Ureas Research Articles

Self‐healing polyacrylate coatings with dynamic H‐bonds between urea groups

AbstractAdding self‐healing properties to coatings is a promising way to increase their lifetime. Despite an increasing popularity, lots of self‐healing polymers are not suited for commercial coatings because they exhibit poor mechanical properties or require expensive products or high healing temperature (> 100°C). One way to obtain self‐healing abilities with good mechanical properties is by using dynamic H‐bonds as they also limit the healing temperature. To do so, urea groups are used since they are well‐known for their bonding capacity and can be readily synthesized. In this study, several methacrylate monomers containing urea groups in their side‐chain were synthesized from easily accessible amines and isocyanates in a one‐step, high‐yield synthesis. They were afterwards used in a copolymer containing methyl methacrylate and butyl acrylate monomers. The self‐healing properties of the resulting coatings were evaluated with gloss recovery and optical microscopy and the presence of H‐bonds in the most promising polymer was investigated with FTIR. The mechanical properties of the coatings as a function of time were checked by nanoindentation creep test. We were able to obtain an affordable, easily prepared polymer that suits the requirements for protective coating applications and shows a complete healing after heating at 75°C for 1 h.

A range of bifunctional vermiculite-based adsorbents for simultaneous removal of Congo red and permanganate

It remains a challenge to design and prepare multifunctional low-cost adsorbents to dispose of diverse pollutants in wastewater. Herein, a series of bifunctional vermiculite-based adsorbents named DDPA-Vt as well as DDPU-Vt, are constructed via gemini surfactants containing pyridine-amide/pyridine-urea groups as modifiers. The morphology, physicochemistry and structure of organo-Vts are confirmed by multifarious probe methods thoroughly. The organo-Vts for the retention of anionic dye (Congo red (CR)) together with heavy metal (permanganate (MnO4-)) are investigated in single/mixed components in depth. More importantly, the maximum adsorption capacities are up to 504/822 mg/g for CR and 279/371 mg/g for MnO4- onto DDPA-Vt/DDPU-Vt, respectively. Pseudo-second-order kinetic model and Freundlich isotherm model could be depicted the adsorption processes. Competing anions have little effect on the adsorption of MnO4-, demonstrating that the organo-Vt could selectively removal MnO4-. Co-adsorption tests display that organo-Vt are still effective retention to CR and MnO4-, especially onto DDPU-Vt. The adsorption mechanism along with adsorptivity-structure relationship betwixt organo-Vt and pollutants are elucidated via characterization of the spent organo-Vts and DFT calculation: (i) π-π, NH-π, hydrophobic and electrostatic interactions are the mechanism for uptake of CR. (ii) Electrostatic interaction and coordination are the driving forces for retention of MnO4-. (iii) The diverse nitrogen-containing groups on the pyridine ring and the spacer have synergistic effects on CR and MnO4- retention. (iv) The greater preference of DDPU-Vt for pollutants is based on the stronger nitrogen atom-donating ability on the urea group. This work displays the potential of organo-Vt in the removal of multi-component sewage, and reclaims a prominent way for the simultaneous removal of anionic pollutants.

Construction of photoswitchable urea-based multiple H-bonding motifs

In this paper, a series of photoactive urea-based multiple H-bonding motifs were rationally constructed by tethering the photoisomerizable azobenzene units aside to the urea groups of several typical urea-constituted H-bonding arrays. Taking the integrated azo units as photoswitches, their phototriggered E/Z isomerization can be used to reversibly manipulate the locking (with intramolecular H-bonds) and unlocking (without intramolecular H-bonds) of the urea H-bonding sites of these motifs, respectively. This feature enables the E/Z photoisomeric urea derivatives to exhibit switchable intermolecular H-bonding affinities, thus achieving unique photocontrolled self/hetero complementary multiple H-bonded dimerization upon irradiation by different light sources. Benefiting from the wide application of urea group, the development of such urea-based multiple H-bonding system with photoswitchable dimerization affinity is promising in providing a generally applicable approach for the construction of copious urea-based H-bonded supramolecular assembly systems and materials with photoregulable properties and functions.

