Photochemical cycloadditions of benzene chromophores incorporated in cyclophane structures are reviewed. Photo-cycloaddition of aromatic molecules and cycloreversion of the adducts, represented by anthracene phtodimerization-dissociation, have attracted much attention from the aspects of light-energy storage system, optical memories, photochromism, etc. By contrast, only limited information has been available concerning photodimerization of benzene chromophores. In the case that benzene chromophores are incorporated in a specific orientation within a cylophane structure, they would undergo cyclodimerization upon photo-illumination. Since benzene dimers have hardly been available by direct benzene cycloaddition, photoreactions of cyclophanes become increasingly attractive processes to reveal photoreactivities of benzenes, furthermore, investigations of detailed properties of benzene dimer are of additional interests.

This review deals with the recent progress that has been made and is still ongoing in the field of photosciences at nanoscale: thermoplasmonics. Our attention is focused mainly on the fundamental aspects of the laser-gold nanoparticle (Au NP) interaction that leads to the particle heating as well as energy deposition to the surrounding media. The former gives rise to the particle melting, deformation, and ablation, which has discussion on the mechanism. The latter generates medium temperature gradients and bubbles resulting from local heating through the heat transfer from the particle to the surroundings. The laser-Au NP interaction can be applied to the material fabrication such as fine tuning of particle size and size distribution by applying high pressures and nanohole fabrication on glass substrates. We also refer to the importance of temperature measurements in dimension smaller than the diffraction limit. We show that this can be achieved by CW laser-Au NP interaction by using the single particle spectroscopy.

DNA is a promising biomaterial as a scaffold for assembling functional molecules on a nanoscale, and many kinds of artificial DNA with molecular arrays organized along the helix axis have been constructed. Here, we demonstrate a unique approach to achieve molecular arrangement and assembly of perylenediimide (PDI) chromophores on DNA by utilizing artificial hydrophobic pockets to accommodate ligand molecules and photochemical behavior of the stacked PDI chromophores constructed inside DNA. We also describe the binding of the PDI chromophore to thymine-containing mismatch base pair in DNA and fluorescence response of PDI in the hydrophobic pocket, which can be applied for fluorescent sensor for nucleic acid and mismatch base pairs.

The possible uses of the mesoporous materials for the applications in the field of such photofunctional materials as photocatalysts, sensing/imaging and other photoresponsive materials have been proposed. Besides the nanostructure design, the developments in the morphosyntheses made mesoporous silicas more attractive as building blocks of photofunctional hybrid materials. This review article summarizes the studies on the photofunctions of mesoporous silicas done in the present author's laboratory; mesoporous silica coating of photocatalyst toward molecular recognitive photocatalytic reaction and the immobilization of photofunctional units in the mesopore with controlled manner (density, orientation and spatial distribution).

Thermally activated delayed fluorescence (TADF) involves reverse intersystem crossing from triplet states into singlet ones, and radiative decays from the singlet states. Promoting reverse intersystem crossing and radiative decay processes makes possible efficient generation of TADF. Since TADF compounds effectively convert triplet states into light, they are promising as an emitter for organic light-emitting diodes (OLEDs). Advantages of TADF compounds are high electroluminescence (EL) efficiency without rare metals and diversity of chemical structures. EL efficiency of TADF-based OLED is close to the theoretical maximum, leading to a paradigm shift from fluorescence and phosphorescence to TADF in the research field of OLEDs. We briefly review recent advances in molecular design of TADF compounds and TADF-based OLEDs.