Phenylenediamine Isomers Research Articles

Synthesis of multi-peak emitting carbon dots using phenylenediamine isomers

Revealing the relationship between structure and optical properties of multi-peak emissive carbon dots (CDs) is important. Three types of multi-peak emission CDs were synthesized by one-step hydrothermal method with phenylenediamine (PD) isomers (o/m/p) and maleic anhydride serving as precursors. During the synthesis process, three PDs exhibited different microstructural and chemical states, resulting in various fluorescence emission centers. The multi-peak emission behavior of o-CDs and m-CDs is composed of molecular fluorophores and carbon core states, while that of p-CDs consists of surface states and carbon core states. These different fluorescence centers lead to diverse fluorescence behaviors of the CDs in different solvents and environments. This work inspires the clarification of the relationship between the structural and optical properties of multi-peak emissive CDs.

Development and workflow of a separation process for optimum design: A case of phenylenediamine

AbstractAn industrial project based upon the multi‐scale objective‐oriented process development (MOPD) method for developing an optimum process for separating phenylenediamine (PDA) isomers was executed. This article reports the first four (4) steps of that project. In the first step, the solution for this separation problem was conceptualized. It is a distillation‐crystallization‐hybrid process. The second step is to validate the concept experimentally from the thermodynamic point of view followed by kinetic considerations. It was found that a 2‐stage crystallization is required to purify the main product isomers to the desirable specification that is higher than 99.5 mol%. A heat and material balance model was then constructed for analyzing and optimizing various design variables, also used to understand the operability of the process. Finally, with proper HAZOP analysis and detailed engineering, the pilot unit was designed. Throughout the project, all exercises and efforts are well focused with clear objectives, hence there are minimum detours on the execution; furthermore, the clear objectives enhanced the communications among various disciplines tremendously. It is a valuable asset for senior management in the allocation of resources and budgets.

Optimal Oxophilicity at the Fe-Nx Interface Enhances the Generation of Singlet Oxygen for Efficient Fenton-Like Catalysis.

In the pursuit of efficient singlet oxygen generation in Fenton-like catalysis, the utilization of single-atom catalysts (SACs) emerges as a highly desired strategy. Here, a discovery is reported that the single-atom Fe coordinated with five N-atoms on N-doped porous carbon, denoted as Fe-N5/NC, outperform its counterparts, those coordinated with four (Fe-N4/NC) or six N-atoms (Fe-N6/NC), as well as state-of-the-art SACs comprising other transition metals. Thus, Fe-N5/NC exhibits exceptional efficacy in activating peroxymonosulfate for the degradation of organic pollutants. The coordination number of N-atoms can be readily adjusted by pyrolysis of pre-assembly structures consisting of Fe3+ and various isomers of phenylenediamine. Fe-N5/NC displayed outstanding tolerance to environmental disturbances and minimal iron leaching when incorporated into a membrane reactor. A mechanistic study reveals that the axial ligand N reduces the contribution of Fe-3d orbitals in LUMO and increases the LUMO energy of Fe-N5/NC. This, in turn, reduces the oxophilicity of the Fe center, promoting the reactivity of *OO intermediate-a pivotal step for yielding singlet oxygen and the rate-determining step. These findings unveil the significance of manipulating the oxophilicity of metal atoms in single-atom catalysis and highlight the potential to augment Fenton-like catalysis performance using Fe-SACs.

Reductive carbon dots for reduction, ratiometric fluorescence determination, and intracellular imaging of Au3+

Many studies show that ortho-phenylenediamine (OPD) produces an oxidized fluorescent product when exposed to an oxidizing agent that enables the direct or indirect fluorescence detection of a range chemical and biochemical analytes. However, there is no report on this unique optical behavior for other two isomers of phenylenediamine. This study demonstrates that a simple hydrothermal treatment of para-phenylenediamine (PPD) in the presence of sulfuric acid results in the formation of fluorescent N, S-doped carbon dots (CDs) with triple functionalities including the reduction of Au3+ into gold nanoparticles (AuNPs), the stabilization of the produced AuNPs, and the determination of Au3+ concentration through an intrinsic ratiometric fluorescence signal. In the presence of Au3+, the blue emission of CDs at 437 nm quenched, and a green emission at 540 nm emerged. The linear concentration range for the determination of Au3+ was 20 nM–16 µM with a detection limit of 16 nM. Additionally, the dual emissive CDs-AuNPs hybrid probe showed potential for the indirect fluorescence ratiometric determination of cysteine and sulfide ions. The linear concentration range for cysteine and sulfide ions were 0.25–8 μM and 0.1–6 μΜ, with detection limits of 0.095 μM and 0.041 μM, respectively. Accordingly, CDs were applied to detect Au3+ and S2− in real water samples. Moreover, the synthesized CDs showed no cytotoxicity for HeLa cells up to 300 µg mL−1, as determined by the MTT assay. Therefore, their potential for intracellular imaging of Au3+ in living cells was also investigated.

