Ethylenediamine Groups Research Articles

Effect of Addition Amount of Ethylenediamine on Interlayer Nanochannels and the Separation Performance of Graphene Oxide Membranes.

In recent years, graphene oxide (GO)-based two-dimensional (2D) laminar membranes have attracted considerable attention because of their unique well-defined nanochannels and deliver a wide range of molecular separation properties and fundamentals. However, the practical application of 2D GO layered membranes suffers from instability in aqueous solutions as the interlayer d-spacing of GO membranes is prone to expansion caused by the hydration effect. In this study, the effects of the ethylenediamine (EDA) addition amount on the structure, crosslinking mechanism and separation performance of GO membranes were investigated systematically, and membrane performance was evaluated using water permeability and dye/salt rejection tests. The experimental results show that the amine groups of EDA chemically bond with the hydroxyl functional group (O=C-OH) of GO after intercalation, as evident from Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). By further controlling the amount of the intercalated EDA, the as-prepared GO composite membranes show nanoscale-tuned d-spacing promising for downstream applications. In the demonstrated dye/salt nanofiltration scenario, the EDA intercalated and crosslinked GO membrane has enhanced permeability by over five times and a better dye rejection rate of over 96% compared with pure GO membranes. These findings highlight a facile strategy for controlling nanochannels by tuning the amounts of reactive intercalants.

Catalytically Active Gold Nanoparticles on Star Block Co-polymer Matrix: Synthesis of Nanocomposite Film Exploring the Langmuir-Blodgett Technique.

Nanocomposites with metal nanoparticles and block copolymers distributed in a stable and robust thin film are preferred for various applications. Here, synthesis of such a nanocomposite is reported, which is composed of gold nanoparticles (AuNPs) embedded in a tetronic 701 (T701) and 90R4 (T90R4) thin film matrix generated using the Langmuir-Blodgett (LB) thin film technique. Tetronics contain a monoprotonated central ethylenediamine group at pH 5 due to the presence of chloroauric acid (HAuCl4) in the subphase, along with poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) blocks, both of which have the capacity to serve as the reducing agent toward chloroaurate anion (AuCl4-). Calorimetric experiments have shown that T90R4 has a better interaction with AuCl4-, probably due to its better electrostatic interaction with AuCl4- ions due to the higher % of the hydrophilic PEO group. On the other hand, the T701-AuNP interaction turned out to be more spontaneous due to the higher hydrophobicity of T701 (higher PPO/PEO ratio). The optical properties and structure/morphology of these nanocomposites are characterized by UV-vis spectroscopy, FTIR spectroscopy, XRD, and TEM. The composite thin film has the ability to catalyze the organic electron transfer process between p-nitrophenol and p-aminophenol in the presence of sodium borohydride. A clear correlation has been found between the reaction rates and the kind of tetronic present in the nanocomposite, which acted as a matrix and stabilizer toward AuNPs.

Dynamics of Lanthanide(III) complexes from crystallographic data and computational studies

In this study we take advantage of the large body of X-ray data reported for lanthanide complexes, as well as their similar coordination chemistry properties, to gain insight on the dynamic processes involving λ ↔ δ configurational changes leading to isomer interconversion. The analysis of X-ray data reveals that different donor groups are characterized by Gaussian distributions of the dihedral N–C–X–Y angles ϕ. In the case of ethylenediamine groups (X = C; Y = N) Gaussian distributions are very narrow, while acetates (X = C; Y = O) provide very broad distributions. The analysis of the potential energy surfaces (PESs) using DFT reveals that ethylenediamine groups are characterised by well-defined deep energy minima, while those of acetate groups are rather swallow. Other donor groups like acetamide, pyridine or phosphinate show intermediate Gaussian distributions with respect to ethylenediamine and acetates. The PESs were fitted to a potential incorporating quadratic, cubic and quartic terms. The quadratic force constants k11 obtained for the different donor types follow the trend of the full width at half maxima (FWHM) of Gaussian distributions obtained from X-ray data. The k11 values are very similar for a given donor group, while the anharmonic cubic (k111) and quartic (k1111) force constants vary significantly depending on the environment of the donor group. Overall, this work demonstrates that the analysis of X-ray crystallographic data in lanthanide complexes can provide very useful information on their coordination chemistry preferences and dynamic processes.

