Overall reaction mechanism of photocatalytic CO2 reduction on a Re(i)-complex catalyst unit of a Ru(ii)-Re(i) supramolecular photocatalyst.

Rhenium(i) complexes fac-[ReI(diimine)(CO)3(L)]n+ are mostly used and evaluated as photocatalysts and catalysts in both photochemical and electrochemical systems for CO2 reduction. However, the selective reduction mechanism of CO2 to CO is unclear, although numerous mechanistic studies have been reported. A Ru(ii)-Re(i) supramolecular photocatalyst with fac-[ReI(diimine)(CO)3{OC(O)OCH2CH2NR2}] (R = C2H4OH) as a catalyst unit (RuC2Re) exhibits very high efficiency, selectivity, and durability of CO formation in photocatalytic CO2 reduction reactions. In this work, the reaction mechanism of photocatalytic CO2 reduction using RuC2Re is fully clarified. Time-resolved IR (TR-IR) measurements using rapid-scan FT-IR spectroscopy with laser flash photolysis verify the formation of RuC2Re(COOH) with a carboxylic acid unit, i.e., fac-[ReI(diimine)(CO)3(COOH)], in the photocatalytic reaction solution. Additionally, this important intermediate is detected in an actual photocatalytic reaction using steady state irradiation. Kinetics analysis of the TR-IR spectra and DFT calculations demonstrated the reaction mechanism of the conversion of the one-electron reduced species of RuC2Re with a fac-[ReI(diimine˙-)(CO)3{OC(O)OCH2CH2NR2}]- unit, which was produced via the photochemical reduction of RuC2Re by 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH), to RuC2Re(COOH). The kinetics of the recovery processes of the starting complex RuC2Re from RuC2Re(COOH) accompanying the release of CO and OH- was also clarified. As a side reaction of RuC2Re(COOH), a long-lived carboxylate-ester complex with a fac-[ReI(diimine)(CO)3(COOC2H4NR2)] unit, which was produced by the nucleophilic attack of TEOA to one of the carbonyl ligands of RuC2Re(CO) with a fac-[ReI(diimine)(CO)4]+ unit, was formed during the photocatalytic reaction. This complex works not only as a precursor in another minor CO formation process but also as an external photosensitiser that photochemically reduces the other complexes i.e., RuC2Re, RuC2Re(COOH), and the intermediate that is reductively converted to RuC2Re(COOH).

A newly developed surgeon-controlled suction device in robotic-assisted thoracoscopic surgery.

INTRODUCTION: Assistant surgeons usually clean the surgical field with a suction cannula in robotic-assisted surgery. This manipulation requires skill and experience to avoid interfering with the operation of the console surgeon. Recently, we created a new suction device that a console surgeon can manipulate with the robotic arms. MATERIALS AND SURGICAL TECHNIQUE: A small metal suction tip with as a lumen and small side pores for suction and can be connected to a silicone tube connected to wall suction. The tip of the silicone tube can be grasped with robotic forceps and used for organ retraction as well as suction. The suction device has been used in eight lung lobectomy cases and four lung segmentectomy cases to date. There were no major difficulties related to the new suction device except for metal tip disconnection and blood clots clogging. DISCUSSION: Our newly developed surgeon-controlled suction device is inexpensive, easy to handle, and useful for suction, blunt dissection, and organ retraction in robotic-assisted thoracoscopic surgery, especially when performing lymph node dissection.

Efficient and accurate KRAS genotyping using digital PCR combined with melting curve analysis for ctDNA from pancreatic cancer patients.

