Search

Time-resolved transient absorption spectra of photo-irradiated 2,2′-pyridil were measured in PVA films. The broad bands at 552 and ∼455 nm, appearing just after photo-excitation of 2,2′-pyridil, ar...

The electronic absorption spectra of N,N′-bis(2-aminobenzylidene)ethylenediaminatocopper(II) (abbreviated to [Cu(amben)]) were measured in ethanol and in a KBr disk. From these spectral data together with the polarization spectrum in a stretched PVA film, the X-ray photoelectron spectra, and a VESCF-MO-CI calculation, the electronic structure of [Cu(amben)] has been clarified. The reduced polarization spectrum shows that [Cu(amben)] has longer-molecular axis (y) polarized bands at 438, 300, 280, 257.7 and 222 nm, and shorter ones (z) at 418, 280, 260, 242.5 and 224 nm. The 300 nm band is assigned to an overlap of the calculated ππ*3 and ππ*4 transitions, which are charge transfer transitions between the two π-electronic systems localized almost independently on the 2-aminobenzylideneimino groups. The solid-state electronic absorption bands, measured in a KBr disk, of [Cu(amben)] are red-shifted by 2-16 nm, and considerably broadened compared with those in ethanol, indicating that the [Cu(amben)] molecules...

The absorption and fluorescence spectra of 1-aminoanthracene (AA) in various solvents have been compared with those of 1-dimethylaminoanthracene (DMAA). This comparison has demonstrated that the amino group of AA in the ground electronic state acts as a proton-acceptor to form the A-type hydrogen bond with alcohol, while that of AA in the excited electronic state acts as a proton-donor to form the B-type one. In the cyclohexane-ethanol mixed solvent, the solute-solvent configuration for the fluorescing excited state of AA changes with the ethanol concentration; it keeps the same type of hydrogen bond with ethanol as that (A-type) in the ground electronic state in the lower ethanol concentrations up to 0.2% and exhibits an intramolecular-like rearrangement of the A-type hydrogen bond into the B-type one in the ethanol concentration range of 0.2—1%. This hydrogen bond rearrangement occurs in cooperation with a bulk reorientation of solvent molecules in the range of 1—100%. AA forms the hydrogen-donor-accept...

A fluorophotometric method was used to obtain equilibrium constants for the formation of a van der Waals molecular complex between fluoranthene and benzene in the ground state. The equilibrium constant for the above-mentioned complex formation is estimated to be 0.13 dm3 mol−1, which compares well with that (K = 0.15 dm3 mol−1) obtained from a traditional electronic absorption method.

The 1H NMR spin-lattice relaxation time T1 in a spin 1/2 1-D antiferromagnetic complex [NiBr(chxn)2]Br2 was observed down to 1.8 K. The observed T1 temperature dependence was well reproduced by the Sachdev’s treatment giving an exchange interaction energy (J) of ca. 2500 K. 1-D spin migration assignable to paramagnetic electrons in impurity amounts of NiII sites was observed at low temperatures.