C-1 symmetry and C-sp2-H...O and C-sp3-H...O hydrogen-bond donor/acceptor ability of the title phase pi-donor are expressed by a glide plane (a +/-c/2 repetition), uniform stacks, and a band structure quarter-filled with holes. Conductivity and spin susceptibility data demonstrate strong Mott localization at ambient pressure which is weakened at high pressure. These results show that the 1/4-Umklapp scattering channel is efficient enough for localization in 1D, strongly correlated electron systems.