A porous hydrogen-bonded organic framework (HOF) composed of N-hetero pi-conjugated molecules (N pi-HOF) is a promising candidate for multifunctional porous materials. However, such HOFs are still limited and only a handful of examples have been reported. In this study, we investigated the positional effects of annelated pyrazine rings on the structure and stability of N pi-HOFs to establish a design principle for N pi-HOFs. A new isomer of hexaazatrinaphthylene (CPBTQ) was synthesized and subjected to N pi-HOF construction, activation, and an evaluation of stability and permanent porosity. A comparison between two kinds of N pi-HOFs composed of isomers (CPBTQ and CPHATN) possessing three pyrazine rings annelated at different positions indicates that the positional difference of the pyrazine rings strongly affects the conformation of the peripheral phenylene groups, which then leads to different structures and stabilities of the N pi-HOFs. The activated N pi-HOF composed of CPBTQ (CPBTQ-1a) is revealed to exhibit a Brunauer-Emmett-Teller surface area of 471 m(2) g(-1) and shows HCl responsiveness thanks to the basic pyrazine rings annelated to the triphenylene core. We believe that the present results can contribute not only to the construction of multifunctional porous materials but also to the chemistry of heteroaromatic compounds.