Stable Ring Research Articles

Corrosion inhibition of aluminum in 1.0M HCl solution by some nonionic surfactant compounds containing five membered heterocyclic moiety

Abstract Three nonionic surfactant (NIS) compounds containing five membered heterocyclic moiety were synthesized and identified from spectral data such as IR and 1HNMR spectra. The inhibiting effect of NIS compounds toward the corrosion of aluminium (Al) in 1.0MHCl solutions was examined using weight loss, thermometric, electrochemical impedance spectroscopy and galvanostatic polarization techniques. The results obtained indicated that the three compounds are good corrosion inhibitors. The inhibition efficiency increases as the concentration of the NIS compounds increases, as well as the decrease in temperature, surface tension and interfacial tension. The polarization measurement showed that these inhibitors are acting as mixed inhibitors mainly cathodic. The inhibition was interpreted in view of spontaneous adsorption of NIS compounds onto the Al surface by forming a stable chelating ring between the Al surface and NIS molecules. The adsorption mechanism obeys Freundlich isotherm. The activated thermodynamic parameters such Ea, ΔH* and ΔS*were calculated and clarified.

Self-Coiling of Single-Stranded Protofibrils into Rings: A Pathway of Alzheimer's β-Peptide Amyloidosis on Lipid Membranes.

An amyloidosis pathway of Alzheimer's β-peptide Aβ40 on lipid membranes, the self-coiling of single-stranded protofibrils into thermodynamically stable ring structures, is uncovered. Distinct from Aβ amyloid structures reported previously, the coiled rings observed here exhibit a narrow distribution of diameters centered at ∼170 nm and their circumference thicknesses increase as a longer single-stranded protofibril wraps around the ring, indicating the coaxial loop-by-loop winding of individual protofibrils. Such self-coiling is dominated by elastic properties of the flexible protofibrils subject to thermal fluctuations and surface interactions, as supported by an entropic elasticity model from polymer physics concepts. This work not only provides insights into the fundamental physics of Alzheimer's β-peptide amyloidosis but also is useful for designing amyloid filament materials.

Green rings of Drinfeld doubles of Taft algebras

In this article, we investigate the representation rings (or Green rings) of the Drinfeld doubles of the Taft algebras. It is shown that these Green rings are commutative rings generated by infinitely many elements subject to certain relations. The generators together with the subjecting relations are given. The stable Green rings of of the Drinfeld doubles of the Taft algebras are also described.

Mellitic Triimides Showing Three One-Electron Redox Reactions with Increased Redox Potential as New Electrode Materials for Li-Ion Batteries.

The mellitic triimide (MTI) bearing three imide groups on a benzene core with C3 symmetry is proposed as a new building block for organic electrode materials in lithium-ion batteries. MTI was anticipated to deliver a higher theoretical specific capacity of up to 282 mAh g-1 with increased reduction potentials compared with the well-known pyromellitic diimide building block bearing two imide groups because the additional imide group can accept one more electron and provide an electron-withdrawing effect. A model compound, ethyl-substituted mellitic triimide (ETTI), shows three well distinguished and reversible one-electron redox reactions at -0.97, -1.62, and -2.34 V versus Ag/Ag+ in 0.1 m tetrabutylammonium hexafluorophosphate electrolyte, but the redox potentials were increased in 2 m lithium bis(trifluoromethanesulfonyl)imide electrolyte: -0.60 V, -0.86 V, and -1.42 V vs. Ag/Ag+ . The DFT calculations revealed that the unique C3 symmetric structural design leads to the higher reduction potential of MTI in the Li-based electrolyte by formation of a stable 7-membered ring with a Li ion and the two carbonyl oxygen atoms from the adjacent imide groups. In a Li-ion coin cell, the ETTI electrode delivered a specific capacity of 176 mAh g-1 , corresponding to 81 % of capacity utilization, with three clear voltage plateaus. The higher average discharge voltage (2.41 V vs. Li/Li+ ) of ETTI allows it to deliver one of the highest specific energies (421 Wh kg-1 ) among reported diimide-based electrode materials. Finally, its redox mechanism was investigated by ex situ FTIR measurements and DFT calculations.

