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Chiral guanidine-catalyzed acylative and silylative dynamic kinetic resolutions of 6-hydroxy-2 H -pyran-3(6 H)-one were achieved. We succeeded in developing a non-enzymatic acylative dynamic kinetic resolution of 6-hydroxy-2 H -pyran-3(6 H)-one with high enantioselectivity, which could be improved by recrystallization. In contrast, the non-enzymatic silylative dynamic kinetic resolution of 6-hydroxy-2 H -pyran-3(6 H)-one was accomplished with a moderate selectivity for the first time. [ABSTRACT FROM AUTHOR]

As a result of full‐scale ongoing global efforts, the power conversion efficiency (PCE) of the organic‐inorganic metal halide perovskite has skyrocketed. Unfortunately, the long‐term operational stability for commercialization standards is still lagging owing to intrinsic defects such as ion migration‐induced degradation, undercoordinated Pb2+, and shallow defects initiated by disordered crystal growth. Herein, we employed multifunctional, non‐volatile tetra‐methyl guanidine hydrochloride [TMGHCL] ionic liquid (IL) as an additive to elucidate defects' passivation effects on organic‐inorganic metal halide perovskite. More specifically, the formation of hydrogen bonds between H+ in GA+ and I− and coordinate bonding between Cl− and undercoordinated Pb2+ could significantly passivate these defects. The hypothesis was confirmed by both experimental and DFT simulations displaying that the optimized ratio of IL integration restrains ion migration, improving grains' size, and significantly elongating the carrier lifetime. Remarkably, the modified cell achieved a peak efficiency of 22.00 % with negligible hysteresis, compared to the control device's PCE of 20.12 %. In addition, the TMGHCL‐based device retains its 93.29 % efficiency after 16 days of continuous exposure to air with a relative humidity of 35±5% and temperature of 25±5 °C. This efficient approach of adding IL to perovskites absorber can produce high PCE and has strong commercialization potential. [ABSTRACT FROM AUTHOR]

There is an urgent unmet need for more targeted and effective treatments for advanced epithelial ovarian cancer (EOC). The emergence of drug resistance is a particular challenge, but small molecule covalent inhibitors have promise for difficult targets and appear less prone to resistance. Michael acceptors are covalent inhibitors that form bonds with cysteines or other nucleophilic residues in the target protein. However, many are categorized as pan-assay interference compounds (PAINS) and considered unsuitable as drugs due to their tendency to react non-specifically. Targeting RPN13/ADRM1-mediated substrate recognition and deubiquitination by the proteasome 19S Regulatory Particle (RP) is a promising treatment strategy. Early candidate RPN13 inhibitors (iRPN13) produced a toxic accumulation of very high molecular weight polyubiquitinated substrates, resulting in therapeutic activity in mice bearing liquid or solid tumor models, including ovarian cancer; however, they were not drug-like (PAINS) because of their central piperidone core. Up284 instead has a central spiro-carbon ring. We hypothesized that adding a guanidine moiety to the central ring nitrogen of Up284 would produce a compound, RA475, with improved drug-like properties and therapeutic activity in murine models of ovarian cancer. RA475 produced a rapid accumulation of high molecular polyubiquitinated proteins in cancer cell lines associated with apoptosis, similar to Up284 although it was 3-fold less cytotoxic. RA475 competed binding of biotinylated Up284 to RPN13. RA475 shows improved solubility and distinct pharmacodynamic properties compared to Up284. Specifically, tetraubiquitin firefly luciferase expressed in leg muscle was stabilized in mice more effectively upon IP treatment with RA475 than with Up284. However, pharmacologic analysis showed that RA475 was more rapidly cleared from the circulation, and less orally available than Up284. RA475 shows reduced ability to cross the blood-brain barrier and in vitro inhibition of HERG. Treatment of mice with RA475 profoundly inhibited the intraperitoneal growth of the ID8-luciferase ovarian tumor model. Likewise, RA475 treatment of immunocompetent mice inhibited the growth of spontaneous genetically-engineered peritoneal tumor, as did weekly cisplatin dosing. The combination of RA475 and cisplatin significantly extended survival compared to individual treatments, consistent with synergistic cytotoxicity in vitro. In sum, RA475 is a promising candidate covalent RPN13i with potential utility for treatment of patients with advanced EOC in combination with cisplatin. [ABSTRACT FROM AUTHOR]

We report a three-stage scheme (1) Pbt–NH2 + CS2 → (Pbt–NH)2C=S (1) (Pbt = 4-(1′,3′-benzothiazole-2′-yl)phenyl), (2) 1 + PPh3 + I2 → Pbt–N=C=N–Pbt (2), (3) 2 + Ph2PH → (Pbt–N)(Pbt–NH)CPPh2 (3) for the synthesis of a novel luminescent phosphoguanidine 3 with an unprecedentedly high yield (90%) at the last catalyst-free stage. It is demonstrated by the density functional theory (DFT) method that high reactivity of 2, leading to such an yield, is explained by a high electrostatic potential at the central carbon atom. For 3, two polymorphs 3α, 3β and a solvatomorph 3γ·THF are prepared. The structures of 2, 3α, 3β, and 3γ·THF are determined by single-crystal XRD. The tendency of crystals of different phenylbenzothiazole derivatives to form different conformations is explained by the computational (DFT) data indicating that the energy change of the molecule of 3 considered as a function of the torsion angle between phenyl and benzothiazole fragments does not exceed 2 kJ/mol in the –15...30° range. Photophysical properties of 3β and 3γ·THF phases are studied. It is shown that these compounds exhibit photoluminescence with an emission maximum at 510 nm. [ABSTRACT FROM AUTHOR]

The world is committed to reducing CO2 emissions, and research on CO2 capture and effective utilization is being actively studied. Among the methods in development, direct air capture (DAC) is classified as a negative emission technology and has attracted significant study. The current problem with CO2 capture technologies for decarbonization is their cost due to the high separation energy required to release CO2. We have developed a new light-swing method that can potentially utilize a natural source of energy, i.e., sunlight, as an alternative to temperature- and pressure-swing methods. Herein, we report photoirradiation-based CO2 capture based on photoisomerization of azobenzene-amine and guanidine derivatives. The visible light-swing CO2 absorption and release system using azobenzene-guanidine has shown potential in DAC systems owing to its reusability. A plausible mechanism for CO2 release under light irradiation involves photoisomerization from trans- to cis-azobenzene in which steric repulsion with other molecules is the driving force, and CO2 is released due to the functional disruption of intermolecular interactions. This concept demonstrates the potential of using various photokinetic molecules as a driving force for light-swing CO2 capture. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and characterization of the novel 2‐aminoguanidine‐derived Schiff base rhenium(I) compounds: fac‐[Re(CO)3(Hguabs)Br]Br (1) (Hguabs ⋅ Cl=2‐((benzothiazole)methyleneamino)guanidine chloride) and fac‐[Re(CO)3(guaquin)Br] (2) (guaquin=2‐((quinolin‐2‐yl)methyleneamino)guanidine). [ABSTRACT FROM AUTHOR]

This article discusses the development of chiral bifunctional NHC-guanidine ligands for asymmetric hydrogenation. The researchers have shown that these ligands can control chemoselectivity in catalytic reactions, allowing for the reduction of esters to alcohols. They have also synthesized chiral bifunctional ligand precursors using commercially available chiral building blocks. These ligands have been tested in the asymmetric copper(I)-catalyzed hydrogenation of acetophenone, demonstrating the potential for stereoinduction. The results suggest that these ligands could have broader applications in asymmetric catalysis. [Extracted from the article]