High N2-selectivity of nitrite reduction by palladium-laden nanocomposite with self-sufficient electron donators

Selectively reducing nitrite to gaseous nitrogen (N2) with an effective and recyclable fashion stands as an attractive alternative for treating the relevant wastewater. Herein, a Pd-based nanocomposite (Pd@EDA-CMPS) was subtly assembled by encapsulating Pd(0) nanoparticles into a porous polystyrene carrier, which was aforehand functionalized with ethylenediamine (EDA) as the endogenous electron donator. Systematical macroscopic experiments confirm that the pre-grafted EDA groups can substantially stimulate the catalytic activity of the laden Pd(0) nanoparticles with high removal efficiency and N2 selectivity of Pd@EDA-CMPS toward nitrite; specifically, high N2 selectivity (86%) was achieved by Pd@EDA-CMPS with an excellent anti-interference ability against competing anion and a broad pH-range applicability (4–11), whereas no N2 production was detected for its counterparts (CMPS, EDA-CMPS, and Pd@CMPS). Spectroscopic analyses reveal that the grafted EDA groups played a decisive role in the formation of H-loaded Pd(0) nanoparticles inside the porous substrate, which joint with the unique pH-buffering ability of EDA drove the reaction to the production of nitrogen (N2) rather than ammonia (NH3). The exhausted Pd@EDA-CMPS can be promisingly regenerated by NaOH (eluting) and NaBH4 (restoring) solution without obvious loss in treatment capacity and N2 selectivity. This work provides a feasible strategy for catalytically reducing nitrite into N2 without the provision of exogenous reductor such as hydrogen.

Enhanced water permeability and antifouling properties of cross-linked graphene oxide composite membranes with tunable d-spacings

Low flux and membrane fouling are major challenges in membrane distillation (MD) for treating concentrated wastewater. This study compared the performance of GO composite membranes with different interlayer distances, by covalently bonding the terminal amine groups of ethylenediamine (EDA) and 1,12-diaminododecane (DADD) with the carboxyl groups present on the GO sheets. The results indicated that the GO-DADD/PTFE membrane, with longer carbon chain cross-linking, achieved the highest flux and antifouling properties. At 70 °C, the pure water flux reached 68.5 kg/m2·h, and the fluxes for treating NaCl, HA containing NaCl, and BSA containing NaCl were 29.8 %, 37.1 %, and 38.5 % higher than the uncrosslinked GO/PTFE, and 95.7 %, 121.2 %, and 146.9 % higher than the PTFE membrane, respectively. Through mathematical models for mass and heat transfer, the study identified the key to this enhancement as the increased d-spacing within the GO layer due to cross-linking, which weakened the Kelvin effect and enhanced the vapor partial pressure on the hot side. The unique surface structure and electrostatic interactions induced by long-chain cross-linking further boosted the antifouling effect. These modifications not only overcome the typical trade-off between retention rates and flux but also offer a scalable and efficient solution for advanced membrane distillation applications.

Detailed Study on the Interfacial Interaction between Different Polyoxometalates and Tetronic Block Copolymers Exploring the Langmuir-Blodgett Technique.

