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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: Jz on February 24, 2022, 12:38:40 AM

Title: Color center vs metal phthalocyanine
Post by: Jz on February 24, 2022, 12:38:40 AM

I know F-center is a kind of color center, which by definition, is a type of crystallographic defect in which an anionic vacancy in a crystal lattice is occupied by one or more unpaired electrons.

But can a f-center be an entire molecule embedded in a solid environment? Or does it only mean the unpaired electron in the solid environment (i.e. alkali halide).

Also, it seems to me the situation is quite similar to a metal center of a metal phthalocyanine, they are both some kinds of impurity and are embedded in a phonon environment. What would be the differences between them regarding their transitions, spectrums and their interactions with the environments?

Thank you.

Title: Re: Color center vs metal phthalocyanine
Post by: Corribus on February 24, 2022, 08:48:23 AM

How do you envision that "an entire molecule in a solid environment" could be the same as an ionic vacancy in a crystal lattice?

The photophysics of metal phthalocyanine are nothing like those of an F-center. For one, in most cases the color arising from porphyrinoids does not come from the metal center - it originates from electronic (π :rarrow: π*) transitions centered on the ring. The metal ion can certainly mediate the nature of the transitions, but you can (and do) also have color-generating transitions without a metal center (so-called free-base form).