In this study, the focus was on synthesizing metal chelates of Fe(III), Ni(II), and Pd(II) using thiazole‐guanidine derivatives. Various spectral and analytical methods were employed to elucidate the structural characteristics and determine the molecular formulae of these metal chelates, including infrared (IR(, 1H‐NMR and 13C‐NMR, ultraviolet–visible (UV–vis), CHN, XRD data, mass spectrometry, thermal conduction, and measures of magnetism, were used to clarify the structures of these compounds. The optimized molecular structures have been scrutinized by the DFT method. Correlation between all spectroscopic methods and DFT calculation revealed an octahedral‐coordinating environment surrounding the Fe3+ ion, [Fe (BTG)2(NO3)2].NO3.2H2O and Ni2+, [Ni (BTG)2(NO3)2].H2O cation and distorted square planner surrounding Pd2+, [Pd (BTG) (COOCH3)2].2H2O cation. The examination of the stability and stoichiometry of complexes in solution using conventional techniques has been incorporated into the investigation's scope. Under mild reaction conditions, the green technique was employed to carry out a condensation reaction for aromatic aldehyde, rhodanine, pipredine, and 5‐aminotetrazol to generate derivatives of 6‐piperidin‐dihydro‐thia‐hexaaza‐s‐indacene derivatives. In comparison to our new complexes, all reaction conditions were optimized for those variable Lewis acid catalysts. In general, tests conducted under high yield, speedy, and environmentally friendly solvent (H2O/EtOH) conditions, the BTGPd catalyst showed superiority over others. Additionally, the hetero‐catalyst recovery proved successful and could be employed with the same efficiency up to six times before the efficiency started to decrease. The effectiveness of this catalytic procedure was validated through a thorough examination using density functional theory (DFT). The DFT analysis showcased the distinctive characteristics of this complex and proposed logical mechanisms that elucidated the crucial physical parameters responsible for the superior catalytic performance of the Pd(II) complex. [ABSTRACT FROM AUTHOR]

This work investigated the cocatalytic activity of recently prepared guanidinium salts containing an oxanorbornane subunit in an (S)-proline-catalyzed aldol reaction. The activity was interpreted by the diastereoselectivity of the reaction (anti/syn ratio) and for the most interesting polycyclic guanidinium salt, the enantioselectivity of the reaction was determined. The results indicated a negative impact on the oxanorbornane unit if present as the flexible substituent. For most of the tested aldehydes, the best cocatalysts provided enantioselectivities above 90% and above 95% at room temperature and 0 °C, respectively, culminating in >99.5% for 4–chloro– and 2–nitrobenzaldehyde as the substrate. The barriers for forming four possible enantiomers were calculated and the results for two anti–enantiomers are qualitatively consistent with the experiment. Obtained results suggest that the representatives of furfurylguanidinium and rigid polycyclic oxanorbornane-substituted guanidinium salts are good lead structures for developing new cocatalysts by tuning the chemical space around the guanidine moiety. [ABSTRACT FROM AUTHOR]

The catalytically active center of the enzyme tyrosinase, standing out for its unusual substrate diversity, consists of a side‐on μ‐η2:η2‐peroxido complex (SP). Several ligand systems stabilizing a SP and able to mimic the catalytic activity of the enzyme towards simple phenolic substrates are known. Only a few catalytically active systems based on the isoelectronic isomer structure of SP, a bis(μ‐oxido)dicopper(III) complex (O), were investigated until now. Two years ago, we presented with the TMGbenza a hybrid guanidine based tyrosinase model system stabilizing an O species with an exceptional substrate diversity. Herein we studied the catalytic activity of another O species stabilized by the bisguanidine ligand TMG2tol. The reaction conditions for the catalytic oxygenation were optimized and a broad spectrum of phenolic substrates like naphthol, quinolinols and indolols was tested. Naturally occurring phenazine derivatives like phenazine‐1‐carboxylamide (PCN) and phenazine‐1‐carboxylic acid (PCA) show antifungal as well as antibacterial activity, functioning as biological control agents against crop disease like take‐all. Hence, the synthesized phenazines were evaluated for their potential antimicrobial activities against representative gram‐positive and gram‐negative bacteria. [ABSTRACT FROM AUTHOR]

Metabolism and biological functions of the nitrogen-rich compound guanidine have long been neglected. The discovery of four classes of guanidine-sensing riboswitches and two pathways for guanidine degradation in bacteria hint at widespread sources of unconjugated guanidine in nature. So far, only three enzymes from a narrow range of bacteria and fungi have been shown to produce guanidine, with the ethylene-forming enzyme (EFE) as the most prominent example. Here, we show that a related class of Fe2+- and 2-oxoglutarate-dependent dioxygenases (2-ODD-C23) highly conserved among plants and algae catalyze the hydroxylation of homoarginine at the C6-position. Spontaneous decay of 6-hydroxyhomoarginine yields guanidine and 2-aminoadipate-6-semialdehyde. The latter can be reduced to pipecolate by pyrroline-5-carboxylate reductase but more likely is oxidized to aminoadipate by aldehyde dehydrogenase ALDH7B in vivo. Arabidopsis has three 2-ODD-C23 isoforms, among which Din11 is unusual because it also accepted arginine as substrate, which was not the case for the other 2-ODD-C23 isoforms from Arabidopsis or other plants. In contrast to EFE, none of the three Arabidopsis enzymes produced ethylene. Guanidine contents were typically between 10 and 20 nmol*(g fresh weight)-1 in Arabidopsis but increased to 100 or 300 nmol*(g fresh weight)-1 after homoarginine feeding or treatment with Din11-inducing methyljasmonate, respectively. In 2-ODD-C23 triple mutants, the guanidine content was strongly reduced, whereas it increased in overexpression plants. We discuss the implications of the finding of widespread guanidine-producing enzymes in photosynthetic eukaryotes as a so far underestimated branch of the bio-geochemical nitrogen cycle and propose possible functions of natural guanidine production. [ABSTRACT FROM AUTHOR]

Scientists and researchers have been searching for drugs targeting the main protease (Mpro) of SARS-CoV-2, which is crucial for virus replication. This study employed a virtual screening based on molecular docking to identify benzoylguanidines from an in-house chemical library that can inhibit Mpro on the active site and three allosteric sites. Molecular docking was performed on the LaSMMed Chemical Library using 88 benzoylguanidine compounds. Based on their RMSD values and conserved pose, three potential inhibitors (BZG1, BZG2, and BZG3) were selected. These results indicate that BZG1 and BZG3 may bind to the active site, while BZG2 may bind to allosteric sites. Molecular dynamics data suggest that BZG2 selectively targets allosteric site 3. In vitro tests were performed to measure the proteolytic activity of rMpro. The tests showed that BZG2 has uncompetitive inhibitory activity, with an IC50 value of 77 µM. These findings suggest that benzoylguanidines possess potential as Mpro inhibitors and pave the way towards combating SARS-Cov-2 effectively. [ABSTRACT FROM AUTHOR]

