Crystal violet lactone in acidic condition (opened ring) is deep blue-purple color, resulting from the absorbance around 600 nm. Why is it not emitting fluorescence from this excitation (FL > 600 nm).
So far, only FL around blue-green (~500 nm) with blue light (420 nm) excitation was ever reported.
The green fluorescence could be resulted from the leuco form (closed ring) or the Sn -> S0.
But what happened to the 600 nm excitation?
Could it be excited state induced rotation of one of the rings leading to non-radiative relaxation?
Or anti-kasha, due to some vibronic coupling dissipating the S1?
If it's from rotation, does it mean in viscous or solid environment, >600 nm FL could be detected?
Dear Bryan Po-Wen Chen,
I think it is possible that in a viscous or solid medium it can be detected at FL > 600 nm. Phthalimide derivatives exhibit similar properties.
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Vladimir S. Pavlovich
- Professor
Thanks for the reference, Prof. Vladimir S. Pavlovich
In my rough TD-DFT calculation, crystal violet lactone in simulation with PCM model, the freely rotating environment eventually lead to >800 nm emission with low oscillation strength (f < 0.002). So it's reasonable that under viscous liquid, it has some chance to emit fluorescence > 600 nm.
However, the emission is probably too weak for pratical applications, which is unfortunate.
It only remains for me to wish you success. I am convinced they will undoubtedly accompany you.
cordially yours
Vladimir S. Pavlovich
Good day, colleagues.
I recommend seeing a grate work of Grabowski, Rotkiewicz and Rettig [Structural changes accompanying intramolecular electron transfer: focus on twisted intramolecular charge-transfer states and structures. Chemical reviews. 2003. 103 (10). 3899-4032.n doi: 10.1021/cr940745l].
For crystal violet and other triarylmethane dyes, see p. 4005 and onward.
Best wishes
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