Highly Branched Tannin-Tris(2-aminoethyl)amine-Urea Wood Adhesives.

Condensed tannin copolymerized with hyperbranched tris(2-aminoethyl)amine-urea formed by amine-amido deamination yields a particleboard thermosetting adhesive without any aldehydes satisfying the requirements of relevant standards for the particleboard internal bond strength. The tannin-triamine-urea cures well at 180 °C, a relatively low temperature for today's particleboard hot pressing. As aldehydes were not used, the formaldehyde emission was found to be zero, not even in traces due to the heating of wood. The effect is ascribed to the presence of many reactive sites, such as amide, amino, and phenolic groups belonging to the three reagents used. The tannin appears to function as an additional cross-linking agent, almost a nucleating agent, for the triamine-urea hyperbranched oligomers. Chemical analysis by MALDI ToF and 13C NMR has shown that the predominant cross-linking reaction is that of the substitution of the tannin phenolic hydroxyls by the amino groups of the triamine. The reaction of tannin with the still-free amide groups of urea is rather rare, but it may occur with the rarer tannin flavonoid units in which the heterocyclic ring is opened. Due to the temperature gradient between the surfaces and the board core in the particleboard during hot pressing, the type and the relative balance of covalent and ionic bonds in the resin structure may differ in the surfaces and the board core.

Microstructure construction design and damping properties of polyurethane microporous elastomer modified by suspension chain extender via end-controlling oriented synthesis

Broadening the damping temperature range of viscoelastic microporous polyurethane elastomers (MPUE) is a challenge to break the limits of practical applications in damping field. Based on the molecular reaction kinetics and the molecular structure design of MPUE, different molecular weight suspension chain extenders were synthesized from polyethylene glycol monomethyl ether (MPEG), isophorone diisocyanate (IPDI) and 2-amino-1,3-propanediol via end-controlling oriented synthesis. The effect of molecular weight and dosages of suspension chain extenders on the damping property of MPUE was studied. It was demonstrated that strong intermolecular hydrogen bonds can be formed between MPUE molecules due to the carbamate groups and urea groups of the suspension chain extenders. The transformations of various motion modes of the suspended chain were driven by the existence of a large number of ether bonds, which can reduce the micro-phase separation degree in the material matrix, resulting in higher kinetic friction between molecular chains. The damping properties of the material were significantly improved, presenting a maximum increase of 62.3% in the effective damping temperature domain, and a maximum increase of 34.0% in the peak loss factor (tan δ), which was attributed to the synergistic compound effect of multiple motion modes. This high damping MPUE has great application prospects in the fields of acoustic noise reduction and household appliances damping.

Synthesis and Catalytic Activity of Bifunctional Phase-Transfer Organocatalysts Based on Camphor.

Ten novel bifunctional quaternary ammonium salt phase-transfer organocatalysts were synthesized in four steps from (+)-camphor-derived 1,3-diamines. These quaternary ammonium salts contained either (thio)urea or squaramide hydrogen bond donor groups in combination with either trifluoroacetate or iodide as the counteranion. Their organocatalytic activity was evaluated in electrophilic heterofunctionalizations of β-keto esters and in the Michael addition of a glycine Schiff base with methyl acrylate. α-Fluorination and chlorination of β-keto esters proceeded with full conversion and low enantioselectivities (up to 29% ee). Similarly, the Michael addition of a glycine Schiff base with methyl acrylate proceeded with full conversion and up to 11% ee. The new catalysts have been fully characterized; the stereochemistry at the C-2 chiral center was unambiguously determined.