A highly sensitive and highly multiplexed quantification technique for nucleic acids is necessary to predict and evaluate cancer treatment by liquid biopsy. Digital PCR (dPCR) is a highly sensitive quantification technique, but conventional dPCR discriminates multiple targets by the color of the fluorescent dye of the probe, which limits multiplexing beyond the number of colors of fluorescent dyes. We previously developed a highly multiplexed dPCR technique combined with melting curve analysis. Herein, we improved the detection efficiency and accuracy of multiplexed dPCR with melting curve analysis to detect KRAS mutations in circulating tumor DNA (ctDNA) prepared from clinical samples. The mutation detection efficiency was increased from 25.9% of the input DNA to 45.2% by shortening the amplicon size. The limit of detection of mutation was improved from 0.41 to 0.06% by changing the mutation type determination algorithm for G12A, resulting in a limit of detection of less than 0.2% for all the target mutations. Then, ctDNA in plasma from pancreatic cancer patients was measured and genotyped. The measured mutation frequencies correlated well with those measured by conventional dPCR, which can measure only the total frequency of KRAS mutants. KRAS mutations were detected in 82.3% of patients with liver or lung metastasis, which was consistent with other reports. Accordingly, this study demonstrated the clinical utility of multiplex dPCR with melting curve analysis to detect and genotype ctDNA from plasma with sufficient sensitivity.

Evaluation of the radiofrequency identification lung marking system: a multicenter study in Japan.

BACKGROUND: The radiofrequency identification (RFID) lung marking system is a novel technique using near-field radio-communication technology. The purpose of this study was to investigate the utility and feasibility of this system in the resection of small pulmonary nodules. METHODS: We retrospectively reviewed clinical records of 182 patients who underwent sublobar resection with the RFID marking system between March 2020 and November 2021 in six tertial hospitals in Japan. Target markings were bronchoscopically made within 3 days before surgery. The contribution of the procedure to the surgery and safety was evaluated. RESULTS: Target nodule average diameter and depth from the lung surface were 10.9 ± 5.4 mm and 14.6 ± 9.9 mm, respectively. Radiologically, one third of nodules appeared as pure ground-glass nodules (GGNs) on CT. The average distance from target nodule to RFID tag was 8.9 ± 7.1 mm. All surgical procedures were completed by video-assisted thoracoscopic surgery. Planned resection was achieved in all cases without any complications. The surgeons evaluated this system as helpful in 93% (necessary: 67%, useful; 26%) of cases. Nodule radiological features (p < 0.001) and type of surgery (p = 0.0013) were associated with the degree of contribution. In most cases, identification of the RFID tag was required within 1 min despite adhesion (p = 0.27). CONCLUSION: The RFID lung marking system was found to be safe and effective during successful sublobar resection. Patients with pure GGNs are the best candidates for the system.

Postoperative tegafur-uracil for stage I lung adenocarcinoma: first real-world data with an exploratory subgroup analysis.

PURPOSE: The effect of postoperative tegafur-uracil on overall survival (OS) after resection of stage I adenocarcinoma has been shown in clinical trials. The purpose of this study was to investigate whether findings from randomized trials of adjuvant tegafur-uracil are reproducible in a real-world setting. METHODS: A retrospective cohort study was performed using a multi-institutional database that included all patients who underwent complete resection of pathological stage I adenocarcinoma between 2014 and 2016. Survival outcomes for patients managed with and without tegafur-uracil were analyzed using the Kaplan-Meier method and a Cox proportional hazards model for the whole patient cohort and in a selected cohort based on eligibility criteria of a previous randomized trial. Propensity score matching was used to adjust for confounding effects. RESULTS: After propensity score matching, the hazard ratios for OS were 0.57 (95% confidence interval (CI) 0.29-1.14, P = 0.11) in the whole cohort and 0.69 (95% CI 0.32-1.50, P = 0.35) in the selected cohort. CONCLUSIONS: The effects of tegafur-uracil in this retrospective study appear to be consistent with those found in randomized clinical trials. These effects may be maximized in patients aged from 45 to 75 years.

Association between oxygen consumption and stepping exercise standardized with a triaxial accelerometer.