Iodide-enhanced palladium catalysis via formation of iodide-bridged binuclear palladium complex

The prevalence of metalloenzymes with multinuclear metal complexes in their active sites inspires chemists’ interest in the development of multinuclear catalysts. Studies in this area commonly focus on binuclear catalysts containing either metal-metal bond or electronically discrete, conformationally advantageous metal centres connected by multidentate ligands, while in many multinuclear metalloenzymes the metal centres are bridged through μ2-ligands without a metal-metal bond. We report herein a μ2-iodide-bridged binuclear palladium catalyst which accelerates the C-H nitrosation/annulation reaction and significantly enhances its yield compared with palladium acetate catalyst. The superior activity of this binuclear palladium catalyst is attributed to the trans effect-relay through the iodide bridge from one palladium sphere to the other palladium sphere, which facilitates dissociation of the stable six-membered chelating ring in palladium intermediate and accelerates the catalytic cycle. Such a trans effect-relay represents a bimetallic cooperation mode and may open an avenue to design and develop multinuclear catalysts.

Exonuclease I-assisted fluorescence aptasensor for tetrodotoxin.

A fluorescence aptasensor for the highly specific and sensitive determination of tetrodotoxin was established with tetrodotoxin-aptamer as the recognition unit, berberine as the signal reporter and exonuclease I as the elimination agent for the background. Berberine has a weak fluorescence emission at 540nm, and it can form the tetrodotoxin-aptamer/berberine complex, resulted in an increased fluorescence. After introducing exonuclease I, it can degrade the single strand oligonucleotides of tetrodotoxin-aptamer into the single nucleotide in the absence of tetrodotoxin, which lead to dramatic fluorescence quenching, and reduce the background signal of sensing system. Once tetrodotoxin is in the presence, tetrodotoxin-aptamer is converted into the stable neck ring conformation, which resists the degradation of exonuclease I and provides a more rigid micro-environment for the excited state of berberine, and then the strong fluorescence is observed. Based on the above properties, an ultrasensitive label-free fluorescence aptasensor for tetrodotoxin is established. The fluorescence aptasensor shows good analytical performance with the linear increase of fluorescence intensity at the tetrodotoxin concentration from 0.030nM to 6.0×103nM. The detection limit of 11.0 pM is much lower than that of other reported sensor methods.

Large eddy simulation of self-excited oscillation inside Helmholtz oscillator

In the present study, a large eddy simulation was conducted to simulate the three-dimensional cavitation turbulence flow inside a Helmholtz oscillator under a high Reynolds number. Numerical results show reasonable agreement with available experimental observations and data. Under the validated solution strategy, the cavitation flow is visualized in a straightforward manner and indicates the primary shedding and secondary shedding induced by the shear layer and collision wall. The evolution and the interactions between cavitation and vortices are well captured and discussed in detail. The results show that flow inside the chamber can be divided into three stages, the boundaries of which are where the vortex reaches the wall surface and where a stable vortex ring is formed on the collision wall. The cavity length has an important influence on frequency, indicating that axial constraints have a greater effect on frequency than radial constraints do. A coherent structure is used to reveal the influence of vortex-wall interactions, and the structure shows that there is a close relationship between the vortex-cavitation interaction and the flow mechanism. Our work provides insight into the internal flow of the Helmholtz oscillator and represents further efforts to demonstrate the mechanism of the oscillation jet.

Ultra-high performance supercritical fluid chromatography combined with quadrupole time-of-flight mass spectrometry for the characterization of pentaerythritol fatty acid esters.

Pentaerythritol fatty acid esters are an excellent lubricant oil additive, due to their good biodegradability, thermal ability, anti-wear, and friction properties. However, to meet the application requirements, fatty acids with different alkyl chain lengths are reacted with pentaerythritol, resulting in complex ester compositions. To reveal the relation between the functionalities and the composition of esters, it is important to develop a method for their analysis. We developed a method using ultra-high-performance supercritical fluid chromatography combined with quadrupole time-of-flight mass spectrometry (UHPSFC/QTOF-MS) to separate and characterize pentaerythritol fatty acid esters. This method has the advantages such as short analysis time and high separation efficiency for such weakly polar compounds; high-resolution mass spectrometry (HRMS) provides exact mass information, enabling the identification of the structure of the pentaerythritol fatty acid esters. Based on the exact masses and characteristic ions, the pentaerythritol fatty acid esters and their main fragmentation pathways were identified; the fatty acid composition was also deduced from characteristic product ions. A dihydrogen rearrangement reaction caused the neutral loss of fatty acid fragment; [M + Na-FA]+ product ions (a stable six-member ring structure) were produced due to the absence of a γ hydrogen in pentaerythritol fatty acid esters. A UHPSFC/QTOF-MS method was successfully employed for the separation of pentaerythritol fatty acid esters. Exact masses and product ion information were determined using HRMS. The composition of the fatty acids was effectively deduced by characteristic ions and their relative abundances. This method is an effective means for the quality control and process optimization of this type of product, serving as a positive reference for further study on pentaerythritol fatty acid esters.