Facile Synthesis of B/P Co-Doping Multicolor Emissive Carbon Dots Derived from Phenylenediamine Isomers and Their Application in Anticounterfeiting.

Carbon dots (CDs) possess a considerable number of beneficial features for latent applications in biotargeted drugs, electronic transistors, and encrypted information. The synthesis of fluorescent carbon dots has become a trend in contemporary research, especially in the field of controllable multicolor fluorescent carbon dots. In this study, an elementary one-step hydrothermal method was employed to synthesize the multicolor fluorescent carbon dots by co-doping unique phenylenediamine isomers (o-PD, m-PD, and p-PD) with B and P elements, which under 365 nm UV light exhibited signs of lavender-color, grass-color, and tangerine-color fluorescence, respectively. Further investigations reveal the distinctness in the polymerization, surface-specific functional groups, and graphite N content of the multicolor CDs, which may be the chief factor regarding the different optical behaviors of the multicolor CDs. This new work offers a route for the exploration of multicolor CDs using B/P co-doping and suggests great potential in the field of optical materials, important information encryption, and commercial anticounterfeiting labels.

A Remarkable Color Rendering Index of 87 in White Laser Lighting Diode Enabled by Amide‐Functionalized Carbon Dots Phosphor with High Photothermal Stability

AbstractCarbon dots (CDs) phosphors in white laser diodes (WLD) have the advantages of sufficient surface functionalization sites and low cost. Specially, their color rendering index (CRI) in WLD is unsatisfactory due to the uncontrollable synthesis process and low thermal stability. Herein, surface nitrogen‐containing groups of CDs are synthesized from phenylenediamine isomers and trimeric acid, and the optical and thermal properties of CDs are modulated by introducing amide bonds (–CONH). By varying the phenylenediamine isomers, CDs synthesized from o‐phenylenediamine, m‐phenylenediamine, and p‐phenylenediamine emit different fluorescence peaks at 534, 498, and 434 nm, respectively. Further investigation shows that the increase of –CONH and adjacent –NH2 favors the reduction of bandgap, which in turn induces redshifted emission. The green‐emitting CDs are also found to be thermally stable at high –CONH contents up to 10.35%. Finally, by assembling the fluorescent film with 450 nm laser diode, WLD with color coordinates of (0.3767, 0.3540), correlated color temperature of 3924 K, and CRI of 87 is realized, and its CRI reaches the advancing value for single phosphors‐based WLD devices. This work will lay the theoretical and experimental foundation for the realization of the low‐cost, high photothermal stability, high‐color‐rendering‐index CDs‐based laser lighting devices.

Fluorescent sensor based on bismuth metal-organic frameworks (Bi-MOFs) mimic enzyme for H2O2 detection in real samples and distinction of phenylenediamine isomers

Although peroxidase-like nano-enzymes have been widely utilized in biosensors, nano-enzyme based biosensors are seldom used for both quantitative analysis of H2O2 and differentiation of isomers of organic compounds simultaneously. In this study, a dual-functional mimetic enzyme-based fluorescent sensor was constructed using metal-organic frameworks (Bi-MOFs) with exceptional oxidase activity and fluorescence properties. This mimetic enzyme sensor facilitated quantitative analysis of H2O2 and accurate discrimination of phenylenediamine isomers. The sensor exhibited a wide linear range (0.5–400 μM) and low detection limit (0.16 μM) for the detection of H2O2. Moreover, the sensor can also be used for the discrimination of phenylenediamine isomers, in which the presence of o-phenylenediamine (OPD) leads to the appearance of a new fluorescence emission peak at 555 nm, while the presence of p-phenylenediamine (PPD) significantly quenched its fluorescence due to the internal filtration effect. The proposed strategy exhibited a commendable capability in distinguishing phenylenediamine isomers, thereby paving the way for novel applications of MOFs in the field of environmental science.