Transition metal complexes of N-substituted guanidinates are widely studied due to their intriguing structures, reactivities, and bonding as homogeneous catalysts and precursors for chemical vapor deposition. In this manuscript, we have isolated a family of pincer complexes, [Pd{κ3(CNN)(OC(O)R′)}] (CNN = N-picolyl-N′,N′′-diarylguanidinate(1−); aryl = 2-RC6H4; R = Me and CF3; R′ = CF3, Me and tBu; A) and studied their reactions with XylN≡C (Xyl = 2,6-Me2C6H3) and PPh3 (Ls′) with the objective of understanding the substituent effects of the pincer complexes upon the nature of the products. In this endeavour, we were able to isolate the respective cationic [Pd{κ3(CNN)(L)}][OC(O)R′] (B) and neutral [Pd{κ3(CNN)(C≡NXyl)}] (CNN = N-picolinoyl-N′,N′′-diarylguanidinate(2−); D) complexes with the latter complexes formed from the former through carboxylate-assisted N–H activation followed by –CH2– → –C(O)– oxygenation of the 2-picolyl unit in the guanidinate(1−) ligand, which is induced by atm. O2. An elusive intermediate, [Pd{κ3(CNN)(C≡NXyl)}] (CNN = N-picolyl-N′,N′′-di(2-tolyl)guanidinate(2−); C) formed during B → D transformation was successfully isolated. The new complexes were fully characterised and the molecular structures of nine complexes were determined by X-ray crystallography. Various intermediates formed during the oxygenation were mapped out using the model complexes through DFT calculations. The solution behaviour of A was studied by multinuclear NMR and their utility as catalysts in Suzuki–Miyaura coupling reactions and base-free cycloisomerization of 4-pentynoic acid was briefly explored. The carboxylate-assisted N–H activation and oxygenation of the Pd(II) bound guanidinate(1−/2−) ligands reported herein represent the redox active behaviour of the ligand towards atm. O2 for the first time. [ABSTRACT FROM AUTHOR]

Polyhexamethylene guanidine phosphate (PHMG-p) is a major component in humidifier disinfectants, which cause life-threatening lung injuries. However, to our knowledge, no published studies have investigated associations between PHMG-p dose and lung damage severity with long-term follow-up. Therefore, we evaluated longitudinal dose-dependent changes in lung injuries using repeated chest computed tomography (CT). Rats were exposed to low (0.2 mg/kg, n = 10), intermediate (1.0 mg/kg, n = 10), and high (5.0 mg/kg, n = 10) doses of PHMG-p. All rats underwent repeated CT scans after 10 and 40 weeks following the first exposure. All CT images were quantitatively analyzed using commercial software. Inflammation/fibrosis and tumor counts underwent histopathological evaluation. In both radiological and histopathologic results, the lung damage severity increased as the PHMG-p dose increased. Moreover, the number, size, and malignancy of the lung tumors increased as the dose increased. Bronchiolar–alveolar hyperplasia developed in all groups. During follow-up, there was intergroup variation in bronchiolar–alveolar hyperplasia progression, although bronchiolar–alveolar adenomas or carcinomas usually increase in size over time. Thirty-three carcinomas were detected in the high-dose group in two rats. Overall, lung damage from PHMG-p and the number and malignancy of lung tumors were shown to be dose-dependent in a rat model using repeated chest CT scans during a long-term follow-up. [ABSTRACT FROM AUTHOR]

A novel approach has been developed for the efficient synthesis of the unsymmetrical (2-aminopyrrolidin-1-yl)carboxamidine alkaloidal core found in cernumidine (1) and its analogs (20a, 20c, 20f, 20i–o). The key transformation in this process involves the utilization of the Curtius rearrangement, which plays a pivotal role in constructing the aminal moiety. One of the major challenges encountered during this synthesis was the instability of the free aminal core intermediate. Furthermore, a noteworthy observation during the synthesis was the racemization process that occurred during the isocyanate trapping by organometallic reagents. Detailed DFT calculations shed light on this phenomenon, revealing a neighboring coordination-induced mechanism. The resulting compounds were subjected to evaluation for their anti-inflammatory properties using lipopolysaccharide-stimulated human THP1 cells. Notably, compounds featuring the guanidine moiety and electron-donating groups exhibited significant anti-inflammatory activity. These findings suggest that these compounds hold promise as potential candidates for further development as anti-inflammatory agents. [ABSTRACT FROM AUTHOR]

Green catalysts used in the transesterification reaction of biodiesel must have biodegradability and non-toxicity as their main characteristics, being thus friendly to the environment, since they perform in processes in which the content of CO2, which is increasing from year to year, should be reduced. As a consequence, their manufacture can be extremely rigorous. This work presents the two-step construction, synthesis, and deposition of such a green heterogeneous catalyst and its testing in the catalysis of the transesterification of triglycerides with methanol, resulting in methyl esters. A CSTR-type reactor was used to perform transesterification, and the biodiesel yields obtained had values in the range of 91.7–95.7%, using 2, 3, and 4 g/g catalyst to oil, under conditions like those for obtaining commercial biodiesel in homogeneous catalysis, i.e., a 65 °C process temperature and a 4:1, 5:1 or 6:1 methanol-to-oil molar ratio. [ABSTRACT FROM AUTHOR]

Multipurpose coordination flexibility of a bioactive ligand 1,3-bis(5-bromo-2-hydroxyphenyl-methylideneamino)guanidine hydrochloride (H5Brsal-dag·HCl) is reported. The chelation of the ligand with Zn(II) ions after deprotonation forms an unusual anionic complex and as an all-rounder, the same ligand gets protonated and acts as a counter cation to produce the complex in good yield. We could synthesize and characterize an analogous Cd(II) complex also by following similar reaction conditions, which further confirms the high flexibility of the ligand and rules out serendipity. The molecular structures of [ZnCl2(H4Brsal-dag)]H6Brsal-dag·DMF·H2O (1) and [CdCl2(H4Brsal-dag)]H6Brsal-dag·DMF·H2O (2) are confirmed by single crystal X-ray diffraction, after characterization by physicochemical methods. The short-term in vitro cytotoxicity assessment against Dalton's Lymphoma ascite tumor cells reveals the efficacies of all the compounds. The antibacterial activity tested against Escherichia coli and Staphylococcus aureus revealed the potential of the complexes compared to the free ligand. The complex 2 is found to be more potent against E. coli than the standard ciprofloxacin. Density functional theory studies were also performed to ascertain the electronic properties, which are in agreement with different putative binding potentials and their efficacies. The Zn(II) complex is found to exhibit promising antioxidant potential and antitumor activity. The versatility of the ligand offers new perspectives in coordination chemistry. [ABSTRACT FROM AUTHOR]

Two compounds, (S)-8-{[(tert-butyldimethylsilyl)oxy]methyl|-1-[(2,2,4,6,7-pentamethyl-2,3-dihydrobenzofuran-5-yl)sulfonyl]-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-α]pyrimidin-1-ium trifluoromethanesulfonate, C27H46N3O4SSi+⋅-CF3O3S-, (1) and (S)-8-(iodomethyl)-1-tosyl-1,3,4,6,7,8-hexahydro-2#-pyri-mido[1,2-α]pyrimidin-1-ium iodide, C15H21IN3O2S⋅+I-, (2), have been synthesized and characterized. They are bicyclic guanidinium salts and were synthesized from N-(tert-butoxycarbonyl)-L-methionine (Boc-L-Met-OH). The guanidine is protected by a 2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl (Pbf, 1) or a tosyl (2) group. In the crystals of both compounds, the guanidinium group is almost planar and the N-H forms an intramolecular hydrogen bond in a six-membered ring to the oxygen atom of the sulfonamide protecting group. [ABSTRACT FROM AUTHOR]