Polyoxometalates (POMs) interact with various biologically relevant entities. A basic understanding of this interaction is very important for various applications in the biological field. In this work, the focus is on the study of the interaction between tetronics and Keggin POMs. T701 and T90R4 are the two tetronics considered here; they have different solubilities in water due to different PPO/PEO ratios. The arrangement of PPO and PEO is also different with respect to the central ethylenediamine groups. Three different Keggin-type POMs, phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA), with different charge densities are chosen for an elaborate investigation using Langmuir-Blodgett technique. The observation is analyzed thoroughly, which shows both electrostatic interaction and adsorption of POMs on the PPO blocks of the tetronics due to the chaotropic effect, which is responsible for the binding of POMs (in subphase) with the tetronic monolayer. This interaction results in an expanded yet rigid monolayer for POM-tetronic association on the surface. Surface pressure vs mean molecular area isotherm is the key characterization to reach the conclusion. UV-vis spectroscopy, NMR, ITC, ellipsometric studies, FTIR, and SEM also serve as supportive characterization techniques.

A highly sensitive and selective impedimetric sensor for the determination of oxytetracycline based on a new polyamine functionalized calix [4] arene

The antibiotic oxytetracycline (OTC), from the tetracycline family of drugs, is generally used to enhance growth as well as to prevent and cure harmful microorganisms in animals and aquaculture. However, improper OTC use exposes people to trace amounts of antibiotics in the food chain, increasing their risk of health problems. For the first time, a new calix [4] arene functionalized at the upper rim by protected ethylenediamine groups has been successfully synthesized and fully characterized by using elemental analysis 1H NMR, 13C NMR, and HRMS. Moreover, indium tin oxide electrode (ITO) modified with the calix [4] arene derivative (EDCA [4]) was successfully prepared using a simple drop-cost method. EDCA [4] film was characterized by static contact angle measurement, cyclic voltammetry measurement, electrochemical impedance spectroscopy, and microscopic surface imaging (SEM). Electrochemical impedance spectroscopy (SIE) measurement showed that the EDCA [4]/ITO exhibited high molecular recognition and consequently displayed a good impedimetric response toward oxytetracycline (OTC).The developed sensor exhibited a wide linear concentration range of 10−10M to 10−5M and a lower detection limit of 2.3 10−11 M. Also, the presented sensor has demonstrated great selectivity and reproducibility, and the designed electrochemical platform was successfully used for detecting trace oxytetracycline in spiked milk samples.

Solvent Annealing Enabling Reconstruction of Cadmium Sulfide Film for Improved Heterojunction Quality and Photovoltaic Performance of Antimony Selenosulfide Solar Cells

AbstractAntimony selenosulfide, Sb2(S,Se)3, has been considered as new‐generation light‐harvesting material for high‐efficiency photovoltaic applications due to its adjustable bandgap, high absorption coefficient, and excellent stability. In terms of device operation, the electron transfer from the electron transporting layer to Sb2(S,Se)3 layer plays a critical role in improving the photovoltaic energy conversion efficiency of solar devices. Intricately manipulating the surface and interface properties has been a great challenge in solar cell fabrications. Herein, an effective approach toward the reconstruction of the CdS interfacial layer, and the following Sb2(S,Se)3 absorber film by utilizing polar ethylenediamine (EDA) solvent annealing at room temperature is developed. It is found that the presence of nitrogen‐containing functional groups of EDA on the CdS surface not only promotes the grain growth and crystallization of CdS, but also induces optimized deposition of Sb2(S,Se)3 films in terms of interfacial contact and defect formation. Finally, the Sb2(S,Se)3 solar cell based on EDA–CdS achieves a top efficiency of 10.10%. This study provides an efficient method and a new understanding of chemically healing inorganic thin films.

