Electroactive Moieties Research Articles

Tetrathiafulvalene-based covalent organic frameworks as high-voltage organic cathodes for lithium batteries

We report a series of 2D tetrathiafulvalene (TTF)-based COFs incorporating different organic linkers between the electroactive moieties that were investigated as p-type organic cathode materials for lithium-organic batteries.

The synthesis of new non-ionic surfactant 1-(2, 4-dinitrophenyl)-3-dodecanoylthiourea: An efficient candidate for drug deliveries and metabolism processes

By utilizing the reaction of lauryl chloride, potassium thiocynate, and 2,4-dinitroaniline, the novel non-ionic surfactant 1-(2, 4-dinitrophenyl)-3-dodecanoylthiourea (DDT) was produced in high yield. Various spectroscopic techniques (1HNMR, 13CNMR, and UV-V) have been used to elucidate the chemical structure of DDT. Additionally, its electrochemical behaviour (electrochemical fate) was elucidated using a cyclic, square wave, and differential pulse voltammetry through a wide pH range. The limit of detection (LOD) and limit of quantification (LOQ) values of the compound were also determined using Square wave voltammetry (SWV). A fascinating fact observed is that the electroactive moieties in the compound are getting oxidized and reduced at a potential very close to 0.0 V, and the potential of the human body is 0.07 V, so the compound investigated can serve as an efficient candidate for the drug deliveries and metabolism processes.

Bis(Vinylenedithio)-Tetrathiafulvalene-Based Coordination Networks.

Novel coordination polymers embedding electroactive moieties present a high interest in the development of porous conducting materials. While tetrathiafulvalene (TTF) based metal-organic frameworks were reported to yield through-space conducting frameworks, the use of S-enriched scaffolds remains elusive in this field. Herein is reported the employment of bis(vinylenedithio)-tetrathiafulvalene (BVDT-TTF) functionalized with pyridine coordinating moieties in coordination polymers. Its combination with various transition metals yielded four isostructural networks, whose conductivity increased upon chemical oxidation with iodine. The oxidation was confirmed in a single-crystal to single-crystal X-ray diffraction experiment for the Cd(II) coordination polymer. Raman spectroscopy measurements and DFT calculations confirmed the oxidation state of the bulk materials, and band structure calculations assessed the ground state as an electronically localized antiferromagnetic state, while the conduction occurs in a 2D manner. These results are shedding light to comprehend how to improve through-space conductivity thanks to sulfur enriched ligands.

A nanoscale observation to explain the discrepancy of electron exchange capacities between biochar containing comparable surface redox-active moieties

Biochar, possessing electron exchange capacities (EEC), is generally involved in environmental redox reactions due to the presence of redox-active moieties (RAMs). The phenomenon that chars containing comparable RAMs possess differential EEC revealed that the accessibility of RAMs is important to the redox properties. However, many studies have focused on the type of RAMs, whereas the distribution has been insufficiently investigated. Herein, we achieved nanoscale observation of electroactive moieties on the surface of six chars using a conductive atomic force microscope. For the two specific kinds of chars with submicron particles and opposite current distributions, the submicron particles took up only 1–4‰wt of biochar accounting for approximately 30–50% of electron-donating capacity (EDC), and electron-accepting capacity (EAC) became 87% and 1.40 times as before after removing submicron particles, respectively. Meanwhile, the combined impact of RAMs and surface topography (that uneven distribution of RAMs resulted in outstanding EEC by enhancing accessibility) was clarified. Furthermore, direct evidence of the link between char structure and EEC (that condensed aromatic structures were indispensable to EAC while both heteroatoms and amorphous aromatics contributed to EDC) was established. These findings can aid in understanding the functions of biochar in biotic and abiotic redox processes.Graphical

Achieving High-Performance Molecular Rectification through Fast Screening Alkanethiol Carboxylate-Metal Complexes Electroactive Units

Achieving High-Performance Molecular Rectification through Fast Screening Alkanethiol Carboxylate-Metal Complexes Electroactive Units

Synthesis and Excimer Formation Properties of Electroactive Polyamides Incorporated with 4,5-Diphenoxypyrene Units.