In order to protect the marine environment, traditional marine antifouling coatings such as tributyltin (TBT)‐based antifouling coatings have been phased out. There is an urgent need to develop environmentally friendly marine antifouling coatings. In this work, the antibacterial poly(hexamethylene guanidine) (PHMG) was introduced into polyurethane (PU) through chemical bond to prepare a green environmentally friendly marine antifouling coating (PU‐PHMG). The morphology, antimicrobial properties, mechanical properties and thermostability of the PU‐PHMG films were investigated. The antimicrobial rates of PU‐PHMG films against E. coli and S. aureus were both more than 99.9% when PHMG content in the films reached 1.0 wt%. The excellent antimicrobial activities can be maintained for more than 90 days due to the non‐leaching characteristic of PHMG. The growth of algae was also inhibited on the surface of PU‐PHMG films. The PU‐PHMG coating is promising for the applications in marine antifouling field. [ABSTRACT FROM AUTHOR]

Argininemia or arginase-1 deficiency constitutes a rare, genetic, metabolic disorder caused by mutations in arginase 1—the last enzyme of the urea cycle—that hydrolyses L-arginine to ornithine and urea. The disease is associated with progressive development of spasticity and other symptoms, including seizures, developmental delay, cognitive impairment, and hepatic pathology. The present review attempts to summarize the current knowledge on the pathophysiology of the disease and highlight novel methods for its evaluation. Different factors, such as the accumulation of arginine, ammonia, and guanidino compounds, act as neurotoxins and may account for the neurological sequelae observed in the disease. New markers, such as arginine/ornithine ratio along with metabolomics, machine learning algorithms, and genetic methods, can be useful in the early diagnosis of argininemia, while mobile phone apps can assist argininemic patients in adhering to the strict diet required. Neurophysiology, multi-modal imaging, and new modelling methods, such as induced pluripotent stem cells, hold promise for providing new insights into the pathophysiology of the disease. There are still many uncertainties regarding the underlying mechanisms of argininemia, but the use of novel modelling methods and new technology can lead to the decipherment of its pathophysiology, improvement of diagnostic accuracy, and better disease management. [ABSTRACT FROM AUTHOR]

The "visible" proton‐conducting pathway offers a distinct advantage for researching the mechanism of proton conducting materials at the molecular level and developing new materials. To achieve this, three crystalline materials are constructed via acid–base chemistry based on phosphomolybdic acid and diversfied guanidine, namely, (CN3H6)6(PMo12O40)2·H2O (GH–PMo12), (CN4H7)3(PMo12O40)·H2O (AGH–PMo12), and (CN5H8)3(PMo12O40)·3.5H2O (DAGH–PMo12). Proton conductivity of GH–PMo12 in the [001] direction reaches up to 0.19 S cm−1 at 85 °C and 98% RH, as elucidated by impedance studies of single crystals. The clear proton transport path is proposed through the analysis of single crystal structure. Moreover, impedance studies of powder crystals reveal that the proton conductivity of GH–PMo12 is higher than that of the other two compounds. The underlying reasons for this result are clarified through the analysis of the pKa, proton density, and spatial structure. Additionally, GH–PMo12 is fabricated into composite membrane with a peak proton conductivity of 5.31 × 10−2 S cm−1, which exhibits promising potential for real‐world applications. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the assumption in amide proton transfer weighted (APTw) imaging that the APT dominates over the relayed nuclear Overhauser enhancement (rNOE) and other CEST effects such as those from amines/guanidines, thereby providing imaging of mobile proteins/peptides. Methods: We introduced two auxiliary asymmetric analysis metrics that can vary the relative contributions from amine/guanidinium CEST and other effects. By comparing these metrics with the conventional asymmetric analysis metric on healthy rat brains, we can approximately assess the contribution from amines/guanidines to APTw and determine whether the APT dominates over the rNOE effect. To further investigate the molecular origin of APTw, we used samples of dialyzed tissue homogenates to eliminate small metabolites and supernatants of homogenates to separate lipids from other components. Results: When the APTw signal is positive using high saturation amplitudes (e.g., 2–3 μT), the contributions from amines/guanidines are significant and cannot be ignored. The APTw signal from the dialyzed homogenates and the controls has negligible changes, indicating that it primarily originates from macromolecules rather than small metabolites. Additionally, the APTw signals with low saturation amplitudes (e.g., 1 μT) were negative in tissue homogenates but positive in their supernatants, suggesting that proteins contribute positively to APTw signals, whereas lipids contribute negatively to it. Conclusion: The positive APTw signal using high saturation amplitudes could have significant contributions from soluble proteins through CEST, including amide/amine/guanidine proton transfer effects. In contrast, the negative APTw signal using low saturation amplitudes has significant contribution from lipids through rNOE. [ABSTRACT FROM AUTHOR]

Two compatibility test types based on gas generation obtained by vacuum stability test (VST) procedure and on heat generation obtained by heat flow microcalorimetry (HFMC) show that nitroguanidine (NGu), CAS‐No. [556‐88‐7], is compatible with ammonium nitrate (AN), CAS‐No. [6484‐52‐2], ammonium dinitramide (ADN), CAS‐No. [140456‐78‐6], 1,1‐diamino‐dinitroethylene (FOX‐7, DADNE), CAS‐No. [145250‐81‐3], N‐guanylurea dinitramide (FOX‐12, GUDN, carbamoylguanidinium dinitramide), CAS‐No. [217464‐38‐5], hexogen (RDX), CAS‐No. [121‐82‐4], octogen (HMX), CAS‐No. [2691‐41‐0], and trinitrotoluene (TNT), CAS‐No. [118‐96‐7]. The evaluations with gas generation and heat generation were done using the so‐called corresponding reactivity quantities RV and RQ, but the assessment criteria are in accordance with the present NATO standards. NGu and ADN show the rare case of reactivity with a negative assessment quantity, that is their inter‐component reactivity quantities show negative values in RV and RQ. The evolved gas volume and the produced heat generation of the 1 : 1 mixture have lower values than the formally calculated values of the mixture. The root cause of this cannot be deduced with mere compatibility testing. A negative assessment quantity RQ is also observed with NGu and TNT at 80 °C, but not at 70 °C. [ABSTRACT FROM AUTHOR]

Guanidine is a privileged scaffold in drug discovery. Herein we report our investigations into the acid promoted amination of pyrimidine‐bearing cyanamide to produce N, N'‐disubstituted guanidines. Hydrochloric acid was found to be a suitable catalyst, and the substrate scope using conventional heating was investigated with 23 aniline derivatives. The highest yield was obtained with anilines having pKa in the range of 2–4. Further, a microwave synthesis was developed using 3‐chloroaniline as a model substrate increasing the yield from 68 to 93 %. The microwave method was especially suited for increasing yields with anilines having pKa > 3. The structure of the pyrimidine‐bearing guanidines was confirmed by NMR spectroscopy, and one representative compound has been evaluated by X‐ray crystallography, showing the trans‐isomer as the only tautomer in solid form. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations at the M062X-D3/def2-TZVP//M062X-D3/def2-SVP level of theory were employed to reveal the mechanism of the reaction between CO2 and styrene oxide for cyclic carbonate, mediated by guanidine and tetrabutylammonium iodide (TBAI) co-catalysts. The noncatalytic reaction occurred via a concerted mechanism, with energy barriers as high as 64.1 and 78.0 kcal mol−1. Three elementary steps were included in the catalytic reaction, and epoxide ring-opening by nucleophilic attack of an iodide anion was predicted to be the rate-determining step (RDS). Guanidine acted as the H-bond donor to activate styrene oxide by (N)H⋯O interaction, facilitating epoxide ring-opening with a low activation barrier (ΔG≠ = 22.2–29.6 kcal mol−1). A good linear correlation between the acidity of the NH group in the guanidine and the energy barrier in the epoxide ring-opening step was observed. The introduction of an amide group could strengthen the hydrogen bonding ability of the guanidine catalyst toward a styrene oxide substrate, decreasing the activation barrier for the cyclic carbonate product. When the guanidine–Cu(I) complex was used as the Lewis acid catalyst, the styrene oxide was activated by O⋯Cu(I) coordination in organometallic catalysis. The energy barriers in the presence of guanidine–Cu(I)/TBAI catalysts could be decreased in contrast to the non-catalytic reaction. [ABSTRACT FROM AUTHOR]