A Self‐Healing and Nonflammable Cross‐Linked Network Polymer Electrolyte with the Combination of Hydrogen Bonds and Dynamic Disulfide Bonds for Lithium Metal Batteries

The self‐healing solid polymer electrolytes (SHSPEs) can spontaneously eliminate mechanical damages or micro‐cracks generated during the assembly or operation of lithium‐ion batteries (LIBs), significantly improving cycling performance and extending service life of LIBs. Here, we report a novel cross‐linked network SHSPE (PDDP) containing hydrogen bonds and dynamic disulfide bonds with excellent self‐healing properties and non‐flammability. The combination of hydrogen bonding between urea groups and the metathesis reaction of dynamic disulfide bonds endows PDDP with rapid self‐healing capacity at 28 °C without external stimulation. Furthermore, the addition of 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) improves the ionic conductivity (1.13 × 10−4 S cm−1 at 28 °C) and non‐flammability of PDDP. The assembled Li/PDDP/LiFePO4 cell exhibits excellent cycling performance with a discharge capacity of 137 mA h g−1 after 300 cycles at 0.2 C. More importantly, the self‐healed PDDP can recover almost the same ionic conductivity and cycling performance as the original PDDP.

Bio-Inspired Bimetallic Cooperativity Through a Hydrogen Bonding Spacer in CO2 Reduction.

At the core of carbon monoxide dehydrogenase (CODH) active site two metal ions together with hydrogen bonding scheme from amino acids orchestrate the interconversion between CO2 and CO. We have designed a molecular catalyst implementing a bimetallic iron complex with an embarked second coordination sphere with multi-point hydrogen-bonding interactions. We found that, when immobilized on carbon paper electrode, the dinuclear catalyst enhances up to four fold the heterogeneous CO2 reduction to CO in water with an improved selectivity and stability compared to the mononuclear analogue. Interestingly, quasi-identical catalytic performances are obtained when one of the two iron centers was replaced by a redox inactive Zn metal, questioning the cooperative action of the two metals. Snapshots of X-ray structures indicate that the two metalloporphyrin units tethered by a urea group is a good compromise between rigidity and flexibility to accommodate CO2 capture, activation, and reduction.

Bio‐Inspired Bimetallic Cooperativity Through a Hydrogen Bonding Spacer in CO2 Reduction

AbstractAt the core of carbon monoxide dehydrogenase (CODH) active site two metal ions together with hydrogen bonding scheme from amino acids orchestrate the interconversion between CO2 and CO. We have designed a molecular catalyst implementing a bimetallic iron complex with an embarked second coordination sphere with multi‐point hydrogen‐bonding interactions. We found that, when immobilized on carbon paper electrode, the dinuclear catalyst enhances up to four fold the heterogeneous CO2 reduction to CO in water with an improved selectivity and stability compared to the mononuclear analogue. Interestingly, quasi‐identical catalytic performances are obtained when one of the two iron centers was replaced by a redox inactive Zn metal, questioning the cooperative action of the two metals. Snapshots of X‐ray structures indicate that the two metalloporphyrin units tethered by a urea group is a good compromise between rigidity and flexibility to accommodate CO2 capture, activation, and reduction.

Toxic Effect Of The Compound {1,3 Bis (P-Hydroxyphenyl) Urea} On Triiodothyronine (T3) Hormone Levels In Pregnant White Rats (Rattus Norvegicus L.)

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed drugs for pregnant women to treat fever, pain and inflammation. Specific NSAIDs can displace thyroid hormone from its protein binding sites, causing thyroid hormone measurement problems. {1,3 bis (p-Hydroxyphenyl)urea} is a modified p-aminophenol compound with potent analgesic and anti-inflammatory activity and less toxicity. This study is a follow-up to previous research to observe the toxic effect on triiodothyronine hormone levels after administration of {1,3 bis(p-Hydroxyphenyl)urea} compound in pregnant white rats. The toxic effect test was carried out by giving the test preparation to pregnant rats, which had been divided into five groups, namely the normal control group (CMC-Na 0.5%), the positive control (Gabapentin 50 mg/kg BW), Compound {1.3 bis (p- Hydroxyphenyl)urea} at a dose of 50 mg/kg BW, 500 mg/kg BW and 1000 mg/kg BW. Mice were given the test preparation every day from the 6th to the 15th day of pregnancy. Blood was taken on the 16th day, and T3 hormone levels were measured using the ELISA method. The results showed that the T3 hormone levels in the {1,3 bis(p-Hydroxyphenyl)urea group had no significant difference from the normal control group, so it was concluded that {1,3 bis(p-Hydroxyphenyl)urea) did not have a significant effect on the hormone T3.

