Effects of Post-Hospital Arrival Factors on Out-of-Hospital Cardiac Arrest Outcomes During the COVID-19 Pandemic.

IMPORTANCE: The relationship between post-hospital arrival factors and out-of-hospital cardiac arrest (OHCA) outcomes remains unclear. OBJECTIVES: This study assessed the impact of post-hospital arrival factors on OHCA outcomes during the COVID-19 pandemic using a prediction model. DESIGN, SETTING, AND PARTICIPANTS: In this cohort study, data from the All-Japan Utstein Registry, a nationwide population-based database, between 2015 and 2021 were used. A total of 541,781 patients older than 18 years old who experienced OHCA of cardiac origin were included. MAIN OUTCOMES AND MEASURES: The primary exposure was trends in COVID-19 cases. The study compared the predicted proportion of favorable neurologic outcomes 1 month after resuscitation with the actual outcomes. Neurologic outcomes were categorized based on the Cerebral Performance Category score (1, good cerebral function; 2, moderate cerebral function). RESULTS: The prediction model, which had an area under the curve of 0.96, closely matched actual outcomes in 2019. However, a significant discrepancy emerged after the pandemic began in 2020, where outcomes continued to deteriorate as the virus spread, exacerbated by both pre- and post-hospital arrival factors. CONCLUSIONS AND RELEVANCE: Post-hospital arrival factors were as important as pre-hospital factors in adversely affecting the prognosis of patients following OHCA during the COVID-19 pandemic. The results suggest that the overall response of the healthcare system needs to be improved during infectious disease outbreaks to improve outcomes.

Pseudo-nephropathy and hyper-excretion of urinary C-peptide: an overlooked adverse effect of an angiotensin receptor-neprilysin inhibitor (ARNI).

Sacubitril/valsartan, which is a combined angiotensin receptor-neprilysin inhibitor (ARNI), is used for the treatment of chronic heart failure and hypertension. Substrates of neprilysin are numerous, and the systemic effects of an ARNI remain to be determined. Increased urinary C-peptide (UCPR) and urinary albumin (UAlb) excretion has been reported with the use of an ARNI, but the mechanism is still unknown. We report an 84-year-old man with type 2 diabetes and hypertension. His UAlb and UCPR excretion and (to a lesser degree) the estimated glomerular filtration rate were increased after ARNI administration. They returned to basal levels after discontinuing ARNI administration. There was little or no change in glycemic control. Therefore, increased glomerular permeability and filtration could partially explain how neprilysin inhibition led to an elevation in UCPR excretion, in addition to other mechanisms, such as impairment of the renal ability to degrade C-peptide. Physicians must be cautious when interpreting the insulin secretion capability by UCPR and nephropathy by UAlb in ARNI-treated patients with diabetes.

Comparison of surgical outcomes of da Vinci surgical systems X and Xi: A single-center study.

BACKGROUND: The da Vinci surgical systems (X and Xi) are fourth-generation systems marketed by Intuitive Inc. The X system is less expensive than the Xi system. This study compared the surgical outcomes of patients who underwent hysterectomy using the X and Xi systems. METHODS: Data from 172 patients who underwent robot-assisted total hysterectomies by four surgeons between April 2019 and March 2023 were retrospectively analyzed in a single-center study. The patients were divided into two groups based on the surgical system used. Approval was granted by the Institutional Review Board of the Tottori University Hospital (22A134). All patients provided opt-out consent in accordance with the institutional guidelines. RESULTS: Operative time (126.6 ± 29.5 for X, 138.2 ± 38.5 for Xi, p = .227) and console time (92.9 ± 27.0 for X, 105.5 ± 34.7 for Xi, p = .089) were insignificantly shorter in group X than in group Xi after propensity score matching for age, body mass index, nulliparity, previous history of abdominal or pelvic surgery, preoperative diagnosis, and surgical approach. No significant differences between X and Xi were observed in a subgroup analysis of patients who underwent robot-assisted total laparoscopic hysterectomy without lymphadenectomy (operative time: 199.0 ± 26.5 for X, 221.5 ± 45.1 for Xi, p = .227; console time: 162.1 ± 25.0 for X, 178.3 ± 0.314 for Xi, p = .314). CONCLUSION: Perioperative outcomes for the X and Xi da Vinci surgical systems were equivalent. The cost-effective X system may allow the widespread use of robotic surgeries.

