Diamine Molecules Research Articles

Carbonized Polymer Dots: Influence of the Carbon Nanoparticle Structure on Cell Biocompatibility.

Carbonized polymer dots (CPDs) were obtained by using microwave irradiation under the same conditions. However, different carbogenic precursors were used, such as aromatic diamine molecules, ortho-phenylenediamine (o-OPDA), and 3,4-diaminobenzoic acid (3,4-DABA). Both carbon nanoparticles showed different structural results based on Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and atomic force microscopy analyses. However, there are similar spectroscopic (UV-visible and fluorescence emission) profiles. The photophysical results, like quantum yield (QY) and fluorescence lifetime, were not identical; CPDs-OPDA has a higher QY and fluorescence lifetime than CPDs-3,4-DABA. CPDs-3,4-DABA presents a more hydrophobic character than CPDs-OPDA and has a more negative superficial charge. Cell viability studies in both standard and tumor lines demonstrated higher cytotoxicity from CPDs-OPDA than that from CPDs-3,4-DABA. The oxidative stress identified in cells treated with CPDs-OPDA was based on reactive oxygen species and associated with nitric oxide production. CPDs-3,4-DABA showed more DPHH inhibition than CPDs-OPDA, indicating the antioxidant activity of CPDs.

Odd-even trends in the series of new bis(α,ω-alkanediamine)dibromocadmium(II) coordination polymers: Crystal structure and thermal decomposition

In this paper, organic-inorganic coordination polymers of the CdBr2(H2N-(CH2)n-NH2) general formula, where n = 4 – 10 and 12, were studied. All the materials were synthesized as very fine powders from metal salt and diamine solutions following an analogous simple procedure. Scanning electron microscopy (SEM) images and recorded powder X-ray diffraction patterns (PXRD) allowed for the assessment of the purity and crystallinity of the products. Based on the collected diffraction data, lattice parameters and symmetry were determined. For five of the synthesized compounds (n = 4, 6, 7, 8, and 12) that were of relatively high purity and sufficient crystallinity, crystal structure models were determined and refined. It was found that the structure symmetry depends on the parity of the number of carbon atoms in the diamine molecules. Structures of the investigated compounds belonging to the even series are centrosymmetric while the ones from the odd series are not (P21 space group). Structures’ symmetry of compounds based on even diamines decreases from P2/m to P1¯ with increasing length of the organic molecules. Diamine molecules are aligned parallel to the diagonals of the (010) faces of the unit cell and there is an almost perfectly linear correlation between the value of a lattice parameter and the number of C atoms. There are, however, separate trends for even or odd series. Differential scanning calorimetry (DSC) and non-ambient PXRD measurements provided information about the thermal decomposition of the materials. The temperature of decomposition decreases with the growing length of diamine molecules and achieves the lowest value (176 °C, 449 K) for the compound with 1,12-diaminododecane (the longest diamine among the studied ones) while the sample with 1,4-diaminobutane is the most stable one (up to around 284 °C, 557 K). The studied compounds also show odd-even separate trends concerning the decomposition temperature. The compounds with even diamines start to decompose at relatively higher temperatures than the ones belonging to the odd series.

Maximizing N-Nitrosamine Rejection via RO Membrane Plugging with Hexylamine and Hexamethylenediamine.

The rapid expansion of urban areas and the increasing demand for water resources necessitate substantial investments in technologies that enable the reuse of municipal wastewater for various purposes. Nonetheless, numerous challenges remain, particularly regarding disinfection by-products (DBPs), especially carcinogenic compounds such as N-nitrosamines (NTRs). To tackle the ongoing issues associated with reverse osmosis (RO) membranes, this study investigated the rejection of NTRs across a range of commercially available RO membranes. In addition, the research aimed to improve rejection rates by integrating molecular plugs into the nanopores of the polyamide (PA) layer. Hexylamine (HEX) and hexamethylenediamine (HDMA), both linear chain amines, have proven to be effective as molecular plugs for enhancing the removal of NTRs. Given the environmental and human health concerns associated with linear amines, the study also aimed to assess the feasibility of diamine molecules as potential alternatives. The application of molecular plugs led to changes in pore size distribution (PSD) and effective pore number, resulting in a decrease in membrane permeability (from 5 to 33%), while maintaining levels suitable for RO processes. HEX and HDMA exhibited a positive effect on NTR rejection with ACM1, ACM5 and BW30LE membranes. In particular, NDMA rejection, the smallest molecule of the tested NTRs, with ACM1 was improved by 65.5% and 70.6% after treatment with HEX and HDMA, respectively.