Structural Tailoring the Phenylenediamine Isomers to Obtain 2D Dion–Jacobson Tin Perovskite Solar Cells with Record Efficiency

Abstract2D Dion–Jacobson (DJ) tin halide perovskite shows impressive stability by introducing diamine organic spacer. However, due to the dielectric confinement and uncontrollable crystallization process, 2D DJ perovskite usually exhibits large exciton binding energy and poor film quality, resulting in unfavorable charge dissociation, carrier transport and device performance. Here, the ortho‐, meta‐, and para‐isomers of phenylenediamine (PDA) are designed for 2D DJ tin halide perovskites. Theoretical simulation and experimental characterizations demonstrate that compared with p‐PDA and m‐PDA, o‐PDA shows larger dipole moment, which further reduces the exciton binding energy for the 2D perovskites. Besides, there is a strong hydrogen bond interaction between o‐PDA cation and inorganic octahedron, which not only improves the structural stability, but also induces larger aggregates in the precursor to form dense and uniform high‐quality films, and strengthens the antioxidant barrier. More interestingly, femtosecond transient absorption further proves that o‐PDA organic spacers can reduce unfavorable small n‐phases, resulting in sufficient and effective charge transfer between different n‐value. As a result, the 2D DJ (o‐PDA)FA3Sn4I13 solar cells achieve a record power conversion efficiency of 7.18%. The study furnishes an effective method to optimize the carrier transport and device performance by tailoring the chemical structure of organic spacers.

Metal Cation-Doped ns-Cucurbit[10]uril: Adsorption of Para-Phenylenediamine.

The separation of phenylenediamine (PDA) isomers is crucial in the field of chemical manufacturing. Herein, we presented a strategy for the separation of PDA isomers (para-phenylenediamine, p-PDA; meta-phenylenediamine, m-PDA; ortho-phenylenediamine, o-PDA) using four supramolecular framework materials of ns-cucurbit[10]uril (ns-Q[10]), (1) ns-Q[10](Cd), (2) ns-Q[10](Mn), (3) ns-Q[10](Cu), (4) ns-Q[10](Pb). Our findings indicated that these supramolecular framework materials of ns-Q[10] showed remarkable selectivity for para-phenylenediamine (p-PDA) in p-PDA, m-PDA, and o-PDA mixtures, respectively. The variations in selectivity observed in these four single-crystal structures arose from variations in the thermodynamic stabilities and binding modes of the host-guest complexes. Importantly, the supramolecular framework based on ns-Q[10] exhibited selective accommodation of p-PDA over its isomers. This study highlighted the practical application of ns-Q[10] in effectively separating PDA isomers and demonstrated the potential utility of ns-Q[10] in isolating other organic molecules.

Application of “Three-in-One” Strategy Based on MOF-199 in Determination of Phenylenediamine Isomers and Cr(VI)

Application of “Three-in-One” Strategy Based on MOF-199 in Determination of Phenylenediamine Isomers and Cr(VI)

The radical scavenging ability of phenylenediamine species: The role of electron and proton transfer processes in their oxidative transformation

A theoretical analysis of the thermodynamics of the oxidation–reduction reaction steps associated with proton-coupled electron transfer is presented for aniline and phenylenediamine isomers. In this context, the radical scavenging ability of the parent molecules and their ionic and/or radical species is compared. The acidity constants evaluated for heterolytic N–H bond decay in an aqueous environment and corresponding electrochemical oxidation potentials, as adapted to the standard hydrogen electrode, were used for the construction of a Pourbaix diagram (electrochemical potential vs. pH). Based on this diagram, the chemically relevant transformation routes for the corresponding radical cations were identified. Finally, the thermodynamics of model proton-coupled electron transfer reactions with hydrogen peroxide are considered. The theoretical data presented are compared and correlated with experimental results, published in the literature. The results obtained allow an estimation to be made of the oxidation mechanisms occurring in polymer matrices, including those containing phenylenediamine antioxidants, in synthetic organic reactions or in processes related to tertiary wastewater purification.

Reaction-time-controlled carbon dots nanoarchitectonics with stable and bright photoluminescence for white light emission

It is still a challenge for multicolor carbon dots (CDs) with stable and bright photoluminescence (PL). The controlling of synthesis becomes a hot topic. In this paper, CDs with blue-, green- and red-emitting named as B-CDs, G-CDs, and R-CDs were prepared using three isomers of phenylenediamine as precursors by one-step solvothermal synthesis. Green and red emitting CDs with C, N and O components named as samples G-CDs and R-CDs revealed uniform nanoparticle distribution with average sizes of 7.2 and 5.7 nm, respectively. The PL peak wavelength of three kinds of CDs were 430, 546 and 613 nm, and their average fluorescence lifetime was 5.32, 22.35, 8.74 ns, respectively. The full width at half maximum of PL spectra of the samples was 65.12, 92.63, 83.62 nm, and their PL quantum yields were 8.19, 43.43, and 5.14%, respectively. The brightly luminescent CDs were further embedded in prepared polyvinyl alcohol films to prepare a white emitting layer by adjusting the ratios of CDs with different emitting color. The composite CDs revealed stable and bright white emitting in the film with a Commission Internationale d'Eclairage (CIE) coordinate of (0.28, 0.33). The result suggested that these unique luminescent CDs have potential applications in various luminescence fields.