Fast-Tracking of the Segmental Orientation in Poly(ethylene oxide)-based Polyurethane Urea by Mechano-optical (Infrared Dichroism and Birefringence) Properties: Degree of the Soft-Segment Ordering Effect

The orientation behavior of segment-specific chemical groups of NH and CH was investigated for poly(ethylene oxide) (PEO)-based polyurethane urea (PUU) during uniaxial stretching using a uniaxial stretching system integrated with spectral birefringence and ultrafast IR spectrometers that capture two polarization states simultaneously. PUUs with 30% by-weight urethane-urea hard segment content were prepared using PEO oligomers with number average molecular weights of 2000, 4600, and 8000 g/mol. High-molecular weight PEO-based PUUs exhibited microphase morphologies with sharp interfaces between the PEO matrix and urethane-urea hard segments, while low-molecular weight PEO-2000 (2000 g/mol)-based PUU exhibited a gradient interphase. This is primarily due to substantial hydrogen-bonding interactions between the urea hard segments and ether groups of highly amorphous PEO-2000 compared with highly crystalline soft segments in PEO-4600 and PEO-8000, which lack significant hydrogen-bonding interactions with urea groups and hence a sharper interface and improved microphase separation. The segment-specific chemical group orientation study revealed that the relaxation and reorganization behaviors are closely dependent on the initial morphology. In microphase-separated PUU with a gradient interphase, responses of the hard and soft segments to deformation are similar even at lower strain levels. For the microphase-separated PUUs with a sharp interface, the low-strain level orientation is localized in the soft-segment regions until the connection with the hard segments drive the orientation in the chain axis toward the stretching direction. This network transition is also reflected in the mechano-optical behavior as a change from a high-strain optical constant to a lower-strain optical constant.

INFLUENCE OF BURNING RATE INHIBITORS ON THE THERMAL BEHAVIOR AND DECOMPOSITION KINETICS OF AMMONIUM PERCHLORATE

The addition of burning rate inhibitors (BRIs) to propellant formulations can be effective in reducing the burning rate of composite solid propellants (CSPs). Ammonium perchlorate (AP) is commonly used as an oxidizer for CSPs and is a major component of propellants. Therefore, it is of great significance to study the thermolysis performance of AP in the presence of BRIs. In this work, differential scanning calorimetry and thermogravimetric analysis were utilized to study the thermolysis of AP. Oxamide (OXA), ammonium sulfate (AS), ammonium oxalate (AO), and carbamide (CA) were selected as the BRIs. The results showed that as the BRI content increased, the endothermic peak remained essentially unchanged. The exothermic peak in the low-temperature decomposition (LTD) stage shifted to a hightemperature field, while the exothermic peak in the high-temperature decomposition (HTD) stage shifted to a low-temperature field. Furthermore, associated kinetic studies showed that the decomposition activation energies of AP with inhibitors during the LTD stage were higher than that of pure AP, proving that the selected BRIs could effectively inhibit the thermolysis of AP. However, during the HTD stage, the values of the activation energies for decomposition gradually increased in the order of AP + AO, AP + OXA, AP + CA, AP, and AP + AS, indicating that only AS had the effect of inhibition at this time.

Anion binding and transport with meso-alkyl substituted two-armed calix[4]pyrroles bearing urea and hydroxyl groups.