A new dietherpyrene-cored diamine monomer, namely, 4,5-bis(4-aminophenoxy)pyrene, was successful synthesized and formed a series of electroactive polyamides with an aryloxy linkage in a polymer main chain and bearing pyrene chromophore as a pendent group using conventional one-pot polycondensation reactions with commercial aromatic/aliphatic dicarboxylic acids. The resulting polyamides exhibited good solubility in polar organic solvents and, further, can be made into transparent films. They had appropriate levels of thermal stability with moderately high glass-transition values. The dilute NMP solutions of these polyamides exhibited pyrene characteristic fluorescence and also showed a remarkable additional excimer emission peak centered at 475 nm. Electrochemical studies of these polymer films showed that these polyamides have both p- and n-dopable states as a result of the formation of radical cations and anions of the electroactive pyrene moieties.

Hole-Transporting Materials for Perovskite Solar Cells Employing an Anthradithiophene Core.

A decade after the report of the first efficient perovskite-based solar cell, development of novel hole-transporting materials (HTMs) is still one of the main topics in this research field. Two of the main advance vectors of this topic lie in obtaining materials with enhanced hole-extracting capability and in easing their synthetic cost. The use of anthra[1,9-bc:5,10-b′c′]dithiophene (ADT) as a flat π-conjugated frame for bearing arylamine electroactive moieties allows obtaining two novel highly efficient HTMs from very cheap precursors. The solar cells fabricated making use of the mixed composition (FAPbI3)0.85(MAPbBr3)0.15 perovskite and the novel ADT-based HTMs show power conversion efficiencies up to 17.6% under 1 sun illumination compared to the 18.1% observed when using the benchmark compound 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD). Detailed density functional theory calculations allow rationalization of the observed opto-electrochemical properties and predict a flat molecular structure with a low reorganization energy that supports the high conductivity measured for the best-performing HTM.

Supramolecular Ladder Assemblies as a Model for Probing Electronic Interactions between Multiple Stacked π-Conjugated Systems.

A series of mono-, di-, and tri-topic receptors in which H-bonding sites, complementary to those of barbituric acid (BA), are fused is used to induce the supramolecular assembly of n×m ladders containing 1, 2, or 3 triphenylenevinylene units appended with BA. The topological constraint enforced by the architectures induces through-space interactions between the electroactive moieties that are reflected in the electronic absorption and emission spectrum. The n=2, m=2 or m=3 architectures undergo two single electron oxidation events, indicative of the formation of the corresponding mono- and di-radical cation species with comproportionation constants of 340 and 70, respectively. Comparison of the electrochemical potentials suggests that the charges are delocalized over the electroactive units in the assembly.

Enabling Racemization of Axially Chiral Subphthalocyanine‐Tetracyanobutadiene‐Aniline Enantiomers by Triplet State Photogeneration

AbstractIn recent years, several tetracyanobuta‐1,3‐diene (TCBD) conjugates have been prepared by linking the tetracyano unit to various electroactive moieties. These push–pull conjugates, besides showing interesting physicochemical properties, are axially chiral, a feature arising from the restricted rotation around the central bond of the butadiene. Yet, only in a few cases, separation and isolation of the enantiomers have been successfully achieved, owing to the configurational lability of the corresponding enantiopure species. Herein, we report the first example of photo‐ and electroactive TCBD‐based derivatives showing unprecedented configurational stability and a peculiar light‐triggered enantiomer conversion mechanism enabled by triple‐state photogeneration. These systems represent a nice addition to the fast‐increasing arsenal of artificial, light‐controllable molecular switches.

Enabling Racemization of Axially Chiral Subphthalocyanine-Tetracyanobutadiene-Aniline Enantiomers by Triplet State Photogeneration.

In recent years, several tetracyanobuta-1,3-diene (TCBD) conjugates have been prepared by linking the tetracyano unit to various electroactive moieties. These push-pull conjugates, besides showing interesting physicochemical properties, are axially chiral, a feature arising from the restricted rotation around the central bond of the butadiene. Yet, only in a few cases, separation and isolation of the enantiomers have been successfully achieved, owing to the configurational lability of the corresponding enantiopure species. Herein, we report the first example of photo- and electroactive TCBD-based derivatives showing unprecedented configurational stability and a peculiar light-triggered enantiomer conversion mechanism enabled by triple-state photogeneration. These systems represent a nice addition to the fast-increasing arsenal of artificial, light-controllable molecular switches.

