Search

The synthesis and characterization of neutral heteroleptic molecular iridium(III) complexes with (2,4-difluoro)phenylpyridine and different pyridine-1,2,4-triazole ligands are described. The studies have shown high external quantum efficiencies and color points better than the standard for blue iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,[C.sup.2]]picolinate.

A comparison of rate constants measured for an intervalence (IV) compounds with electron-transfer parameters obtained from its optical absorption spectrum is done using resonance Raman analysis. It is suggested that the Zhu-Nakamura preexponential factor provides good consistency for the ESR rate constants using a value, averaged single-mode which closer to those predicted from the resonance Raman spectroscopic data but need slightly higher electronic coupling than [V.sub.Hush].

Photochemical charge separation within aromatic hydrazines and the effect of exited-state intervalence in dihydrazines are studied. The results suggest that the most noticeable consequence of the exited-state intervalence is, under 60% as large for Hy2(super 14)NA compared to Hy(super 1)NA and for a significantly smaller Strokes shift for the distributed compared to the monosubstituted compounds Hy2(super 26)NA compared to Hy(super 2)NA.

Analysis of optical spectra of a pseudo-para-dinitro[2.2]paracyclophane radical anion using Marcus-Hush theory reveals that its off diagonal coupling element, Hab, is large enough, relative to its reorganization energy, to change from a localized class II compound to a delocalized class II compound by changing solvents.

A model for the quantitative treatment of dihydrazine diradical dication, which possesses mixed valence excited states is introduced and utilized for explaining the observed spectroscopic consequences. Results indicate that the excited-state mixed valence could play an important role in the electronic spectra of many organic and inorganic compounds.

The electron transfer (ET) in four symmetrically substituted naphthalene-bridged bis-hydrazine radical cations is compared within the Marcus-Hush framework. The results show that ET rates estimated for four naphthalene bridged bis-hydrazine radical cations vary significantly and show no correlation with the distance between the charge-bearing units.

The optical spectrum of 2,7-dinitronaphthalene radical anion generated by Na(Hg) reduction in acetonitrile containing a large excess of cryptand[2.2.2] exhibits a Hush-type intervalence charge-transfer band at 1070nm, estimated to correspond to an off-diagonal matrix coupling element. Intramolecular electron transfer rate constants are predicted within an order of magnitude by a Marcus-Hush-type two-state classical model analysis of the optical spectrum.

Research has been conducted on intervalence radical anions which demonstrate charge-transfer bands in their near-IR spectra. The authors discuss the absorption bands of delocalized dinitroaromatic anions with aromatic bridges, and compare their optically derived electron transfer parameters with those of radical anions.