Calix[4]pyrroles bearing hydroxyl (1) or urea (3) groups attached to the meso-positions with propyl linkers were synthesized as cis- and trans-isomers. The anion binding properties of cis-1 and cis-3 were screened with ion-mobility mass spectrometry, where cis-1 formed complexes with Cl-, Br- and H2PO4-, whereas cis-3 formed complexes with most of the investigated anions, including Cl-, Br-, I-, NO3-, ClO4-, OTf-, SCN- and PF6-. The structures of the chloride complexes were further elucidated with density functional theory calculations and a crystal structure obtained for cis-1. In solution, chloride and dihydrogenphosphate anion binding with cis-1 and cis-3 were compared using 1H NMR titrations. To assess the suitability of two-armed calix[4]pyrroles as anion transporters, chloride transport studies of cis-1, cis-3 and trans-3 were performed using large unilamellar vesicles. The results revealed that cis-3 had the highest activity among the investigated calix[4]pyrroles, which was related to the improved affinity and isolation of chloride inside the binding cavity of cis-3 in comparison to cis-1. The results indicate that appending calix[4]pyrroles with two hydrogen bonding arms is a feasible strategy to obtain anion transporters and receptors with high anion affinity.

Chiral bifunctional organocatalysts for enantioselective synthesis of 3-substituted isoindolinones.

A series of chiral bifunctional organocatalysts were prepared and used for enantioselective synthesis of 3-substituted isoindolinones from 2-formylarylnitriles and malonates through aldol-cyclization rearrangement tandem reaction in excellent yields and enantioselectivites (up to 87% yield and 95% ee) without recrystallization. In this investigation, we found that chiral tertiary-amine catalysts with a urea group can afford 3-substituted isoindolinones both in higher yields (87% vs. 77%) and enantioselectivities (95% ee vs. 46% ee) than chiral bifunctional phase-transfer catalysts.

Synthesis and study of the agrochemical properties of urea salts with nitric and orthophosphoric acid

The paper presents the results of the synthesis, IR spectroscopic and agrochemical study of the products of adduct formation (internal salts) of urea with nitric and orthophosphoric acids. It has been established that the synthesized substances are hygroscopic, readily soluble in water. IR spectral data indicate that, depending on the “acid : urea” ratio in the final products CO, NH2, urea groups and acid molecules are involved in the formation of various compositions: [H2O···(NH2)2C(OH)+···-ONO2] and [O2N-O-···+H3N(H2N)C(OH)+···-O-NO2], [-NH3+···-O-P(O)(OH)2] and [C(OH)+···-O-P(O)(OH)2] salt bridges. The solubility of poorly soluble salts, which are included in a series of metal ion compounds accumulating in the soil under the action of urea mononitrate, has been studied. According to the results of an agrochemical study of the effect of synthesized urea salts on the digestibility of P2O5 by Tr-B and citric acid in the soil, an increase in these parameters under the action of urea dinitrate and diorthophosphate was found to be within 8.26–11.52 and 8.28–9.52%, relative to control 1.07 and 0.787%, respectively.

Protonophoric and mitochondrial uncoupling activity of aryl-carbamate substituted fatty acids.

Aryl-urea substituted fatty acids are protonophores and mitochondrial uncouplers that utilise a urea-based synthetic anion transport moiety to carry out the protonophoric cycle. Herein we show that replacement of the urea group with carbamate, a functional group not previously reported to possess anion transport activity, produces analogues that retain the activity of their urea counterparts. Thus, the aryl-carbamate substituted fatty acids uncouple oxidative phosphorylation and inhibit ATP production by collapsing the mitochondrial proton gradient. Proton transport proceeds via self-assembly of the deprotonated aryl-carbamates into membrane permeable dimeric species, formed by intermolecular binding of the carboxylate group to the carbamate moiety. These results highlight the anion transport capacity of the carbamate functional group.

Contrasting-functionality-decked robust MOF for moisture-tolerant and variable-temperature CO2 adsorption with in-built urea group mediated mild condition cycloaddition

A robust MOF containing three dissimilar functionalities reveals moisture-tolerant CO2 scavenging with radical increase in high-temperature selectivity and promotes unconventional organic-functionality-actuated CO2 fixation under mild conditions.

