Customized Integrating-Sphere System for Absolute Color Measurement of Silk Cocoon with Corrugated Microstructure.

Silk fiber, recognized as a versatile bioresource, holds wide-ranging significance in agriculture and the textile industry. During the breeding of silkworms to yield new varieties, optical sensing techniques have been employed to distinguish the colors of silk cocoons, aiming to assess their improved suitability across diverse industries. Despite visual comparison retaining its primary role in differentiating colors among a range of silk fibers, the presence of uneven surface texture leads to color distortion and inconsistent color perception at varying viewing angles. As a result, these distorted and inconsistent visual assessments contribute to unnecessary fiber wastage within the textile industry. To solve these issues, we have devised an optical system employing an integrating sphere to deliver consistent and uniform illumination from all orientations. Utilizing a ColorChecker, we calibrated the RGB values of silk cocoon images taken within the integrating sphere setup. This process accurately extracts the authentic RGB values of the silk cocoons. Our study not only helps in unraveling the intricate color of silk cocoons but also presents a unique approach applicable to various specimens with uneven surface textures.

Selecting the Appropriate Radiation Therapy Technique for Extensive Brain Metastases from Tens to Hundreds: Should the Latest Technique Always Be the Best Option?

Brain metastases (BMs) are one of the most common metastatic lesions in adult cancer patients and the most common intracranial neoplasms in adult patients. Especially for multiple BMs, historically, whole-brain radiotherapy (WBRT) has been performed as the mainstay of therapy, which improves neurological symptoms and median survival. However, WBRT could negatively impact the patient's quality of life due to late complications. Owing to these complications, attempts have been made to use the latest radiotherapy (LRT) such as stereotactic radiosurgery (SRS) and intensity-modulated radiotherapy (IMRT) to treat BMs. However, for the extensive BMs (ranging from tens to hundreds), there are currently no prospective studies comparing WBRT with LRT such as IMRT or SRS. For extensive brain metastases, LRT cannot be the best option. Instead, upfront WBRT should be considered given its advantages and disadvantages, rather than LRT. We hope that faster and more reliable LRT for extensive BMs will be applicable for clinical practice without any clinical concerns in the near future.

Influence of Electronic Environment on the Radiative Efficiency of 9-Phenyl-9H-carbazole-Based ortho-Carboranyl Luminophores.

The photophysical properties of closo-ortho-carboranyl-based donor-acceptor dyads are known to be affected by the electronic environment of the carborane cage but the influence of the electronic environment of the donor moiety remains unclear. Herein, four 9-phenyl-9H-carbazole-based closo-ortho-carboranyl compounds (1F, 2P, 3M, and 4T), in which an o-carborane cage was appended at the C3-position of a 9-phenyl-9H-carbazole moiety bearing various functional groups, were synthesized and fully characterized using multinuclear nuclear magnetic resonance spectroscopy and elemental analysis. Furthermore, the solid-state molecular structures of 1F and 4T were determined by X-ray diffraction crystallography. For all the compounds, the lowest-energy absorption band exhibited a tail extending to 350 nm, attributable to the spin-allowed π-π* transition of the 9-phenyl-9H-carbazole moiety and weak intramolecular charge transfer (ICT) between the o-carborane and the carbazole group. These compounds showed intense yellowish emission (λem = ~540 nm) in rigid states (in tetrahydrofuran (THF) at 77 K and in films), whereas considerably weak emission was observed in THF at 298 K. Theoretical calculations on the first excited states (S1) of the compounds suggested that the strong emission bands can be assigned to the ICT transition involving the o-carborane. Furthermore, photoluminescence experiments in THF‒water mixtures demonstrated that aggregation-induced emission was responsible for the emission in rigid states. Intriguingly, the quantum yields and radiative decay constants in the film state were gradually enhanced with the increasing electron-donating ability of the substituent on the 9-phenyl group (‒F for 1F < ‒H for 2P < ‒CH3 for 3M < ‒C(CH3)3 for 4T). These features indicate that the ICT-based radiative decay process in rigid states is affected by the electronic environment of the 9-phenyl-9H-carbazole group. Consequently, the efficient ICT-based radiative decay of o-carboranyl compounds can be achieved by appending the o-carborane cage with electron-rich aromatic systems.

