A series of twenty-one new rare-earth p-iodobenzoic acid complexes, [RE(L1)3(L2)(H2O)]2 (RE = La3+ (1) Ce3+ (2)), [RE(L1)3(L2)]2·H2O (RE = Ce3+ (2′), Pr3+ (3), Nd3+ (4), Sm3+ (5)), Eu3+ (6), Gd3+ (7), Tb3+ (8), Dy3+ (9), Ho3+ (10), Er3+ (11), Tm3+ (12), Yb3+ (13), Lu3+ (14), Y3+ (15)), [RE(L1)3(L2)(H2O)]2 (RE = Yb3+ (13′), Lu3+ (14′), Y3+ (15′)), and RE2(L1)4(L2)2(Ox) (RE = Er3+ (11′), Tm3+ (12′)); L1: p-iodobenzoic acid; L2: 2,2′:6′,2′′-terpyridine; Ox: oxalic acid, have been hydrothermally synthesized and structurally characterized by single crystal and powder X-ray diffraction. The series includes binuclear complexes [(La3+–Ce3+), (Ce3+–Y3+)], mononuclear complexes (Yb3+–Y3+), and oxalate-bridged binuclear complexes (Er3+–Tm3+), formed as a result of in situ ligand synthesis. All twenty-one complexes feature halogen- and π-based supramolecular interactions which assemble the molecular complexes into one, two, and three dimensions. Solid-state visible and near-IR luminescence spectra were collected on complexes 5, 6, 8, 9, 12, and 13 and characteristic emission was observed. The local coordination geometry over the p-iodobenzoic acid series were analyzed and then compared to the previously described and characterized RE-p-chlorobenzoic acid and RE-p-bromobenzoic acid analogues. Additionally, structural trends and supramolecular motifs were extracted from this series of materials and compared with the previously reported p-chloro- and p-bromo materials.