OBJECTIVE: According to the current American College of Chest Physicians (ACCP) guideline, a cardiopulmonary exercise test (CPET) is indicated in patients with lung cancer being considered for lung surgery. The measurement of maximum oxygen consumption ([Formula: see text] max) is not sufficiently prevalent because it requires special technical equipment. Considering that stepping is a simple and common exercise, we aimed to establish a simple and reproducible test with standardization of exercise intensity using a triaxial accelerometer. METHODS: Twenty healthy volunteers (10 male, 10 female) were included in the study. The subjects were obliged to step on the same spot at the rate of 80 and 110 counts for 1 min each and then step as quickly as possible for the last minute. Oxygen consumption ([Formula: see text]) (mL/kg/min) for every breath was continuously measured during the exercise. A triaxial accelerometer was attached to the hip of test subjects whereby metabolic equivalents (METs) at each test level were measured. RESULTS: The mean age of the study subjects was 42.9 ± 11.4 (mean ± SD). The mean value of [Formula: see text] at each level increased linearly along with the stepping level in each individual but varied among subjects. Using METs instead of step counts minimized the difference in regression lines among subjects. A receiver operating characteristic analysis revealed the possibility of [Formula: see text] prediction for the critical values of 10 and 20 mL/kg/min using METs. CONCLUSION: A simple and reproducible stepping test was suggested as applicable to standardizing the intensity of exercise using a triaxial accelerometer.

Epidermal growth factor receptor tyrosine kinase inhibitors as first-line treatment for postoperative recurrent EGFR-mutated lung adenocarcinoma: a multi-institutional retrospective study.

OBJECTIVES: The aim of this study was to analyse the long-term survival outcomes and prognostic factors of patients receiving epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) as first-line treatment for postoperative recurrent EGFR-mutated lung adenocarcinoma. METHODS: Using a multi-institutional database, we performed a retrospective chart review to identify all patients who had undergone complete resection of stage I-III EGFR-mutated lung adenocarcinoma at 11 acute care hospitals between 2009 and 2016 and had received first-line EGFR-TKI treatment for postoperative recurrence. Adverse events, progression-free survival (PFS) and overall survival (OS) were investigated. Survival outcomes were assessed using Kaplan-Meier analysis. Cox proportional hazards models were used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for PFS and OS. RESULTS: The study sample comprised 154 patients with a median age of 69. The total numbers of events were 101 for PFS and 60 for OS. The median PFS and OS were 26.1 and 55.4 months, respectively. In the multivariable analysis, EGFR ex 21 L858R mutation (HR: 1.71, 95% CI: 1.15-2.55) and shorter disease-free intervals (HR: 0.98, 95% CI: 0.96-0.99) were significantly associated with shorter PFS. Age (HR: 1.03, 95% CI: 1.00-1.07), smoking history (HR: 2.31, 95% CI: 1.35-3.94) and pathological N2 disease at the initial surgery (HR: 2.30, 95% CI: 1.32-4.00) were significantly associated with shorter OS. CONCLUSIONS: First-line EGFR-TKI treatment was generally associated with favourable survival outcomes in patients with postoperative recurrent EGFR-mutated lung adenocarcinoma. EGFR ex 21 L858R mutation may be an important prognostic factor for shorter PFS.

Thoracic composite hemangioendothelioma with neuroendocrine marker expression.

BACKGROUND: Composite hemangioendothelioma is an extraordinarily rare form of vascular neoplasm which develops predominantly in the skins and soft tissues of the adults. Neuroendocrine marker expression in composite hemangioendothelioma is considered as specifically relevant to the more aggressive behavior. CASE PRESENTATION: The patient was a 71-year-old man complaining continuous back pain. Computed tomography (CT) showed that 10 cm of contrast-enhanced soft tissue mass was occurring on the right posterior chest wall and developing adjacent to the spinal canal. Via the laminectomy, the tumor end was identified and separated from the dura mater. Then, via the posterolateral thoracotomy, the en bloc resection was achieved by separating the tumor from the diaphragm and vertebras. Histologic examination showed a complex combination of epithelioid and retiform hemangioendothelioma areas which were positive for anti-synaptophysin staining. At 12-month follow-up, there were no signs of tumor recurrence on CT, and the patient had no symptom. CONCLUSIONS: We achieved the complete resection of a huge thoracic neuroendocrine composite hemangioendothelioma developing adjacent to the spinal canal. The combination of the posterior lumbar laminectomy and the following posterior thoracotomy is a viable approach to radically resect a thoracic neuroendocrine composite hemangioendothelioma involving chest wall.

