While m-, and p-dicyanobenzene are somewhat difficult to obtain, what about other related compounds? The reason that DCB's are such good electron acceptors is that any added charge is delocalized throughout the benzene ring. On top of that, the nitrile groups are strongly electron withdrawing, thus reducing electron density on the ring, making it easier for the ring to accept that extra electron.
So, you need to find something analagous to m-DCB, but a bit more ubiquitous. You need something that can accept a free electron, without irreversibly reacting with anything because of it. You'll need something aromatic to get that delocalization effect, and also some electron withdrawing groups on it for stabilization. As it turns out, m- and p-dinitrobenzene (DNB's) fit this description perfectly, and are used industrially for similar purposes. DNB is commonly used to stop free-radical chain reactions in polymer syntheses. In the industrial case, DNB's are added to scavenge for free electrons, essentially putting an end to any chain reaction that involves them. In the case of DCB's and photoamination and DNB's and free-radical inhibition, the catalyst performs the same task -- temporarily holding onto electrons to affect the rate of reaction.
BTW, DNB's are very cheap, as you may expect (after all, how difficult is it to dinitrate benzene?)
I've often wondered why Masahide Yasuda never published photoamination experiments using any catalysts other than DCB's. I have a feeling he may have looked into this earlier in his career, but I haven't found any article on it yet. I have his phone number laying around somewhere, and I've often thought about giving him a call to discuss this with him. However, as soon as I start making plans for this in my head, I remember that I have the common sense to know that I shouldn't harrass the poor slob. Its just one of those basic rules of life: never stalk obscure Japanese chemistry professors, unless you have a really good reason to.