Development and Validation of an E-Learning Educational Program for Acquiring Basic Knowledge in Inflammatory Bowel Disease Nursing.

Introduction: This study focuses on developing and validating an e-learning educational program for nurturing inflammatory bowel disease (IBD) nursing specialists. Methods: The program was developed using the attention, relevance, confidence, and satisfaction models within the instructional design framework. The program validation encompassed four steps: (1) nurses took a basic IBD knowledge test (pretest), (2) participants scoring <80% were encouraged to undergo web-based training, (3) a follow-up test (posttest) gauged post-training improvement, and (4) participant satisfaction with e-learning was assessed. Results: The analysis included 63 participants. The average score in the pretest was 81.3%, 40 participants exceeded the pretest passing score, which is 80% (average: 88.3%), and 23 participants failed (average: 69.1%). Of those who failed, 19 participants showed improvement after undergoing web-based training, with their posttest scores exceeding the passing threshold (average: 97.4%). The comparison results between the passing and failing groups revealed no correlation between the baseline characteristics of the participants. The participants were highly satisfied with the e-learning program. Conclusion: The program was effective as an educational program for acquiring basic knowledge to foster IBD nursing professionals. The learning design was adapted to the participants' lifestyles and tailored to the readiness of the nurse, ensuring a satisfactory e-learning user experience for the nurses.

A Man with Primary Hyperchylomicronemia with Triglyceride Levels Exceeding 11,000 mg/dL was Well Controlled by Pemafibrate Combined with Dietary Therapy: A Case Report.

A 50-year-old man with a triglyceride (TG) level of 11,397 mg/dL was admitted to our hospital. He consumed a high-fat and high-carbohydrate diet as well as more than 100 g of alcohol per day. He had type 2 diabetes and obesity and had previously suffered from severe acute pancreatitis twice. A genetic analysis revealed compound heterozygous mutations in APOA5 (c.56C>G and c.553G>T). In addition to low-fat meals and alcohol cessation, administration of pemafibrate lowered his triglyceride levels to <150 mg/dL.

Dysregulation of the TCF4 Isoform in Corneal Endothelial Cells of Patients With Fuchs Endothelial Corneal Dystrophy.

Purpose: This study evaluated the dysregulation of TCF4 isoforms and differential exon usage (DEU) in corneal endothelial cells (CECs) of Fuchs endothelial corneal dystrophy (FECD) with or without trinucleotide repeat (TNR) expansion in the intron region of the TCF4 gene. Methods: Three RNA-Seq datasets of CECs (our own and two other previously published datasets) derived from non-FECD control and FECD subjects were analyzed to identify TCF4 isoforms and DEU events dysregulated in FECD by comparing control subjects to those with FECD with TNR expansion and FECD without TNR expansion. Results: Our RNA-Seq data demonstrated upregulation of three TCF4 isoforms and downregulation of two isoforms in FECD without TNR expansion compared to the controls. In FECD with TNR expansion, one isoform was upregulated and one isoform was downregulated compared to the control. Additional analysis using two other datasets identified that the TCF4-277 isoform was upregulated in common in all three datasets in FECD with TNR expansion, whereas no isoform was dysregulated in FECD without TNR expansion. DEU analysis showed that one exon (E174) upstream of the TNR, which only encompassed TCF4-277, was upregulated in common in all three datasets, whereas eight exons downstream of the TNR were downregulated in common in all three datasets in FECD with TNR expansion. Conclusions: This study identified TCF4-277 as a dysregulated isoform in FECD with TNR expansion, suggesting a potential contribution of TCF4-277 to FECD pathophysiology.

