We report three-dimensional morphological chirality induction using a magnetic field. A right- or left-handed circular helix of zinc silicate membrane tube is selectively formed by application of a magnetic field (5−15 T), whereas the tube grows straight upward at zero field. Square and triangular helixes are also prepared. The results are interpreted in terms of the boundary-assisted magnetohydrodynamics mechanism in which the Lorentz force on ions in solution results in one-way convection of the solution near the boundary.

During the past 2 decades, a number of studies have been concerned with the role of spin-orbit coupling (SOC) interaction in chemical reactions, such as the recombination of diradi~alsl-~ and photoinduced electron and hydrogen transfer reaction^.^-^ Direct SOC interaction due to heavy atoms decreases sharply as the distance of pair radicals increases and works effectively in exciplexes or contact radical pairs (RPs). Since the SOC interaction causes sublevel selective reactions from the triplet exciplex or contact RP to a singlet state product, the electron spin polarization should be observed in the transient radicals which escaped from the nonequilibrated intermediates.In this communication, we present evidence for SOC-induced electron spin polarization in the photoinduced electron transfer reactions between xanthene dyes and p-quinones. Remarkable heavy atom effects on the radical yield and enhancement factor of the CIDEP signals were observed. Quinones used were carefully purified by double sublimation in the dark. Xanthene dyes were purified by recrystallization from ethanol. Fresh 1-propanol (reagent grade, Nacalai Co.) was used as the solvent without further purification. The timeresolved continuous wave (CW) EPR spectroscopy was described in a previous paper.'O FT-EPR measurements were carried out using an X-band pulsed EPR spectrometer (Bruker ESP 380E) equipped with the dielectric resonator (Qloo)." All spectra were measured at room temperature.'* The time-resolved CW-EPR spectra were measured for quinone anion radicals generated from the photosensitized reduction of 2,5-dichloro-p-benzoquinone (ClzBQ), p-benzoquinone (BQ), and duroquinone (DQ) with eosin Y (FlB$-).(1) Salem, L.; Rowland, C. (7) Khudyakov, I. V.; Serebrenikov, Y. A,; Turro, N. J. Chem. Rev. 1993, 93, 537 and references therein. (8) Klimtchuk, E. S.; Itinyi, G.; Khudyakov, I. V.; Margulis, L. A.; Kuzmin, V. A. J. Chem. SOC., Faraday Trans. 1 1989, 85, 4119. (9) Kikuchi, K.; Hoshi, M.; Niwa, T.; Takahashi, Y.; Miyashi, T. J. Phys. Chem. 1991, 95, 38. (10) Katsuki, A.; Tero-Kubota, S . ; Ikegami, Y. Chem. Phys. Lett. 1993, 209,258. For time-resolved CW-EPR measurements, a dye laser (Lumonics HD-300) pumped by excimer laser (Lumonics HE-400, XeCl308 nm) was used as the light pulse source.(1 1) Electron spin echo (ESE) detection technique was used to eliminate the dead-time problem in the FID measurements. The echo signal was extracted from the transient signals generated from a two-pulse (n/2-5n, t = 88 ns) sequence. The unwanted FID signals were suppressed by 4-step phase cycling (Keijzers, C. P.; Reijerse, E. J.; Schmidt, J., Eds. Pulsed EPR: a newfield of applications; North Holland: Amsterdam, 1989). The FT-EPR spectroscopy was equipped with a Nd:YAG laser (Quanta-Ray GCR-l4S, 532 nm) as the light source.(12) The sample solution was deoxygenated by argon gas bubbling and flowed into a quartz cell within EPR cavity. Measurements were performed on the 1-propanol solution with concentrations: 1 x mol dm-3 for xanthene dyes and 1 x mol dm-...