. In this study, we design and prepare a three-component sensing material comprising reduced graphene oxide (rGO) as the substrate, silver iodide (AgI) particles as active sites, and polystyrene sulfonate as an additive. The AgI particles enable reversible adsorption and conversion of I2 molecules into polyiodides, inducing substantial charge density variation in rGO. This mechanism facilitates exceptional sensitivity and selectivity, ultrafast response and recovery times, and room-temperature operation. A multifunctional sensor prototype fabricated utilizing this material achieves the fastest reported response/recovery times (22/22 seconds in dynamic mode and 4.2/11 seconds in static mode) and a detection limit of 25 ppb, surpassing standards set by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH), while outperforming commercial I2 gas sensors. This work provides profound insights into the design of I2 sensing materials and mechanisms for real-world applications.

Configurational and Conformational Analysis of 5-deoxy-5-iodo-α,β-D-ribose with 3-Sphere Approach

Configurational and conformational analysis with 3-Sphere approach on selective iodination of α, β-methyl D-ribofuranose (2-α:2-β) with iodotriphenilphosphonium iodide complex [Ph₃P⁺I]I^- generated in situ, under RT, reflux, microwave and sonochemistry. Introduction of the unit and hypersphere trigonometric equations, under Hopf fibration and Lie algebra theories, on Lambert-Wu methods enable calculation of the dihedral angles from NMR data (¹³C chemical shift, vicinal coupling constant ³<I>J</I><SUB>HH</SUB>[Hz]) and the ratio of anomers. The conformation/configuration at anomeric position is <i>cis</i>: <i>trans</i> with <i>axial</i>:<i>axial</i> 3-α:3-β<i> </i>(³<I>J</I><SUB>H1H2</SUB> 3 or 4.5:0[Hz])<i> </i>or <i>equatorial</i>:<i>axial</i> 3-α:3-β (³<I>J</I><SUB>H1H2</SUB> 6 or 4.5:0[Hz]) as state based on dihedral angles θ<SUB>H1H2</SUB>[deg], recorded carbon chemical shift δ_Cn[deg] and VISION molecular models. The conformation of 3-β anomer is ³E, and in case of 3-α anomer ₃E on Altona’s map, the last having the succession of sign (+, -, -) with θ<SUB>H3H4</SUB>^α <i>trans-ee</i>, or alternatively ³₂T conformation having the succession of sign (-, +, -) with θ<SUB>H3H4</SUB>^α <i>trans-aa</i>. An equilibrium between ₃E^α and ³₂T^α was confirmed by ³<I>J</I><SUB>H1H2</SUB> of 4.5[Hz], <i>i.e.</i> negative θ<SUB>H1H2</SUB>^α with ³₂T and <i>equatorial</i> OCH₃, or positive θ<SUB>H1H2</SUB>^α with ₃E and axial OCH₃. The APT experiment (attached proton test) demonstrated the formation of tetrahydro 2H-pyran-2-ol as side product after selective iodination of methyl 5-deoxy-<i>β</i>-D-ribofuranoside 2-β.

Selective Iodination Enables Anthocyanin Synthesis to Be More General.

The current synthesis routes of anthocyanins are relatively complicated, which significantly hinders their development. We optimized the method by introducing a selective iodination reaction and also established a general scheme for preparing anthocyanin diglycosides. This method allows anthocyanin synthesis to require fewer steps and costs. Based on this, we prepared four common anthocyanins and two anthocyanin diglucosides and measured their antioxidant and anti-insulin resistance activities.

Native Amino Group Directed Site-Selective ε-C(sp2)-H Iodination of Primary Amines.

Selective remote C-H activating amines using unmodified NH2 as a native directing group demonstrate compelling synthetic utilities. The 3-arylpropan-1-amine moiety is present in many drugs and candidates in clinical trials. Selective iodination of 3-arylpropan-1-amines on remote aryl rings gives valuable intermediates for modifying bioactive molecules and synthesizing quinolones. Here we report the first palladium-catalyzed selective ε-C(sp2)-H iodination of free 3-arylpropan-1-amines via a seven-membered palladacycle.