Association between COVID-19 severity and relatively high serum adiponectin levels at the time of admission.

At the beginning of 2020, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to epidemics worldwide. Obesity and visceral fat accumulation have been reported to be independent risk factors for severe COVID-19. Several reports have focused on the levels of adipocytokines/adipokines, including adiponectin (APN), which is exclusively secreted from adipocytes, although the importance of these factors in acute disease conditions remains unclear. Therefore, we investigated the relationship between serum adiponectin levels and COVID-19 severity. Patients with COVID-19 who were admitted to Sumitomo Hospital (Osaka, Japan) from May through October 2021 were included. A total of 107 patients were enrolled in this study. We obtained the anthropometric and clinical laboratory data of the patients at the time of admission and examined the associations between various parameters and COVID-19 severity. The mean period from onset to admission was 6.5 ± 2.8 days. We divided the patients into "non-severe" (mild, moderate-I and moderate-II) (n = 80) and "severe" (n = 27) groups. The "severe" patients were significantly older than "non-severe" patients. Additionally, no significant differences were observed in BMI, sex, or the period from onset to admission. The serum adiponectin levels of "severe" patients at the time of admission were significantly greater than those of "non-severe" patients even after adjusting for age, sex, and BMI. These results suggest that the serum APN levels at the time of admission can predict COVID-19 severity. However, further investigations on the changes in APN levels in acute diseases are needed.

Investigation of biomarkers to predict outcomes in allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Various biomarkers have been developed and evaluated to predict the prognosis and complications of allogeneic hematopoietic cell transplantation (HCT). Most previous studies conducted on different biomarkers evaluated single effects such as those associated with inflammation, immunology, iron metabolism, and nutrition, and only a few studies have comprehensively analyzed markers. OBJECTIVE: The study aimed to survey comprehensive multiple markers prior to HCT and extract those that significantly predict the outcomes. STUDY DESIGN: A prospective multicenter observational study was performed. (UMIN000013506) Patients undergoing HCT for hematologic diseases were consecutively enrolled. Besides the usual clinical biomarkers, serum samples for extra-clinical biomarkers were collected and cryopreserved before starting the conditioning regimen. A total of 32 candidate biomarkers were selected, 23 from hematology, biochemistry, immunology, nutrition, and iron metabolism, and 9 from composite markers. Based on the area under the curve (AUC) values for survival, promising biomarkers was extracted. Internal validation for these markers was applied based on bootstrap methods. Setting the cut-off values for them, log-rank test was applied and outcomes including overall survival (OS), relapse, and non-relapse mortality (NRM) were evaluated using multivariate analyses. Furthermore, detailed analysis including transplant-related complications and external validation were conducted focusing on C-reactive protein (CRP) to platelet (Plt) ratio. RESULTS: A total of 152 patients with hematologic malignancies were enrolled from April 2014 to March 2017. CRP, soluble interleukin-2 receptor (IL2R), CRP to albumin (Alb) ratio, CRP to Plt ratio, Plt to IL2R ratio, and IL2R to Alb ratio were identified as promising markers. Internal validation successfully confirmed their reliability of AUC and multivariate analysis demonstrated the statistical significance between the higher and the lower markers. Above all, a higher CRP to Plt ratio was significantly associated with a lower OS (hazard ratio [HR] 2.77; 95% confidence interval [CI] 1.30-5.91; P = 0.008) and higher non-relapse mortality rates (HR 2.79; 95%CI 1.14-6.80; P = 0.024) at 180 days. Furthermore, univariate analysis showed that a higher CRP to Plt ratio was significantly associated with a higher incidence of sinusoidal obstructive syndrome (P < 0.001) and bloodstream infection (P = 0.027). An external validation test confirmed the significance of the CRP to Plt ratio for these outcomes. CONCLUSION: The multicenter prospective observational study successfully identified significant biomarkers in patients with hematologic malignancies who received HCT. In particular, CRP to Plt ratio was identified as a novel and useful biomarker for predicting transplant outcomes. Further investigations are needed to validate the novel markers, analysis of the pathophysiology, and application to treatment settings other than HCT.

