Text this: The crystal structure of poly[(μ 2-1-(1-imidazolyl)-4- (imidazol-1′-yl-methyl)benzene κ 2 N:N′)-(μ 2-3-nitrobenzene -1,2-dicarboxylato-k4,O,O′:O′′,O′′′]zinc(II)-κ 2, C21H15N5O6Zn