Preparation of spiroborate supramolecular and peapod polymers containing a photoluminescent ruthenium(ii) complex

The immobilization of functional metal complexes onto polymer supports remains one of the most important research areas. In this study, we prepared spiroborate supramolecular and peapod polymers containing a cationic photoluminescent ruthenium(ii) complex. The supramolecular polymer was obtained by mixing spiroborate cyclic trimer bearing homoallyl group and a ruthenium(ii) tris(bipyridyl) complex, and was further converted into the corresponding peapod polymer by olefin metathesis polymerization. The structure of these polymers was determined by 1H NMR, dynamic light scattering, inductively coupled plasma-atomic emission spectroscopy, energy dispersive X-ray analyses, and atomic force microscopy. The absorption and emission behaviors of the ruthenium(ii) complex were almost the same for the free form and the supramolecular polymer in the mixed solvent of N,N-dimethylformamide and chloroform, although the emission intensity decreased when the chloroform portion was increased. On the other hand, the hypsochromism was observed upon the emission of the ruthenium(ii) complex in the peapod polymer, probably due to the rigidochromic effect of the tight encapsulation by the peapod structure.


Dynamic light scattering (DLS) experiment (Fig. 2)
Dynamic light scattering experiments were performed using a Malvern Instruments Zetasizer-Nano ZS equipped with a 4 mW He-Ne laser (633 nm wavelength) at a fixed detector angle of 90°. Measurements were performed at 20 °C. For data analysis, the viscosity and refractive index of DMF at 20 °C (0.9200 mPa·s and 1.431, respectively) were used. The measurements were performed in square quartz cell. The autocorrelation functions of the backscattered light fluctuations were analyzed (Stokes-Einstein) using the DTS v4.20 software (Malvern) that provided the hydrodynamic diameter (Dh), polydispersity and the size distribution. In preparation of sample solutions, 1.0 mg of Ru-SP or Ru-PP was dissolved in 2.0 mL of DMF in a vial, and transferred into a 10 mm glass cuvette.

UV-vis and photoluminescence analyses (Fig. 3)
UV-vis spectra were recorded on a JASCO V-660. Each sample concentration was adjusted to 10 μM (for [Ru(bpy)3](PF6)2) or 40 mg/L (for Ru-SP and Ru-PP) in each solvent. The measurements were performed in square quartz cell at 25 °C. Photoluminescence spectra were recorded on a SHIMADZU RF-5300PC. Each sample concentration was adjusted to 10 μM (for [Ru(bpy)3](PF6)2) or 40 mg/L (for Ru-SP and Ru-PP) in each solvent. The measurements were performed in square quartz cell at 25 °C.

Atomic force microscopic (AFM) observation (Figs. 4 and S3)
Atomic force microscopy (AFM) studies were performed with a Shimadzu SPM-9700 microscope. All experiments were carried out in dynamic mode at ambient atmosphere. A silicon cantilever was used with a resonance frequency of 150 kHz. The sample was prepared by dropping DMF/chloroform (ca. 1:20 (v/v)) solution of Ru-SP or Ru-PP (1.4 mg/L) on a HOPG substrate.

Supporting Information
S4 ICP-AES analysis (Fig. S1) ICP-AES analyses were carried out on a SPECTRO ARCOS FHX22 inductively coupled plasma-optical emission spectrometer equipped with a radial torch, linear CMOS array detector, and nebulizer chamber for sample introduction. The plasma conditions used were an rf power of 1.20 kW applied to the plasma and flow rates of 13 L/min for the plasma gas, 0.8 L/min for the auxiliary gas, and 0.8 L/min for the nebulizer gas. The pump ratio of the sample uptake was 1.8 mL/min for each of three replicate scans. Elemental standard solutions to ICP-AES optimization were purchased from FUJIFILM Wako pure chemicals (for B and Fe) or Acros Organics (for Ru). In preparation of sample solution, 1.0 mg of each sample was subjected to wet ashing using the mixed acid of 60% HNO3 aq, 60% HClO4 aq, and conc. H2SO4 (10:5:3 volume ratio) and diluted with deionized water with adjusting total volume to 10 mL necessary to perform the ICP-AES determinations. Plasma emission was detected at 249.773 nm (for B), and Fe-PP (red).

S6
Energy dispersive X-ray analysis (Fig. S2) Energy dispersive X-ray (EDX) measurements were performed using Oxford Instruments INCA X-Max 80 detector installed in a JEOL JEM-2100 transmission electron microscope. PP powders dispersed in methanol were crushed in an agate mortar, and the obtained PP fragments were deposited on a Cu microgrid. EDX spectra were collected with 200 kV electron beam with a size of approximately 300 nm. For quantitative data analysis, Cliff-Lorimer method was employed.