Probiotic-derived ferrichrome induces DDIT3-mediated antitumor effects in esophageal cancer cells.

Esophageal cancer, which is common among the elderly, has the poorest prognosis among gastrointestinal cancers. Previously, we demonstrated that ferrichrome, produced by the probiotic Lactobacillus casei, exhibited anti-tumor effects in various gastrointestinal cancers, including colorectal and gastric cancers, with minimal effects on non-cancerous intestinal cells. However, it remains unclear whether ferrichrome exerts anti-tumor effects in esophageal cancer. A sulforhodamine B assay revealed that ferrichrome suppressed esophageal adenocarcinoma (OE33, OE19) and squamous cell carcinoma (KYSE70) cells. Ki-67 staining indicated that ferrichrome inhibited the proliferation of esophageal cancer cells. Cell cycle analysis showed that ferrichrome inhibited the DNA synthesis. TUNEL staining revealed that ferrichrome-induced DNA fragmentation. We also confirmed the cleavage of caspase-9 and PARP in ferrichrome-treated cells. Reverse transcription polymerase chain reaction demonstrated an increase in the mRNA of DNA damage-inducible transcript 3 (DDIT-3), a key regulator of programmed cell death, in ferrichrome-treated OE33 cells. In an in vivo OE33 xenograft model, intraperitoneal administration of 5-mg/kg ferrichrome for 14 days resulted in an almost complete inhibition of tumor growth. However, 14 days of intraperitoneal administration of 20-mg/kg 5-fluorouracil (5-FU), but not 20-mg/kg ferrichrome, induced weight loss and myelosuppression in both young and aged mice. Our findings indicate that ferrichrome induces DNA damage-inducible transcript-3, thereby producing anti-tumor effects, including cell cycle arrest and apoptosis, with minimal adverse effects in esophageal cancer cells. This illustrates the high potential of ferrichrome as an anti-tumor drug against esophageal carcinoma.

Outcome of robot-assisted surgery for stage IA endometrial cancer compared to open and laparoscopic surgeries: a retrospective study at a single institution.

Few studies have compared the efficacy of robot-assisted, laparoscopic, and open surgeries for endometrial cancer. When considering the position of robotic surgery in Japan, it was necessary to determine whether it was effective or not. We aimed to compare the efficacy and safety of these three types of surgeries for early-stage endometrial cancer. In total, 175 patients with endometrial cancer of preoperative stage IA, who had undergone laparotomic (n = 80), laparoscopic (n = 40), or robot-assisted (n = 55) modified radical hysterectomy at our hospital from 2010 to 2022, were included; surgical outcomes, perioperative complications, and prognoses were compared. Total operative and console times for robot-assisted surgery between patients who did or did not undergo pelvic lymphadenectomy were assessed. The robot-assisted group had the shortest total operative time. The estimated blood loss was lower in the laparoscopic and robot-assisted groups than in the laparotomy group. In advanced postoperative stage IA cases, there were no differences in progression-free and overall survival among the three groups. In the robot-assisted group, the operative time decreased as the number of operations increased; the learning curve was reached after 10 cases each of patients with and without pelvic lymphadenectomy. The frequency of perioperative complications of Clavien-Dindo classification Grade 1 or higher was the lowest in the robot-assisted group (p = 0.02). There were no complications of Clavien-Dindo classification Grade 2 or higher in the robot-assisted group. Robot-assisted surgery for stage IA endometrial cancer, a minimally invasive procedure, has fewer operative times and complications than those of laparoscopic and open surgeries in a single institution in Japan.

