Assignment of the optical spectrum of metal porphyrin and phthalocyanine radical anions

The approach developed previously to assign the major π → π* and π* → π* bands in the optical spectra of metallophthalocyanine radical species [ MPc (−n)](n−2)− (n = 1–6), which was based on spectral band deconvolution analyses of the UV-vis absorption and magnetic circular dichroism (MCD) spectra and ZINDO calculations, is reviewed in this paper and extended to the major bands observed in the spectrum of the zinc tetraphenylporphyrin radical anion [ ZnTPP (−3)]−. The magnetic circular dichroism spectrum is dominated by an intense pseudo A term associated with the B (or Soret) transition with bands at 445 and 465 nm. Weaker bands associated with the π* → π* transition out of the partially filled LUMO give rise to two widely separated, oppositely signed, coupled B terms in the MCD spectrum at 538 and 910 nm. The Q transition is assigned to a weak absorption band at 750 nm and a shoulder slightly to the blue at 728 nm.

Estimation of the infrared absorption of ZnCl2–KBr glass by molecular dynamics

Molecular dynamic calculations have been made on glasses in the ZnCl2–KBr system in order to estimate the infrared (IR) absorption of these glasses. Oxygen-free glass was estimated to be transparent up to 25 μm. Glasses containing oxygen impurities were estimated to be transparent only up to 16 μm, with a weak absorption band around 10.4 μm. This agrees with experimental results of glasses in the ZnCl2–KBr–PbBr2 system.

An investigation of X-irradiated KCl:H and NaCl:H

The e.p.r. spectrum of a new hydrogen atom centre called the U 3 centre has been observed after X-irradiation of KC1 :H crystals at low temperatures and has been assigned to hydrogen atoms in chlorine sites. The centre bleaches thermally at 145 °K with an activation energy of 043 ± 0.03 eV. Optical bleaching experiments indicate that the centre has a weak absorption band peaking at 2-9 eV. The centre cannot be produced by ultraviolet irradiation. A production mechanism involving V k centres is proposed and is discussed in detail. The U 3 centre has also been observed in NaCl:H.

Rotatory dispersion in the amine series III-The absorption spectra of diamines

In view of the striking effect on the rotatory powers of optically active amines which occur when the lone-pair of electrons on the amino-nitrogen atom is saturated, as described in the two preceding papers, it was of importance to investigate the corresponding changes which are indicated in the absorption spectra the corresponding changes which are indicated in the absorption spectra of simple amino compounds. Absorption spectra are therefore now recorded for hydrazine and for ethylene-diamine, and the effect on these spectra of varying the acid concentration of the solutions has been measured. No previous measurements of the absorption of hydrazine in solution have been recorded, but sunao and Imanishi (1931) observed a series of bands between 2400 and 2200 A in the vapour. Ethylene-diamine has been examined by Bielecki and Henri (1913), and Castille and Ruppol (1928) have investigated its hydrochloride. The latter authors reported a weak absorption band in aqueous solutions of the salt (ϵ max = 0·4 at 2631 A), but this observation is not confirmed by the present results. It may be attributed to the presence of an impurity, since, in the first series band (ϵ max = 2 at 2631 A) was also seen, but after recrystallization of the salt it disappeared completely.