Complexes of N, N- and N, N, N- Sulfonamide Ligands as Therapeutic and Diagnostic Agents

Ethylenediamine, diethylenetriamine and dipicolylamine have been used as the carrier ligands to synthesize bidentate (N,N) or tridentate (N,N,N) chelate systems that coordinate with metal centers. The terminal amine groups of ethylenediamine and diethylenetriamine and the central amine group of dipicolylamine can be easily substituted to give sulfonamide ligands having bulky aromatic fragments. In the formation of metal sulfonamides, the sulfonamide nitrogens of primary or secondary sulfonamidesdeprotonate and coordinate with metal centers forming M-N bonds while the free amines coordinate to metal centers through lone pairs. The reported synthetic approaches and the properties of these complexes and ligands are discussed in this review. The bulky sulfonamide moieties bring about unique biological features to the ligand system while enhancing the fluorescent properties of the ligand. The metal center itself incorporates interesting biological features to the complex. These properties of the metal center andthe ligand show a synergistic effect in the complexes that may come in handy when designing therapeutic or diagnostic agents. The increased lipophilicity of the ligands and thereby the complexes will ensure better uptake by target cells making them ideal candidates for biological applications.
 Keywords: Sulfonamide, ethylenediamine, diethylenetriamine, dipicolylamine

Preparation, Characterization and Evaluation of a Novel Drug Carrier for the Controlled Release of Curcumin.

The upsurge of cancer demands intense, rapid and effective intervention from the scientific society. Even though nanoparticles helped achieving this, maintaining its size without using toxic capping agents is challenging. Phytochemicals having reducing properties is a proper substitute and the efficiency of such nanoparticles could be further improved by grafting with suitable monomers. It could be further protected from rapid biodegradation by coating with suitable materials. This approach was utilized wherein, the green synthesized silver nanoparticles (AgNps) were initially functionalized with -COOH to couple with -NH2 groups of ethylene diamine. It was then coated with polyethylene glycol (PEG) and hydrogen bonded with curcumin. The formed amide bonds could effectively uptake drug molecules and sensed environmental pH. Swelling studies and release profiles confirmed selective drug release. All these results along with those obtained from MTT assay, suggested the potential applicability of the prepared material in pH sensitive drug delivery of curcumin.

Reductive ethylenediamine group immobilized in hybrid Pd-based nanocomposite for efficiently sequestrating selenate

Reductive sequestration of selenate [Se(VI)] has emerged as an effective and promising approach in consideration of the poor adsorptive selectivity toward Se(VI) by regular adsorption processes, where the adsorption efficiency for Se(VI) would be typically compromised by the coexisting anions, especially sulfate anion, which has similar structure and property as that of selenate. Herein, we propose a synergistic strategy of ion-exchange and catalytic reduction for this purpose; that is, a Pd-embedded hybrid nanocomposite (Pd-EDA@CMPS) was subtly assembled by in situ nucleating Pd-nanoparticle inside a porous polystyrene adsorbent possessing ethylenediamine (EDA) functional group, which is a reversible redox unit and served as electron donator for Se(VI) reduction, and the embedded Pd nanoparticle exhibited superior catalytic reduction activity and stability for sustainable use. The reduction product, i.e., Se(IV), was immediately in-situ sequestrated inside the hybrid nanocomposite. Macroscopic batch experiments verified the outstanding anti-interference of Se(VI) removal by Pd-EDA@CMPS against the ubiquitous competing anions such as sulfate, chloride, bicarbonate, and phosphate even with 100-times higher concentration. Furthermore, the notable applicability of Pd-EDA@CMPS in a wide pH range (i.e., 3.0 ∼ 11.0) was confirmed, and an interesting pH-buffering effect may be responsible for such a satisfied performance. Besides the excellent hydraulic properties and mechanical strength, the exhausted Pd-EDA@CMPS can be regenerated by successive treatment with NaOH and NaBH4 solution for reuse without obvious loss in capacity.

