Crystal structure of catena-poly[2,2′-bipyridinyl-6,6′-dicarboxylato- κ 4 N , N ′, O , O ′)-( μ 2 -2,2′-bipyridinyl-6′-carboxyl-6-carboxylato- κ 5 N , N ′, O , O ′:O′′)samarium(III)] monohydrate, C 24 H 13 N 4 O 8 Sm · H 2 O