Electrochemistry and transport properties of electrolytes modified with ferrocene redox-active ionic liquid additives

Used in their pure, undiluted form, ionic liquids usually result in Li-ion battery electrolytes with inadequate performance due low Li+ transport numbers (tLi+). Alternatively, they can be used as additives dissolved in carbonates to maintain a high tLi+ while providing the electrolyte with additional properties such as resistance to combustion, current collector passivation, and decreased Li dendritic growth. Additional properties can be imparted to the ionic liquid via the modification of their structure. Ionic liquids modified with electroactive moieties such as ferrocene (Fc-IL) can be used as an additive in Li-ion battery (LiB) electrolytes to prevent cathode over-oxidation via the redox shuttle mechanism. The aim of the present work is to evaluate the properties of LiB electrolytes modified with such Fc-IL at different concentrations. At low concentrations (0.3–0.5 mol/L), the redox-active ionic liquid behaves as expected for a redox shuttle. We show that at 1 mol/L, however, the redox ionic liquid yields a different discharge behavior after the overcharging step, providing an increase in discharge capacity. This behavior is linked to the deposition of the ferrocenium-IL at the positive electrode. Such electrolyte is non-flammable and is highly efficient to achieve shuttling of excess charge. Based on this principle, it is expected that novel ionic liquids can be designed for development of other types of additives and contribute to developing safer battery electrolytes. As a part of this commemorative issue, this contribution highlights the type of collaborative research currently being done on energy storage devices at the Department of Chemistry at the Université de Montréal.

All-screen-printed graphite sensors integrating permanent bonded magnets. Fabrication, characterization and analytical utility

Electrochemical magneto assays have been extremely popular thanks to the facile manipulation of magnetic nanoparticles (MNPs) by a magnetic field. To this end, various related accessories, such as magnetic electrode shafts, electrochemical cells integrating (electro)magnets, magnetic stickers etc. have been developed aiming to attract MNPs on the electrode surface. Herein, we introduce for the first time screen-printed electrodes (SPEs) coupled with screen-printed permanent bonded magnets as a compact, portable, cheap and disposable alternative to aforementioned products. The bonded magnet (3 mm ∅, 56 ± 6 μm thick) consists of micro sized NdFeB particles dispersed in a thixotropic ink, and it was printed on a 100 μm thick polyester film, aligned with the electroactive surface of the SPE, which is printed on the other side of the substrate. Various parameters, such as the composition of the NdFeB/ink blend, the thickness and the pattern (compact or hole-engraved) of the printed magnet, and the thickness of the substrate were investigated by both experimental and theoretical studies. After the magnetization of the bonded magnet with a vibrating sample magnetometer at 2 T, a sufficient magnetic field strength was obtained. The performance is enhanced if a void round area is created in the center of the magnet to introduce a further area of strong field gradient. This pattern allows the development of stronger attracting forces to MNPs, higher MNPs loading and a better distribution of them on the electrode surface. The effective electron transfer between Fe3O4 MNPs and the electrode surface is shown with the electrochemical conversion of surface confined Fe3O4 MNPs to Prussian blue electroactive moieties and the amperometric determination of hydrogen peroxide, while the ultrasensitive determination of riboflavin using Ag/Fe3O4 MNP modified magnet-SPEs is demonstrated.

Electroactive Covalent Organic Frameworks: Design, Synthesis, and Applications.

Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers with tailorable compositions, porosities, functionalities, and intrinsic chemical stability. The incorporation of electroactive moieties in the structure transforms COFs into electroactive materials with great potential for energy-related applications. Herein, the recent advances in the design and use of electroactive COFs as capacitors, batteries, conductors, fuel cells, water-splitting, and electrocatalysis are addressed. Their remarkable performance is discussed and compared with other porous materials; hence, perspectives in the development of electroactive COFs are presented.