Lymph node dissection in thymic carcinomas and neuroendocrine carcinomas.

OBJECTIVES: Although lymph node (LN) metastases are not uncommon in thymic carcinomas, preoperative LN evaluation, intraoperative lymph node dissection (LND) and postoperative outcomes remain unknown. The aim of this study was to elucidate the characteristics of and outcomes in patients with thymic carcinomas and thymic neuroendocrine carcinomas undergoing LND. METHODS: A retrospective chart review was performed using our multi-institutional database to identify patients who underwent resection and LND for thymic carcinoma or thymic neuroendocrine carcinoma between 1991 and 2018. An enlarged mediastinal LN was defined as having a short-axis diameter >1 cm. We assessed survival outcomes using the Kaplan-Meier analysis. RESULTS: N1-level LND was performed in 41 patients (54.6%), N2-level LND in 14 patients (18.7%) and both-level LND in 16 patients (21.3%). Pathological LN metastasis was detected in 20 patients (26.7%) among the 75 patients undergoing LND. There was a significant difference in the number of LN stations (P = 0.015) and metastasis factor (P = 0.0042) between pathologically LN-positive and pathologically LN-negative patients. The sensitivity of enlarged LNs on preoperative computed tomography was 18.2%. There was a tendency towards worse overall survival of pathologically N2-positive patients, although the difference was not statistically significant (P = 0.15). CONCLUSIONS: Preoperative CT appears to play a limited role in detecting pathological LN metastases. Our findings suggest that the significance of N1- and N2-level LND should be evaluated in prospective studies to optimize the postoperative management of patients with thymic carcinomas and neuroendocrine carcinomas.

Effect of oxybutynin patch versus mirabegron on nocturia-related quality of life in female overactive bladder patients: A multicenter randomized trial.

OBJECTIVES: To investigate the effect of oxybutynin patch versus ß3-adrenoceptor agonist mirabegron on nocturia-related quality of life in female overactive bladder patients. METHODS: In the present study, female overactive bladder patients were enrolled. The patients were randomly allocated into two groups: the oxybutynin patch group and the mirabegron group. Each of the drugs was given for 8 weeks. The changes in the total Nocturia Quality of Life Questionnaire score were evaluated. Parameters on a frequency volume chart were also evaluated. RESULTS: In total, 100 patients (51 oxybutynin patch, 49 mirabegron) were treated with oxybutynin patch or mirabegron. The changes in the Nocturia Quality of Life Questionnaire score 4 weeks after administration were 3.8 ± 18.6 and 8.7 ± 13.1 with the oxybutynin patch group and the mirabegron group, respectively, which were significantly higher than those at the baseline. Furthermore, the changes in the Nocturia Quality of Life Questionnaire score 8 weeks after administration were 4.3 ± 16.5 and 7.7 ± 12.3, respectively. A statistical difference was seen only in the mirabegron group. Regarding the Nocturia Quality of Life Questionnaire subscores, oxybutynin patch and mirabegron significantly improved the Nocturia Quality of Life Questionnaire bother/concern subscore 4 and 8 weeks after administration, whereas the Nocturia Quality of Life Questionnaire sleep/energy subscore was not significantly improved in each period. Eight weeks after administration, 24-h frequency, 24-h urinary urgency and mean voided urine volume were improved in both groups statistically. CONCLUSIONS: The oxybutynin patch improves quality of life, focusing mainly on nocturia by improving the bother/concern subscores of the Nocturia Quality of Life Questionnaire in the short term.