The behavior of polyhexamethylene guanidine (PHMG), the causative agent of many humidifier-induced lung diseases, is not well known because of its various oligomer structures and analytical difficulties. The aim of this study was to identify different PHMG oligomer types both in solution and aerosols and to estimate the airborne concentration of oligomers during humidifier use. Three products containing PHMG as the main component were diluted to the manufacturer's recommended concentration (6.5 ppm) or the worst-case concentration (65 ppm or 125 ppm). Samples were qualitatively and quantitatively analyzed with liquid chromatography-quadrupole time-of-flight (LC-qToF) mass spectrometry in the diluted solution and in the air at 0.5 m and 1 m. The LC-qToF data were processed using UNIFI software to characterize the PHMG structure. For all products in both the humidifier solution and air, the linear type was predominant over the branched/cyclic structure, but each product had different characteristics. The linear structure in the Oxy product, the main product of lung diseases, accounted for 90.6%, while that of the Scunder and BOC Sciences' products accounted for 78.6% and 75.8%, respectively. The concentration of the oligomer in air for the Oxy product was estimated to be 35.89 and 390.96 μg/m3 at 6.5 and 65 ppm, respectively. Most of the oligomers in the solution were found in air at a short distance (0.5 m), with a negligible concentration beyond 1 m. Oligomers with 1–7 monomer units were identified in the humidifier solution, whereas mainly monomers, dimers, and trimers were identified in the air. The results of this study will facilitate further investigations of the mechanisms of lung disease by identifying the behaviors and forms of PHMG in the air, along with previously revealed toxicity results. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a complex group of infectious and parasitic diseases that afflict many thousands of individuals across five continents. Leishmaniasis treatment remains a challenge because it relies on drugsknown for their high toxicity and limited efficacy, making itimperative to identify new molecules that offer greater effectiveness and safety. This study sought to explore the impact of seven synthetic guanidine derivatives (LQOF-G1, LQOF-G2, LQOF-G6, LQOF-G7, LQOF-G32, LQOF-G35 and LQOF-G36) onthe parasite Leishmania (Viannia) braziliensis and in vitro macrophage infection by this parasite, as well as cytotoxic approaches in vitro models of mammalian host cells and tissues. The synthesized compounds showed purity ≥ 99.65% and effectively inhibited parasite growth. LQOF-G1 proved the most potent, yielding the best half-maximal inhibitory concentration (IC50) values against promastigotes (4.62 μmol/L), axenic amastigotes (4.27 μmol/L), and intracellular amastigotes (3.65 μmol/L). Notably, the antileishmanial activity of LQOF-G1, LQOF-G2, and LQOF-G6 was related to immunomodulatory effects, evidenced by alterations in TNF-α, IL-12, IL-10, nitric oxide (NO), and reactive oxygen species (ROS) levels in the supernatant of culture macrophages infected with L. (V.) braziliensis and coincubated with these compounds. LQOF-G2 and LQOF-G36 compounds exhibited vasodilator and spasmolytic effects at higher concentrations (≥100 μmol/L). Generally, LQOF-G1, LQOF-G2, and LQOF-G32 compounds were found to be nontoxic to assessed organs and cells. No toxic effects were observed in human cell lines, such as HEK-293, CaCo-2 and A549, at concentrations ≥ 500 μmol/L. Collectively, data have shown unequivocal evidence of the effectiveness of these compounds against L. (V.) braziliensis parasite, one of the causative agents of Tegumentary Leishmaniasis and Mucocutaneous Leishmaniasis in America. [ABSTRACT FROM AUTHOR]

The aim of the present framework is to synthesize and characterize new cobalt(II) (C1), nickel(II) (C2), and copper(II) (C3) mixed‐ligand complexes incorporating bioactive 8‐hydroxyquinoline moiety, with synthesized 2‐(1H‐benzimidazol‐2‐yl)guanidine (BG) ligand, for investigating their antibacterial, antifungal, and anti‐inflammatory potential. The metal complexes structure had been elucidated by the use of a wide range of methods, including elemental analysis, Fourier transform infrared (FT‐IR), mass spectra, UV–vis spectra, magnetic susceptibility, thermogravimetric (TG) analysis, and the molar ratio technique of stoichiometry analysis. The resulted metal complexes were found to have octahedral structures in molar ratio of M:BG:Qu as 1:1:2. Density functional theory (DFT) had been used to determine the optimal molecular structure and quantum chemical properties of each material. After that, we looked into the metal complexes' anti‐inflammatory and antibacterial properties by testing them in vitro. The disc diffusion test showed that the metal complexes were far more potent against bacteria/fungi than the original ligands. The egg albumin denaturation technique showed that the metal complexes were more potent anti‐inflammatory candidates than the free ligands and comparable with the standard reference. Molecular docking analysis against 5JQ9, 6CLV, and cyclooxygenase‐2 (COX‐2; 5IKT) confirmed the bioactivity behavior of the metal complexes. C3 has the greatest binding affinity among the metal complexes tested. These findings proposed that the metal complexes could form the basis of future antibiotics and anti‐inflammatory candidates. Finally, the in vitro activities were reviewed in relation to the DFT and molecular docking data. [ABSTRACT FROM AUTHOR]

Polyhexamethylene guanidine phosphate (PHMG-p) is a common biocidal disinfectant that is widely used in industry and household products. However, PHMG-p was misused as a humidifier disinfectant (HD) in South Korea, which had fatal health effects. Various health problems including cardiovascular diseases were observed in HD-exposed groups. However, the potential underlying mechanism of HD-associated cardiovascular diseases is poorly understood. Here, we examined the procoagulant activity of platelets caused by PHMG-p and clarified the underlying mechanism. PHMG-p enhanced phosphatidylserine (PS) exposure through alteration of phospholipid transporters, scramblase, and flippase. Intracellular calcium elevation, intracellular ATP depletion, and caspase-3 activation appeared to underlie phospholipid transporter dysregulation caused by PHMG-p, which was mediated by oxidative stress and mitochondrial dysfunction. Notably, antioxidant enzyme catalase and calcium chelator EGTA reversed PHMG-p-induced PS exposure and thrombin generation, confirming the contributive role of oxidative stress and intracellular calcium in the procoagulant effects of PHMG-p. These series of events led to procoagulant activation of platelets, which was revealed as enhanced thrombin generation. Collectively, PHMG-p triggered procoagulant activation of platelets, which may promote prothrombotic risks and cardiovascular diseases. These findings improve our understanding of HD-associated cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Brilacidin, a mimetic of host defense peptides (HDPs), is currently in Phase 2 clinical trial as an antibiotic drug candidate. A recent study reported that brilacidin has antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by inactivating the virus. In this study, we discovered an additional mechanism of action of brilacidin by targeting heparan sulfate proteoglycans (HSPGs) on the host cell surface. Brilacidin, but not acetyl brilacidin, inhibits the entry of SARS-CoV-2 pseudovirus into multiple cell lines, and heparin, an HSPG mimetic, abolishes the inhibitory activity of brilacidin on SARS-CoV-2 pseudovirus cell entry. In addition, we found that brilacidin has broad-spectrum antiviral activity against multiple human coronaviruses (HCoVs) including HCoV-229E, HCoV-OC43, and HCoV-NL63. Mechanistic studies revealed that brilacidin has a dual antiviral mechanism of action including virucidal activity and binding to coronavirus attachment factor HSPGs on the host cell surface. Brilacidin partially loses its antiviral activity when heparin was included in the cell cultures, supporting the host-targeting mechanism. Drug combination therapy showed that brilacidin has a strong synergistic effect with remdesivir against HCoV-OC43 in cell culture. Taken together, this study provides appealing findings for the translational potential of brilacidin as a broad-spectrum antiviral for coronaviruses including SARS-CoV-2.