Solid-phase extraction of palladium, platinum, and gold from water samples: comparison between a chelating resin and a chelating fiber with ethylenediamine groups

Dissolved palladium (Pd), platinum (Pt), and gold (Au) form inert chloride complexes at low concentrations of pmol/kg in environmental water, thus rendering difficulty in the development of a precise analytical method for these metals. Herein, we report the preconcentration of Pd, Pt, and Au with a chelating fiber Vonnel-en and a chelating resin TYP-en with ethylenediamine (en) groups. Batch adsorption experiments reveal the adsorption capacity of Vonnel-en for Pd(II), Pt(IV), and Au(III) in 0.10 M HCl as 0.53, 0.22, and 0.27 mmol/g, respectively. The adsorption capacity of TYP-en for Pd(II), Pt(IV), and Au(III) in 0.10 M HCl is 0.31, 0.17, and 0.52 mmol/g, respectively. In column extraction experiments using small-volume samples containing Pd(II), Pt(II), Pt(IV), Au(I), or Au(III) at concentrations of μmol/kg, TYP-en is able to quantitatively recover Pd, Pt, and Au from 0.01 to 0.2 M HCl irrespective of their oxidation states. In contrast, Vonnel-en is unable to quantitatively recover Au(I). In column extraction experiments using large-volume samples containing Pd(II), Pt(IV), and Au(III) at concentrations of pmol/kg, the recovery of Pd(II), Pt(IV), and Au(III) by TYP-en from 0.07 M HCl is 100–105%. However, the recovery of Pd(II), Pt(IV), and Au(III) by Vonnel-en from 0.03 to 0.3 M HCl is 102–110, 7–15, and 20–52%, respectively. Thus, the chelating resin TYP-en has a high potential for the multielemental determination of Pd, Pt, and Au in environmental water.Graphical abstract

Simultaneously Sequestrating and Reducing Bichromate by the Built-in Ethylenediamine Group inside Polystyrene Adsorbent

Simultaneous sequestration and reduction of bichromate [Cr(VI)] poses an attractive and practical fashion for treating Cr(VI)-contaminated wastewater, for it not only immobilizes the pollutant but also reduces its toxicity. To this end, an EDA-functionalized adsorbent (EDA@CMPS) was developed with a simple one-step method by integrating ethylenediamine (EDA, a reversible redox unit) onto the skeleton of chloromethylated polystyrene adsorbent (CMPS), and it can sequestrate Cr(VI) and in situ reduce Cr(VI) to Cr(III), which was then immediately locked inside the adsorbent phase. Batch experiments confirmed that EDA@CMPS had a high removal capacity toward Cr(VI) (419 mg/g, at 25 °C), a large proportion of which was reduced to Cr(III) without leaking into the aqueous phase at pH ≥ 2. Ubiquitous anions (Cl–, NO3–, SO42–, and H2PO4–) and cations (Mg2+ and Ca2+) have a certain effect on the removal efficiencies, but EDA@CMPS still demonstrated satisfied Cr(VI) removal even with the competing ions at 100-times higher concentration. FT-IR and XPS analyses revealed that the amine group of EDA was responsible for sequestrating and reducing Cr(VI), where the amine group was oxidized into an imine group, which then played a key role in immobilizing the generated Cr(III) via chelation. Attractively, even under neutral conditions, EDA@CMPS also demonstrated decent removal and reduction performance toward Cr(VI). Furthermore, the yielded imine group can be perfectly restored to an amine group by simple alkali-acid treatment. Repeated removal–regeneration cycles verified the reusability of EDA@CMPS in treating Cr(VI) solution. Fixed-bed column experiments and treatment of a real electroplating wastewater further validated the potential of EDA@CMPS in treating Cr(VI) wastewater for practical application.

