Three　rare　earth　compounds　with　3-methylbenzoic　acid　(HMeBA)　have　been　hydrothermally　synthesized　directly:　Gd-2(MeBA)(6)(o-Phen)(2)　1　(o-Phen　=　o-phenanthroline),　[Gd-2(MeBA)(6)(2,2＇-bpy)](n),　2　(2,2＇-bpy　=　2,2＇-bipyridine)　and　Gd　(MeBA)(3)center　dot(4,4＇-bpy)(0.5)　3　(4,4＇-bpy　=　4,4＇-bipyridine).　These　crystal　structures　were　determined　by　single-crystal　X-ray　diffraction　with　the　following　data:　1:　monoclinic,　Cc;　2:　monoclinic,　P2(1)/n;　3:　Triclinic,　P　-　1.　The　compound　1　is　a　zero-dimensional　Bi-nuclear　oligomer　and　ligand　-o-phenanthroline　participates　in　the　coordination;　the　compound　2　is　a　one-dimensional　chain　and　the　second　ligand　-2,2＇-bpy　participates　in　coordinating　with　the　Gd　ion;　in　particular,　due　to　the　existence　of　the　second　ligand　-4,4＇-bpy　which　acts　as　the　bridge,　the　compound　3　is　the　two-dimensional　layer.　Additionally,　in　order　to　explore　the　structural　characteristic,　photo-luminescent　and　the　2D-IR　correlation　spectroscopy　containing　the　temperature-induced　structural　variations　and　magnetism-induced　structural　variations　are　used.　Crown　Copyright　(C)　2012　Published　by　Elsevier　B.V.　All　rights　reserved.