Prediction scoring system based on clinicohematologic parameters for cervical cancer patients undergoing chemoradiation.

OBJECTIVE: A scoring system based on clinicohematologic parameters in cervical cancer patients receiving chemoradiation has not been reported to date. The aim of this study was to determine the prognostic value of clinicohematologic parameters in patients with cervical cancer undergoing chemoradiation and to develop a prediction scoring system based on these results. METHODS: A total of 107 patients who received definitive chemoradiation for cervical cancer were enrolled in this study. The clinical data and hematologic parameters were retrospectively reviewed, and their prognostic value in predicting survival was analyzed. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) and the changes in these hematologic parameters (ΔNLR, ΔPLR, and ΔLMR) between pre- and post-treatment were calculated to determine the specific value of these parameters for predicting patient survival. RESULTS: The median follow-up time was 39.9 (range 2.7-114.6) months. The 3-year overall survival rate and progression-free survival rate were 80.9% (95% CI 72.7 to 90.0) and 53.4% (95% CI 44.1 to 64.8), respectively. The median progression-free survival was 67.5 months and the median overall survival was not reached. According to multivariable analysis, a ΔNLR≥0 was significantly associated with decreased progression-free survival (HR=2.91, 95% CI 1.43 to 5.94) and overall survival (HR=3.13, 95% CI 1.18 to 8.27). In addition, age (age <58.5 years; progression-free survival: HR=2.55, 95% CI 1.38 to 4.70; overall survival: HR=4.49, 95% CI 1.78 to 11.33) and the International Federation of Gynecology and Obstetrics (FIGO) stage (Ⅲ-Ⅳ; progression-free survival: HR=2.49, 95% CI 1.40 to 4.43; overall survival: HR=3.02, 95% CI 1.32 to 6.90) were identified as predictors of poor survival. CONCLUSIONS: Both the age and FIGO stage, as clinical parameters, and the ΔNLR, as a hematologic parameter, were independent prognostic factors for survival for cervical cancer patients treated with chemoradiation. Based on these results, we developed a risk score-based classification system for predicting survival.

Tumor Boost Using External Beam Radiation in Cervical Cancer Patients Unable to Receive Intracavitary Brachytherapy: Outcome From a Multicenter Retrospective Study (Korean Radiation Oncology Group 1419).

PURPOSE: We conducted this study to evaluate the outcomes of external-beam radiotherapy tumor boost (EBRT-B) in cervical cancer patients who could not receive intracavitary brachytherapy. METHODS: A total of 11 hospitals provided the data of patients who received EBRT-B during the period from January 2005 through October 2012. RESULTS: A total of 75 patients were included. The median radiotherapy dose was 46 Gy (range, 40-54 Gy) for whole pelvis and 24 Gy (range, 9-35 Gy) for EBRT-B. Initial tumor responses assessed at 2 to 6 months after radiotherapy were as follows: 46 with complete response, 22 with partial response, 2 with stable disease, and 3 with progressive disease. After a median follow-up time of 33 months, 30 patients (40.0%) showed disease progression including 21 (28.0%) with local progression. The 5-year local failure-free survival rate was 70.0%. Achieving complete response at the first follow-up visit and an overall treatment time of 53 days or less were significantly related to favorable local failure-free survival. The rate of grade 3 or higher toxicity was 2.6%. CONCLUSIONS: Approximately 70% of patients had local tumor control after curative radiotherapy using EBRT-B. Early tumor response and overall treatment time of 53 days or less were closely associated with favorable local control.

Magnetic resonance imaging during definitive chemoradiotherapy can predict tumor recurrence and patient survival in locally advanced cervical cancer: A multi-institutional retrospective analysis of KROG 16-01.