Constructing a novel “turn-on” fluorescent sensor based on phenazine macrocycle through halogen bond interaction for the naked-eye detection of phenylenediamine isomers

Developing a visual color change pathway to differentiate and identify three phenylenediamine isomers remains an extremely fascinating and critical task. Herein, we first reasonably introduced iodine molecule(I2) to regulate the stimuli-responsive properties of phenazine macrocycle(PNH), and thus a novel “turn-on” fluorescence sensing platform(PNH-I2) was constructed through intermolecular halogen bonding. This platform PNH-I2 enabled the naked-eye identification and ultra-sensitive detection of o-phenylenediamine(OPD), m-phenylenediamine(MPD) and p-phenylenediamine(PPD) at low concentration levels(2 μM). The lowest detection limits(LODs) for OPD and MPD reached 6.97 × 10−9 M and 2.90 × 10−9 M, respectively, which were much lower than those reported literatures. More importantly, the test box based on PNH-I2 could be used as intelligent fluorescence display material, which had good application value in the detection and identification of three phenylenediamine isomers. Moreover, the fluorescence sensor PNH-I2 could successfully perceive the presence of OPD and MPD in real water sample. Such a novel strategy is expected to open up new applications of phenazine derivatives in environmental science.

Chiral dual-emission composite material fluorescein/CCQDs @ZIF-8 for highly efficient recognition of phenylenediamine isomers and their oxidized product.

As a new type of fluorescent nanomaterial, chiral carbon quantum dots (CCQDs) have the advantages of wide source, good water solubility and high chemical stability, and have been widely used in drug detection, bioimaging and chemical sensing. In this work, a chiral dual-emission hybrid material fluorescein/CCQDs@ZIF-8 (1) was synthesized by in-situ encapsulation strategy. Luminescence emission position of CCQDs and fluorescein are almost unchanged after the encapsulation into ZIF-8. The luminescent emissions of CCQDs and fluorescein can be observed to be located at 430nm and 513nm, respectively. When 1 is soaked in pure water, ethanol, dimethylsulfoxide, DMF, DMA and targeted substances solution for 24h, 1 can maintain its structural stability. Photo-luminescent (PL) studies show that 1 can discriminate p-phenylenediamine (PPD) from m-phenylenediamine (MPD) and o-phenylenediamine (OPD), which can detect the presence of PPD with high sensitivity and selectivity (ratiomeric fluorescent probe with KBH: 1.85×103 M-1 and detection limit: 8.51μM). Further, 1 also effectively distinguish the oxidized product of these phenylenediamine(PD) isomers. 1 can be used as a "turn-off" fluorescent probe to detect oxidized product of PPD (ratiomeric fluorescent probe with KSV: 6.82×102 M-1 and detection limit: 0.112mM) and a "turn-on" fluorescent probe to detect oxidized product of MPD (ratiomeric fluorescent probe: KBH: 1.65×103 M-1 and detection limit: 35.03μM) and oxidized product of OPD (ratiomeric fluorescent probe: KBH: 2.40×106 M-1 and detection limit: 0.105μM). Further, for the convenience of practical application, 1 can be developed as fluorescence ink and be prepared into a mixed matrix membrane. When the target substances are gradually added to the membrane, significant luminescence change with obvious color change can be observed.

WITHDRAWN: Application of “three-in-one” strategy based on MOF-199 in degradation and determination of phenylenediamine isomers and Cr (VI)

WITHDRAWN: Application of “three-in-one” strategy based on MOF-199 in degradation and determination of phenylenediamine isomers and Cr (VI)

Toward understanding the regioselectivity of the one‐pot reaction of phenylene diamines with aldehydes and cyclopentadiene (Povarov reaction). Combined experimental and theoretical approaches

AbstractThree‐component acid‐catalyzed cyclocondensation of isomeric phenylenediamines with aldehydes and cyclopentadiene (CPD) was studied. In the M06‐2X//B3LYP/6–311 + G(d,p) + IEFPCM(SMD) approximation, a quantum chemical model was developed, energies of the PES stationary points were determined, and activation barriers were found for the CPD addition to the protonated Schiff base (rate‐limiting step) and for electrophilic carbocation cyclization to give endo, endo (syn)‐ or endo, exo (anti)‐cyclopentene‐annulated octahydropyridoquinoline‐ and octahydrophenanthroline‐based cycloadducts. The calculation results are in full agreement with the experimental data, which indicate that the cyclocondensation involving p‐phenylenediamine affords both types of cycloadducts, whereas the reactions of o‐ or m‐phenylenediamine lead to regioselective formation of octahydro‐1,10‐phenanthroline‐ or octahydropyridoquinoline‐based product, respectively. According to homo‐ and heteronuclear correlation 1Н and 13С NMR experiments and X‐ray diffraction data, the newly formed asymmetric centers of the cyclopentene‐annulated tetrahydroquinoline moiety in the polycyclic products have exo (endo)‐cis‐orientation.

