pyCOFBuilder: A Python Package for Automated Creation of Covalent Organic Framework Models Based on the Reticular Approach.

Covalent organic frameworks (COFs) have gained significant popularity in recent years due to their unique ability to provide a high surface area and customizable pore geometry and chemistry, making them an ideal choice for a wide range of applications. However, exploring COFs experimentally can be arduous and time-consuming due to their immense number of potential structures. As a result, computational high-throughput studies have become an attractive option. Nevertheless, generating COF structures can also be a challenging and time-consuming task. To address this challenge, here, we introduce the pyCOFBuilder, an open-source Python package designed to facilitate the generation of COF structures for computational studies. The pyCOFBuilder software provides an easy-to-use set of functionalities to generate COF structures following the reticular approach. In this paper, we describe the implementation, main features, and capabilities of the pyCOFBuilder, demonstrating its utility for generating COF structures with varying topologies and chemical properties. pyCOFBuilder is freely available on GitHub at https://github.com/lipelopesoliveira/pyCOFBuilder.

Safety, immunogenicity, and effectiveness of COVID-19 vaccines for pregnant persons: A protocol for systematic review and meta analysis.

INTRODUCTION: Numerous vaccines have been evaluated and approved for coronavirus disease 2019 (COVID-19). Since pregnant persons have been excluded from most clinical trials of COVID-19 vaccines, sufficient data regarding the safety of these vaccines for the pregnant person and their fetus have rarely been available at the time of product licensure. However, as COVID-19 vaccines have been deployed, data on the safety, reactogenicity, immunogenicity, and efficacy of COVID-19 vaccines for pregnant persons and neonates are becoming increasingly available. A living systematic review and meta-analysis of the safety and effectiveness of COVID-19 vaccines for pregnant persons and newborns could provide the information necessary to help guide vaccine policy decisions. METHODS AND ANALYSIS: We aim to conduct a living systematic review and meta-analysis based on biweekly searches of medical databases (e.g., MEDLINE, EMBASE, CENTRAL) and clinical trial registries to systematically identify relevant studies of COVID-19 vaccines for pregnant persons. Pairs of reviewers will independently select, extract data, and conduct risk of bias assessments. We will include randomized clinical trials, quasi-experimental studies, cohort, case-control, cross-sectional studies, and case reports. Primary outcomes will be the safety, efficacy, and effectiveness of COVID-19 vaccines in pregnant persons, including neonatal outcomes. Secondary outcomes will be immunogenicity and reactogenicity. We will conduct paired meta-analyses, including prespecified subgroup and sensitivity analyses. We will use the grading of recommendations assessment, development, and evaluation approach to evaluate the certainty of evidence.

Diastereoselectivity Switch During Alkene Reductions: Diastereodivergent Syntheses of Molecular Fossils via MHAT or Homogeneous Catalytic Hydrogenation Reactions.

Sixteen geosterane derivatives were synthesized in up to 57 % overall yields in four steps harnessing the olefin cross-metathesis (OCM) and Metal hydride H atom transfer (MHAT) or homogeneous hydrogenation reactions as key steps. Drawing on this strategy, the diastereomeric ratio (d. r.) reached up to 24 : 1 for the thermodynamic isomer and 7 : 1 for the other isomer in the hydrogenation step. In a geological sample from northeast Brazil, we confirmed the putative structures previously assumed as methyl 2-(3α-5αH-cholestan) acetate, methyl 2-(3ß-5αH-cholestan)acetate, and methyl 6-(3ß-5αH-cholestan)hexanoate, as well three new molecular fossils of approximately 120 million years old. We also proved the migration marking ability of those carboxylic acids derived from forerunner geosteranes during an oil migration event, which suggests their aptitudes as molecular odometers. Our approach demonstrated swiftness and effectiveness in preparing a molecular library of geological biomarkers would also be appropriate to generate stereochemical diversity in molecular libraries for medicinal chemistry and natural product anticipation.

Taming the Antiferromagnetic Beast: Computational Design of Ultrashort Mn-Mn Bonds Stabilized by N-Heterocyclic Carbenes.