Organism tolerance thresholds for emerging contaminants are vital to the development of water quality criteria. Acute (96-h) and chronic (10-day) effects thresholds for neonicotinoid pesticides clothianidin and thiamethoxam, and the carbamate pesticide methomyl were developed for the midge Chironomus dilutus to support criteria development using the UC Davis Method. Median lethal concentrations (LC50s) were calculated for acute and chronic exposures, and the 25% inhibition concentrations (IC25) were calculated for the chronic exposures based on confirmed chemical concentrations. Clothianidin effect concentrations were 4.89 µg/L, 2.11 µg/L and 1.15 µg/L for 96-h LC50, 10-day LC50 and 10-day IC25, respectively. Similarly, thiamethoxam concentrations were 56.4 µg/L, 32.3 µg/L and 19.6 µg/L, and methomyl concentrations were 244 µg/L, 266 µg/L and 92.1 µg/L. Neonicotinoid effect concentrations compared favorably to previously published 96-h and 14-day LC50 concentrations, and methomyl effect concentrations were within the acute survival range reported for Chironomus species and other organisms.

To obtain biologically active species, a series of decavanadates (Hpbg)4[H2V10O28]·6H2O (1) (Htbg)4[H2V10O28]·6H2O; (2) (Hgnd)2(Hgnu)4[V10O28]; (3) (Hgnu)6[V10O28]·2H2O; and (4) (pbg = 1-phenyl biguanide, tbg = 1-(o-tolyl)biguanide, gnd = guanidine, and gnu = guanylurea) were synthesized and characterized by several spectroscopic techniques (IR, UV-Vis, and EPR) as well as by single crystal X-ray diffraction. Compound (1) crystallizes in space group P-1 while (3) and (4) adopt the same centrosymmetric space group P21/n. The unusual signal identified by EPR spectroscopy was assigned to a charge-transfer π(O)→d(V) process. Both stability in solution and reactivity towards reactive oxygen species (O2− and OH·) were screened through EPR signal modification. All compounds inhibited the development of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis bacterial strains in a planktonic state at a micromolar level, the most active being compound (3). However, the experiments conducted at a minimal inhibitory concentration (MIC) indicated that the compounds do not disrupt the biofilm produced by these bacterial strains. The cytotoxicity assayed against A375 human melanoma cells and BJ human fibroblasts by testing the viability, lactate dehydrogenase, and nitric oxide levels indicated compound (1) as the most active in tumor cells. [ABSTRACT FROM AUTHOR]

The combination of transparency, antibacterial activity, and flexbility is of great importance for practical applications in industry. However, this remains a huge challenge to date. In this work, a ternary system of polystyrene (PS), styrene‐butadiene block copolymer (SBC), and polyhexamethylene guanidine (PHMG) is reported via a green melt blending method. Because of the excellent compatibility of the components, the elongation at break of the composite increased by 3.0%. The composite shows high optical transparency of 81.8% owing to the similar refractive index of PS, SBC, and PHMG. More importantly, the addition of 0.3 wt% PHMG endows the composite with splendid antibacterial property, which eliminates 99.9% of E. coli and restrains the formation of the biological membrane. The composite is expected to find promising applications in medical industry and electrical apparatus. [ABSTRACT FROM AUTHOR]

A guanidine compound was isolated and identified from Buthus martensii Karsch. Based on its characteristic structure, we used it as a lead compound to carry out structural optimization and subsequent fungicidal evaluation. Here 18 guanidine derivatives were designed and synthesized by a facile method, and their structures were characterized by 1H, 13C NMR, and HRMS. Biological assay indicated that most of the title compounds possess potential fungicidal activities against Alternaria altanata, and Penicillium digitatum. Especially, 5a, 5d, and 5i showed inhibition rates (IR) of 41.9, 41.9, and 44.2% respectively against P. digitatum at a concentration of 25 mg/L, whose activities surpassed that of hymexazol. This is the first report on the active derivatives from B. martensii in application of plant protection, providing scientific references for the development and utilization of active ingredients from scorpions. [ABSTRACT FROM AUTHOR]

A small library of substituted cyclic guanidine incorporated benzothiazole-6-sulphonamides was synthesized. All obtained compounds were investigated for their inhibitory activity against the key brain-associated human carbonic anhydrase isoform hCA VII (a promising target for the treatment of neuropathic pain) and three isoforms expressed in brain and other tissues, hCA I, II, and IV. Sulphaguanidine derivatives 9a–d were inactive on the all investigated isoforms while the primary sulphonamide containing guanidines 6a–c and 7a–c were inactive towards hCA IV but displayed inhibiting properties on hCA I, II, and VII with KIs values in the low nanomolar to micromolar ranges. The results indicated that isoforms hCA II and VII were potently and selectively inhibited by these compounds, whereas the cytosolic hCA I was less sensitive to inhibition. The derivatives reported in this study might be useful for design of more potent and selective inhibitors of hCA II and VII. [ABSTRACT FROM AUTHOR]

The fracture of guanidine-containing polymers and the chemical and physicomechanical properties of the synthesized materials under the influence of hydrocarbon-oxidizing bacteria (HOB) were studied. Scanning electron microscopy revealed the formation of a HOB biofilm on the surface of the studied materials. Such polymers inhibited catalase and lipolytic activity 1.3–3 times compared to the environment under control. According to the obtained data, the fracture of guanidine polymers was insignificant (4.4–6.53%). The physicomechanical properties of the materials – tensile strength and relative elongation practically did not change during 180 days of the experiment. These results are consistent with the results of IR microscopy. The method of thermogravimetric analysis showed that for the two studied materials, the initial temperature of decomposition did not decrease and their properties after exposure to the HOB did not change. It can be assumed that under the influence of bacteria on the surfaces of these polymers, minor surface biodegradation may have occurred. Therefore, the tested polyurethane-based material is promising for protecting various structures against biodamage. [ABSTRACT FROM AUTHOR]

Ethoxyamine derivatives of humic acids have been obtained by mechanochemical synthesis via the simultaneous interaction of humic acids with poly(ethylene glycol) (PEG-6000 and PEG-1500) and an aminating reagent (urea, hydroperitum, or cyanoguanidine) in a vibrating apparatus. Reaction products have been characterized by IR spectroscopy, acid–base potentiometric titration, and viscometry. Tensiometric and rheological characteristics of the surface layers of solutions of salts of the synthesized derivatives of humic acids have been studied by the pendant drop and oscillating pendant drop methods. The solutions of the salts of ethoxyaminohumic acids have been found to exhibit a pronounced surface activity at the air–water interface. The experimental dependences of the viscoelastic modulus on the surface pressure and the concentration of the solutions of ethoxyaminohumic acid salts are in satisfactory agreement with the functions calculated in terms of the theoretical model of bimolecular adsorption. The presence of amino groups in the structure of ethoxyaminohumic acids predetermines their high solubility in the acidic pH region. The simultaneous incorporation of ethoxy and amino groups into humic acid macromolecules makes it possible to obtain a novel type of surfactants, which combine three functions, i.e., the functions of anionic, cationic, and nonionic surfactants. [ABSTRACT FROM AUTHOR]