Fluorescent-tagged water with carbon dots derived from phenylenediamine as an equipment-free nanotracer for enhanced oil recovery

Chemical enhanced oil recovery (EOR) through waterflooding is the most commonly used method to improve crude oil displacement and extraction however; the impact of environmental side effects may remain ambiguous. Regarding, flooding tagged water with tracers provides a better understanding of the fate of injected water and the reservoir conditions more than oil recovery. This study's main focus is the proposed carbon dots (CDs) to develop fluorescent-tagged with dual functions as a sensing and an enhancing agent for EOR operations. Different physicochemical and optical properties were obtained for CDs by tuning the surface chemistry of phenylenediamine (PD) isomers and tartaric acid (TA) via the solvothermal method which leads to green, and yellow fluorescent emissions. Size distribution and colloidal and thermal stability of the prepared nanofluids carrying CDs were controlled by atomic force microscope (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, and thermogravimetric analysis (TGA). Long-time emission stability in high temperature and salinity such as conditions found in the oil reservoirs was precisely detected by fluorescence spectroscopy and a portable UV cabinet as the on-site detection method to confirm the sensing ability of CDs. While, rheological parameters of nanofluids such as viscosity, wettability alteration, and fluid/crude oil interfacial tension were evaluated to support the potential of CDs as an enhancing agent to sweep crude oil on the carbonate rock reservoirs. The oil displacement mechanism was monitored on the micromodel pattern by recording 27.8 % and 20.5 % displacement factors for the prepared nanofluids carrying 200 ppm CDs.

Molecular insights into the complex formation between dodecamethylcucurbit[6]uril and phenylenediamine isomers

Molecular insights into the complex formation between dodecamethylcucurbit[6]uril and phenylenediamine isomers

PH and solvent induced discoloration behavior of multicolor fluorescent carbon dots

Green, blue and pink fluorescent carbon dots (o/m/p-CDs) were prepared by one-step hydrothermal method with three isomers (o/m/p) of phenylenediamine as nitrogen and carbon sources and ethanol as solvent. The obtained carbon dots exhibited different luminescence behaviors, and the luminescence behaviors were affected by solvent and pH. More interestingly, m-CDs exhibited obvious discoloration behavior under different pH conditions and had excellent linear relationship under acidic and basic conditions, respectively. Furthermore, we combined m-CDs with test paper, PVA film, and cotton fabric, respectively, to prepare composites for visual pH detection. The as-prepared composite material has excellent visual detection effect for a small amount of test sample (<5 μL) in the fine pH range (0.5 unit), and could be applied to trace pH detection.

Preparation and evaluation of ultra-long open-tubular capillary columns modified with zeolitic imidazolate framework-8 incorporated polymeric porous layer for liquid chromatography

An ultra-long (5 m) open tubular capillary liquid chromatographic column was prepared by incorporating Metal Organic Framework (MOF), zeolitic imidazolate framework-8 (ZIF-8), directly into polymer coating, which was synthesized by the copolymerization of 4-vinylbenzyl chloride and divinylbenzene, on the capillary inner surface. The prepared ZIF-8 incorporate polymeric open tubular capillary column (denoted as ZIF-8-p(VBC/DVB) OTCC) was evaluated with thiourea, alkylbenzenes and polycyclic aromatic hydrocarbons as probe molecules. The results showed that the ultra-long column achieved absolute column efficiency of 130,000 plates for thiourea, and the incorporation of ZIF-8 effectively improved the chromatography performance of the OTCC. Baseline separation of aromatic compounds and position isomers was achieved based on multiple interactions provided by the zeolitic imidazolate framework and polymer, including hydrophobic interaction, π-π stacking interaction and the coordination effect. The RSD values (run-to-run, day-to-day, column-to-column, n = 3) of retention time of phenylenediamine isomers and propylbenzene isomers were less than 0.7%, 1.2% and 4.0% respectively, suggesting excellent repeatability. Finally, the prepared ZIF-8-p(VBC/DVB) OTCC was applied to the separation of hydroxyacetophenone isomers with satisfied results.