Effect of Deuteration on Relaxation Dynamics of the Perylene Excimer Studied by Subnanosecond Transient Absorption Spectroscopy.

We studied the effect of deuteration on the relaxation dynamics of the excimer of perylene in solution using subnanosecond time-resolved transient absorption spectroscopy based on the randomly interleaved pulse-train method. We found that the deuterated perylene excimer in solution had a longer lifetime than the undeuterated excimer but that deuteration had a little effect on the ground-state and transient absorption spectra of the excimer, suggesting that deuteration altered the relaxation dynamics by inducing small changes in vibrational properties. To confirm the origin of the deuteration effect, we quantitatively analyzed the kinetics of transient absorption decay, including the decay of triplet-triplet absorption. In addition, we evaluated the effects of temperature on the lifetime of the excimers. On the basis of these results, we concluded that the rate of internal conversion was suppressed by deuteration. By comparing our results with previously reported results on the effect of deuteration on the fluorescence properties of crystalline perylene, we proposed a model that may explain the effect of deuteration on the lifetime of the perylene excimer in solution.

Fully Printed Wearable Microfluidic Devices for High-Throughput Sweat Sampling and Multiplexed Electrochemical Analysis.

Although the recent advancement in wearable biosensors provides continuous, noninvasive assessment of physiologically relevant chemical markers from human sweat, several bottlenecks still exist for its practical use. There were challenges in developing a multiplexed biosensing system with rapid microfluidic sampling and transport properties, as well as its integration with a portable potentiostat for improved interference-free data collection. Here, we introduce a clean-room free fabrication of wearable microfluidic sensors, using a screen-printed carbon master, for the electrochemical monitoring of sweat biomarkers during exercise activities. The sweat sampling is enhanced by introducing low-dimensional sensing compartments and lowering the hydrophilicity of channel layers via facile silane functionalization. The fluidic channel captures sweat at the inlet and directs the real-time sweat through the active sensing electrodes (within 40 s) for subsequent decoding and selective analyses. For proof of concept, simultaneous amperometric lactate and potentiometric ion sensing (Na+, K+, and pH) are carried out by a miniature circuit board capable of cross-talk-free signal collection and wireless signal transduction characteristics. All of the sensors demonstrated appreciable sensitivity, selectivity, stability, carryover efficiency, and repeatability. The floating potentiometric circuits eliminate the signal interference from the adjacent amperometric transducers. The fully integrated pumpless microfluidic device is mounted on the epidermis and employed for multiplexed real-time decoding of sweat during stationary biking. The regional variations in sweat composition are analyzed by human trials at the underarm and upperback locations. The presented method offers a large-scale fabrication of inexpensive high-throughput wearable sensors for personalized point-of-care and athletic applications.

Are volume-dependent parameters in positron emission tomography predictive of postoperative recurrence after resection in patients with thymic carcinoma?

This study aimed to investigate the association between the volume-dependent parameters in 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG PET/CT) and a recurrence of thymic carcinoma. A retrospective chart review was performed based on our multi-institutional database to identify patients undergoing PET prior to resection of thymic carcinoma or neuroendocrine carcinoma between 1991 and 2018. The PET parameters (metabolic tumor volume and total lesion glycolysis) were evaluated retrospectively. The relevant factors were extracted and a survival analysis was performed using the Kaplan-Meier method. Sixteen patients were thus deemed to be eligible for analysis. The median follow-up period following resection was 2.65 years (range: 0.96-0.68 years). The recurrence-free survival was significantly longer in patients with a metabolic tumor volume < = 22.755 cm3 and with total lesion glycolysis < = 105.4006 g/mL (p = 0.001 and 0.001, respectively, by a log-rank test). The metabolic tumor volume and total lesion glycolysis may, therefore, be predictive of the postoperative recurrence of thymic carcinoma.

The treatment and survival of patients with postoperative recurrent thymic carcinoma and neuroendocrine carcinoma: a multicenter retrospective study.