Evolution mechanism of surface hydroxyl groups of silica during heat treatment

The surface hydroxyl groups of nano-silica have a great influence on its application properties. In this paper, the changes of the number of various hydroxyl groups after dehydroxylation and rehydration progress of silica were quantitatively analyzed by thermogravimetric (TG) analysis and 29Si Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) measurements. According to the different stability of Si-O-Si bond formed after dehydroxylation, we propose two types of hydroxyl groups depending on the relative positions of them: chain adjacent hydroxyl groups (C-OHs) and spatially adjacent hydroxyl groups (S-OHs). DFT calculations indicate that two C-OHs dehydroxylation form a four-atoms ring structure, and the resulting OSiO bond angle deviation from optimal value is up to 19.56°, and the average bond length of the SiO bond increase more than 4.66%. Further more, its rehydration reaction activation energy (Ear) is very low, even only 0.21 kJ/mol, so it is easy to re-open and return to hydroxyl groups under environmental conditions. Conversely, the S-OHs dehydroxylation form a stable multi-atoms ring. The DFT calculations are a good illustration of the phenomenon in which some unstable siloxane bonds in a dehydroxylated sample are restored to hydroxyl groups in TG analysis and 29Si MAS NMR measurements.

Fully bio‐based thiol‐ene photocured thermosets from isosorbide and tung oil

AbstractDirect preparation of coatings from neat vegetable oils without any pretreatment or modification is an elegant way of demonstrating the potential of renewable sources and it is also in line with the principles of Green Chemistry. In this work, photocured coatings were prepared from tung oil (TO), hazelnut oil (HN), and isosorbide. First, a dithiol derivative of isosorbide (ISTMP) was synthesized and then mixed with TO, HN, and a cationic photoinitiator. For comparison, formulations were also prepared by using two different commercial thiol compounds. Coating formulations were applied onto glass substrates and cured under UV light where oxidative polymerization and photoinitiated thiol‐ene addition reactions took place concomitantly. Double bond conversion percentages, thermal degradation properties, water contact angles, and surface hardness of the coatings were determined. Furthermore, a model reaction between ISTMP and oleic acid was performed to prove that ISTMP reacts with the fatty acid. ISTMP containing formulation displayed a fast initial double bond conversion and its water contact angle value was found as 88 ± 3°. Rigid and thermally stable isosorbide ring improved both the thermal properties and the surface hardness of the coatings.

On the finiteness of the derived equivalence classes of some stable endomorphism rings

We prove that the stable endomorphism rings of rigid objects in a suitable Frobenius category have only finitely many basic algebras in their derived equivalence class and that these are precisely the stable endomorphism rings of objects obtained by iterated mutation. The main application is to the Homological Minimal Model Programme. For a 3-fold flopping contraction f :X rightarrow {mathrm{Spec};},R, where X has only Gorenstein terminal singularities, there is an associated finite dimensional algebra A_{{text {con}}} known as the contraction algebra. As a corollary of our main result, there are only finitely many basic algebras in the derived equivalence class of A_{text {con}} and these are precisely the contraction algebras of maps obtained by a sequence of iterated flops from f. This provides evidence towards a key conjecture in the area.

Thermomechanical and Morphological Properties of Poly(ethylene terephthalate)/Anhydrous Calcium Terephthalate Nanocomposites.