The use of biocidal agents is a common practice for protection against biofouling in biomass-rich environments. In this paper, oligohexamethyleneguanidine (OHMG) polymer, known for its biocidal properties, was further modified with para-aminosalicylic acid (PAS) to enhance its properties against microorganisms coated with a lipid membrane. The structure of the product was confirmed by 1H NMR, 13C NMR, and FTIR spectroscopy. The values of the minimum inhibitory concentration (MIC) against Mycobacterium smegmatis ATCC 607 and Pseudomonas chlororaphis 449 were found to be 1.40 and 1.05 μg/mL, respectively. The synthesized substance was used as an additive to the polymer matrix of the composite optical oxygen sensor material. A series of samples with different contents of OHMG-PAS was prepared using a co-dissolution method implying the fabrication of a coating from a solution containing both polymers. It turned out that the mutual influence of the components significantly affects the distribution of the indicator in the matrix, surface morphology, and contact angle. The optimal polymer content turned out to be wt.3%, at which point the water contact angle reaches almost 122°, and the fouling rate decreases by almost five times, which is confirmed by both the respiratory MTT assay and confocal microscopy with staining. This opens up prospects for creating stable and biofouling-resistant sensor elements for use in air tanks or seawater. [ABSTRACT FROM AUTHOR]

A simple procedure for the synthesis of N-substituted 2-amino-1,4,5,6-tetrahydropyrimidines from isocyanates with a wide variety of substituents was developed. [ABSTRACT FROM AUTHOR]

Aiming to address the insufficient endocytosis ability of traditional albumin drug conjugates, this paper reports elegant guanidine modification to improve efficacy for the first time. A series of modified albumin drug conjugates were designed and synthesized with different structures, including guanidine (GA), biguanides (BGA) and phenyl (BA), and different quantities of modifications. Then, the endocytosis ability and in vitro/vivo potency of albumin drug conjugates were systematically studied. Finally, a preferred conjugate A4 was screened, which contained 15 BGA modifications. Conjugate A4 maintains spatial stability similar to that of the unmodified conjugate AVM and could significantly enhance endocytosis ability (p*** = 0.0009) compared with the unmodified conjugate AVM. Additionally, the in vitro potency of conjugate A4 (EC50 = 71.78 nmol in SKOV3 cells) was greatly enhanced (approximately 4 times) compared with that of the unmodified conjugate AVM (EC50 = 286.00 nmol in SKOV3 cells). The in vivo efficacy of conjugate A4 completely eliminated 50% of tumors at 33 mg/kg, which was significantly better than the efficacy of conjugate AVM at the same dose (P** = 0.0026). In addition, theranostic albumin drug conjugate A8 was designed to intuitively realize drug release and maintain antitumor activity similar to conjugate A4. In summary, the guanidine modification strategy could provide new ideas for the development of new generational albumin drug conjugates. [ABSTRACT FROM AUTHOR]

This paper presents definitive structural evidence for N,P(III)‐monophosphaamidines in P=C and N=C isomeric forms from a combination of new syntheses, single‐crystal X‐ray diffraction (SC‐XRD), solid‐state NMR and FTIR. Evidence is also provided for C‐amino‐(σ2,λ3)‐phosphaalkene and C‐(σ3,λ3)‐phosphinoimine tautomerism in solution using multi‐nuclear NMR methods. Synthesis and SC‐XRD structure determination of a trisubstituted N,N',P(III)‐monophosphaguanidine is presented, the first structure of a phospha(III)guanidine with two ionizable H atoms. The structural evidence is convincing for an N=C geometry, resulting in both N−H and P−H in the molecule. A detailed computational investigation using DFT methods is presented, with the goal of understanding the tautomeric structure preferences both at the fundamental level (parent molecules with all substituents on the heteroatoms being hydrogen) and using the full structures containing the very bulky 2,6‐diisopropylphenyl (Dipp) substituents employed in this study. Arguments are espoused for treating phospha(III)amidines and ‐guanidines as new types of functional groups, similar to but distinct from the familiar organic analogues. Limited reactivity studies and a voltammetry study of one phospha(III)amidine are included with the supporting information. [ABSTRACT FROM AUTHOR]

The development of highly efficient and environmentally friendly solvents for dissolving cellulose, which is the most abundant natural polymer on Earth, remains a challenge, hindering its full utilization. Herein, a green protic ionic liquid, 1,1,3,3-tetramethylguanidinium methoxyacetate ([TMGH][MAA]), was found to exhibit attractive capacity to dissolve natural cellulose with an appropriate TMG/MAA molar ratio of 7 : 3 at 80 °C. The solubility of cotton linter and ultra-high molecular weight cotton fibers reached 13% (w/w) and 3% (w/w), respectively, surpassing that of most solvent systems currently used for the dissolution of cellulose. The experimental and simulation results verified that the excellent dissolution ability of [TMGH][MAA] for cellulose is mainly attributed to the destruction of the intrinsic hydrogen-bond networks in cellulose by the synergistic interactions of the [TMGH] cations and [MAA] anions with the hydroxyl groups in the cellulose chains, acting as highly efficient "intermolecular scissors". The superiority of this novel dissolution system was further demonstrated by the remarkable comprehensive properties of the regenerated cellulose film including satisfactory thermostability, high transparency, and excellent mechanical properties. Furthermore, the satisfactory recovery performance of this solvent highlights its significant feasibility for large-scale industrial manufacturing. The proposed [TMGH][MAA] in this study exhibits great potential as a next-generation processing solvent for dissolving, and thus processing cellulose, promoting the sustainable development of high-value-added cellulose materials. [ABSTRACT FROM AUTHOR]

Three GUBZCu, GUBZVO, and GUBZPd chelates have been prepared from 2‐guanidino benzimidazole (GUBZ ligand) by a bidentate coordinating approach. FT‐IR, mass, and NMR spectra; magnetic moment; CHN analysis; UV–Vis spectra; molar conductance; and TGA were studied to describe and estimate the molecular formulae of tested molecules. The stability constant for GUBZ complexes was estimated in the solution. Also, the pH profile displays the extra stability of tested complexes. Structure elucidation of the studied complexes had been supported by density functional theory (DFT) along with calculated electronic and vibrational spectra. Electronic absorption spectra were estimated practically through UV–Vis spectra and theoretically performed using the time‐dependent TD‐DFT/B3LYP, for computing the absorption maximum, oscillator strength, and excitation energy of the tested compounds. This study was done into these chelates' catalytic performances for the environmentally friendly synthesis of 7‐amino‐4,5‐dihydro‐tetrazolo[1,5‐a]pyrimidine‐6‐carbonitrile derivatives utilizing aromatic aldehyde, malononitrile, and 5‐amino tetrazole as reactants. The used reactions have been directed in a concerned environment through a green solvent. The obtained results verified the promising catalytic activity and selectivity of the tested complexes. All tested reaction conditions have been enhanced between variable Lewis acid catalysts in associating to our studied complexes. GUBZPd catalyst presented an advantage in overall tests through high yield, green conditions, and short time. Also, the regaining of hetero‐catalyst has prospered as well as recycled through the same effectiveness up to four or five times, and then the performance has been reduced. The mechanism of action has been recommended depending on the capability of the Pd (II) complex for totaling extra bonds above the z‐axis as well as reinforced with theoretical study. This strategy's simplicity, safety, commercially accessible catalyst, stability, fast reaction time, and outstanding yields may be used in the industry in the future. [ABSTRACT FROM AUTHOR]