Relationship between Uric Acid, Creatinine, Urea and Triglyceride Production in Gout

Background: Gout is a disorder that manifests as a spectrum of clinical and pathologic features built on a foundation of an excess body burden of uric acid, Hyperuricemia and gout are two of the most common metabolic diseases, there has been an increase in the prevalence and has attracted attention as an adult lifestyle-associated disease.
 Objective: The present study was carried to determine the prevalence of goat and uric acid, creatinine, urea, and triglyceride production in patients with hyperuricemia.
 Materials and Methods: Cross sectional study was done to examine associative between (November 2017 to February 2018). Totally 66 patient attended from ( Hawler Private Hospital, Rezgari Governmental Hospital, Ankawa Private Laboratory) in Erbil and may have hyperuricemia can be developed to gout disease from both males (32) and females (34) .the age 18 up to 70 who included in this study. Biochemical tests were performed for all patients (uric acid test, urea test, creatinine test, triglyceride test). These samples were analyzed by using blood serum rather than urine.
 Results: In male statistical analysis showed that significant correlation between high uric acid and age, the age group (41-60) years was significantly higher compared to other age groups (P < 0.05), and in female statistical analysis showed that significant correlation between high uric acid and age, the age group (61-80) years was significantly higher compared to other age groups (P < 0.05). In male statistical analysis showed that significant correlation between high creatinine and age , the age group (41-60) years was significantly higher compared to other age groups (P < 0.05), in female statistical analysis showed that significant correlation between high creatinine and age, the two age groups (41-60) & (61-80) years were significantly higher compared to other age group (P < 0.05). In male statistical analysis showed that significant correlation between high urea and age, the age group (41-60) years was significantly higher compared to other age groups (P < 0.05), in female statistical analysis showed that non-significant correlation between high urea and age groups (P > 0.05). In male statistical analysis showed that significant correlation between high TG and age , the age group (41-60) years was significantly higher compared to other age groups (P < 0.05), in female statistical analysis showed that non-significant correlation between high TG and age groups (P > 0.05).
 Conclusion: gout is a very common form of arthritis might be increasing hinderance of activity of daily living, lifestyle and environmental factors. Although not life-threatening, it has a significant impact on quality of life. The results provide support for possible linkage of influencing creatinine and triglyceride and uric acid and triglyceride with gout.

Fasting sugar, blood pressure and uric acid are factors related to positive Kidney disease and an impaired GFR

The purpose of this study is to determine the association between fasting sugar level, urea, creatinine, uric acid, blood pressure, and glomerular filtration rate (GFR) in renal disease patients.The current study found that men patients had lower blood sugar, fasting blood glucose, and serum creatinine levels than women patients. however, there was no significant difference between groups of blood urea, uric acid, Glumoular filter, and blood pressure. Also, there is no significant difference in patients based on age in the current study, and there is a very strong positive link between random glucose level and fasting glucose level.

Design, Synthesis and Antiproliferative Evaluation of Bis-Indole Derivatives with a Phenyl Linker: Focus on Autophagy

This work deals with the study of the synthesis of new bis-indole analogues with a phenyl linker derived from indole phytoalexins. Synthesis of target bis-indole thiourea linked by a phenyl linker was achieved by the reaction of [1-(tert-butoxycarbonyl)indol-3-yl]methyl isothiocyanate with p-phenylenediamine. By replacing the sulfur of the thiocarbonyl group in bis-indole thiourea with oxygen using mesityl nitrile oxide, a bis-indole homodimer with a urea group was obtained. A cyclization protocol utilizing bis-indole thiourea and methyl bromoacetate was applied to synthesize a bis-indole homodimer with a thiazolidin-4-one moiety. Bis-indole homodimers derived from 1-methoxyspirobrassinol methyl ether were prepared by bromospirocyclization methodology. Among the synthesized analogues, compound 49 was selected for further study. To evaluate the mode of the mechanism of action, we used flow cytometry, Western blot, and spectroscopic analyses. Compound 49 significantly inhibited the proliferation of lung cancer cell line A549 with minimal effects on the non-cancer cells. We also demonstrated that compound 49 induced autophagy through the upregulation of Beclin-1, LC3A/B, Atg7 and AMPK and ULK1. Furthermore, chloroquine (CQ; an autophagy inhibitor) in combination with compound 49 decreased cell proliferation and induced G1 cell cycle arrest and apoptosis. Compound 49 also caused GSH depletion and significantly potentiated the antiproliferative effect of cis-platin.