Calcium terephthalate anhydrous salts (CATAS), synthetized by reaction of terephthalic acid with metal (Ca) oxide were incorporated at different weight contents (0–30 wt. %) in recycled Poly(ethylene terephthalate) (rPET) by melt processing. Their structure, morphology, thermal and mechanical properties (tensile and flexural behavior) were investigated. Results of tensile strength of the different formulations showed that when the CATAS content increased from 0.1 to 0.4 wt. %, tangible changes were observed (variation of tensile strength from 65.5 to 69.4 MPa, increasing value for E from 2887 up to 3131 MPa, respectively for neat rPET and rPET_0.4CATAS). A threshold weight amount (0.4 wt. %) of CATAS was also found, by formation at low loading, of a rigid amorphous fraction at the rPET/CATAS interface, due to the aromatic interactions (π−π conjugation) between the matrix and the filler. Above the threshold, a restriction of rPET/CATAS molecular chains mobility was detected, due to the formation of hybrid mechanical percolation networks. Additionally, enhanced thermal stability of CATAS filled rPET was registered at high content (Tmax shift from 426 to 441 °C, respectively, for rPET and rPET_30CATAS), essentially due to chemical compatibility between terephthalate salts and polymer molecules, rich in stable aromatic rings. The singularity of a cold crystallization event, identified at the same loading level, confirmed the presence of an equilibrium state between nucleation and blocking effect of amorphous phase, basically related to the characteristic common terephthalate structure of synthetized Ca–Metal Organic Framework and the rPET matrix.

On the role of vortex-ring formation in influencing air-assisted spray characteristics of n-heptane

Air-assisted spray characteristic in a constant-volume vessel has been investigated experimentally. Influences of injection control parameters such as fuel injection duration ΔTf, fuel-air injection interval ΔTf-a and air injection duration ΔTa on the spray characteristics were studied. Results show that two distinct spray shapes were observed under appropriate control parameters, namely, “spindle-shaped” spray and “anchor-shaped” spray. The “anchor-shaped” spray which promotes spray spread possesses relatively smaller spray tip penetration, but better spray spread which is beneficial to fuel/air mixing. The enhancement on spray spread for “anchor-shaped” spray is attributed to the formation of vortex-ring near spray tip under relatively low spray velocity. Non-monotonic spray dispersion area ratio Rd can be observed with increasing ΔTf, ΔTf-a and ΔTa. Droplet velocity decreases with ΔTf increasing, which suppresses droplet breakup therefore results in the increasing of droplet size. However, the formation of the vortex-ring weakens this increasing trend of droplet size. Increasing of ΔTf-a tends to generate stable vortex ring hence stable droplet velocity and SMD. In terms of air injection duration ΔTa, droplet velocity was observed to change non-monotonically with ΔTa increasing, due to the “spindle-shaped — anchor-shaped — spindle-shaped” spray shape transition.

Surgical effectiveness of ankle "Logsplitter" injury plus avulsion fractures without tibiofibular joint screwing

Objective To explore the surgical efficacy of trans-syndesmotic ankle fracture dislocation (the Logsplitter injury) plus the Tillaux-Chaput fracture/the Wagstaffe-Lefort fracture and the Volkmann fracture without tibiofibular joint screwing. Methods Between January 2015 and December 2018, 16 adult patients with the Logsplitter injury plus avulsion fractures were treated by open reduction and internal fixation at Department of Orthopaedics, The Sixth Affiliated Hospital, Xinjiang Medical University. They were 11 males and 5 females with an average age of 36.4 years (range, from 27 to 56 years). There were 2 open fractures (one type Ⅱ and one type ⅢA by the Anderson-Gustilo classification) and 14 closed ones; all fractures were type 44-C by the AO/OTA classification; according to the Lauge-Hansen classification, there were 9 cases of pronation-abduction rotation, 3 cases of pronation-external rotation and 4 cases of supination-external rotation. The fibular fractures were treated through a single lateral approach followed by plate fixation. The Volkmann fractures were fixed with screws and the Tillaux-Chaput fractures/the Wagstaffe-Lefort fractures with screws or Kirschner wires. The ankle functions were assessed postoperatively using the ankle-hindfoot rating system of the American Orthopaedic Foot and Ankle Society (AOFAS), and the dysfunction index and bother index of Short Musculoskeletal Function Assessment (SMFA). Results All the patients were followed up for 8 to 27 months (average, 21.3 months). X-ray films showed complete fracture healing in all cases after 12 to 18 weeks postoperatively (mean, 14.8 weeks). At the last follow up, 13 patients walked normally and 2 with mild discomfort. Their AOFAS scores averaged 96.3 (range, from 86 to 100), giving 12 excellent, 3 good and one poor cases; their SMFA dysfunction index was 15.9 (range, from 8 to 17)and SMFA bother index 6.5 (range, from 3 to 9)at the last follow-up. Conclusions In the treatment of trans-syndesmotic ankle fracture dislocation - the Logsplitter injury, open reduction and internal fixation of the Tillaux-Chaput fracture/the Wagstaffe-Lefort fracture and the Volkmann fracture to reconstruct the lower tibiofibular horizontal stable ring , without tibiofibular joint screwing, can obtain satisfactory clinical results. Key words: Ankle joint; Fractures; Fracture fixation, internal; Logsplitter injury; Distal tibiofibular syndesmosis

Distribution of radiation exposure in patients with partially stable and unstable pelvic ring fractures: first-time use of highly accurate assessment by Monte Carlo calculations.

