Nope, the canon episode "Covenant" where Dukat kidnaps Kira to that station.
We were never led to believe there was anything of importance in the system it is located in
But we know the station
is in that system. We can speculate that it is there for some reason, as the Cardassians wouldn't build it there for no reason.
Of course, it may be that such stations are not built on the spot, but rather towed to the location. This goes against some ideas from various novels and comics, but I don't think canon requires us to believe that it's impossible to tow a station of that type from star to star. Perhaps Empok Nor was underway to some place of importance when the towing was aborted? Say, the world in need of an ore refinery/intimidation platform was lost in the old war with the Federation, and no other world in similar need was found?
It just looks a bit odd to me that Empok Nor is so well equipped, with a Quark's-like bar area and all, if the station is only in the process of being towed to its operational area.
Do we have some reason to think this star system did
not have a planet that produced ore to be refined? I would imagine the refining systems would form a lion's share of the station's structures, and would look much the same even if Empok Nor did not have the same intimidation hardware as Terok Nor did - i.e. if Empok Nor orbited a world that lacked a native population.
Timo Saloniemi