Diamine Groups on the Surface of Silica Particles as Complex-Forming Linkers for Metal Cations

Novel spherically shaped organosilica materials with (propyl)ethylenediamine groups were obtained via a modified one-pot Stöber co-condensation method. The porosity of these materials was tuned with the controlled addition of three silica monomers acting as structuring agents (tetraethoxysilane and bridged silanes with ethylene and phenylene bridges). The morphologies and structures of the synthesized materials were studied by SEM, DRIFT spectroscopy, CHNS elemental analysis, low-temperature nitrogen adsorption-desorption, and electrokinetic potential measurements. Their sizes were in the range of 50 to 100 nm, depending on the amount of structuring silane used in the reaction. The degree of the particles' agglomeration determined the mesoporosity of the samples. The content of the (propyl)ethylenediamine groups was directly related with the amount of functional silane used in the reaction. The zeta potential measurements indicated the presence of silanol groups in bissilane-based samples, which added new active centers on the surface and reduced the activity of the amino groups. The static sorption capacities (SSCs) of the obtained samples towards Cu(II), Ni(II), and Eu(III) ions depended on the porosity of the samples and the spatial arrangement of the ethylenediamine groups; therefore, the SSC values were not always higher for the samples with the largest number of groups. The highest SSC values achieved were 1.8 mmolCu(II)/g (for ethylene-bridged samples), 0.83 mmolNi(II)/g (for phenylene-bridged samples), and 0.55 mmolEu(III)/g (for tetraethoxysilane-based samples).

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1-15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210-596 m2·g-1, an apparent density of 0.403-0.740 cm3·g-1 and a porosity of 60-78%. The actual cobalt content in the aerogels was 0.01-1.50 mmol per 1 g of SiO2, which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO3)2], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K.

Synthesis, antimicrobial and anticancer activities of Tetronic 1107 Schiff bases

AbstractAs a result of the serious issues connected to the bacterial infections, there is an imperious need to improve strong and ecofriendly antimicrobial polymers to overcome the limitations of conventional antimicrobial agents. In this trend, poloxamines (Tetronics) which are X‐shaped poly(ethylene oxide)–poly(propylene oxide) diblocks linked to a focal ethylenediamine group; were successfully modified to produce Tetronic Schiff base for enhancing the biological activities of Tetronic 1107. Modification of tetronic 1107 (T1107) was proceeded throughout chloroacetylation of T1107 followed by amination using p‐phenylenediamine then the latter was treated with different aldehydes to yield Tetronic Schiff bases. Characterization of Tetronic Schiff bases was carried out by 1H‐NMR, Fourier‐transform infrared spectroscopy, X‐ray diffraction, elemental analysis and thermogravimetric analysis (TGA) analyses. The antimicrobial activities of four tested compounds coded (EK1, EK2, EK3, and EK4) were quantified using Microtiter‐assay methods. The obtained data revealed potential antimicrobial activities for tested compounds against all tested microbes with priority against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. Sample coded EK4 exhibited the most effective treatment against P. aeruginosa, Candida albicans, S. aureus and E. Coli with minimal inhibitory concentration values of 6, 16, 12.5, and 1.5 μM, respectively. Furthermore, the safety results confirmed that EK4 and EK1 were the safest treatment with IC50 values of 76.01 and 62.67 μM, respectively. In addition, all tested compounds showed significant anticancer effects against MDA‐MB‐231cell line, while EK3 was effective treatment against A549 cell line with IC50 values of 39.63 μM. Meanwhile, both EK2 and EK4 showed the highest selectivity index (SI) values against MDA‐MB‐231 cell line with values 2.5 and 3.07, respectively. Interestingly, EK4 showed the maximum SI values on A549 and Hep‐G2 cell lines with values 1.62 and 1.52, respectively.

Novel Naphthalimide‐Based Self‐Assembly Systems with Different Terminal Groups for Sensitive Detection of Thionyl Chloride and Oxalyl Chloride in Two Modes