OBJECTIVE: Definitive chemoradiotherapy (CRT) followed by brachytherapy is a standard treatment for locally advanced cervical cancer. During CRT, marked reduction of cervical tumor is often observed in magnetic resonance imaging (MRI). The primary aim of this study was to assess the association between tumor response in MRI using FIGO classification and clinical outcomes. METHODS: Multi-institutional data were retrospectively reviewed to identify the significance of MR tumor response on tumor recurrence and patient survival. 225 patients with histologically confirmed squamous cell carcinoma of the cervix, staged as FIGO Ib2-IVa on initial pelvic MRI, were included. Post-CRT MRI was performed median 35days after the beginning of CRT and before brachytherapy. A median 54Gy of external radiation was given with weekly cisplatin during CRT. RESULTS: 112 (49.7%) of the 225 patients showed a positive response in post-CRT MRI and were named the responsive arm. After a median follow-up time of 36.2months, the responsive arm had significantly lower para-aortic recurrence (7.5% vs. 12.4%; p=0.04) and distant metastasis (13.2% vs. 27.6%; p=0.03) rates than did the non-responsive arm. The responsive arm had significantly higher 3-year cause-specific survival rate (94.6% vs. 81.1%, p<0.01) than did the non-responsive arm. In the multivariate analysis, tumor size (hazard ratio, 1.91 and 95% confidence interval, 1.07-3.43; p=0.028) and positive MR response (hazard ratio, 1.75 and 95% confidence interval, 1.06-2.27; p=0.045) were significant factors for recurrence-free survival CONCLUSION: Early tumor response evaluation with MRI using FIGO classification effectively predicted distant tumor metastasis and disease-specific survival in locally advanced cervical cancer.

Tumour size, volume, and marker expression during radiation therapy can predict survival of cervical cancer patients: a multi-institutional retrospective analysis of KROG 16-01.

OBJECTIVE: The aim of this multi-institutional study was to determine the prognostic impact of tumour parameters, such as tumour size (TS), tumour volume (TV), and marker expression, on survival during radiation therapy (RT) for cervical cancer patients. METHODS: A total of 231 patients with histologically confirmed cervical cancer, classified as Federation of Gynecology and Obstetrics (FIGO) Ib2-IVa, were enrolled in this study. Pre- and mid-RT pelvic magnetic resonance imaging (MRI) and squamous cell carcinoma antigen (SCC-ag) analysis were performed twice, during RT and just before brachytherapy. RESULTS: The median follow-up time was 27.8months (range, 2-116months). Multivariate analysis revealed that stage (odds ratio [OR], 2.936 and 95% confidence interval [CI], 1.119-7.707; P=0.029), tumour volume reduction rate (TVRR) (OR, 3.435 and 95% CI, 1.062-11.106; P=0.039), and SCC-ag reduction rate (SCCRR) (OR, 5.104 and 95% CI, 1.769-14.727; P=0.003) were independently associated with overall survival (OS), while pre-RT TS (OR, 2.148 and 95% CI, 1.221-3.810; P=0.009), mid-RT TV (OR, 3.106 and 95% CI, 1.685-5.724; P<0.0001) and SCCRR (OR, 1.954 and 95% CI, 1.133-3.369; P=0.016) were associated with progression-free survival (PFS). Based on the prognostic factor analysis, patients with the highest prognostic risk score of 3 showed poorer overall survival and progression free survival than patients with lower prognostic risk scores. CONCLUSION: We identified that tumour parameters such as TVRR, SCCRR, pre-RT TS, and mid-RT TV areindependent and strong prognostic parameters for patients with cervical cancer receiving RT. This scoring system-based prognostic factor analysis could be used to help develop optimized treatment plans for cervical cancer patients during RT.

Oncologic Outcomes After Adjuvant Radiotherapy for Stage II Endometrial Carcinoma: A Korean Radiation Oncology Group Study (KROG 14-10).