The development of complexes featuring low-valent, multiply bonded metal centers is an exciting field with several potential applications. In this work, we describe the design principles and extensive computational investigation of new organometallic platforms featuring the elusive manganese-manganese bond stabilized by experimentally realized N-heterocyclic carbenes (NHCs). By using DFT computations benchmarked against multireference calculations, as well as MO- and VB-based bonding analyses, we could disentangle the various electronic and structural effects contributing to the thermodynamic and kinetic stability, as well as the experimental feasibility, of the systems. In particular, we explored the nature of the metal-carbene interaction and the role of the ancillary η6 coordination to the generation of Mn2 systems featuring ultrashort metal-metal bonds, closed-shell singlet multiplicities, and positive adiabatic singlet-triplet gaps. Our analysis identifies two distinct classes of viable synthetic targets, whose electrostructural properties are thoroughly investigated.

A Carbocationic Triarylmethane-Based Porous Covalent Organic Network.

A thermally stable carbocationic covalent organic network (CON), named RIO-70 was prepared from pararosaniline hydrochloride, an inexpensive dye, and triformylphloroglucinol in solvothermal conditions. This nanoporous organic material has shown a specific surface area of 990 m2 g-1 and pore size of 10.3 Å. The material has CO2 uptake of 2.14 mmol g-1 (0.5 bar), 2.7 mmol g-1 (1 bar), and 6.8 mmol g-1 (20 bar), the latter corresponding to 3 CO2 molecules adsorbed per pore per sheet. It is shown to be a semiconductor, with electrical conductivity (σ) of 3.17×10-7  S cm-1 , which increases to 5.26×10-4  S cm-1 upon exposure to I2 vapor. DFT calculations using periodic conditions support the findings.

Enzyme Immobilization in Covalent Organic Frameworks: Strategies and Applications in Biocatalysis.

The development of efficient catalytic systems is a fundamental aspect for the straightforward production of chemicals. During the last years, covalent organic frameworks (COFs) emerged as an exciting class of organic nanoporous materials. Due to their pre-designable structure, they can be prepared with distinct physicochemical characteristics, specific pore sizes, and tunable functional groups. Moreover, associated with their stability in different media, these materials are considered promising supports for enzyme immobilization. Herein, it is highlighted the recent literature of enzyme immobilization in COFs, the main immobilization strategies, and the catalytic applications of these composites.

Design, Synthesis and Characterization of Nickel-Functionalized Covalent Organic Framework NiCl@RIO-12 for Heterogeneous Suzuki-Miyaura Catalysis.

A series of nickel-decorated covalent organic frameworks, NiCl@RIO-12, were prepared using the post-synthetic modification strategy, that is, by reacting NiCl2 with pristine RIO-12 under alkaline conditions. Interestingly, they retained their crystallinity and the amount of nickel incorporated could be tuned from 3.6 to 25 wt % according to the reaction conditions. The incorporation of a higher amount of nickel in NiCl@RIO-12 consistently led to a lower Brunauer-Emmett-Teller surface area. Additionally, no agglomeration of nickel particles was found and a relatively homogeneous dispersion of nickel could be ascertained by SEM and TEM-EDS. The paramagnetic material exhibited promising catalytic activity in Suzuki-Miyaura cross-coupling under microwave heating. Thus, NiCl@RIO-12 notably demonstrated good thermal stability and its recyclability showed no substantial loss of activity after 3 cycles.

Spiro-Carbon: A Metallic Carbon Allotrope Predicted from First Principles Calculations.

A structurally stable microporous metallic carbon allotrope, poly(spiro[2.2]penta-1,4-diyne) or, for short, spiro-carbon, with I41 /amd (D4h ) symmetry is predicted by first-principles calculations using density functional theory (DFT). The calculations of electronic, vibrational, and structural properties show that spiro-carbon has lower relative energy than other elusive carbon allotropes such as T-Carbon and 1-diamondyne (Y-Carbon). Its structure can be pictured as a set of trans-cisoid-polyacetylene chains tangled and interconnected together by sp3 carbon atoms. Calculations reveal a metallic electronic structure arising from an "intrinsic doping" of trans-cisoid-polyacetylene chains with sp3 carbon atoms. Possible synthetic routes and various simulated spectra (XRD, NMR, and IR absorption) are provided in order to guide future efforts to synthesize this novel material.

Measurement error, microcephaly prevalence and implications for Zika: an analysis of Uruguay perinatal data.

