Email (record): catena-Poly[[[(2,2′-bipyridine-κ(2) N,N′)(dimethyl sulfoxide-κO)(nitrato-κ(2) O,O′)bis­muth(III)]-μ-5-carb­oxy­benzene-1,3-dicarboxyl­ato-κ(4) O (1) ,O (1′) :O (3) ,O (3′)] dimethyl sulfoxide monosolvate]