OBJECTIVE: The aim of this study was to investigate the survival, patterns of failure, and prognostic factors in patients with stage II endometrial carcinoma treated with adjuvant radiotherapy. METHODS: We reviewed the medical records of patients who underwent total hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection followed by adjuvant radiotherapy in 10 participating hospitals of the Korean Radiation Oncology Group. Most patients received adjuvant external beam radiation therapy, with a median dose of 50.4 Gy; approximately 50% of these patients received an additional brachytherapy boost, with a median dose of 18 Gy. Adjuvant chemotherapy was administered to 19 patients. RESULTS: A total of 122 patients were examined. Over a median follow-up period of 62.7 months (range, 1.9-158.8 months), the 5-year overall survival (OS) and disease-free survival rates were found to be 91.1% and 85.1%, respectively. Recurrence was observed in 14 patients (11.5%), including 3 with local recurrence and 11 with distant metastases as the first site of recurrence. Univariate analysis indicated that lymphovascular invasion was related to an unfavorable OS. An age of 60 years or above, histologic grade 3, and lymphovascular invasion were identified as risk factors for OS. Because there were several risk factors related to OS, we assigned patients to a high-risk group (defined as cases with ≥1 risk factors) and a low-risk group. The 5-year OS rate of the high-risk group was significantly inferior to that of the low-risk group (82.9% vs 100%, P = 0.003). CONCLUSIONS: The high-risk group had a significantly poorer survival rate than the low-risk group, and distant metastasis was the main pattern of recurrence, thus indicating that further adjuvant chemotherapy should be considered in high-risk patients.

The Predictive Value of Tumor Size, Volume, and Markers During Radiation Therapy in Patients With Cervical Cancer.

OBJECTIVES: We investigated the prognostic significance of changes in primary tumor volume and serum squamous cell carcinoma antigen (SCC-ag) levels during radiation therapy (RT) in patients with cervical cancer. METHODS: We conducted a review of 40 patients treated with RT. All patients received external beam RT and intracavitary brachytherapy. The primary tumor volume and squamous cell carcinoma antigen levels were measured pre-RT and mid-RT. Overall survival (OS) and progression free survival (PFS) were estimated, and possible prognostic factors for survival were analyzed. RESULTS: The correlation coefficient between primary tumor volume reduction rate (pTVRR) and serum squamous cell carcinoma antigen reduction rate in all patients was 0.550 (P < 0.001). In univariate analysis, stage more than II (P <0.001), pre-RT pTV of 55 cm or more (P = 0.05), mid-RT tumor size of 4 cm or more (P = 0.004), and pTVRR of 90% or less (P = 0.031) were significant unfavorable prognostic factors for PFS, whereas stage (P = 0.009) was the only significant prognostic factor for OS. Multivariable analysis revealed that none of these factors were independently associated with PFS or OS. CONCLUSIONS: There was a significant correlation between pTVRR and squamous cell carcinoma antigen reduction rate. Our findings indicate that the tumor parameters such as pre-RT pTV, mid-RT tumor size, and pTVRR are associated with PFS in women with cervical cancer.

Clinical applicability of biologically effective dose calculation for spinal cord in fractionated spine stereotactic body radiation therapy.

BACKGROUND: The aim of the study was to investigate whether biologically effective dose (BED) based on linear-quadratic model can be used to estimate spinal cord tolerance dose in spine stereotactic body radiation therapy (SBRT) delivered in 4 or more fractions. PATIENTS AND METHODS: Sixty-three metastatic spinal lesions in 47 patients were retrospectively evaluated. The most frequently prescribed dose was 36 Gy in 4 fractions. In planning, we tried to limit the maximum dose to the spinal cord or cauda equina less than 50% of prescription or 45 Gy2/2. BED was calculated using maximum point dose of spinal cord. RESULTS: Maximum spinal cord dose per fraction ranged from 2.6 to 6.0 Gy (median 4.3 Gy). Except 4 patients with 52.7, 56.4, 62.4, and 67.9 Gy2/2, equivalent total dose in 2-Gy fraction of the patients was not more than 50 Gy2/2 (12.1-67.9, median 32.0). The ratio of maximum spinal cord dose to prescription dose increased up to 82.2% of prescription dose as epidural spinal cord compression grade increased. No patient developed grade 2 or higher radiation-induced spinal cord toxicity during follow-up period of 0.5 to 53.9 months. CONCLUSIONS: In fractionated spine SBRT, BED can be used to estimate spinal cord tolerance dose, provided that the dose per fraction to the spinal cord is moderate, e.g. < 6.0 Gy. It appears that a maximum dose of up to 45-50 Gy2/2 to the spinal cord is tolerable in 4 or more fractionation regimen.