Speciation analysis of iodine in seaweed: optimisation of extraction procedure and chromatographic separation

Environmental context Seaweed is a good natural dietary source of iodine and some types of seaweed are rich in iodine. Iodine has a diverse chemistry in seaweeds and may exist as different chemical species; however, the occurrence and identity of the individual species are still not fully elucidated. Hence, development of sensitive and selective iodine speciation methods for studies of iodine chemistry and biotransformation in seaweeds are needed.Rationale Iodine is an essential element required for human health and metabolism. Seafood and especially seaweed can accumulate iodine to high amounts. Iodine may exist in different chemical forms (species) in seaweeds.Methodology The present study describes the development and optimisation of a method for iodine speciation analysis in seaweed based on high performance liquid chromatography–inductively coupled plasma–mass spectrometry (HPLC-ICP-MS). The extraction procedure was conducted in two steps, pancreatic enzymatic extraction followed by alkaline extraction with tetramethylammonium hydroxide for optimum extraction efficiency without compromising species integrity.Results and discussion Total iodine and iodine species were determined in a range of brown (6 samples), red (6 samples) and green (3 samples) seaweeds. A large variation in the total iodine content of the different seaweeds was observed (33–5611 µg g–1 dry weight) with the highest levels encountered in brown seaweed. Iodine speciation analysis revealed differences in the speciation profile of the different types of seaweed. In all seaweeds iodide was the predominant species, and minor contents of MIT (monoiodotyrosine) and DIT (diiodotyrosine) were found in most seaweeds. Furthermore, peaks originating from six unknown iodine-containing species were observed in the chromatograms, especially in red and green seaweeds, while less abundant in brown seaweeds. The speciation method presented here will be valuable in future studies on iodine speciation in seaweed and an important tool for the investigation of iodine speciation and biotransformation in marine algae.

Electrochemically Generated Iodine Cations from a Glassy Carbon Electrode for Highly Selective Iodination of Anisole

The synthesis of aryl iodides from commercially available raw chemicals by simple, cheap and green strategies is of fundamental significance. Aryl iodides can undergo a series of homo-/cross-coupling reactions for the synthesis of important industrial chemicals and materials. Traditional methods require the electrophilic substitution on aromatic compounds by iodine or hypervalent iodine compounds, which suffers from the use of erosive halogens or hazardous oxidants. With the development of green chemistry in the field of electrochemical synthesis, anodic oxidation-derived I+ cations have been used for substitution reactions. However, the selectivity of the iodination by these electrochemical methods remains unsatisfactory. We believed that the anolyte is contaminated by trace platinum species from the working electrode. Herein, we report the generation of active I+ species from the anodic oxidation of I2 in acetonitrile using a glassy carbon electrode. With the presence of H+, electrolyte prepared with a glassy carbon anode can react with anisole to selectively form 4-iodoanisole with a yield as high as 97%. On contrast, the electrolytes prepared from Pt and graphite anodes finished the reaction with yields of 16% and 60% for 4-iodoanisole, respectively. This electrochemical method also applies to the iodination of toluene, benzonitrile and bromobenzene, delivering the target para-iodination products with 92%, 84%, and 73% yields, respectively. Thus, an atom-efficient and highly selective aryl iodination method was developed without the use of excessive oxidants.

Parts-per-billion (ppb) selective iodine sensors leveraging metal–organic framework nanoenvironment

Ultra-sensitive and highly selective iodine gas sensors play a crucial role during the nuclear radiation leak for a timely detection and mitigation of pollution, ensuring the safety of a vast number of operators and subsequent integrity of the facility. Herein, we rationally designed a metal–organic framework (MOF) that exhibits an outstanding performance with an almost billionfold enhancement in the electrical response due to its optimized hydrophobicity, which allows the easy migration of iodine molecules through the channels and the presence of suitable interaction sites, temporarily anchoring the target molecule for ultra-trace sensing. The prototype sensor tested in demanding environments demonstrates its high selectivity, ultra-trace parts per billion (ppb)-level sensitivity, good reversibility, and a very fast response time even at high frequencies compared to existing adsorbents, including commercially available materials. Further, the iodine sensing at the atomic level was studied in detail by measuring the electrical response of a single crystal and, the optimal thickness of the MOF layer was identified for an industrially-viable prototype sensor by using inkjet printing. In a wider perspective, we propose a general strategy for engineering electrically efficient sensing materials that will enable the construction of high-sensitivity iodine sensors targeting a safe and sustainable future.

Switchable, Reagent-Controlled C(sp3)-H Selective Iodination and Acetoxylation of 8-Methylquinolines.

An efficient Pd-catalyzed C(sp3)-H selective iodination of 8-methylquinolines is reported herein for the first time. Because of the versatility of organic iodides, the method offers a facile access to various C8-substituted quinolines. By slightly switching the reaction conditions, an efficient C(sp3)-H acetoxylation of 8-methylquinolines has also been enabled. Both approaches feature mild reaction conditions, good tolerance of functional groups, and a broad substrate scope.

