The synthesis of three different europium tetracyanoplatinates all incorporating 2,2':6',2 ''-terpyridine (terpy) have been carded out in acetonitdie/water mixtures by reaction of Eu3+ salts with terpy and potassium tetracyanoplatinate. The use of different Eu3+ sources results in the isolation of Eu(C15H11N3)(H2O)(2)(NO3)(Pt(CN)(4))center dot CH3CN (1), {Eu(C15H11N3)(H2O)(3)}2(Pt(CN)(4))(3)center dot 2H(2)O (2), or [Eu(C15H11N3)(H2O)(2)(CH3COO)(2)](2)Pt(CN)(4)center dot 3H(2)O (3) for the nitrate, triflate, or acetate salts, respectively. All three compounds have been prepared as colorless crystals, and single-crystal X-ray diffraction has been used to investigate their structural features. Crystallographic data (MoK alpha, lambda = 0.71073 angstrom, T = 290 K): 1, monoclinic, space group P2(1)/c, a = 12.835 (1), b = 15.239(1), c = 13.751(2) angstrom, beta = 105.594(9)degrees, V= 2590.8(5) angstrom(3), Z = 4; 2, triclinic, space group P(1) over bar, a = 9.1802(8) angstrom, b = 10.8008(9) angstrom, c = 13.5437(9) angstrom, alpha = 84.491(6)degrees, beta = 75.063(7)degrees, gamma = 79.055(7)degrees, V = 1272.4(2) angstrom(3), Z = 1; 3, triclinic, space group P(1) over bar, a = 12.110(3) angstrom, b = 12.7273(11) angstrom, c = 18.7054(16) angstrom, alpha = 92.859(7)degrees, beta = 92.200(11)degrees, gamma = 118.057(10)degrees, V = 2534.8(7) angstrom(3), Z = 2. Variation of the counteranions in these systems provides the opportunity to modify the structures and coordination environment of Eu3+ for 1-3. Compounds 1 and 2 are both one-dimensional, polymeric compounds that contain Eu3+ ions chelated by terpy and bridged by tetracyanoplatinate anions. 3 is a zero-dimensional complex salt in which Eu3+ is coordinated by terpy, acetate, and water, but not tetracyanoplatinate. The structural differences result in varying sensitization phenomena for the three compounds. Compounds 1 and 2 display efficient donor- acceptor intramolecular energy transfer (IET) where dual donor species, terpyricline and tetracyanoplatinate, simultaneously enhance the acceptor Eu3+ emission. In both compounds the donor species are directly coordinated to the acceptorion, and hence a highly efficient dual-donor effect is exhibited for the IET mechanisms. In 3 where only the terpy ligand is directly coordinated to Eu3+, the sensitization involves only one donor species. The Pt(CN)(4)(2-) unit in 3, which lacks direct bonding to Eu3+, exhibits strong emission indicating the lack of cooperative enhancement of the lanthanide emission.