Neoadjuvant treatment of mid-to-lower rectal cancer with oxaliplatin plus 5-fluorouracil and leucovorin in combination with radiotherapy: a Korean single center phase II study.

PURPOSE: To evaluate the safety and efficacy of neoadjuvant chemoradiation with oxaliplatin and 5-fluorouracil (5-FU) in advanced mid-to-lower rectal cancer. METHODS: This was a single-arm, open-label phase II study conducted between August 2008 and August 2010. Thirty-one patients (n = 31) with clinical stage T3/T4 or lymph node positive rectal adenocarcinoma located in the middle or lower rectum without metastasis were enrolled onto the study. Data were analyzed according to the intention-to-treat principle. RESULTS: Thirty-one patients were enrolled into the study. Six patients (19.4%) experienced grade 3 diarrhea. Grade 2 nausea and vomiting occurred in 5 and 2 patients, respectively. Severe neurotoxicity was not observed. Grade 1 sensory neuropathy occurred in 10 patients (32.3%). Sphincter-saving surgery was performed in 29 patients (93.5%). The mean distance of the tumor from the anal verge was 4.9 cm. Anastomotic leakage occurred in 4 of 29 (13.8%) patients. The circumferential resection margin was involved in 2 patients (6.5%). Overall, 23 patients (77.4%) responded to treatment. The complete pathologic response (ypCR) rate was 12.9%. There was no death secondary to toxicity, and the mean follow-up time was 12.3 months. CONCLUSION: The overall toxicity of oxaliplatin and continuous 5-FU/leucovorin infusion in combination with radiation was well tolerated. Neoadjuvant chemoradiation for patients with locally advanced rectal cancer was associated with higher rates of sphincter preservation and downstaging, but did not significantly increase ypCR. The impact of this neoadjuvant chemoradiation regimen on survival will be determined by longer follow-up studies.

A urethral clear cell carcinoma case successfully treated with organ preservation surgery and adjuvant chemoradiation.

Urethral clear cell carcinoma is an aggressive tumor rarely observed in the urinary tract. To date, the diagnostic workup of such cases has not yet been standardized, and there has been no established standard treatment approach. The present study reports a rare case of urethral clear cell carcinoma successfully treated with organ preservation strategies and adjuvant chemoradiation with the goal of organ preservation. This treatment approach could be used for patients who refuse radical surgery and patients with concerns about severe morbidity from radical surgery, even in advanced-stage urethral clear cell carcinoma.

Prediction of Radiotherapy Compliance in Elderly Cancer Patients Using an Internally Validated Decision Tree.

This study aims to analyze the relationship between the available variables and treatment compliance in elderly cancer patients treated with radiotherapy and to establish a decision tree model to guide caregivers in their decision-making process. For this purpose, 456 patients over 74 years of age who received radiotherapy between 2005 and 2017 were included in this retrospective analysis. The outcome of interest was radiotherapy compliance, determined by whether patients completed their scheduled radiotherapy treatment (compliance means they completed their treatment and noncompliance means they did not). A bootstrap (B = 400) technique was implemented to select the best tuning parameters to establish the decision tree. The developed decision tree uses patient status, the Charlson comorbidity index, the Eastern Cooperative Oncology Group Performance scale, age, sex, cancer type, health insurance status, radiotherapy aim, and fractionation type (conventional fractionation versus hypofractionation) to distinguish between compliant and noncompliant patients. The decision tree's mean area under the curve and 95% confidence interval was 0.71 (0.66-0.77). Although external validation is needed to determine the decision tree's clinical usefulness, its discriminating ability was moderate and it could serve as an aid for caregivers to select the optimal treatment for elderly cancer patients.

Bayesian network structure for predicting local tumor recurrence in rectal cancer patients treated with neoadjuvant chemoradiation followed by surgery.