Social Self-Sorting of Quasi-Racemates: A Unique Approach for Dual-Pore Molecular Crystals.

Despite recent advances in porous organic molecular crystals, the engineering of dual-pore systems within the intermolecular voids remains a significant challenge. In this study, we have achieved the crystallization-induced social self-sorting of "quasi-racemic" dialdehydes into a macrocyclic imine. X-ray crystallographic analysis unambiguously characterizes the resulting structure as incorporating two quasi-racemate pairs with four diamine molecules. Notably, different alkyl substituents on the quasi-racemates afford two types of one-dimensional pores within the macrocyclic imine crystal. The different adsorption properties of these pores were substantiated through adsorption experiments. An intriguing helical arrangement of guest molecules was observed within one of the pores. This study provides pioneering evidence that the social self-sorting of quasi-racemates offers a new methodology for creating dual-functional supramolecular materials.

Montmorillonite Membranes with Tunable Ion Transport by Controlling Interlayer Spacing.

Membranes incorporating two-dimensional (2D) materials have shown great potential for water purification and energy storage and conversion applications. Their ordered interlayer galleries can be modified for their tunable chemical and structural properties. Montmorillonite (MMT) is an earth-abundant phyllosilicate mineral that can be exfoliated into 2D flakes and reassembled into membranes. However, the poor water stability and random interlayer spacing of MMT caused by weak interlamellar interactions pose challenges for practical membrane applications. Herein, we demonstrate a facile approach to fabricating 2D MMT membranes with alkanediamines as cross-linkers. The incorporation of diamine molecules of different lengths enables controllable interlayer spacing and strengthens interlamellar connections, leading to tunable ion transport properties and boosted membrane stability in aqueous environments.

Latest Advancements in the Development of High-Performance Lignin- and Tannin-Based Non-Isocyanate Polyurethane Adhesive for Wood Composites.

The depletion of natural resources and increasing environmental apprehension regarding the reduction of harmful isocyanates employed in manufacturing polyurethanes (PUs) have generated significant attention from both industrial and academic sectors. This attention is focused on advancing bio-based non-isocyanate polyurethane (NIPU) resins as viable and sustainable substitutes, possessing satisfactory properties. This review presents a comprehensive analysis of the progress made in developing bio-based NIPU polymers for wood adhesive applications. The main aim of this paper is to conduct a comprehensive analysis of the latest advancements in the production of high-performance bio-based NIPU resins derived from lignin and tannin for wood composites. A comprehensive evaluation was conducted on scholarly publications retrieved from the Scopus database, encompassing the period from January 2010 to April 2023. In NIPU adhesive manufacturing, the exploration of substitute materials for isocyanates is imperative, due to their inherent toxicity, high cost, and limited availability. The process of demethylation and carbonation of lignin and tannin has the potential to produce polyphenolic compounds that possess hydroxyl and carbonyl functional groups. Bio-based NIPUs can be synthesized through the reaction involving diamine molecules. Previous studies have provided evidence indicating that NIPUs derived from lignin and tannin exhibit enhanced mechanical properties, decreased curing temperatures and shortened pressing durations, and are devoid of isocyanates. The characterization of NIPU adhesives based on lignin and tannin was conducted using various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), matrix-assisted laser desorption/ionization with time-of-flight (MALDI-TOF) mass spectrometry, and gel permeation chromatography (GPC). The adhesive performance of tannin-based NIPU resins was shown to be superior to that of lignin-based NIPUs. This paper elucidates the potential of lignin and tannin as alternate sources for polyols in the manufacturing of NIPUs, specifically for their application as wood adhesives.

