Figure 3

(a) Schematic illustration of the hexagonal columnar liquid-crystalline phases of G-quartets: In the Φ_dc phase (left), G-quartets in each column are displaced laterally around average columnar axes. In the Φ_oc phase (right), both G-quartet correlations within each column and column-column correlations are long-range. At the Φ_dc → Φ_oc transition, intercolumnar spacings between the neighboring columns (d_int) decrease by 6.5–7 Å. (b) 1D intensity profiles (i.e., x-ray scattering intensities vs. momentum transfer in the radial direction) from GMP-quadruplex arrays at [KCl] = 0.3 M, showing the Φ_dc → Φ_oc transition: Essentially similar patterns were obtained with the intermolecular quadruplex (Fig. 2a), duplex (Fig. 2b), and triplex (Fig. 2c) (see SI Appendix). In the course of the Φ_dc → Φ_oc transition, the shape of the diffraction peak changes dramatically while the peak center is shifted to a higher q_r value. Two distinct types of peaks in the intensity profile coexist over a small range of Π, i.e., a phase-coexistence region. The procedure for x-ray diffraction peak fits is described in SI Appendix. Insets: X-ray images of the GMP-quadruplex arrays in the Φ_dc (left) and Φ_oc (right) phases. Higher order diffraction rings in the x-ray images of the Φ_oc phase confirm hexagonal packing (see SI Appendix). (c) 1D intensity profiles from 22-mer HT-quadruplex (Fig. 1a,b) arrays at [KCl] = 0.3 M.