Background and Purpose: Tumor recurrence, a characteristic of malignant tumors, is the biggest concern for rectal cancer survivors. The epidemiology of the disease calls for a pressing need to improve healthcare quality and patient outcomes. Prediction models such as Bayesian networks, which can probabilistically reason under uncertainty, could assist caregivers with patient management. However, some concerns are associated with the standard approaches to developing these structures in medicine. Therefore, this study aims to compare Bayesian network structures that stem from these two techniques. Patients and Methods: A retrospective analysis was performed on 6754 locally advanced rectal cancer (LARC) patients enrolled in 14 international clinical trials. Local tumor recurrence at 2, 3, and 5-years was defined as the endpoints of interest. Five rectal cancer treating physicians from three countries elicited the expert structure. The algorithmic structure was inferred from the data with the hill-climbing algorithm. Structural performance was assessed with calibration plots and area under the curve values. Results: The area under the curve for the expert structure on the training and validation data was above 0.9 and 0.8, respectively, for all the time points. However, the algorithmic structure had superior predictive performance over the expert structure for all time points of interest. Conclusion: We have developed and internally validated a Bayesian networks structure from experts' opinions, which can predict the risk of a LARC patient developing a tumor recurrence at 2, 3, and 5 years. Our result shows that the algorithmic-based structures are more performant and less interpretable than expert-based structures.

Tuning optical properties of poly(3-hexylthiophene) nanoparticles through hydrothermal processing.

Poly(3-hexylthiophene) (P3HT) nanoparticles (NPs) were prepared by a reprecipitation method. Hydrothermal processing applied external pressure to the pristine P3HT NPs at temperatures ranging from 60 to 150 °C. Optical absorption and photoluminescence (PL) spectra for the hydrothermally treated P3HT NPs varied markedly with the processing temperature. With increasing treatment temperature, the absorption peak broadened and the peak position shifted from 510 to 623 nm; moreover, the intensity ratio of the 0-1 to 0-0 emission varied. These changes were caused by interactions between the P3HT main chains and alkyl side groups and conformational modifications induced by the high pressure during the hydrothermal process. The evolution of the optical absorption spectra of the P3HT NPs during the hydrothermal processing was strongly correlated with the variation of PL excitation spectra and with the PL emission spectra of a single NP.

A rare malignant periurethral carcinosarcoma with aggressive behavior: A case treated with a multimodal treatment approach.

Carcinosarcoma is an aggressive tumor that can develop in any organ but is rarely observed in the urinary tract. Given the radioresistant nature of carcinosarcoma and the rapidly regrowing tumor after primary surgery, carcinosarcomas that developed in the body showed poor outcomes regardless of aggressive management. However, the specific optimal treatment for periurethral carcinosarcoma remains unknown. The present study reports a rare case of periurethral carcinosarcoma with metastasis of the skull after receiving surgery for primary tumors with adjuvant concurrent chemoradiation therapy.

Overall survival nomogram for patients with spinal bone metastases (SBM).

•Demographic features are essential for a more personalize survival prediction of spinal bone metastasis (SBM).•Women have a relatively better survival chance than men before 75 years, while men have better survival after this age.•SBM survival is not dependent on the number of spinal metastases.

Short-course radiotherapy and chemotherapy for conversion surgery in patients with unresectable metastatic rectal cancer: a preliminary case series study.

Purpose: Curative treatment is challenging in patients with locally advanced rectal cancer and unresectable metastases. The aim of this study was to evaluate the clinical outcomes of short-course radiotherapy (RT) followed by systemic chemotherapy for patients with rectal cancer with mesorectal fascia (MRF) involvement and unresectable distant metastases. Methods: The study included consecutive patients diagnosed as having metastatic mid-to-low rectal cancer treated with short-course RT followed by systemic chemotherapy for conversion radical or palliative surgery between 2014 and 2019 at Gil Medical Center. The patients had primary rectal tumors involving the MRF and unresectable distant metastases. The treatment strategies were determined in a multidisciplinary team discussion. Results: Seven patients (five men and two women) underwent short-course RT (5×5 Gy) and preoperative systemic chemotherapy. The median age was 68 years (range, 46-84 years), and the median distance from the anal verge to the primary tumor was 6.0 cm (range, 2.0-9.0 cm). During the median follow-up period of 29.4 months, three patients underwent conversion radical surgery with R0 resection, two underwent palliative surgery, and two could not undergo surgery. No postoperative major morbidity or mortality occurred. The patients who underwent conversion complete radical surgery showed good long-term survival outcomes, with an overall survival time of 29.4-48.8 months and progression-free survival time of 14.7-41.1 months. Conclusion: Short-course RT followed by systemic chemotherapy could provide patients with unresectable stage IV rectal cancer a chance to undergo to conversion radical surgery with good long-term survival outcomes.