Phenothiazine cyclic hexamers: synthesis, properties, and complexation behavior with C60.

Phenothiazine cyclic hexamers linked at the 3,7-positions were synthesized. Effects of the cyclic structure as well as substituent effects of the nitrogen atom were disclosed. Furthermore, the cyclic hexamer encapsulated C60 inside the ring in a 1 : 1 ratio giving a Saturn-type complex in solution. The structure and interactions were discussed based on DFT calculations.

Sialidase NEU3 Contributes to the Invasiveness of Bladder Cancer.

Bladder cancer is the 10th most commonly diagnosed cancer worldwide. The current standard treatment for advanced bladder cancer is neoadjuvant cisplatin (NAC)-based chemotherapy followed by cystectomy. However, the response rate to chemotherapy is only 50%, owing to cisplatin resistance, and there is a need for novel therapies. Because the invasiveness of bladder cancer greatly influences patient prognosis, a mechanistic analysis of the invasive function can lead to therapeutic targets. Sialidases, which remove sialic acid residues from the nonreducing ends of sugar chains and catalyze the initial reaction in the degradation of sugar chains, are predicted to be involved in cell invasion and motility. However, the involvement of sialidases in bladder cancer, especially their relationship with the invasive ability, remains unclear. Here, using patient tissues and multiple bladder cancer cell lines, we show that the sialidase NEU3 is highly expressed in bladder cancer. Analysis of NEU3's function using its siRNA-mediated knockdown revealed that NEU3 contributes to bladder cancer invasiveness. Mechanistic analysis showed that NEU3 activates ERK and PI3K signaling. Our results show that NEU3 is involved in the malignancy of bladder cancer, and its suppression may lead to novel treatments for bladder cancer.

Fatal poisoning due to ingestion of boiled oleander leaf extract.

Nerium oleander is an ornamental evergreen shrub belonging to the family Apocynaceae. The Apocynaceae family includes the attractive evergreen shrub known as oleander. The cardiotoxic glycoside, oleandrin, is present in all portions of the common oleander plant. Oleander consumption can result in deadly situations accidentally or as a suicide attempt. After consuming kettle-boiled oleander leaf extract as part of a suicide attempt, an 80-year-old man was discovered comatose in his home and taken to our emergency room. The patient's heart rate was 30 beats per minute, and he had hypotension. Arterial blood gas analysis revealed remarkable metabolic acidosis and hyperkalemia (K: 7.7 mEq/L). An electrocardiogram showed a wide QRS wave, similar to a sine curve. The patient collapsed following cardiac arrest soon after hospital arrival. Veno-arterial extracorporeal membrane oxygenation was initiated; however, the patient eventually died. The serum level of oleandrin at hospital arrival, subsequently measured by LC-MS/MS, was found to be 33.4 ng/mL, far above the levels reported in previous fatal cases.

Clinical significance of total nucleated cell count in bone marrow of patients with acute lymphoblastic leukemia who underwent allogeneic hematopoietic stem cell transplantation.

The clinical implications of recipient bone marrow nucleated cell count (NCC) prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) remain unknown. We conducted a multicenter retrospective study to evaluate the clinical significance of bone marrow NCC prior to allo-HSCT in patients with acute lymphoblastic leukemia. Patients who were in remission and underwent the initial allo-HSCT were included and stratified into high- and low-NCC groups using an NCC of 10 × 104/µL as the cut-off. The 3-year overall survival (OS), non-relapse mortality (NRM), and relapse rates for the high- and low-NCC groups were 51.2 vs. 84.5% (p < 0.001), 27.5 vs. 6.5% (p < 0.001), and 31.1 vs. 24.4% (p = 0.322), respectively. The high-NCC group had significantly poorer OS and higher NRM when compared with the low-NCC group. In summary, high recipient bone marrow NCC is associated with higher NRM and lower OS following allo-HSCT.

