ABSTRACT
The photo-quenching mechanism of 2-(4-phenylboronic acid)-1-pyrenemethamide (C1-APB), which has potential application as a saccharide-recognition sensor, was investigated. By performing temperature-dependent time-resolved photoluminescence measurements, we determined the mechanism responsible for the photo-quenching properties of C1-APB to be a photoinduced electron transfer (PET). Moreover, the dependence of the electron transfer rate (kPET) on the solvent water concentration was explored in detail, and it was found that kPET increased by many orders of magnitude with increasing water concentrations. This phenomenon was analyzed using the Marcus model, in which the electron transfer can be represented by a potential diagram involving the potential barrier (ΔGa) and frequency factor (A). With the aid of temperature-dependent measurements, the contribution of ΔGa and A to the increase in kPET was successfully analyzed independently, which allowed us to discuss the effect of water molecule orientation and change in molecular structure of C1-APB. The temperature-dependence measurements performed in this study offer a powerful research tool for investigating the PET process, and will contribute to the development of molecular recognition fluorescent sensors.
ABSTRACT
LEOPARD syndrome is a rare congenital disease characterized by seven features. Besides the original clinical manifestations, hypertrophic cardiomyopathy was reported as an additional laboratory finding recently. We gave general anesthesia to a child of this syndrome, and encountered ECG changes during emergence from anesthesia. The diagnosis was made in her infancy, and had been receiving beta-blocker treatment ever since. The preoperative examination showed remarkable right axis deviation in ECG, and asymmetric ventricular septal hypertrophy in echocardiography. After the operation, several kinds of arrhythmia (i.e. atrioventricular junctional rhythm, atrioventricular dissociation, etc), were observed and they continued for a few minutes. Careful planning for the perioperative management of this syndrome is mandatory. The cardiomyopathy must be examined beforehand. We made an effort to prevent the extreme changes of pre- and after-load during the general anesthesia.