Alteration of intramolecular electronic transition via deboronation of carbazole-based o-carboranyl compound and intriguing 'turn-on' emissive variation.

The conversion of closo-o-carborane-containing compounds to the nido-o-species via deboronation causes photophysical changes that could be used for sensing applications. 9-Methyl-9H-carbazole-based closo- (closo-Cz) and nido-o-carboranyl (nido-Cz) compounds were prepared and fully characterised by multinuclear NMR spectroscopy and elemental analysis, and the solid-state molecular structure of closo-Cz was analysed by X-ray crystallography. Although the closo-compound exhibited an emissive pattern centred at λ em = ca. 530 nm in the rigid state only (in THF at 77 K and as a film), nido-Cz demonstrated intense emission in the near-UV region (λ em = ca. 380 nm) in both solution and film states at 298 K. The positive solvatochromic effect of nido-Cz and the results of theoretical calculations for both the o-carboranyl compounds supported that these emissive features originate from intramolecular charge transfer (ICT) corresponding to the o-carborane. Furthermore, the calculations verified that the electronic role of the o-carboranyl unit changed from acceptor to donor upon deboronation from closo-Cz to nido-Cz. Investigations of the radiative decay mechanisms of closo-Cz and nido-Cz according to their quantum efficiencies (Φ em) and decay lifetimes (τ obs) suggested that the ICT-based radiative decays of closo-Cz and nido-Cz readily occur in the film (solid) and solution state, respectively. These observations implied that the emission of closo-Cz in the solution state could be drastically enhanced by deboronation to nido-Cz upon exposure to an increasing concentration of fluoride anions. Indeed, turn-on emissive features in an aqueous solution were observed upon deboronation, strongly suggesting the potential of closo-Cz as a turn-on and visually detectable chemodosimeter for fluoride ion sensing.

Impact of deboronation on the electronic characteristics of closo-o-carborane: intriguing photophysical changes in triazole-appended carboranyl luminophores.

5-Phenyl-1,2,4-triazole-appended closo- (CB1 and CB2) and nido-o-carboranyl (nido-CB1 and nido-CB2) compounds were prepared and fully characterized using multinuclear NMR spectroscopy and elemental analysis. The solid-state molecular structures of both closo-compounds were analyzed by X-ray crystallography. Although the closo-compounds exhibited dual emissive patterns in the rigid state (in THF at 77 K), which were assignable to a π-π* local excitation (LE)-based emission (λem = ca. 380 nm) on the triazole moieties and to an intramolecular charge transfer (ICT)-based emission (ca. 460 nm) in which the o-carborane units acted as the acceptor (A), at 298 K in THF, the LE-based emission dominated. In contrast, the nido-compounds exhibited an intensive emission originating from ICT transitions in which the o-carborane units reversibly acted as the donor (D). In particular, the positive solvatochromic effects of both nido-compounds and the results of theoretical calculations for the o-carboranyl compounds supported the electronic role of the o-carboranyl unit in each compound. Investigation of the radiative decay mechanism of the closo- and nido-compounds using their quantum efficiency (Φem) and decay lifetime (τobs) suggested that the ICT-based radiative decay of nido-compounds occurred more efficiently than the LE-based decay of closo-compounds. These results implied that emission from the closo-compounds was drastically enhanced by the deboronation reaction upon exposure to an increasing concentration of fluoride anions, and finally became similar to the emission color (sky-blue) of the nido-compounds.