Ultra-stable fluorescent 2D covalent organic framework for rapid adsorption and selective detection of radioiodine

Abstract Radioactive iodine is a harmful substance produced by nuclear fission, and its hazard to the human body should not be underestimated. In this work, a novel adsorbent COF-PA containing quinoline and phenylacetylene units for dual chemical adsorption of iodine is designed and prepared. It exhibits the fastest adsorption rate (1.3 g h−1) among 2D covalent organic frameworks and also possesses remarkable adsorption capacity and efficiency at low concentration of iodine vapor. When the weight ratio of adsorbent to iodine is 1:1, the adsorption efficiency of COF-PA reaches 90%. Moreover, COF-PA can maintain good crystallinity when soaked in common organic solvents and strong acids (12 M HCl) and bases (14 M NaOH) for one week, and its stability is of great significance for the real industrial applications. Unexpectedly, COF-PA shows strong fluorescence, which can be specifically quenched by iodine and thus be applied for selective iodine detection.

Regioselective iodination of activated arenes using KI-DMSO in aqueous hydrochloride

The KI-DMSO in aqueous hydrochloride has been utilized for selective iodination of activated arenes. The iodination of substrate such as hydroxyacetophenones, amines, phenols, anisole and toluene took place with high regioselectivity and mono-iodination was found to occur. The electron releasing substituents (–CH3, –OCH3, –OH, –NH2) exclusively form para substituted product while ortho-iodination occurred only when para-position was blocked by other substituents. The method is simple and noteworthy for reactive arenes with comprises some advantages as easy reaction procedure, short reaction time (5–12 min.) and fair to good yield of aryl iodides (65–90%). The structure of aryl iodide was established on the basis of spectral and elemental data.

Green and selective iodination of diamondoid adamantane by β-cyclodextrin as a molecular reactor

β-Cyclodextrin (β-CD) is a versatile and naturally occurring host which strongly binds adamantane and its derivatives. Based on this binding, we prepared a host–guest inclusion complex of β-CD with adamantane, and selectively iodinated the included adamantane to 1-iodoadamantane by iodoform. The only formed monoiodo product confirmed our initial assumption that three out of the four methine groups of the guest adamantane are shielded when adamantane is included into the cavity of β-CD and, therefore, iodination just takes places on the methine group directing to the outside of the cavity of β-CD.

PEDOT: PSS coating on gold microelectrodes with excellent stability and high charge injection capacity for chronic neural interfaces

PEDOT: PSS has become one of the best choices as coating material of neural interfaces electrodes for its excellent biocompatibility, chemical steadiness and extremely inhomogeneous topography that facilitate reversible faradaic charge injection. However, chronic application of this material is still a matter of challenge for its poor adhesion to metallic electrodes. This study presents two new methods that increases stability and stimulation capacity of PEDOT: PSS (poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate)) coated neural interfaces electrodes. These improvements in the characteristics make PEDOT: PSS as a promising coating material for the long-term stable bidirectional neural application. The first process ensures long-term stability of PEDOT: PSS coating. The stability improvement is done by creating a rough and porous surface with selective iodine etching of Au electrodes. The pores act as anchors and increases mechanical bonding between PEDOT: PSS coating and electrode surface, hence the stability of the coating increases. PEDOT: PSS coating on iodine etched gold electrode showed 100% stability under strong ultrasonic stability test compared to non-etched electrodes. Long-term in vitro continuous stimulation for 7 days was performed to evaluate the stability of the coating. 1 μm thick PEDOT:PSS coating on iodine etched Au electrode completely survived under 604 million continuous current pulses that was evaluated by SEM image and electrochemical impedance spectroscopy (EIS). The second process improves the characteristics of PEDOT: PSS coated electrodes in terms of stimulation capacity. This is done by electrochemical modification of PEDOT: PSS coating surface by applying a cyclic voltammetry method. A perfect and effective method is developed by comparative analysis and optimizing the parameters of cyclic voltammetry. The PEDOT: PSS coating presented here (1 μm thick) reduces the impedance of bare Au electrode by around 99%. This electrochemical modification method further reduces the impedance of this PEDOT: PSS coated electrode by 33%. Moreover, this method reduces electrode polarization under stimulation by 30.5%. Reduced electrode impedance and polarization under stimulation are beneficial for increasing safe charge injection limit of the electrode for stimulation. Both processes facilitate the use of PEDOT: PSS coating as a true long-term stable and promising material on gold microelectrodes of neural interfaces.

Iodine in Metal-Organic Frameworks at High Pressure.

Capture of highly volatile radioactive iodine is a promising application of metal-organic frameworks (MOFs), thanks to their high porosity with flexible chemical architecture. Specifically, strong charge-transfer binding of iodine to the framework enables efficient and selective iodine uptake as well as its long-term storage. As such, precise knowledge of the electronic structure of iodine is essential for a detailed modeling of the iodine sorption process, which will allow for rational design of iodophilic MOFs in the future. Here we probe the electronic structure of iodine in MOFs at variable iodine···framework interaction by Raman and optical absorption spectroscopy at high pressure ( P). The electronic structure of iodine in the straight channels of SBMOF-1 (Ca- sdb, sdb = 4,4'-sulfonyldibenzoate) is modified irreversibly at P > 3.4 GPa by charge transfer, marking a polymerization of iodine molecules into a 1D polyiodide chain. In contrast, iodine in the sinusoidal channels of SBMOF-3 (Cd- sdb) retains its molecular (I2) character up to at least 8.4 GPa. Such divergent high-pressure behavior of iodine in the MOFs with similar port size and chemistry illustrates adaptations of the electronic structure of iodine to channel topology and strength of the iodine···framework interaction, which can be used to tailor iodine-immobilizing MOFs.