Organic Diamine‐Regulated Vanadium Oxides as Cathode Materials for High‐Performance Sodium Ion Batteries

AbstractPre‐intercalating ions between VO layers is considered to be an effective strategy to modulate the interlayer spacing of 2D vanadium oxides. However, the rigid pre‐intercalated ions hardly keep stable during repeated charging/discharging process and their sizes limit the extent of interlayer spacing expansion, which inevitably lead to poor rate capability and cycle stability. In this work, aliphatic diamines are adopted as pre‐intercalated guests to elastically modulate the interlayer spacing of VO layers by tuning the chain length of the organic diamine molecules. Benefiting from the strong interaction between the terminal doubly protonated amine and the polar negative oxygen bridge of the VO layers, the aliphatic diamine molecules can act as a structural stabilizer between the layers and boost fast Na ion diffusion (10−8 to 10−10 cm2 s−1). The sodium ion battery based on the first synthesized 1,6‐hexanediamine pre‐intercalated vanadium oxide supported on nickel foam hybrid cathode achieves a large specific capacity of 597 mAh g−1 at 0.09 A g−1, as well as superior rate performance and cycling stability. This work provides a strategy to elastically modulate 2D layered materials with tunable interlayer spacing for batteries based on large‐size‐ions.

Theoretical study on the solvent‐free self‐catalyzed coupling mechanism of a chiral vicinal diamine and isobutyraldehyde mediated by the outgrowth H2O

AbstractThe self‐catalyzed addition of a chiral vicinal diamine with two isobutyraldehyde molecules and the subsequent diaza‐Cope rearrangement between two diimines were investigated systematically by M06‐2X method in conjunction with the 6‐311+G(d) basis set. Our theoretical model shows that, 1) the solvent‐free coupling of the vicinal diamine and isobutyraldehyde molecules produces a relative stable compounds with an imidazolidine‐dihydro‐1,3‐oxazine fused ring instead of imine intermediates; 2) the assistance of a yielded water molecule can significantly decrease the free‐energy barriers of the ring‐recombination and ring‐opening processes by borrowing a hydrogen atom from it; 3) the two addition processes with the free‐energy barriers of 150.0 and 159.0 kJ/mol, respectively, and the successive formation of the five‐membered ring with a barrier of 164.1 kJ/mol control the whole reaction system.

Potential Regulation for Surface-Enhanced Raman Scattering Detection and Identification of Carotenoids.

Surface-enhanced Raman scattering (SERS) is often impaired by the limited affinity of molecules to plasmonic substrates. Here, we use carbon fiber microelectrodes modified with silver nanoparticles as a plasmonic microsubstrate with tunable affinity for enrichment and molecular identification by SERS. The silver nanoparticles self-assemble by electrostatic interaction with diamine molecules that are electrochemically grafted onto the surface of the microelectrodes. β-carotene and trans-β-Apo-8'-carotenal, producing similar resonant SERS spectra, are employed as model molecules to study the effect of electroenrichment and SERS screening for different electrode potentials. The data show that at a characteristic electrode potential, the low affinity of polyene chains without hydrophilic groups to the substrate can be overcome. Different potentials were applied to recognize the two types of carotenoids by their typical SERS signal, and the applicability of this strategy was further confirmed in the environment of a real cell culture. The results indicate that by regulating the potential, carotenoid molecules with a similar molecular structure can be selectively quantified and identified by SERS. The developed SERS-active microelectrode is expected to help the development of portable, miniaturized point-of-care diagnostic SERS sensors.

Tunable Ion Transport with Freestanding Vermiculite Membranes.

Membranes integrating two-dimensional (2D) materials have emerged as a category with unusual ion transport and potentially useful separation applications in both aqueous and nonaqueous systems. The interlayer galleries in these membranes drive separation and selectivity, with specific transport properties determined by the chemical and structural modifications within the inherently different interlayers. Here we report an approach to tuning interlayer spacing with a single source material─exfoliated and restacked vermiculite with alkanediamine cross-linkers─to both control the gallery height and enhance the membrane stability. The as-prepared cross-linked 2D vermiculite membranes exhibit ion diffusivities tuned by the length of the selected diamine molecule. The 2D nanochannels in these stabilized vermiculite membranes enable a systematic study of confined ionic transport.