BACKGROUND AND OBJECTIVE: The Zika virus outbreak has drawn attention to microcephaly, whose definition is based on head circumference measuring below a percentile or number of SDs below the mean. The objective of this analysis was to assess how differences in measurement precision might affect prevalence and trends of microcephaly. METHODS: Data from all births in Uruguay during 2010-2015 were obtained from the Perinatal Information System. The prevalence of births with microcephaly was calculated based on head circumference measurement at birth applying the INTERGROWTH-21st standards for sex and gestational age, and compared by method of ascertaining gestational age. RESULTS: Rounding and digit preference was observed: 74% of head circumference measurements were reported as a whole centimetre value. The prevalence of births varied substantially by the criterion used to define microcephaly (<3 SD, <2 SD, <3rd percentile for gestational age) and could be halved or doubled based on adding or subtracting a half-centimetre from all reported head circumference measurements. If 4 days were added to gestational age calculations, rather than using completed gestational weeks (without days) for gestational age reporting, the prevalence was 1.7-2 times higher. DISCUSSION: Rounding in measurement of head circumference and reporting preferences of gestational age may have contributed to a lower prevalence of microcephaly than expected in this population. Differences in head circumference measurement protocols and gestational age dating have the potential to affect the prevalence of babies reported with microcephaly, and this limitation should be acknowledged when interpreting head circumference data collected for surveillance.

Enzyme-Decorated Covalent Organic Frameworks as Nanoporous Platforms for Heterogeneous Biocatalysis.

Sustainability in chemistry heavily relies on heterogeneous catalysis. Enzymes, the main catalyst for biochemical reactions in nature, are an elegant choice to catalyze reactions due to their high activity and selectivity, although they usually suffer from lack of robustness. To overcome this drawback, enzyme-decorated nanoporous heterogeneous catalysts were developed. Three different approaches for Candida antarctica lipase B (CAL-B) immobilization on a covalent organic framework (PPF-2) were employed: physical adsorption on the surface, covalent attachment of the enzyme in functional groups on the surface and covalent attachment into a linker added post-synthesis. The influence of the immobilization strategy on the enzyme uptake, specific activity, thermal stability, and the possibility of its use through multiple cycles was explored. High specific activities were observed for PPF-2-supported CAL-B in the esterification of oleic acid with ethanol, ranging from 58 to 283 U mg-1 , which was 2.6 to 12.7 times greater than the observed for the commercial Novozyme 435.

Use of antenatal corticosteroids at health facilities and communities in low-and-middle income countries.

BACKGROUND: Antenatal corticosteroids (ACS) for women at high risk of preterm birth is an effective intervention to reduce neonatal mortality among preterm babies delivered in hospital settings, but has not been widely used in low-middle resource settings. We sought to assess the rates of ACS use at all levels of health care in low and middle income countries (LMIC). METHODS: We assessed rates of ACS in 7 sites in 6 LMIC participating in the Eunice Kennedy Shriver National Institute of Child Health and Human Development's Global Network for Women and Children's Health Research Antenatal Corticosteroids Trial (ACT), a cluster-randomized trial to assess the feasibility, effectiveness, and safety of a multifaceted intervention designed to increase the use of ACS. We conducted this analysis using data from the control clusters, which did not receive any components of the intervention and intended to follow usual care. We included women who delivered an infant with a birth weight <5th percentile, a proxy for preterm birth, and were enrolled in the Maternal Newborn Health (MNH) Registry between October 2011 and March 2014 in all clusters. A survey of the site investigators regarding existing policies on ACS in health facilities and for health workers in the community was part of pre-trial activities. RESULTS: Overall, of 51,523 women delivered in control clusters across all sites, the percentage of <5th percentile babies ranged from 3.5 % in Kenya to 10.7 % in Pakistan. There was variation among the sites in the use of ACS at all hospitals and among those hospitals having cesarean section and neonatal care capabilities (bag and mask and oxygen or mechanical ventilation). Rates of ACS use for <5th percentile babies in all hospitals ranged from 3.8 % in the Kenya sites to 44.5 % in the Argentina site, and in hospitals with cesarean section and neonatal care capabilities from 0 % in Zambia to 43.5 % in Argentina. ACS were rarely used in clinic or home deliveries at any site. Guidelines for ACS use at all levels of the health system were available for most of the sites. CONCLUSION: Our study reports an overall low utilization of ACS among mothers of <5th percentile infants in hospital and clinic deliveries in LMIC. TRIAL REGISTRATION: clinicaltrials.gov ( NCT01084096 ).

The Antenatal Corticosteroids Trial (ACT)'s explanations for neonatal mortality - a secondary analysis.