Electrochemical oxidation of asymmetric chalcones containing two terminal electroactive moieties

The electrochemical behavior of two new chalcones, containing carbazole cycle and N,N-disubstituted amino group as terminal electron-donating moieties, was studied. In order to determine a detailed mechanism of their electrochemical oxidation and reduction, comparative analysis of cyclic voltammograms of the chalcones and starting compounds was carried out. It was proven that replacing the N,N-dimethylamino group in the structure of a chalcone with a diphenylamino group significantly changes not only the basic electrochemical characteristics (reduces the HOMO energy value and increases the LUMO energy and the band gap values), but also generally affects the polymerization process. It was also proven that the chalcone containing both a carbazole fragment and a diphenylamino group in its structure is capable of forming oligomeric structures under electrochemical oxidation conditions, due to the sequential dimerization of both electron-donating fragments.

Antimicrobial Photodynamic Polymeric Films Bearing Biscarbazol Triphenylamine End-Capped Dendrimeric Zn(II) Porphyrin.

A novel biscarbazol triphenylamine end-capped dendrimeric zinc(II) porphyrin (DP 5) was synthesized by click chemistry. This compound is a cruciform dendrimer that bears a nucleus of zinc(II) tetrapyrrolic macrocycle substituted at the meso positions by four identical substituents. These are formed by a tetrafluorophenyl group that possesses a triazole unit in the para position. This nitrogenous heterocyclic is connected to a 4,4'-di(N-carbazolyl)triphenylamine group by means of a phenylenevinylene bridge, which allows the conjugation between the nucleus and this external electropolymerizable carbazoyl group. In this structure, dendrimeric arms act as light-harvesting antennas, increasing the absorption of blue light, and as electroactive moieties. The electrochemical oxidation of the carbazole groups contained in the terminal arms of the DP 5 was used to obtain novel, stable, and reproducible fully π-conjugated photoactive polymeric films (FDP 5). First, the spectroscopic characteristics and photodynamic properties of DP 5 were compared with its constitutional components derived of porphyrin P 6 and carbazole D 7 moieties in solution. The fluorescence emissions of the dendrimeric units in DP 5 were more strongly quenched by the tetrapyrrolic macrocycle, indicating photoinduced energy transfer. In addition, FDP 5 film showed the Soret and Q absorption bands and red fluorescence emission of the corresponding zinc(II) porphyrin. Also, FDP 5 film was highly stable to photobleaching, and it was able to produce singlet molecular oxygen in both N,N-dimethylformamide (DMF) and water. Therefore, the porphyrin units embedded in the polymeric matrix of FDP 5 film mainly retain the photochemical properties. Photodynamic inactivation mediated by FDP 5 film was investigated in Staphylococcus aureus and Escherichia coli. When a cell suspension was deposited on the surface, complete eradication of S. aureus and a 99% reduction in E. coli survival were found after 15 and 30 min of irradiation, respectively. Also, FDP 5 film was highly effective to eliminate individual bacteria attached to the surface. In addition, photodynamic inactivation (PDI) sensitized by FDP 5 film produced >99.99% bacterial killing in biofilms formed on the surface after 60 min irradiation. The results indicate that FDP 5 film represents an interesting and versatile photodynamic active material to eradicate bacteria as planktonic cells, individual attached microbes, or biofilms.

Oligomers containing pyridinyl-substituted carbazole rings as host materials for phosphorescent OLEDs

Two oligoethers containing electroactive pendent pyridinyl-carbazole moieties have been synthesized by the multi-step synthetic route. Full characterization of their structures is presented. The oligomers represent derivatives of very high thermal stability with initial thermal degradation temperatures exceeding 400 °C. Glass transition temperatures of the amorphous materials were also very high and reached values of 124 °C and 145 °C, respectively. Bipolar chemical structure having oligomer, i.e. poly{3-(2-methoxy-3-pyridinyl)-9-(3-methyloxetan-3-yl)methyl-carbazole} was tested as host material for green phosphorescent organic light emitting diode using tris(2-phenylpyridine)iridium(III) as a triplet emitter. A green device containing 10 wt% of the green guest demonstrated among all the devices the best performance with current efficiency of 8.8 cd/A and power efficiency of 5.1 lm/W at 100 cd/m2. At higher brightness, such as 1000 cd/m2, used for illumination applications, this PhOLED showed enhanced efficiency of 11.7 cd/A (5.4 lm/W) with brightness exceeding 4000 cd/m2.