Ag(μ‐en)][ReO4]: An Intermediate during Preparation of the Ethylene Epoxidation Catalyst

AbstractPreparation of a catalyst for the ethylene oxide production requires impregnation of a porous corundum support with an aqueous silver ethylene diamine oxalate complex solution, to which among others NH4[ReO4] is added. Here we report on [Ag(μ‐en)][ReO4] that precipitates from such a mixture. Single crystal structure analysis has revealed a striking similarity of the [Ag(μ‐en)]+ entity with the same complex cation encountered in[Ag(μ‐en)]2(C2O4)×2H2O. Silver is coordinated end‐on to the nitrogen atoms of the en ligands. The [ReO4]− anions are not bonded to the silver cations, but instead involved in N−H⋅⋅⋅O hydrogen bonds to the ethylene diamine molecules. The first step of thermal degradation occurs at approximately the same temperature for both, the main component precipitate [Ag(μ‐en)]2(C2O4)×2H2O and [Ag(μ‐en)][ReO4], warranting proximity of the rhenium promoter and the elemental silver deposit. At 300 °C, the temperature at which the catalyst for EO synthesis is commonly calcined, the decomposition product of plain [Ag(μ‐en)][ReO4] under synthetic air is Ag[ReO4], in full analogy to industrial manufacturing process for selected Re‐promoted EO catalyst formulations.

Effects of monomer rigidity on microstructures and properties of novel polyamide thin-film composite membranes prepared through interfacial polymerization for pervaporation dehydration

In this study, thin-film composite (TFC) membranes were produced through interfacial polymerization between diamine and trimesoyl chloride on a polyetherimide (PEI) support. The TFC membranes with different diamines, 4,4′-((propane-2,2-diylbis(4,1-phenylene))bis(oxy))dianiline (BAPP), 4,4′-((methylene bis(4,1-phenylene))bis(oxy))dianiline (MPDA), and 6,6′-bis(4-aminopheoxy)-4,4,4′,4′,7,7′-hexamethyl-2,2′-spirobichroman (SBC), were denoted as TFCPEI/B, TFCPEI/M, and TFCPEI/S, respectively. These three aromatic diamines have different central moieties that affect reactivity during the interfacial polymerization reaction. The crosslinking degree of the TFC membranes increased in the following order: TFCPEI/S < TFCPEI/M < TFCPEI/B. Positron annihilation lifetime spectroscopy analysis also unveils that TFCPEI/B had the lowest free volume. These results reveal that the appropriate steric structure of the diamine molecules can create less compact structure without impeding the formation of the crosslinked polyamide selective layer. Moreover, the TFCPEI/B membrane had a flux of approximately 705 ± 46 g∙m−2 h−1, and the water concentration in the permeate was maintained at approximately 99.8 wt% at 25°C during the 70 wt% isopropanol solution dehydration. Furthermore, the TFCPEI/B membrane can be operated under broad operating conditions and possesses high long-term stability.

CO2capture by aqueous mixture of 1,8‐diaminooctane promoted MDEA and MEA: CO2loading, kinetic study, and regenerability

AbstractThe main aim of the current research is to determine the kinetics, CO2loading, absorption rate, and regenerability of 1,8‐diaminooctane (DAO) promoted MEA and MDEA solvents in a lab‐scale experimental setup. The DAO is a linear diamine molecule with a long distance between amine groups and low vapor pressure. In the first step, the CO2loading and rate of solutions are measured in a well‐mixed isothermal batch reactor at the CO2pressure range 0.2–1.2 bar, the temperature range of 303–313 K, and promoter volume fraction of 0%–10%. It appears the equilibrium loading of MEA is less sensitive to an increase in dissolved CO2concentration compared to the promoted samples due to the stability of MEA carbamate. Afterward, to investigate the regenerability of the prepared solutions, the effective loading of samples is determined through the designed regeneration test. The results show that the addition of a small quantity of 1,8‐diaminooctane reveals a considerable enhancement in the rate and CO2loading of the base solutions. The maximum loading of 0.95 mol CO2per mol amine is obtained by 1,8‐diaminooctane promoted MDEA (10%) at equilibrium temperature 313.15 K, and pressure 1.01 bar.

