Current topics in the thermogravimetric-differential thermal analysis (TG-DTA) of inclusion compounds (ICs) synthesized using one-dimensional (1-D) organic porous materials such as 2,4,6-tris-(4-chlorophenoxy)-1,3,5-triazine (CLPOT), and 4-X-phenylnitronylnitroxide (4-XPNN) radicals such as phenylnitronylnitroxide (PhNN) and p-nitrophenylnitronylnitroxide (p-NPNN), are reviewed. Each NN radical included in the CLPOT nanochannels with spacer molecules such as N-phenyl maleimide (N-PhMI) for dilution, or even without spacer molecules, was stable above ca. 200 °C, at which temperatures bulk PhNN or p-NPNN are usually decomposed. These results demonstrate that NN radicals can be included in CLPOT nanochannels and remain stable, even during electron spin resonance (ESR) spectroscopy at high temperatures up to 150 °C. Therefore, NN groups may be used as an ESR spin probe like many of the derivatives of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) to examine the local structure of crystalline/amorphous porous materials, polymers, and membranes.