Consideration of phosphorescence and fluorescence properties:

To narrow things down, lets say we are talking about a purely organic small molecule (SM) luminophore in the solid state (crystalline).

Static quenching is defined as a complex formation between a luminophore and a quencher and is the main cause behind aggregation caused cuenching (ACQ). From what I have read the ACQ mainly arises from pi-pi interactions between the luminophores. Thus the hypothetical SM luminophore acts as a quencher to itself.

There are several indirect ways to minimize ACQ which mostly relies on:

a) luck -> for example C-H ....pi interactions provide alternative for pi-pi interactions thus eliminating the quencher out of the equation,

b) even more luck -> in extremely rare cases the ‘’pi-pi interactions’’ are out of the orbital overlap range (higher then 4 angstroms) thus the non-radiative energy transfer can not happen.

c) The only robust way to remove ACQ would be sterical hinderance (largely discussed as aggregation induced emission (AIE)). In these molecules highly substituted, rigid and twisted structures are used, and by doing that pi-pi interactions are supressed due to sterical reasons (lets not discuss the AIE mechanism here because it would take too long). Nevertheless even in AIE molecules occasionally strong pi-pi interaction can form due to conjugation extension etc., and in these cases AIE is quenched.

So now to my question: Are there any direct ways to eliminate static quenching/ACQ in small luminescent molecules?

By direct I mean if static quenching is a complex formation between luminophore (L) and a quencher (Q) and could be depicted as L-Q, then the solutions above (a-c) forms a relatively non-interacting (N) complex with the luminophore (L) not allowing the energy transfer to take place (L-N for depiction).

So are there any known strong interactions with a luminophore (L-Int) that would either not cause ACQ/static quenching or increase the emssion when the interaction is formed in the solid state?

Thanks in advance,

Kaspars