BACKGROUND: The Antenatal Corticosteroid Trial assessed the feasibility, effectiveness, and safety of a multifaceted intervention to increase the use of antenatal corticosteroids (ACS) in mothers at risk of preterm birth at all levels of care in low and middle-income countries. The intervention effectively increased the use of ACS but was associated with an overall increase in neonatal deaths. We aimed to explore plausible pathways through which this intervention increased neonatal mortality. METHODS: We conducted a series of secondary analyses to assess whether ACS or other components of the multifaceted intervention that might have affected the quality of care contributed to the increased mortality observed: 1) we compared the proportion of neonatal deaths receiving ACS between the intervention and control groups; 2) we compared the antenatal and delivery care process in all births between groups; 3) we compared the rates of possible severe bacterial infection between groups; and 4) we compared the frequency of factors related to ACS administration or maternal high risk conditions at administration between the babies who died and those who survived 28 days among all births in the intervention group identified as high risk for preterm birth and received ACS. RESULTS: The ACS exposure among the infants who died up to 28 days was 29 % in the intervention group compared to 6 % in controls. No substantial differences were observed in antenatal and delivery care process between groups. The risk of pSBI plus neonatal death was significantly increased in intervention clusters compared to controls (2.4 % vs. 2.0 %, adjusted RR 1.17, 95 % CI 1.04-1.30, p = 0.008], primarily for infants with birth weight at or above the 25(th) percentile. Regarding factors related to ACS administration, term infants who died were more likely to have mothers who received ACS within 7 days of delivery compared to those who survived 28 days (26.5 % vs 17.9 %, p = 0.014), and their mothers were more likely to have been identified as high risk for hypertension and less likely for signs of preterm labor. CONCLUSIONS: These results suggest that ACS more than other components of the intervention may have contributed to the overall increased neonatal mortality. ACS may have also been involved in the observed increased risk of neonatal infection and death. Further trials are urgently needed to clarify the effectiveness and safety of ACS on neonatal health in low resource settings.

The Antenatal Corticosteroids Trial (ACT): a secondary analysis to explore site differences in a multi-country trial.

BACKGROUND: The Antenatal Corticosteroid Trial (ACT) assessed the feasibility, effectiveness, and safety of a multifaceted intervention to increase the use of antenatal corticosteroids (ACS) in mothers at risk of preterm birth at all levels of care in low and middle-income countries. The intervention effectively increased the use of ACS but had no overall impact on neonatal mortality in the targeted <5(th) percentile birth weight infants. Being in the intervention clusters was also associated with an overall increase in neonatal deaths. We sought to explore plausible pathways through which this intervention increased neonatal mortality. METHODS: We conducted secondary analyses to assess site differences in outcome and potential explanations for the differences in outcomes if found. By site, and in the intervention and control clusters, we evaluated characteristics of the mothers and care systems, the proportion of the <5(th) percentile infants and the overall population that received ACS, the rates of possible severe bacterial infection (pSBI), determined from clinical signs, and neonatal mortality rates. RESULTS: There were substantial differences between the sites in both participant and health system characteristics, with Guatemala and Argentina generally having the highest levels of care. In some sites there were substantial differences in the health system characteristics between the intervention and control clusters. The increase in ACS in the intervention clusters was similar among the sites. While overall, there was no difference in neonatal mortality among <5(th) percentile births between the intervention and control clusters, Guatemala and Pakistan both had significant reductions in neonatal mortality in the <5(th) percentile infants in the intervention clusters. The improvement in neonatal mortality in the Guatemalan site in the <5(th) percentile infants was associated with a higher level of care at the site and an improvement in care in the intervention clusters. There was a significant increase overall in neonatal mortality in the intervention clusters compared to the control. Across sites, this increase in neonatal mortality was statistically significant and most apparent in the African sites. This increase in neonatal mortality was accompanied by a significant increase in pSBI in the African sites. CONCLUSIONS: The improvement in neonatal mortality in the Guatemalan site in the <5(th) percentile infants was associated with a higher level of care and an improvement in care in the intervention clusters. The increase in neonatal mortality in the intervention clusters across all sites was largely driven by the poorer outcomes in the African sites, which also had an increase in pSBI in the intervention clusters. We emphasize that these results come from secondary analyses. Additional prospective studies are needed to assess the effectiveness and safety of ACS on neonatal health in low resource settings. TRIAL REGISTRATION: clinicaltrials.gov (NCT01084096).

