Exciton Phenomena in Cu(II) Complexes

Exchange interaction at the supramolecular level. EPR investigation of two copper (II) compounds: [Cu2(acac)2(phen)2(bpe)](CIO4)2·(bpe)·CH3CN·H2O and [Cu2(acac)2(phen)2(bpp)](CIO4)2·6H2O (bpe=trans-1,2-bis(4-pyridyl)ethylene, bpp=bis(4-pyridyl)propane)

“…The peculiarities of the X-band spectrum marked by arrows in Fig. 3a ate similar to those observed for the polycrystalline spectra of triplet excitons when the interaction between triplet states averages incompletely the fine structure of the spectrum [3].…”

“…Computer calculations of polycrystalline spectra of interacting dimers allow us to study the regularities of the accumulation of the additional signal when the interdimer interaction does not average the fine structure for all orientations of the D-tensors in the magnetic field. The nature of this additional signal was understood [3] but only calculated spectra and their analysis allow us to determine the dependence of the accumulation of this signal and of its position on the ratio between parameters describing the system ({D}, {g}, J'), and the frequency of the microwave fiel& It is shown that the frequency dependence of the effective values of the g-tensor may be due to the influence of the additional signal, although this signal is not vividly manifested. The results of the present analysis disclose new possibilities of EPR for the investigation of weak exchange between dimer fragments on polycrystalline samples since they show that in addition to the line width, the form and position of the additional signal can be used to estimate the interdimer exchange.…”

“…In this situation additional lines together with signals corresponding to the canonical orientations of the D-tensor can be detected in the polycrystalline spectrum. For example, such lines were revealed in EPR spectra of triplet excitons [3].…”