Electrochemical films deposition and electro-optical properties of bis-carbazol-triphenylamine end-caped dendrimeric polymers

A family of structurally related π-conjugated star-shape bis-carbazol-triphenylamine end-caped dendrimers was designed, synthetized and characterized as novel organic optoelectronic materials. These compounds hold triphenylamine and carbazole electroactive moieties as dendrimer core and/or periphery groups. Homogeneous and stable electrogenerated polymeric films were obtained from dendrimers over Pt and ITO electrodes. These films showed charge conductivities, reversible electrochemical behavior and electrochromic effect. The hole mobility of the electrodeposited films was found to be dependent of the dendrimeric structure and film morphologies, indicating that the shape and size of the studied dendrimers have a strong effect on their charge transport properties. These results provide data that will contribute to the systematic study for the design of new dendrimers as starting materials for conductive polymers films with potential applications in optoelectronic devices.

Electrochemical detection of nitrite and ascorbic acid at glassy carbon electrodes modified with carbon nano-onions bearing electroactive moieties

In this work, we evaluate two novel surfaces for the simultaneous detection of nitrite and ascorbic acid in aqueous media. Glassy carbon electrodes were first modified with small carbon nano-onions (GCE/CNO) and further functionalized either by electrografting ortho-aminophenol (oAP) groups or by physical adsorption of thionine to give electroactive surfaces that were characterized by cyclic voltammetry. The modified surfaces exhibited a fast electrochemical response and were able to detect the presence of nitrite and ascorbic acid by amperometry. The presence of both CNOs and the electroactive moiety on the electrode surface enhanced the sensitivity and lowered the limit of detection of the determinations as compared to GCE modified only with oAP or thionine. The CNO-modified electrodes showed good reproducibility and stability with time and were applied in the detection of ascorbic acid in orange juice.

Multifunctional and Stable Monolayers on Carbon: A Simple and Reliable Method for Backfilling Sparse Layers Grafted from Protected Aryldiazonium Ions.

A new strategy for preparation of robust multifunctional low nanometer thickness monolayers on carbon substrates is presented. Beginning with protected aryldiazonium salts, sparse monolayers of ethynyl-, amino-, and carboxy-terminated tethers are covalently anchored to the surface. The layers are then backfilled with a second modifier via the nucleophilic addition of an amine derivative to the surface. Through use of electroactive moieties coupled to the tethers, and an electroactive amine for backfilling, electrochemical measurements reveal that backfilling approximately doubles the surface concentration of the monolayer. Cyclic voltammetry of solution-based redox probes at the modified surfaces is consistent with the expected blocking properties at various stages of surface preparation. Fractional surface coverages of the layers are estimated using electrochemically determined surface concentrations of modifiers and computationally derived modifier footprints. Assuming free rotation of the coupled ferrocenyl or nitrophenyl groups leads to physically unreasonable fractional surface coverages, indicating that these larger modifiers must be rotationally restricted. Using a conformationally constrained model produces lower bound estimates of the total fractional surface coverage close to 0.4, with tether-only coverages close to 0.2. The backfilled tether layers constitute practical platforms for controlled construction of complex interfaces with many potential applications including sensing, molecular electronics, and catalysis.

Hierarchical Self-Assembly and Digital Memory Characteristics of Crystalline–Amorphous Brush Diblock Copolymers Bearing Electroactive Moieties

Two series of crystalline–amorphous brush diblock copolymers bearing electroactive moieties were newly synthesized by sequential anionic ring-opening copolymerizations of glycidyl derivatives and subsequent selective postfunctionalizations; their homopolymers and analogues were additionally synthesized. Self-assembly structural details and electrical memory behaviors of these polymers in nanoscale thin films were investigated. The diblock copolymers revealed complex hierarchical self-assembly structures depending on the compositions. The self-assembly structure and orientation of the crystalline block chains were severely affected by the geometrical confinement (i.e., size and shape) stemming from microphase separation. Such film morphologies were found to significantly influence the electrical properties; they exhibited electrical properties from p-type permanent memory behavior to dielectric-like behavior. The memory behaviors were governed by the trap-limited space charge limited conduction mechanism c...