PURPOSE: There are few data available on the outcomes of postoperative recurrent thymic carcinoma (TC) and thymic neuroendocrine carcinoma (TNEC). The aim of this study is to evaluate the treatment and survival in patients with recurrent TC and TNEC after undergoing surgical resection. METHODS: A retrospective chart review was performed using our multicenter database to identify patients with a postoperative recurrence of TC and TNEC from 1995 to 2018. The clinicopathological factors were reviewed and the survival outcomes were analyzed. RESULTS: Sixty patients were identified among 152 patients who underwent resection of TC and TNEC. The median follow-up period from the first recurrence was 14.8 months (range 0-144). The 5-year post-recurrence survival was 23% for the whole cohort. According to a univariable analysis, advanced stage [hazard ratio (HR) 2.81, 95% confidence interval (CI) 1.09-9.54], interval between primary surgery and recurrence (HR 0.97, 95% CI 0.95-0.99), any treatment for recurrence (HR: 0.27, 95% CI 0.13-0.58) and chemotherapy for recurrence (HR: 0.46, 95% CI 0.22-0.95) were significant factors related to post-recurrence survival. CONCLUSIONS: Chemotherapy rather than surgery appears to be the mainstay treatment for managing patients with postoperative recurrent TC and TNEC and it may also be considered in multidisciplinary management. Further studies with a larger sample size are required to confirm our findings.

10-Plex Digital Polymerase Chain Reaction with Four-Color Melting Curve Analysis for Simultaneous KRAS and BRAF Genotyping.

Digital PCR (dPCR) is a promising method for performing liquid biopsies that quantifies nucleic acids more sensitively than real-time PCR. However, dPCR shows large fluctuations in the fluorescence intensity of droplets or wells due to insufficient PCR amplification in the small partitions, limiting the multiplexing capability of using the fluorescence intensity. In this study, we propose a measurement method that combines dPCR with melting curve analysis for highly multiplexed genotyping. A sample was digitized into a silicon chip with up to 2 × 104 wells in which asymmetric PCR was performed to obtain more single-stranded amplicons that were complementary to molecular beacon probes. Fluorescence images were captured while controlling the temperature of the chip, and the melting curve was measured for each well. Then, genotyping was performed by using the fluorescence intensity, the dye color of the probe, and the melting temperature (Tm). Because the Tm of the PCR products is not highly dependent on the amplification efficiency of PCR, genotyping accuracy is improved by using Tm values, enabling highly multiplexed genotyping. The concept was confirmed by simultaneously identifying wild-type KRAS, BRAF, and eight mutants of these genes (G12D, G12R, G12V, G13D, G12A, G12C, G12S, and V600E) through four-color melting curve analysis. To the best of our knowledge, this is the first demonstration of the genotyping of 10 DNA groups including single mutations of cancer-related genes by combining dPCR with four-color melting curve analysis.

Low-frequency noise induced by cation exchange fluctuation on the wall of silicon nitride nanopore.

Nanopore-based biosensors have attracted attention as highly sensitive microscopes for detecting single molecules in aqueous solutions. However, the ionic current noise through a nanopore degrades the measurement accuracy. In this study, the magnitude of the low-frequency noise in the ionic current through a silicon nitride nanopore was found to change depending on the metal ion species in the aqueous solution. The order of the low-frequency noise magnitudes of the alkali metal ionic current was consistent with the order of the adsorption affinities of the metal ions for the silanol surface of the nanopore (Li

Survival outcomes of patients with high-grade and poorly differentiated thymic neuroendocrine carcinoma.