AbstractTwo novel naphthalimide derivatives‐based chemosensors with the terminal groups of ethanediamine and 1,3‐diaminopropane (1 and 2) were designed and synthesized. Two compounds exhibited obvious solvatochromism properties. They could respond to some kinds of acyl chlorides through reaction with the ethylenediamine group and propylene diamine group at 4‐site. It was found that they had different response performance due to their different terminal groups. Compound 1 could sensitively detect thionyl chloride (SOCl2) and oxalyl chloride ((COCl)2) with the low limit detection (LOD) of 29.54 nΜ and 151.6 pM in the solution state, respectively. Moreover, film 1 could also respond to the abovementioned acyl chloride gases with LOD of 35.5 and 91.98 ppb, respectively. It was different that compound 2 could selectively detect (COCl)2 with a low LOD of 243.4 pM and 35 ppb for its solution and film state, respectively. NMR and HRMS experiments well demonstrated that the different detection mechanism occurred on two sensors. From this work, it was concluded that the little difference between the terminal reaction sites of naphthalimide greatly affected the detection performance, which would open a window for design functional self‐assembly sensors for acyl chlorides based on naphthalimide derivatives.

Step-stool conformation of a cyclic Schiff base derived from ethylenediamine and heptane-2,4,6-trione: evidence for partial hydrolysis in metal coordination.

A Schiff base derived from ethylenediamine and heptane-2,4,6-trione, namely, 5,9,14,18-tetramethyl-1,4,10,13-tetraazacyclooctadeca-5,8,14,17-tetraene-7,16-dione (C18H28N4O2), abbreviated H4daaden, was prepared and characterized for the first time by single-crystal X-ray diffraction. The atoms of the Schiff base occupy two different planes and thus the molecule is essentially nonplanar. An axis running through the C-C atoms of the ethylenediamine groups separate the two planes and these two planes are connected by bridging ethylene groups showing an angle of 117.34 (8)°. As a result, the side view of the molecule shows a `step-stool' conformation. The nonplanar nature of the Schiff base plays an important role in metal coordination, which leads to partial hydrolysis of the ring structure.

Antiproliferative Properties of 7,8-Ethylene Diamine Chelator-Lipophilic Fluoroquinolone Derivatives Against Colorectal Cancer Cell Lines.

Cancer is one of the most overwhelming diseases nowadays. It is considered the second cause of death after cardiovascular diseases. Due to the diversity of its types, stages and genetic origin, there is no available drug to treat all cancers. Serious side effects and resistance of existing drugs are other problems in the struggle against cancer. In such quest, fluoroquinolones (FQs) promising as antiproliferative compounds due to safety, low cost and lack of resistance. Therefore, this work aims at developing lipophilic FQs and screening their antiproliferative activity against colorectal cancer. Nine prepared FQs were investigated for antiproliferative activity utilizing in vitro SRB method. In comparison to the antiproliferative agent cisplatin; the assessment of antiproliferative activities of these novel FQs in a panel of Colorectal Cancer Cell (CRC) lines (HT29, HCT116, SW620, CACO2, SW480) and normal periodontal ligament fibroblasts for safety examination was performed. Antibacterial activity (MIC) was conducted against Staphylococcus aureus and Escherichia coli standard strains using the broth double dilution method. Antioxidant properties were suspected as the mechanism of antiproliferative activity; thus, a DPPH test was performed to analyze radical scavenging potency of FQs compared to ascorbic acid as reference agent. FQs compounds 3-5(a-c) were prepared, characterized and their structure was confirmed using spectroscopy techniques. All compounds manifested good to excellent antiproliferative activity on HT29, HCT116, and SW620 with high safety index. The reduced series 4a, 4b and 4c exerted excellent micro to nano -molar antiproliferative activities on HT29, HCT116, and SW620 which were stronger than the reference cisplatin against all cells. The reduced group of compounds 4(a-c) revealed higher potency vs. both nitro and triazolo groups. On cell lines HT29, HCT116, and SW620, reduced 4a with 7,8-ethylene diamine,the substitution revealed the highest antiproliferative efficacy (IC50 value) approaching nano molar affinity with higher safety vs. cisplatin. The most active compound, 4a, exhibited significant potency against HCT116, and SW620 with IC50 0.6 and 0.16 μM respectively. Novel FQs (4a, 4b and 4c) also showed strong radical scavenging activity with IC50 values (μM) 0.06, 23, and 7.99, respectively. Exquisitely 4a revealed a similar pattern of activity to doxorubicin, indicating a similar mechanism of action. Strong antiproliferative and weak antibacterial activities of series 4 endorse that their mechanism involves eukaryotic topoisomerase II inhibition. This work has revealed novel FQs with excellent anticancer activity against 5 colorectal cancer (HT29, HCT116, SW620, CACO2, SW480) cell lines with a potential chelation mechanism due to 7,8-ethylene diamine chelator bridge. The new FQs have confirmed that more lipophilic compounds could be more active as hypothesized. The p-halogenated aniline, N1-Butyl group in addition to 3-COOH, 8-NH2 are all essential requirements for strong antiproliferative FQ of our FQ scaffold. This work emphasizes the role of C-8 amino as part of ethylene diamine group as an essential requirement for antiproliferative FQs for the first time in the literature, entailing its role toward potential antineoplastic FQs.