Modification of GO-based pervaporation membranes to improve stability in oscillating temperature operation

Graphene oxide (GO)-based pervaporation membranes have great potential for desalination and lithium containing brine enrichment. However, they experienced critical challenges when used in aqueous solution and exposed to oscillating temperatures due to swelling and microdefects. In this work, the GO-based membranes were fabricated by the filtration of GO suspension with sulfonate-containing diamine molecules on porous substrates, then dip-coated with chitosan and polyvinyl alcohol (PVA). The resultant GO-based membranes demonstrated 99.99% salt rejection during pervaporation using NaCl or lithium-containing concentrated inland brine with humic acid as the feed solution under oscillating temperature. The intercalation of diamine molecules inside the GO nanochannels was able to increase water flux by 20% while the coated chitosan/PVA layer reduced structural defects and undesired scaling/fouling on the membrane surface resulting in minimal reduction of water flux (16%) over 72 h of oscillating temperature pervaporation. Moreover, the membrane exhibited good stability after chemical cleaning. The proposed GO-based membranes provided significant performance sustainability in concentrated inland brine and oscillating feed temperature condition.

On the Stability of Pt‐Based Catalysts in HBr/Br2 Solution

AbstractStability studies on supported metal nanoparticles are essential for gaining insight into the design and optimization of high‐performance materials. In this work, the dissolutions of Pt‐based catalysts in HBr/Br2 mixture of various concentration regimes were studied and correlated with material structural properties. The dissolution of metal nanoparticles was enhanced by adding Br2 to the HBr solution. Comparing with commercial Pt/C catalyst, the well‐alloyed PtIr/C catalyst was observed to exhibit high resistance towards dissolution. In addition, regulating the accessibility of the metal sites to dissolution‐inducing species contributed to the marked stability of the nanoparticles in HBr/Br2 solutions, as shown for the surface‐modified PtIr/C catalysts with organic diamine molecules.

Chemical welding of diamine molecules in graphene oxide nanosheets: Design of precisely controlled interlayer spacings with the fast Li+ diffusion coefficient toward high-performance storage application

A facile method of chemical welding was proposed to construct the diamine molecules (xDM, x = 2, 3, 4, 6 and 8) pillared- and strained-graphene oxides (GO) with controllable interlayer spacing via the dehydration condensation reaction between GO and xDM. The interlayer spacing of xDM pillared- and strained-GO (GO-xDM) is controllably enlarged by choosing the length of xDM, which determines the pillaring effects. The GO-xDM exhibits a low diffusion barrier and ultrafast Li+ diffusion dynamics due to its enlarged interlayer spacing, which leads the excellent Li+ storage rate capability. The effects of interlayer spacing on Li+ diffusion dynamics are clarified that GO-2DM with the interlayer spacing of 0.911 nm displays the excellent Li+ storage performance and fast Li+ diffusion dynamics (DLi+=2.4 × 10−7 cm2 s−1). The GO-2DM presents a high capacity of 291.8 mAh g−1 at a current density of 0.1 A g−1 and a high-rate capability of 120.8 mAh g−1 at a current density of 5.0 A g−1. The GO-2DM//AC lithium-ion hybrid capacitor delivers a high energy density of 103.6 Wh kg−1 at a power density of 55.8 W kg−1, even reaches 2777.8 W kg−1 at a power density of 61.1 Wh kg−1. The approach of chemical welding provides a novel perspective for controllably enlarging interlayer spacing and designing two-dimensional (2D) energy storage materials with high-rate capability.

Localized and Delocalized States of a Diamine Cation: Resolution of a Controversy.