High-grade and poorly differentiated thymic neuroendocrine carcinoma is the rarest entity in thymic epithelial tumours. The aim of this study is to report survival data in a multi-institutional database in comparison to data in the literature. Retrospective chart review was performed on the basis of our multi-institutional database to identify patients undergoing the resection of poorly differentiated thymic neuroendocrine carcinoma between 1991 and 2018. Relevant factors were extracted, and survival analysis was performed using the Kaplan-Meier method. Twenty-one patients were identified. Five-year overall survival and recurrence-free survival were 64.6% and 51.8%, respectively. Twelve (57.1%) patients had recurrences. Due to the scarcity of data reported in the literature, our data may be used as a standard in high-grade and poorly differentiated thymic neuroendocrine carcinoma.

Thoracoscopic rib resection and reconstruction of chest wall: Our clinical experience.

Chest wall resection is traditionally performed via open thoracotomy, a procedure that increases surgical morbidity and reduces postoperative quality of life. Conversely, thoracoscopic chest wall resection may minimize invasiveness but the optimal procedure remains uncertain. We previously reported rib resection using a pneumatic high-speed power drill during video-assisted thoracoscopic surgery for selected lung cancer patients. In this report, we present two cases of chest wall tumor resected using the drill via the thoracoscopic approach. We also report thoracoscopic chest wall reconstruction in one patient using a patch sheet.

Impact of the macrocyclic structure and dynamic solvent effect on the reactivity of a localised singlet diradicaloid with π-single bonding character.

Localised singlet diradicals are key intermediates in bond homolysis processes. Generally, these highly reactive species undergo radical-radical coupling reaction immediately after their generation. Therefore, their short-lived character hampers experimental investigations of their nature. In this study, we implemented the new concept of "stretch effect" to access a kinetically stabilised singlet diradicaloid. To this end, a macrocyclic structure was computationally designed to enable the experimental examination of a singlet diradicaloid with π-single bonding character. The kinetically stabilised diradicaloid exhibited a low carbon-carbon coupling reaction rate of 6.4 × 103 s-1 (155.9 µs), approximately 11 and 1000 times slower than those of the first generation of macrocyclic system (7.0 × 104 s-1, 14.2 µs) and the parent system lacking the macrocycle (5 × 106 s-1, 200 ns) at 293 K in benzene, respectively. In addition, a significant dynamic solvent effect was observed for the first time in intramolecular radical-radical coupling reactions in viscous solvents such as glycerin triacetate. This theoretical and experimental study demonstrates that the stretch effect and solvent viscosity play important roles in retarding the σ-bond formation process, thus enabling a thorough examination of the nature of the singlet diradicaloid and paving the way toward a deeper understanding of reactive intermediates.

Reaction of Oxygen with the Singlet Excited State of [n]Cycloparaphenylenes (n = 9, 12, and 15): A Time-Resolved Transient Absorption Study Seamlessly Covering Time Ranges from Subnanoseconds to Microseconds by the Randomly-Interleaved-Pulse-Train Method.

Reaction of 3O2 with singlet excited state (S1) of highly luminescent cycloparaphenylenes (CPPs), i.e., [n]CPP where n = 9, 12, and 15 in solution has been studied by transient absorption (TA) measurements seamless for the time range from subnanosecond to microsecond based on the randomly-interleaved-pulse-train (RIPT) method recently developed by our group. We found efficient quenching of S1 by 3O2 through observation of Sn ← S1 transient absorption and the steady state fluorescence measurements. Concomitantly, we have become aware of the acceleration of the rate of intersystem crossing (ISC) from S1 to the triplet excited state (T1) through the observation of the evident enhancement of Tn ← T1 absorption intensity. We have established the analysis procedure to evaluate the rate constant of ISC (kISC0) in the absence of O2 and the bimolecular rate constant of ISC induced by 3O2 (kISCO2) only by using TA decay data in the presence of O2. On the basis of these analyses, we further succeeded in determining the quantum yield of T1 (ΦT) with and without O2. In addition, the absorption coefficient of T1 (εT1) and S1 (εS1) could be estimated with reference to that of T1 of C60. These photophysical parameters are largely dependent on the ring size, where the lifetime of S1 (τS) in the absence and presence of O2 dominates ΦT as well as the quantum yield of fluorescence (ΦF).