COMPLEXATION OF CIS-Pd(NH3)2Cl2 AND Pd(en)Cl2 WITH 1-AMINOPROPYLIDENE­DIPHOSPHONIC ACID

The complexation of cis-Pd(NH3)2Cl2 and Pd(en)Cl2 (en – ethylenediamine) with 1-aminopropylidene-1,1-diphosphonic acid (APrDP, H4L) in solutions with extracellular concentration of chloride ions (0.15 mol/L) at the rations Pd(II):APrDP=1:1, 1:2 and 2:1 has been stu­di­ed by pH-potentiometry, electron and NMR spectroscopy.
 It has been found that upon interaction in the system cis-Pd(NH3)2Cl2:AprDP=1:1, complexes of the equimolar composition [PdHL(NH3)Cl]2- (lgβ=38.84(4)), [PdHL(NH3)2]- (lgβ=43.14(2)) and [PdL(NH3)2]2- (lgβ=34.91(2)) are formed depending on pH, in which the APrDP molecule is coordinated in a bidentate fashion to the cent­ral ion by the nitrogen atom of the amine group and oxygen atom of the phosphonic group. In the case of twofold excess of ligand, bisligand complexes [PdH4L2]2- (lgβ=59.64(9)), [PdH3L2]3- (lgβ=57.39(19), [PdH2L2]4- (lgβ=52.37(17), [PdHL2]5- (lgβ=44.71(9)) [PdL2]6- (lgβ=36.57(6)) are formed, in which two APrDP molecules are coordinated in a bidentated fashion. At pH>6, complexes [PdHL2(NH3)]5- (lgβ=48.57(6)) and [PdL2(NH3)2]6- (lgβ=42.76(8)) are formed, in which the coordinated phosphonic groups of APrDP are sequentially replaced upon coordination by NH3. molecules.
 In the systems Pd(en)Cl2:APrDP=1:1 and 1:2, complexes only of equimolar composition: [Pd(en)(H2L)] (lgβ=28.88(9)), [Pd(en)(HL)]- (lgβ=24.67(8)) and [Pd(en)L]2- (lgβ=16.84(9)) are formed, whose coordination sphere contains the nitrogen atom of the amine group and oxygen atom of the phosphonic group of APrDP and two nitrogen atoms of the amine groups of an ethylenediamine.
 At the ratio Pd(II):APrDP=2:1, the formation of binuclear complexes {[Pd(NH3)2]2L} (lgβ=63.58(22)) and {[Pd(en)]2L} (lgβ= 25.18(4)), in which two palladium atoms have a different coordination environment. The coordination sphere of one of the palladium contains a nitrogen atom of the amine group and an oxygen atom of the phospho­nic group of APrDP, and two NH3 molecules or two amine groups of ethylenediamine. The other palladium coordinates two oxygen atoms of phoshonic groups of APrDP and two NH3 molecules or two amine groups of ethylenediamine.