Masako Sakuragi

Bio: Masako Sakuragi is an academic researcher from Japanese Ministry of International Trade and Industry. The author has contributed to research in topics: Liquid crystal & Photochromism. The author has an hindex of 14, co-authored 41 publications receiving 553 citations. Previous affiliations of Masako Sakuragi include University of Tsukuba & Chiba University.

The role of triplet state of nitrospiropyran in their photochromic reaction

Abstract: The effects of intermolecular and intramolecular triplet quenchers and sensitizers on the photochromism of nitrospiropyran have been examined in order to clarify the role of the triplet state (3A*) as well as that of the excited singlet state (1A*). The rates of photocoloration and fatigue were significantly affected: the quenchers retarded both rates, while the sensitizers retarded the former but enhanced the latter rate. It can be concluded that more than 90% of the total amount of photomerocyanin is generated from 1A* in the photostationary state and that fatigue proceeds mainly through 3A*.

Time-Resolved Absorption Studies on the Photochromic Process of 2H-Benzopyrans in the Picosecond to Submillisecond Time Domain

Abstract: Picosecond to submillisecond photochromic reactions of 2,4-diphenyl-2H-benzopyran and 2,2,4-triphenyl-2H-benzopyran have been investigated by time-resolved absorption spectroscopy. The C−O bond cleavage of the benzopyrans (closed forms) occurs via the first excited singlet state within 2 ps to produce vibrationally excited open forms in the ground electronic state. In the subnanosecond to submillisecond time domain, several decay components with almost the same spectral profiles are observed. These components are assigned to respective stereoisomers with respect to two double bonds and one single bond of the open enone forms. From the pump-laser power dependencies of the yields of the open forms, it is suggested that the photocleavage gives at first only the open forms revertible to the closed form by a single-bond rotation, and that the photoexcitation of the first generated open forms gives rise to other open forms which need a double-bond rotation for reversion to the closed form. The photochromic reac...

Spiropyran-based dynamic materials

Abstract: In the past few years, spiropyran has emerged as the molecule-of-choice for the construction of novel dynamic materials. This unique molecular switch undergoes structural isomerisation in response to a variety of orthogonal stimuli, e.g. light, temperature, metal ions, redox potential, and mechanical stress. Incorporation of this switch onto macromolecular supports or inorganic scaffolds allows for the creation of robust dynamic materials. This review discusses the synthesis, switching conditions, and use of dynamic materials in which spiropyran has been attached to the surfaces of polymers, biomacromolecules, inorganic nanoparticles, as well as solid surfaces. The resulting materials show fascinating properties whereby the state of the switch intimately affects a multitude of useful properties of the support. The utility of the spiropyran switch will undoubtedly endow these materials with far-reaching applications in the near future.

A Compilation of Singlet Oxygen Yields from Biologically Relevant Molecules

Abstract: Singlet molecular oxygen, 02(’Ag) , has been intensively investigated over the last few decades, primarily in relation to photosensitization reactions. In combination with the increasing awareness and interest in singlet oxygen has been the development of various methodologies for the detection and quantification of singlet oxygen production. A large body of literature now exists concerning the singlet oxygengenerating abilities of a large variety of endogenous and exogenous compounds that can be photoactivated in the UV and visible regions of the electromagnetic spectrum. The purpose of this review was to compile data from many different sources to provide a convenient resource for biological scientists with interest in this area. This compilation is essentially an updated subset of the excellent comprehensive review on singlet oxygen yields by Wilkinson et af. (l), which, unlike this compilation, was not limited to biological molecules. The data are current up to the early months of 1999. The following tables include various related parameters in addition to the central parameter of the quantum yield of singlet oxygen generation (QA) for a given photosensitizer. The methodology or technique used to measure the QA value for each entry is given and ranges from direct detection of the luminescence produced on relaxation of singlet oxygen (time-resolved [TRILIT or steady-state [SSIL]), calorimetric