A highly stable soft porous coordination polymer (PCP), namely [Cu-3(TP)(4)(N-3)(2)(DMF)(2)]center dot 2H(2)O. 2DMF (1), has been synthesized via an in situ synthesis of 4-tetrazole pyridine (TP) under solvothermal conditions (DMF = N,N'-dimethylformamide). Remarkably, the solvent molecules in 1 can be respectively exchanged with cyclohexane (C6H12), cyclopentane (C5H10), decahydronaphthalene (C10H18), 1,4-dioxane (C4H8O2), and tetrahydropyrane (C5H10O) in single-crystal to single-crystal (SCSC) manners to yield [Cu-3(TP)(4)(N-3)(2)(DMF)(2)]center dot 3C(6)H(12) (1a), [Cu-3(TP)(4)(N-3)(2)(DMF)(2)]center dot 2C(5)H(10) (1b), [Cu-3(TP)(4)(N-3)(2)(DMF)(2)]center dot H2O center dot C10H18 (1c), [Cu-3(TP)(4)(N-3)(2)(DMF)(2)]center dot C4H8O2 (1d), [Cu-3(TP)(4)(N-3)(2)]center dot 3C(4)H(8)O(2) (1e), and [Cu-3(TP)(4)(N-3)(2)]center dot 2H(2)O center dot C5H10O (1f). Further, the occluded cyclohexane molecules in la can be removed by heating to give its porous guest-free form [Cu-3(TP)(4)(N-3)(2)(DMF)(2)] (1g). Particularly, in water, 1 can lose its coordinated N-3 anions to generate [Cu(TP)(2)(H2O)(4)]center dot 4H(2)O (1h). More interestingly, the soft PCP (1) demonstrates the guest selectivity for the cycloalkane solvents, namely cyclohexane, cyclopentane, and decahydronaphthalene, in SCSC manners for the first time, attributed to the synergy effect between the size and geometry of the solvent and the shape of the framework cavity. Moreover, the desolvated samples of le show the highly selective gas adsorption of CO2 over N-2, indicating its potential application in the separation of the CO2/N-2 mixture.