A Multifaceted Strategy to Implement Brief Smoking Cessation Counseling During Antenatal Care in Argentina and Uruguay: A Cluster Randomized Trial.

INTRODUCTION: Argentina and Uruguay have a high prevalence of smoking during pregnancy. However, and despite national recommendations, pregnant women are not routinely receiving cessation counseling during antenatal care (ANC). We evaluated a multifaceted strategy designed to increase the frequency of pregnant women who received a brief smoking cessation counseling based on the 5As (Ask, Advise, Assess, Assist, and Arrange). METHODS: We randomly assigned (1:1) 20 ANC clusters in Buenos Aires, Argentina and Montevideo, Uruguay to receive a multifaceted intervention to implement brief smoking cessation counseling into routine ANC, or to receive no intervention. The primary outcome was the frequency of women who recalled receiving the 5As during ANC at more than one visit. Frequency of women who smoked until the end of pregnancy, and attitudes and readiness of ANC providers towards providing counseling were secondary outcomes. Women's outcomes were measured at baseline and at the end of the 14- to 18-month intervention, by administering questionnaires at the postpartum hospital stay. Self-reported cessation was verified with saliva cotinine. The trial took place between October 03, 2011 and November 29, 2013. RESULTS: The rate of women who recalled receiving the 5As increased from 14.0% to 33.6% in the intervention group (median rate change, 22.1%), and from 10.8% to 17.0% in the control group (median rate change, 4.6%; P = .001 for the difference in change between groups). The effect of the intervention was larger in Argentina than in Uruguay. The proportion of women who continued smoking during pregnancy was unchanged at follow-up in both groups and the relative difference between groups was not statistically significant (ratio of odds ratios 1.16, 95% CI: 0.98-1.37; P = .086). No significant changes were observed in knowledge, attitudes, and self-confidence of ANC providers. CONCLUSIONS: The intervention showed a moderate effect in increasing the proportion of women who recalled receiving the 5As, with a third of women receiving counseling in more than one visit. However, the frequency of women who smoked until the end of the pregnancy was not significantly reduced by the intervention. IMPLICATIONS: No implementation trials of smoking cessation interventions for pregnant women have been carried out in Latin American or in middle-income countries where health care systems or capacities may differ. We evaluated a multifaceted strategy designed to increase the frequency of pregnant women who receive brief smoking cessation counseling based on the 5As in Argentina and Uruguay. We found that the intervention showed a moderate effect in increasing the proportion of women receiving the 5As, with a third of women receiving counseling in more than one visit. However, the frequency of women who smoked until the end of the pregnancy was not significantly reduced by the intervention.

A population-based, multifaceted strategy to implement antenatal corticosteroid treatment versus standard care for the reduction of neonatal mortality due to preterm birth in low-income and middle-income countries: the ACT cluster-randomised trial.

BACKGROUND: Antenatal corticosteroids for pregnant women at risk of preterm birth are among the most effective hospital-based interventions to reduce neonatal mortality. We aimed to assess the feasibility, effectiveness, and safety of a multifaceted intervention designed to increase the use of antenatal corticosteroids at all levels of health care in low-income and middle-income countries. METHODS: In this 18-month, cluster-randomised trial, we randomly assigned (1:1) rural and semi-urban clusters within six countries (Argentina, Guatemala, India, Kenya, Pakistan, and Zambia) to standard care or a multifaceted intervention including components to improve identification of women at risk of preterm birth and to facilitate appropriate use of antenatal corticosteroids. The primary outcome was 28-day neonatal mortality among infants less than the 5th percentile for birthweight (a proxy for preterm birth) across the clusters. Use of antenatal corticosteroids and suspected maternal infection were additional main outcomes. This trial is registered with ClinicalTrials.gov, number NCT01084096. FINDINGS: The ACT trial took place between October, 2011, and March, 2014 (start dates varied by site). 51 intervention clusters with 47,394 livebirths (2520 [5%] less than 5th percentile for birthweight) and 50 control clusters with 50,743 livebirths (2258 [4%] less than 5th percentile) completed follow-up. 1052 (45%) of 2327 women in intervention clusters who delivered less-than-5th-percentile infants received antenatal corticosteroids, compared with 215 (10%) of 2062 in control clusters (p<0·0001). Among the less-than-5th-percentile infants, 28-day neonatal mortality was 225 per 1000 livebirths for the intervention group and 232 per 1000 livebirths for the control group (relative risk [RR] 0·96, 95% CI 0·87-1·06, p=0·65) and suspected maternal infection was reported in 236 (10%) of 2361 women in the intervention group and 133 (6%) of 2094 in the control group (odds ratio [OR] 1·67, 1·33-2·09, p<0·0001). Among the whole population, 28-day neonatal mortality was 27·4 per 1000 livebirths for the intervention group and 23·9 per 1000 livebirths for the control group (RR 1·12, 1·02-1·22, p=0·0127) and suspected maternal infection was reported in 1207 (3%) of 48,219 women in the intervention group and 867 (2%) of 51,523 in the control group (OR 1·45, 1·33-1·58, p<0·0001). INTERPRETATION: Despite increased use of antenatal corticosteroids in low-birthweight infants in the intervention groups, neonatal mortality did not decrease in this group, and increased in the population overall. For every 1000 women exposed to this strategy, an excess of 3·5 neonatal deaths occurred, and the risk of maternal infection seems to have been increased. FUNDING: Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Interest of pregnant women in the use of SMS (short message service) text messages for the improvement of perinatal and postnatal care.