Machine learning-based analysis of regional differences in out-of-hospital cardiopulmonary arrest outcomes and resuscitation interventions in Japan.

Refining out-of-hospital cardiopulmonary arrest (OHCA) resuscitation protocols for local emergency practices is vital. The lack of comprehensive evaluation methods for individualized protocols impedes targeted improvements. Thus, we employed machine learning to assess emergency medical service (EMS) records for examining regional disparities in time reduction strategies. In this retrospective study, we examined Japanese EMS records and neurological outcomes from 2015 to 2020 using nationwide data. We included patients aged ≥ 18 years with cardiogenic OHCA and visualized EMS activity time variations across prefectures. A five-layer neural network generated a neurological outcome predictive model that was trained on 80% of the data and tested on the remaining 20%. We evaluated interventions associated with changes in prognosis by simulating these changes after adjusting for time factors, including EMS contact to hospital arrival and initial defibrillation or drug administration. The study encompassed 460,540 patients, with the model's area under the curve and accuracy being 0.96 and 0.95, respectively. Reducing transport time and defibrillation improved outcomes universally, while combining transport time and drug administration showed varied efficacy. In conclusion, the association of emergency activity time with neurological outcomes varied across Japanese prefectures, suggesting the need to set targets for reducing activity time in localized emergency protocols.

Explainable Prediction Model of the Need for Emergency Hemostasis Using Field Information During Physician-Staffed Helicopter Emergency Medical Service Interventions: A Single-Center, Retrospective, Observational Pilot Study.

OBJECTIVE: Early recognition of hemostasis is important to prevent trauma-related deaths. We conducted a pilot study of a predictive model of hemostatic need using factors that can be collected during helicopter emergency medical service (HEMS) interventions until transport hospital selection using cases from our institution. METHODS: This single-center, retrospective, observational pilot study included 251 trauma patients aged ≥ 18 years treated with HEMS between April 2017 and March 2022, in Nara Medical University. Cardiac arrest and pre-HEMS treatment patients were excluded. Emergency hemostatic surgery prediction models were constructed using the light gradient boosting machine cross-validation method using objective data that could be collected before hospital determination. The accuracy of this model was compared with that of the ground emergency medical service-based model, and factors influencing outcome were visualized using Shapley additive explanations. RESULTS: The predictive accuracy of the model with HEMS intervention factors was an area under the receiver operating characteristic curve of 0.80, superior to the 0.73 accuracy area under the receiver operating characteristic curve for ground emergency medical services constructed with contact information. Clinically important factors, such as shock index, blood pressure changes, and ultrasound findings, had a significant impact on outcomes, with nonmonotonic effects observed across factors. CONCLUSION: This pilot study suggests that predictive models of emergency hemostasis can be built using limited prehospital information. To validate this model, a larger, multicenter study is recommended.

Huge Leiomyomas Arising from Bilateral Uterine Remnants in a Mayer-Rokitansky-Küster-Hauser Syndrome Patient with Coexisting Myotonic Dystrophy Type 1: A Case Report and Literature Review.

Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) is a rare congenital anomaly of the genital tract. Since the secretion of sex hormones from the ovaries is preserved, leiomyomas and adenomyomas, which are estrogen-dependent diseases, may develop from the uterine remnant. In contrast, patients with myotonic dystrophy type 1 (DM1), the most common dystrophy in adults, are considered to be at high risk for benign tumors of the female reproductive system, such as uterine leiomyomas and ovarian cysts. A rare case of huge leiomyomas arising from bilateral uterine remnants in a woman with MRKHS with coexisting DM1 is presented. Her chief complaint was abdominal distension. On pelvic magnetic resonance imaging (MRI), two solid pelvic masses showing low signal intensity on T2-weighted imaging were seen. Both the uterine corpus and cervix were unclear, but bilateral ovaries were observed normally on MRI. Two uterine leiomyoma-like masses connected by a band of fibrous tissue were found by laparotomy. As with the MRI findings, the uterine cervix and vagina could not be detected macroscopically. Normal bilateral adnexa and round ligaments were identified. All of her symptoms improved after hysterectomy.

