Regular assembly of cage siloxanes by hydrogen bonding of dimethylsilanol groups

A new class of ordered silica-based materials has been prepared by hydrogen bond-directed assembly of cage siloxanes modified with dimethylsilanol groups, providing a soft-chemical approach to crystalline silica materials with molecularly designed architectures.


Discussion on Fig. S4 (analysis of the diffraction data)
The ED pattern taken along the axis normal to the basal plane (Fig. S4(a)) indicates square arrays of distinct spots with tetragonal symmetry, indicating that molecules 1 are arranged in square lattice in the in-plane direction.The lattice constants were estimated to be a = b = ca.1.07 nm.According to the two-dimensional structure, several peaks in the XRD patterns were assigned to the 10, 11, 20, 21, 22, 30, 31, and 32 diffractions which are shown by the vertical blue lines in the Figure S4(b).The 10 peak in the XRD pattern of 1 after drying for 10 h is difficult to be resolved because of the overlapping with the peak at d=1.11 nm; however, the observation of the higher order peaks strongly suggests that the 10 peak is present at d=1.07 nm.Such peaks due to the two-dimensional structure were observed, being independent of the drying period.Therefore, it is suggested that the two-dimensional arrangement of 1 within the a-b plane was not affected by the drying.The other peaks are possibly due to the diffractions associated with the structures along the c direction.In the case of 1 after drying for 10 h, most of the peaks were roughly attributable to a monoclinic lattice with the lattice constants a = b = 1.07 nm, c = 1.12 nm, and β = 96.9°.The peaks (l ≠ 0) were not found in the XRD patterns of 1 after drying for 1 h and before drying.The observed peaks in the XRD patterns were also roughly attributable to the monoclinic lattices (for 1 after drying for 1 h, a = b = 1.07 nm, c = 1.40 nm, and β = 98.0°, and for 1 before drying, a = b = 1.07 nm, c = 1.60 nm, and β = 97.2°).Several peaks are not assignable to the structures, which is probably due to intermediate phases.These analyses suggest that only out-of-plane structure (c and β values) changed during the drying.Such a behavior is quite similar to that of layered compounds accommodating solvent molecules in the interlayer galleries, whose interlayer distances decrease along with the progress of the evaporation of the solvent molecules from the interlayer.
Fig. 4(c).The samples for SEM measurements were prepared with the same way as

Fig. S3
Fig. S3 FT-IR spectra of the crystals of 1 (a) before and (b) after heat treatment.

Fig. S4
Fig. S4 (a) ED pattern of 1 after drying for 10 h.The incident electron beam is normal to the basal plane.(b) XRD patterns of the crystals of 1 before drying (top), after drying for 1 h (middle) and 10 h (bottom).Blue lines and their indices show the angles and assignments of the peaks corresponding to the two dimensional lattice observed in ED pattern(a), respectively.

Fig. S7
Fig. S7 Liquid-state 1 H NMR spectrum of the sample shown in Fig. S4(a) dissolved in THF-d 8 .

Fig. S10 A
Fig. S10 A possible configuration of the interconnected network formed by polycondensation of silanol groups of 1.

Fig
Fig. S12 N 2 adsorption-desorption isotherm of 1 after heating at 150 °C for 8 d.