BACKGROUND: Mobile health (mHealth) is emerging as a useful tool to improve healthcare access especially in the developing world, where limited access to health services is linked to poor antenatal care, and maternal and perinatal mortality.The objective of this study is to 1) understand pregnant women's access and usage of cell phones and 2) survey the health information needs and interests in a population attending public hospitals and health centers of two cities in Argentina. This information is not available and it is the basis to develop a strategy for improving maternal care via cell phones. METHODS: Questionnaires were verbally administered to pregnant women who were attending an antenatal care visit in community health centers and public hospitals in Rosario, Santa Fe and Mercedes, Corrientes. Participants were 18 years of age or older and had previously given birth. The data obtained was qualitative and analyzed using SPSS version 18. RESULTS: A total of 147 pregnant women meeting inclusion criteria (Rosario: 63; Mercedes: 84) were approached and verbally consented to participate. The average age was 29.5 years, most lived in urban areas (89%) with a mean travel time of 43.4 minutes required to get to the health center and 57.3 minutes to get the hospital.Ninety-six percent of women (n = 140) responded that they would like to receive text messages and cell phone calls with information regarding prenatal care, although the topics and period of time to receive information varied greatly. CONCLUSIONS: Considering the vast majority of the interviewed women had access to and were interested in receiving text messages and calls with educational information regarding pregnancy and infant health, pregnant women in Argentina could benefit from such an mHealth program. The low access to Internet suggests it is not an option for this population; however, this cannot be assumed as representative of the country's situation.To retain active participation, other forms of health communication, such as a 2-way text message systems or toll-free numbers, could be considered in the future. Cost of use and implementing these options should be studied.

The three-component biginelli reaction: a combined experimental and theoretical mechanistic investigation.

Biginelli reactions have been monitored by direct infusion electrospray ionization mass spectrometry (ESI-MS) and key cationic intermediates involved in this three-component reaction have been intercepted and further characterized by tandem MS experiments (ESI-MS/MS). Density functional theory calculations were also used to investigate the feasibility of the major competing mechanisms proposed for the Biginelli reaction. The experimental and theoretical results were found to corroborate the iminium mechanism proposed by Folkers and Johnson, whereas no intermediates directly associated with either the more energy demanding Knoevenagel or enamine mechanisms could be intercepted.

Derivatives of spiropentadiene dication: new species with planar tetracoordinate carbon (ptC) atom.

In this work, nine tetrasubstituted derivatives [NH(2), OCH(3), Li, Na, Si(CH(3))(3)/SiH(2)CH(3,) P(CH(3))(2), Cl, F, and CN] of the spiropentadiene dication were analyzed within the framework of QTAIM. In the studied series, the electron-withdrawing substituents destabilize the ptC-containing spiropentadiene dication. On the other hand, stabilization of this dication is possible for electron-donating substituents only through sigma bonds, such as Li and Na. In all studied systems, according to QTAIM, the pi-electron system does not participate in the stabilization of the ptC atom in the spiropentadiene dication. sigma-electron-donating groups stabilize the spiropentadiene dication system by increasing the charge density of C(ext)-ptC bonds, whereas electron-withdrawing groups remove the charge density from C(ext)-ptC bonds.