Radiological examinations including X-ray and CT play a critical role in the assessment and treatment of trauma patients. The ionizing radiation used is known to be carcinogenic. However, little is known about the total radiation exposure in trauma patients. The objective of this study was to accurately estimate radiation exposure of patients with severe pelvic ring fractures. In this retrospective dynamic cohort study, adult patients with partially stable and unstable pelvic ring fractures were included. For each patient, data concerning demography and injury characteristics were collected. Subsequently, the total effective radiation dose due to all trauma-related X-rays and CT scans during initial assessment, treatment and follow-up was calculated using Monte Carlo software. A total of 114 patients were included. The median total effective dose was 49.7 millisievert (mSv). 57 patients (50.0%) received more than 50mSv and 13 patients (11.4%) received more than 100mSv. 62.4% of the total effective dose was received within the 24h after admission. The median total effective dose for survivors (n = 95) was 52.0mSv. Polytrauma patients received a significantly higher total effective dose than non-polytrauma patients. This study showed that a substantial number of patients with partially stable and unstable pelvic ring fractures have an increased cancer risk due to trauma-related medical imaging. Physicians should be aware of the amount of radiation their patients are exposed to, and minimize imaging related increase of cancer risks during initial assessment, treatment and follow-up.

Association Between Stability and Urologic Lesions in Pelvic Ring Fractures. A Case Series Report

Purpose Pelvic ring fractures represent a subgroup of potentially serious injuries due to the fractures themselves, as well as the associated injuries. In fact, over 4% of cases have concomitant lower urinary tract injuries. The aim of this study was to analyze the relationship between the instability of pelvic ring fractures and the presence of lower urinary tract lesions. Materials and methods A retrospective review of patients with pelvic ring fractures at our center between 2007 and 2015 was performed. Fractures were categorized according to the Tile classification system. Patients with lower urinary tract lesions were selected and categorized according to the lower urinary tract lesion identified (urinary bladder, urethral or combined). Subsequently, a statistical analysis was carried out to assess the association between these variables. Results 614 patients with pelvic ring fracture were included, corresponding to 260 (42.3%) men and 354 (57.7%) women. 25 patients (4.1%) were diagnosed of lower urinary tract injury (17 bladder injuries, 8 urethral injuries and 0 combined injuries). Urethral injuries were more frequent among men (1.9% incidence in men vs 0.8% in women). A lower incidence of lower urinary tract lesions was detected in stable pelvic ring fractures (type A, p 0.02). Overall, type C3 showed the highest incidence of lower urinary tract lesions (22.2% incidence, p = 0.04). Conclusion In our series, a greater incidence of higher urinary tract injuries was observed in patients with unstable pelvic ring fractures (Tile type B and C) with respect to stable fractures (Tile type A). Therefore, a high index of suspicion should be maintained in order to identify high risk patients.

Outcome of Percutaneous Iliosacral Screw Fixation of Sacroiliac Joint Disruptions

Background: Closed reduction and percutaneous fixation of sacroiliac joint disruptions has the advantage of minimal invasion of compromised soft tissue, limited blood loss, decreased operation time, and decreased infection rates. The objectives of this study was to evaluate the functional and radiological outcome after percutaneous fixation of sacroiliac joint (SIJ) disruptions by cannulated screw. Objectives: Management of sacroiliac joint disruptions by closed reduction and percutaneous fixation by iliosacral screw. Patients and Methods: This study was carried out in Orthopedic Surgery Department, Zagazig University Hospitals, during the period from May 2018 to September 2019. The study included 12 patients with age ranged from 19-59 years, 7 males and 5 females. Mode of injury was road traffic accident in 58.3% of cases and fall from height in 41.7%, right side was affected in 6 patients, left side was affected in 5 patient and one patient was affected bilaterally. Results: All patients were evaluated clinically according to Majeed scoring system. The overall Majeed score was satisfactory in 75%, while unsatisfactory results were in 25% of cases. Postoperative radiological evaluation was done according to Matta and tornetta. 25% patients had excellent results, 50% had good results and 25% had fair results. Postoperative complication were superficial infection in 6 patients and one patient had chronic posterior pelvic pain. Conclusion: Percutaneous method of fixation of the SIJ disruptions is effective and favourable method ensuring low operative time, high chance of obtaining stable pelvic ring with minimal blood loss, low incidence of complications and good rehabilitation results especially early mobilization.