N-methyl-D-aspartate (NMDA) receptors are inhibited by many amidine and guanidine compounds. In this work, we studied the mechanisms of their inhibition by sepimostat—an amidine-containing serine protease inhibitor with neuroprotective properties. Sepimostat inhibited native NMDA receptors in rat hippocampal CA1 pyramidal neurons with IC50 of 3.5 ± 0.3 µM at −80 mV holding voltage. It demonstrated complex voltage dependence with voltage-independent and voltage-dependent components, suggesting the presence of shallow and deep binding sites. At −80 mV holding voltage, the voltage-dependent component dominates, and we observed pronounced tail currents and overshoots evidencing a "foot-in-the-door" open channel block. At depolarized voltages, the voltage-independent inhibition by sepimostat was significantly attenuated by the increase of agonist concentration. However, the voltage-independent inhibition was non-competitive. We further compared the mechanisms of the action of sepimostat with those of structurally-related amidine and guanidine compounds—nafamostat, gabexate, furamidine, pentamidine, diminazene, and DAPI—investigated previously. The action of all these compounds can be described by the two-component mechanism. All compounds demonstrated similar affinity to the shallow site, which is responsible for the voltage-independent inhibition, with binding constants in the range of 3–30 µM. In contrast, affinities to the deep site differed dramatically, with nafamostat, furamidine, and pentamidine being much more active. [ABSTRACT FROM AUTHOR]

Nitroguanidine (NQ) in solvent-based triple-base propellants (STP) has a propensity to peel off and detach from the matrix, leading to significant defects, such as interface debonding within the propellant’s microstructure. This ultimately results in reduced and unstable mechanical properties. To address this critical issue, an efficient and eco-friendly manufacturing process was employed to successfully produce solventless triple-base propellants (SLTPs) as a comparison to conventional STPs. SLTP samples exhibit a mutually supportive three-dimensional spatial structure, with NQ crystals within the propellant matrix more securely bonded to the interface. They also demonstrate higher relative density (1.68 g⋅cm−3 ), more stable molding dimensions (no contraction), and enhanced tensile strength (41.92 MPa). Quasi-static structural failure tests reveal that the standard deviation of compressive strength for SLTP samples in three axes is smaller, registering at 1.10. The dynamic structural damage performance analysis indicates that the failure of energetic composite materials is attributable to separation fracture damage after the appearance of cracks on the tensile surface at −40 and 25°C. Furthermore, the structural failure of these materials occurs due to significant collapse failure after the compression surface bends inward at 50°C. Consequently, the present study offers a reliable theoretical foundation and procedural strategy for enhancing the structural strength of triple-base propellants. [ABSTRACT FROM AUTHOR]

The transition metal frustrated Lewis pair compounds [(Cym)M(κ3S,P,N-HL1)][SbF6] (Cym = η6-p-MeC6H4iPr; H2L1 = N-(p-tolyl)-N′-(2-diphenylphosphanoethyl)thiourea; M = Ru (5), Os (6)) have been prepared from the corresponding dimer [{(Cym)MCl}2(μ-Cl)2] and H2L1 by successive chloride abstraction with NaSbF6 and AgSbF6 and NH deprotonation with NaHCO3. Complexes 5 and 6 and the previously reported phosphano–guanidino compounds [(Cym)M(κ3P,N,N′-HL2)][SbF6] [H2L2 = N,N′-bis(p-tolyl)-N′′-(2-diphenylphosphanoethyl) guanidine; M = Ru (7), Os (8)] and pyridinyl–guanidino compounds [(Cym)M(κ3N,N′,N′′-HL3)][SbF6] [H2L3 = N,N′-bis(p-tolyl)-N′′-(2-pyridinylmethyl) guanidine; M = Ru (9), Os (10)] heterolytically activate H2 in a reversible manner affording the hydrido complexes [(Cym)MH(H2L)][SbF6] (H2L = H2L1; M = Ru (11), Os (12); H2L = H2L2; M = Ru (13), Os (14); H2L = H2L3; M = Ru (15), Os (16)). DFT calculations carried out on the hydrogenation of complex 7 support an FLP mechanism for the process. Heating 9 and 10 in methanol yields the orthometalated complexes [(Cym)M(κ3N,N′,C-H2L3-H)][SbF6] (M = Ru (17), Os (18)). The phosphano–guanidino complex 7 activates deuterated water in a reversible fashion, resulting in the gradual deuteration of the three cymene methyl protons through sequential C(sp3)–H bond activation. From DFT calculations, a metal–ligand cooperative reversible mechanism that involves the O–H bond activation and the formation of an intermediate methylene cyclohexenyl complex has been proposed. Complexes 5–10 catalyse the hydrogenation of the C＝C double bond of styrene and a range of acrylates, the C＝O bond of acetophenone and the C＝N bond of N-benzylideneaniline and quinoline. The C＝C double bond of methyl acrylate adds to catalyst 9, affording complex 19 in which a new ligand exhibiting a fac κ3N,N′,C coordination mode has been incorporated. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of sulfaguanidine was investigated in PBS buffer aqueous solutions. Cyclic voltammograms have shown that (1) the Sg provided a well‐defined irreversible oxidation peak (2) the signal‐to‐background current ratio is 3 times higher at COOH‐MWCNT coated GCE than that of bare GCE and (3) the modifying GCE surface by COOH‐MWCNT led to a significant improvement (2.7 folds) of the electrochemical response. It has been shown that Sg oxidizes according to a diffusion‐controlled mechanism. A linear calibration curve was obtained for the oxidation of Sg at 10–70 μM. The COOH‐MWCNT coated GCE has also been successfully used for the determination of Sg in real samples. [ABSTRACT FROM AUTHOR]

A novel and efficient synthetic method utilizing CBr4 as a thiophilic reagent to facilitate one-pot oxidative condensation of amines with N,N′-disubstituted thioureas affording diverse set of guanidine derivatives is reported. The present protocol offers a valid alternative to the classical method involving toxic heavy metal salts activation due to the use of an easily available, cheap, and environmentally genial reagent, CBr4. The salient features of this protocol are its inexpensiveness, simple reaction conditions, easy purification of the products, and high yields. [ABSTRACT FROM AUTHOR]

Lipophilic oligonucleotide conjugates represent a powerful tool for nucleic acid cellular delivery, and many methods for their synthesis have been developed over the past few decades. In the present study, a number of chemical approaches for the synthesis of different fork- and comb-like dodecyl-containing oligonucleotide structures were performed, including use of non-nucleotide units and different types of phosphate modifications such as alkyl phosphoramidate, phosphoryl guanidine, and triazinyl phosphoramidate. The influence of the number of introduced lipophilic residues, their mutual arrangement, and the type of formed modification backbone on cell penetration was evaluated. The results obtained indicate great potential in the developed chemical approaches, not only for the synthesis of complex oligonucleotide structures but also for the fine-tuning of their properties. [ABSTRACT FROM AUTHOR]