Signaling Recognition Events with Fluorescent Sensors and Switches.

Ru(II) polypyridine complexes: photophysics, photochemistry, eletrochemistry, and chemiluminescence

6. Rehybridization of the Acceptor (RICT) 3908 7. Planarization of the Molecule (PICT) 3909 III. Fluorescence Spectroscopy 3909 A. Solvent Effects and the Model Compounds 3909 1. Solvent Effects on the Spectra 3909 2. Steric Effects and Model Compounds 3911 3. Bandwidths 3913 4. Isoemissive Points 3914 B. Dipole Moments 3915 C. Radiative Rates and Transition Moments 3916 1. Quantum Yields and Radiationless Deactivation Processes 3916

Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

Photophysics, photochemistry and solar energy conversion with tris(bipyridyl)ruthenium(II) and its analogues

External magnetic field and magnetic isotope effects on the dynamic behavior of radical pairs in solutions have been studied theoretically, where the relaxation of their electron spins was taken into account. The decay observed with some radical pairs in micellar solutions under high magnetic fields is successfully interpreted in terms of the relaxation mechanism, and the magnetic field dependence of the relaxation rates is calculated for a model system.

Theoretical study of relaxation mechanism in magnetic field effects on chemical reactions.

Photoelectron spectra were measured in the region between 6 and 21 eV for aniline, N,N-dimethylaniline, phenol, anisole, benzonitrile, acetophenone, nitrobenzene, and their methyl derivatives. The observed spectra were interpreted in terms of their MO’s obtained by the CNDO/2 and EHMO methods, the methyl-substituent effect and the steric hindrance effect being considered. Both effects are essential for the reliable assignment of the observed photoelectron spectra. We found a general tendency that the interaction of the doubly degenerate highest occupied orbitals (e1g) of the benzene ring with the highest occupied orbital of a substituent group is important for the interpretation of the observed lower energy (7∼12 eV) bands. The only exceptional case is the nitrobenzenes in which the lowest vacant orbital of the substituent group is rather close to the highest occupied orbitals of the benzene ring and the interaction between them is important. The effects of the substituent groups upon the observed photoel...

Photoelectron Spectra of Substituted Benzenes

Determinations of the highest occupied (HB, HS) and the lowest vacant levels (VB, VS) were made with benzene and some substituent groups using experimental knowledge of their ionization potentials and their near ultraviolet absorption spectra On the basis of the relative height of these levels, monosubstituted benzenes can be classified into following three groups: (1) | VS–HB | | VB–HS | for ortho‐, para‐directing molecules: (3) | VS–HB | ≈ | VB–HS | for styrene By the aid of a simple quantum‐mechanical treatment, it becomes sure that in the case of (1) the interaction between levels VS and HB is predominant and the migrating electron flows out of benzene into the substituent: on the other hand in the case of (2) the interaction between levels VB and HS is the stronger and the migrating electron moves in the reverse direction: and finally, in the case of (3), both interactions referred to in the foregoing should be taken into account with almost equal importanceFurthermore, it was shown that the difference in the ionization potential between the meta‐ and the ortho‐, para‐directing monosubstituted benzenes can be interpreted by taking into consideration the interaction of HB with HS or VS, and that the absorption bands in the wavelength region 2300∼2600A, observed with meta‐directing molecules, may be regarded as due to the transition between two levels which occur by the interaction between levels VS and HB

Saburo Nagakura

Papers

Theoretical study of relaxation mechanism in magnetic field effects on chemical reactions.

Photoelectron Spectra of Substituted Benzenes

The Relation between Energy Levels of Substituent Groups and Electron Migration Effects in Some Monosubstituted Benzenes

The Molecular Structure of N-Methylacetamide

Temperature dependence of fluorescence lifetimes of trans-stilbene