Synthesis, Self-Assembly and Characterization of Tandem Triblock BPOSS-PDI-X Shape Amphiphiles

In this article, we report the facile synthesis, self-assembly, and characterization of shape amphiphiles (BPOSS-PDI-X) based on isobutyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS), perylene tetracarboxylic diimide (PDI), and (60)fullerene (C60) moieties. Firstly, an asymmetrically functionalized diblock shape amphiphile precursor (BPOSS-PDI-OH) was obtained through the one-pot reaction between perylene-3,4,9,10-tetracarboxylic dianhydride and two different amines, namely BPOSS-NH2 and 3-amino-1-propanol. It was further conjugated with C60-COOH to give a tri-block shape amphiphile (BPOSS-PDI-C60). Their chemical structures were thoroughly characterized by NMR, IR and MALDI-TOF MS spectrometry. In order to gain insights on the structure-property relationship, their self-assembly in gas phase, in solution, and in solid state were characterized using traveling wave ion mobility mass spectrometry (TWIM-MS), UV/Vis absorption, fluorescence emission spectrophotometer, and transmission electron microscopy, respectively. It was found that BPOSS-PDI-OH formed more complicated dimers than BPOSS-PDI-C60. Both samples showed unique aggregation behaviors in solution with increasing concentration, which could be attributed neither to H- nor to J-type and might be related to the discrete dimers. While BPOSS-PDI-C60 could hardly crystalize into ordered structures, BPOSS-PDI-OH could form nanobelt-shaped single crystals, which may hold potential applications in microelectronics.

stated above and collected with a weight of typically 3 mg. The samples were heated at a rate of 10 °C min −1 from 0 °C to 800 °C under the protection of nitrogen (40 mL/min).
One-dimensional (1D) wide angle X-ray diffraction (WAXD) experiments were conducted using a Rigaku Multiflex 2 kW automated diffractometer using Cu Kα radiation (0.1542 nm) in reflection mode. The detector scanning rate was 1° per minute, and the 2θ angle was ranged between 1.7° and 20.0°. The peak positions were calibrated using silicon powder in the high angle region (>15°) and silver behenate in the low angle region (<15°). Background scattering was subtracted from the sample patterns. In order to observe different types of crystal, various solution evaporation rates were applied (from slow to very slow) to form single crystal mats either directly on the X-ray sample holder or in a well-sealed vial before being deposited onto the X-ray sample holder.
For transmission electron microscopy (TEM, Philips Tecnai 12 at an accelerating voltage of 120 kV) experiments, the single crystals were prepared on a carbon coated mica surface. Clean TEM copper grids (400 mesh, SPI) were then used to pick up the film. Before TEM observation, samples were put into a vacuum oven for 12 hours to remove the residual solvent and moisture. Bright field (BF) images and selective area electron diffraction (SAED) patterns were then taken. The d-spacings were calibrated using a TiCl standard.
UV/Vis spectra were recorded on a Lambda 35 (Perkin Elmer) spectrophotometer using 1 mm cuvette. The excitation and emission spectra of the samples were investigated on a FP-6600 steadystate fluorescence spectrophotometer. Sample solutions with different concentrations are put still overnight to reach the equilibrium state and confirmed no precipitates before testing. All the measurements were carried out at room temperature in ambient air and the analysis range was 200-800 nm with a resolution of 1nm.
Electrospray ionization (ESI) mass spectra were obtained on a Waters Synapt HDMS quadrupole/time-of-flight (Q/ToF) tandem mass spectrometer equipped with traveling wave ion mobility (TWIM) separation. The TWIM device is located between the Q/ToF mass analyzers and consists of three parts, a trap cell, ion mobility (IM) cell, and a transfer cell. The trap and transfer cells can be used for conventional tandem mass spectrometry experiments via collisionally activated dissociation (CAD). The ion mobility cell is used in IM separations. The following parameters were used in the TWIM-MS experiments: ESI capillary voltage, 3.5 kV; sample cone voltage, 35 V; extraction cone voltage, 3.2 V; desolvation gas flow, 800 L/h (N2); trap collision energy (CE), 6 eV; transfer CE, 4 eV; trap gas flow, 1.5 mL/min (Ar); IM gas flow, 22.7 mL/min (N2); sample flow rate, 10 μL/min; source temperature, 30 °C; desolvation temperature, 40 °C; IM traveling wave velocity, 380 m/s; and IM traveling wave height, 15 V. In the tandem mass spectrometry (MS/MS) experiments, argon was used as the collision gas and the trap CE was varied from 6 to 37 eV to cause fragmentation. The sprayed solution was prepared by dissolving ~1 mg of sample in 1 mL of a MeOH/THF (v/v) 1/3 mixture and adding 5 μL of 10 mg/mL NaTFA in THF as the cationizing agent.