Solvent‐Free Conversion of Alcohols to Alkyl Iodides and One‐Pot Elaborations Thereof

AbstractCombination of iodine and triphenylphosphine in the presence of a slight stoichiometric excess of 2,6‐lutidine provided effective iodination of alcohols under solvent–free conditions. Several substrates with different polarity, not necessarily soluble in the reaction system, were iodinated in short times without the need for microwave irradiation, ultrasonication or ionic liquids. The scope of this method with complex molecules was especially demonstrated in the fast and selective iodination of primary hydroxyl groups on both protected and unprotected carbohydrates, proving compatible with a variety of functional groups. In addition, a large number of one – pot elaborations of alkyl iodides thus obtained was successfully performed through the application of unprecedented fully solvent – free sequences. In particular, direct installation of either nitrogen or sulfur functionalities and generation of useful saccharide building – blocks were achieved in remarkably short times avoiding the use of polar high boiling solvents.

Syntheses of (-)-Tripterifordin and (-)-Neotripterifordin from Stevioside.

We report short syntheses of (-)-tripterifordin and (-)-neotripterifordin, potent inhibitors of HIV replication, from stevioside, a natural sweetener used worldwide. The key transformations are reduction at C13 through the formation of a tertiary chloride and subsequent three-step lactonization including a selective iodination at C20 by the photoreaction of the C19-alcohol. The title compounds were reliably obtained from stevioside in 9 and 11 steps (with 5-7 isolation steps), respectively. Additionally, the related lactone-containing ent-kaurenes, doianoterpenes A and B, and two more natural products were synthesized.

Iodinated cobalt corroles

Cobalt(III) complexes of selectively [Formula: see text]-pyrrole-iodinated corroles were prepared and characterized for the first time. X-ray crystallographic data reveals that the corrole macrocycle remains quite planar despite of the presence of multiple iodine substituents. The redox potentials increase linearly with the number of iodine substituents, much more for reduction than for oxidation, in a similar pattern to that of previously reported gold(III), gallium(III), and aluminum(III) complexes of [Formula: see text]-pyrrole-iodinated corroles. Their effect on reduction potential is much larger than what is observed for analogous gallium(III) and aluminum(III) corroles, wherein the chelated element is not redox active. Interestingly, the effect of iodine is similar to that of the much more electronegative halides, which is attributed to a stronger [Formula: see text]-back donation by the latter. One advantage of achieving selective iodination, in terms of the number and positioning, is that is provides an entry to further functionalization of the corrole skeleton via nucleophilic aromatic substitution.

A Metal‐Free Iodination of Aryl Ethers and Phenols Using I2

AbstractI2/DMSO mediated method for deprotection and selective iodination of allyl aryl ethers and phenols has been developed. A wide range of allyl aryl ethers and phenols have been efficiently iodinated to the respective iodophenols in one pot.

Chemodivergent, Tunable, and Selective Iodine(III)-Mediated Bromo-Functionalizations of Polyprenoids.

Mild oxidation of bromides by iodine(III) reagents generated active electrophilic bromination species that were reacted with polyprenoids. By simple and minor variations of an I(III)/Br combination, the reactivity could be selectively steered toward dibromination, oxybromination, or bromocyclization, giving access to a wide array of brominated motifs.

Polymer Supported Triphenylphosphine-methylacrylate Complex: An Efficient Catalyst for the Selective Iodination of Alcohols

Polymer Supported Triphenylphosphine-methylacrylate Complex: An Efficient Catalyst for the Selective Iodination of Alcohols

Synthesis of pyrrole-imidazole polyamide oligomers based on a copper-catalyzed cross-coupling strategy

Pyrrole-imidazole (Py-Im) polyamides are useful tools for chemical biology and medicinal chemistry studies due to their unique binding properties to the minor groove of DNA. We developed a novel method of synthesizing Py-Im polyamide oligomers based on a Cu-catalyzed cross-coupling strategy. All four patterns of dimer fragments could be synthesized using a Cu-catalyzed Ullmann-type cross-coupling with easily prepared monomer units. Moreover, we demonstrated that pyrrole dimer, trimer, and tetramer building blocks for Py-Im polyamide synthesis were accessible by combining site selective iodination of the pyrrole/pyrrole coupling adduct.