X-BAND AND Q-BAND ESR STUDY OF NEW POLY-CUPC COMPOUNDS SYNTHESIZED UNDER HIGH-PRESSURE - THE POSSIBILITY OF 2-DIMENSIONAL SHEET POLYMERS

We have tried to prepare the metallophthalocyanine sheet polymer (poly -MPPc) by applying high pressure and temperature. The poly-CuPc and po ly-NiPc compounds synthesized under 5 GPa at 400-780-degrees-C are sys tematically studied here with the use of X- and Q-band ESR spectroscop y. In addition to the broad ESR signal derived from the local spins on Cu2+, new paramagnetic species appear which exhibit an anisotropic sp ectrum with an axial symmetry having linewidth DELTAH = 1-1.2 G. The p rincipal values of the g tensor of this new signal are 2.0024 in the p arallel component and 2.0030 in the perpendicular one. Spin concentrat ion of these new species is estimated to be (7-9) X 10(19) spins g-1 w hich is approximately two orders of magnitude greater than that of the CuPc sheet oligomer which was synthesized under ambient pressure. The substitution of the central metal does not strongly influence the ESR properties of the narrow signal. We suppose that the new signal comes from the delocalized pi-electrons of the sheet polymer. On the other hand, in the samples synthesized at temperatures higher than 650-degre es-C, the broad and narrow signals merge into a single symmetric signa l. We explain the ESR properties of these compounds from the viewpoint of the sheet polymer model.