Recent Rydberg spectroscopy measurements of a diamine molecule, N,N′-dimethylpiperazine (DMP), indicate the existence of a localized electronic state as well as a delocalized electronic state. This implies that the cation, DMP+, can similarly have its positive charge either localized on one of the N atoms or delocalized over both. This interpretation of the experiments has, however, been questioned based on coupled cluster calculations. In this article, results of high-level multireference configuration interaction calculations are presented where a localized state of DMP+ is indeed found to be present with an energy barrier separating it from the delocalized state. The energy difference between the two states is in excellent agreement with the experimental estimate. The results presented here, therefore, support the original interpretation of the experiments and illustrate a rare shortcoming of CCSD(T), the “gold standard” of quantum chemistry. These results have implications for the development of density functionals, as most functionals fail to produce the localized state.

Non-innocent Intercalation of Diamines into Tetragonal FeS Superconductor

We report two solvothermal pathways toward intercalated iron sulfide, [Fe8S10]Fe(en)3·en0.5 (en = ethylenediamine), featuring [Fe8S10]2– layers stacked by [Fe(en)3]2+ cations and free ethylenediamine molecules. [Fe8S10]Fe(en)3·en0.5 is synthesized in a simple single-step method from Fe and S in ethylenediamine with addition of NH4Cl mineralizer as well as from solvothermal treatment of mackinawite, tetragonal FeS. In situ synchrotron powder X-ray diffraction experiments reveal a clear transformation of tetragonal FeS into [Fe8S10]Fe(en)3·en0.5 upon reaction with ethylenediamine. In-house control synthetic experiments confirmed the chemical process, whereby ethylenediamine leaches iron solely from the tetragonal Fe–S layers to form [Fe(en)3]2+ complexes and thereby oxidize the intralayer iron to Fe2.25+. Our report emphasizes that, in layered iron chalcogenides, diamines can intercalate as charged coordination complexes in tandem with neutral diamine molecules.

Preparation of defected SWCNTs decorated with en-APTAS for application in high-performance nitric oxide gas detection.

We demonstrate highly sensitive and selective chemiresistive-type NO gas detection using defected single-walled carbon nanotubes (SWCNTs) decorated with N-[3-(trimethoxysilyl)propyl]ethylene diamine (en-APTAS) molecules. The defected SWCNTs were prepared via furnace annealing at 700 °C and confirmed by transmission electron microscopy. A single en-APTAS molecule has two amine groups acting as adsorption sites for NO gas, which can improve the NO response. The NO response was further enhanced when the defected SWCNTs were utilized because NO sensing reactions could occur on both the inner and outer walls of the defected SWCNTs. The en-APTAS decoration improved the NO response of the SWCNT-based gas sensing devices by 2.5 times; when the defected SWCNTs were used, the NO response was further improved by 3 times. Meanwhile, the recovery performance in a time-resolved response curve was significantly improved (45 times) via a simple rinsing process with ethanol. Specifically, the fabricated device did not respond to carbon monoxide (CO) or BTEX gas (i.e., a mixture of benzene, toluene, ethyl benzene, and xylene), indicating its high selectivity to NO gas. The results show the possibility of a high-performance SWCNT-based NO gas sensor applicable to healthcare fields requiring ppb-level detection, such as in vitro diagnostics (IVDs) of respiratory diseases.

Assessing nickel oxide electrocatalysts incorporating diamines and having improved oxygen evolution activity using operando UV/visible and X-ray absorption spectroscopy.

The electrolysis of water using renewable energy is a promising approach to developing a sustainable hydrogen-based economy. To improve the efficiency of this process, it will be necessary to develop highly active electrocatalysts that promote the oxygen evolution reaction (OER). In the present study, the OER activity of a nickel oxide electrocatalyst was dramatically improved following the addition of a diamine to the electrolyte solution during electrodeposition. Operando UV/vis absorption spectroscopy was used to assess a number of nickel catalysts containing various diamines and other organic compounds. The data indicate that Ni(II) complexes were formed with the diamines during electrodeposition. Consequently, the catalytic activity of these materials was enhanced based on increased concentrations of active reaction sites for the OER process. Ni K-edge X-ray absorption spectra showed that these catalysts were composed of γ-NiOOH with a Ni3.6+ valence state. The coordination of the diamine molecules to the γ-NiOOH produced structural distortion that contributed to improved OER activity. This structural distortion is likely the most important factor in enhancing the OER activity of inorganic-organic composite catalysts.