Decaying localized structures beyond Turing space in an activator–inhibitor system

We perform numerical simulations beyond Turing space in an activator–inhibitor system involving quadratic and cubic nonlinearities . We show that while all the three fixed points of the system are stable nodes, it exhibits spatially stable patterns as diverse as labyrinths, worms, negatons, and combination of them. The transition among the patterns is found to be dependent on the relative strength (h) of quadratic and cubic couplings. The labyrinths and worms are formed for small values of h while stable negatons are obtained for $$0.0891\le h\le 0.1106$$. The negatons start showing decaying behavior for $$h\ge 0.1135$$ and, finally they vanish at random positions by emitting remnant solitary waves, yielding a pattern of stable concentric rings. The spatial extension of the concentric rings is found to depend on the initial concentration profile of the decaying negatons. The resulting concentric rings do not decay further due to limitation of numerical precision. We also find that the transient period for each pattern also depends on h.

New Fluorescent, Thermally Stable and Film Forming Polyimines Containing Naphthyl Rings

Three new aliphatic-aromatic polymers having naphthyl rings were prepared by the polycondenstion of dialdehydes or diketone monomers with 1,5-naphthalenediamine or 1,4-phenylenediamine. The monomers were prepared by the reaction of aromatic aldehyde or ketone with 1,6-dibromohexane. The molecular mass of the monomers was confirmed through E.I mass spectroscopy. The structures of monomers and polymers were characterized by 1HNMR, FT-IR, UV-Vis Spectroscopy, SEM and TG/DTA. Fluorescence emissions of monomers and polymers were recorded and their quantum yields were calculated, all the compounds showed fluorescence property and indicated violet, blue-green, orange and red light emissions. The quantum yields of the polymers were obtained within the range of 0.04 to 24.3%. The semicrystalline and amorphous nature of the polymers was analyzed through powdered X-ray diffraction. Antimicrobial activities of the polymers were examined against different bacterial and fungal species. Thin film forming ability of the synthesized polymers was evaluated by making their blends with PVC (poly vinyl chloride) in different w/w% ratios.

A quest for stable 2,2,9,9-tetrahaloplumbacyclonona-3,5,7-trienylidenes at density functional theory

In contrast to cyclonona-3,5,7-trienylidene (1H) which turns out as a boat-shaped transition state for having a negative force constant, its heavier plumbylenic analogous (2X) where X = H, F, Cl, Br, and I emerge as boat-shaped minima. This unsubstituted carbene has a triplet ground state while exclusive of 2I which initially takes on a triplet multiplicity and eventually transforms to a less stable intramolecular ring opening product; all of the plumbylenes (2H, 2F, 2Cl, and 2Br) have a singlet ground state. Hence, stability anticipated by the singlet (S)–triplet (T) splitting (ΔES-T) decreases by going down in the group 17 column: 2Br > 2Cl > 2F > 2H > 1H > 2I. Also, the HOMO-LUMO gap (ΔEHOMO-LUMO) increases as a result of substituting. From a thermodynamic perspective, our scrutinized 2Br, 2Cl, and 2F are found 1.5–2 times more stable than that of the reported cyclopenta-2,4-dienplumbylene and 2,5-bis(halobora)-cyclopentenplumbylenes analogues, respectively. From a kinetic perspective, these nine-membered plumbylenes are found 20–26 kcal/mol more stable than that of their corresponding five-membered congeners. The NBO analysis on stable singlet 2Br shows that there is a mesomeric interaction between bromine lone-pair electron and the Pb divalent atom of 2Br with bonding (σ) and anti-bonding (σ*) orbitals of carbon–bromine and carbon–lead. The main stabilizing effect appears to be π- and σ-bond hyperconjugation among the iodine heteroatom and divalent center of triplet 2I. This research signifies the thermodynamic and kinetic stabilities of the biggest unsaturated cyclic plumbylenes hoping to prompt the experimental attention toward them.