A new 1,4-diazabicyclo[2.2.2]octane (DABCO)-based quaternary ammonium compound is designed, synthesized, and used as structure-directing agent (SDA) for molecular sieve synthesis. Several 1,1'-alkylenedi(4-aza-1-azonia-2,5-dimethyl-bicyclo [2.2.2] octane) type SDAs are used in all-silica synthesis mixtures. Among the SDAs tested, the use of 1, 1'-butylenedi-(4-aza-1-azonia-2,5 5-dimethylbicyclo[2.2.2]octane) gives a new phase (GUS-1), whereas the use of other SDAs gives zeolite beta ((*)BEA), ZSM-12 (MTW), and ZSM-5 (MR). The GUS-1 is indexed in the orthorhombic crystal class with refined lattice constants a = 16.4206(4) Angstrom, b = 20.0540(4) Angstrom and c = 5.0464(1) Angstrom. The crystalline architecture of GUS-1 shows the same [001] projection of the framework as that of mordenite (MOR), and is characterized by a one-dimensional 12-membered ring channel system that is closely related to the channels of ZSM-12. The GUS-1 is stable to heat upon calcination at 700 degreesC in air. The calcined material exhibits adsorption capacity that is comparable to typical large-pore one-dimensional microporous silicates. The behavior of the SDA during synthesis is also discussed.