We have recently reported phospholipid bicelles (bilayered micelles) that have positive anisotropy of the magnetic susceptibility and align with their normals parallel to an external magnetic field [J Am. Chem. Soc. 2001, 123, 1537]. Improvements have been made via the synthesis of a new phospholipid, 1-dodecanoyl-2-(4-(4-biphenyl)butanoyl)-sn-glycero-3-phosphocholine (DBBPC). Bicelles can be formed by mixing DBBPC with a short-chain phospholipid, 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) in a ratio between 5.1:1 and 6.5:1 in an aqueous medium. The P-31 NMR spectra clearly show that these bicelles align with their principal axes parallel to the magnetic field within a wide temperature range. The 31 P chemical shifts indicate that the conformation of the polar headgroup in these bicelles may be different from that in common bicelles. The phase behavior of a mixture of DBBPC/DHPC with 6:1 mole ratio was investigated in the temperature range of 10-75degreesC using P-31, H-2, and Na-23 NMR. At lower temperatures (10-54degreesC), the system is dominated by the bicellar phase. At higher temperatures (54-75degreesC), isotropic micelles are formed and coexist with the bicelles. The partial alignment of maltotriose in the DBBPC/DHPC system was studied at three temperatures, and the H-1-C-13 dipolar coupling constants are compared with those obtained for two other bicelle solutions.