Recurrent ventricular arrhythmia due to aconite intoxication successfully treated with landiolol: A case report.

BACKGROUND: Ventricular arrhythmias, such as ventricular tachycardia and fibrillation, are the main causes of death in patients with aconite poisoning. CASE SUMMARY: A 51-year-old man presented to our emergency department because he was vomiting after ingesting aconite root to attempt suicide. On arrival, the patient was hemodynamically unstable, and his electrocardiogram revealed polymorphic ventricular extrasystoles and non-sustained ventricular tachycardia. Amiodarone was immediately administered for ventricular arrhythmia. However, the patient remained unresponsive. We administered continuous intravenous landiolol as the ventricular arrhythmia worsened, gradually suppressing it. The patient returned to sinus rhythm 16 h after arriving at the hospital. Some aconitum alkaloids act on voltage-gated Na+- channels and induce ventricular or supraventricular tachyarrhythmias. Landiolol suppresses sympathetic nerve activity through its blocking effect, preventing arrhythmia. CONCLUSION: Landiolol can be a therapeutic option for amiodarone-refractory ventricular arrhythmias caused by aconite intoxication.

Isolation and Structures of Polyarene Palladium Nanoclusters.

We report that surrounding coordination of neutral six-membered arene rings affords molecularly well-defined organotransition metal nanoclusters. With the use of [2.2]paracyclophane as the face-capping arene ligand, we have isolated two polyarene palladium nanoclusters, one consisting of a hexakis-arene ligand shell and a hexagonal close-packed Pd13 anticuboctahedron trichloride core, and the other consisting of an octakis-arene ligand shell and a non-close-packed Pd17 square gyrobicupola dichloride core, both with Pd-Pd direct bonding. The µ4-facial coordination mode of arene was discovered through the structural characterization of the Pd13 cluster. Their Pd13 and Pd17 cores, which are distinct from the previously identified face-centered-cubic Pd13 core surrounded by seven-membered cycloheptatrienyl, are explained by stereochemical and theoretical analyses.

A series of boron difluoride complexes of azinylcarbazoles: synthesis and structure-property relationships.

A series of boron difluoride (BF2) complexes of azinylcarbazoles 1b-1h were synthesized, and the effects of the structure of azine moieties on the photophysical and electrochemical properties of the BF2 complexes were clarified. UV-vis analysis of 1b with quinoline, 1c with isoquinoline, and fully fused 1d revealed that fusion with a benzene ring to a pyridylcarbazole BF2 complex (1a) resulted in red shifts of longest-maximum absorption wavelengths (λmax). UV-vis analysis of 1e and 1f with pyrimidine, 1g with pyridazine, and 1h with pyrazine revealed that substitution of a carbon atom to a nitrogen atom in 1a also resulted in red shifts of λmax. The fluorescence quantum yields (Φf) decreased from 1a to 1b-1h, and especially, the fluorescence of 1e, 1g, and 1h was quenched in solution. At 77 K, the emission intensities of 1b-1h were significantly increased compared with those at ambient temperature, and they also exhibited phosphorescence with relatively narrow energy gaps between the singlet and triplet excited states. These results on the emission at 77 K indicate that the quench of fluorescence from 1e, 1g, and 1h at ambient temperature originates from both internal conversions and intersystem crossing. In the solid state, all of the complexes including 1e, 1g, and 1h exhibited emission. Distinctive aggregation-induced emission properties were observed for 1e-1h. Electrochemical measurements revealed that the replacement of the pyridine moiety in 1a with azine moieties reduced electrochemical gaps mainly due to a decrease in the LUMO levels. The effects of azine moieties on electronic structures were also discussed based on theoretical calculations.