Synthesis And Properties Of Heptafluorobutyl-substituted Perylenetetracarboxylic Diimide Dimer

Perylenetetracarboxylic diimides(PDIs) are among the most valuable functional dyes with promising application potentials in many areas of scientific research. The unique optical and electronic properties of PDIs, such as strong photoelectrochemical activity and semiconducting properties, have attracted extensive attention in the areas of electronic and optoelectronic devices, chemical sensors and catalysis. Our research work has been mainly focused on the following two respects:A novel amphiphilic heptafluorobutyl-substituted perylenetetracarboxylic diimide dimer, 1-amino-3,5-[N-amino-N’-heptafluorobutyl-1,6,7,12-tetra(tert-butylphenoxy)- 3,4:9,10-perylene diimide]- 2, 4, 6- triazine(2PDIF-TAZ), is designed and synthesized. The self-assembly properties in the mixed tetrahydrofuran/water(THF/H2O) solvent systems with changing volume ratios are comparatively studied by scanning electron microscopy(SEM), electronic absorption, fluorescence spectroscopy and X-ray diffraction(XRD) technique. The conducting properties were evaluated by current–voltage(I–V) measurements. Competition and/or cooperation between the inter-molecular hydrogen bonding, the van der Waals interaction of the 2PDIF-TAZ molecules, and in particular solvent-solute interaction leads to the formation of the microstructures with distinctly different morphology as follows: micro-flower clusters, micro-bowknots and nano-hollow spheres in 75/25, 50/50 and 25/75 THF/H2O(v/v) solvent mixtures, respectively. Analysis of the spectral changes for the aggregates relative to that in pure THF solution revealed the J-aggregate nature of 2PDIF-TAZ in the self-assembled microstructures. However, the difference in the shift of the absorption bands for the micro-flower clusters, micro-bowknots and nano-hollow spheres indicates the dependence of the solvent-2PDIF-TAZ intermolecular interaction during the self-assembly process, which counterbalances the intermolecular interactions of 2PDIF-TAZ molecules, particularly the hydrogen bonding, the π-π stacking and hydrophobic interaction between side groups. XRD results clearly reveal a definite trend toward stronger intermolecular interactions follows the order of nano-hollow spheres < micro-flower clusters < micro-bowknots, further confirming the effect of the solvent on tuning the intermolecular interaction and in turn the intermolecular stacking of 2PDIF-TAZ molecules in the self-assembled microstructures. Moreover, the conductivity of the micro-bowknots is more than ca. 1 order of magnitude higher than those of micro-flower clusters and nano-hollow spheres. In addition, the highly hydrazine sensing response has also been observed in these microstructures. Compared to the self-assembled microstructures in air, upon saturated with hydrazine vapor, the conductivity is dramatically increased by about 3, 4, and 5 orders of magnitude for micro-bowknots, micro-flower clusters and nano-hollow spheres, respectively. In particular, devices based on nano-hollow spheres appear to exhibit the best response for hydrazine sensing among solution-processed PDI-based aggregates reported so far. The present result not only provides a facile approach to controlling and tuning the morphology of the PDI-based molecules through the combination of molecular design and controlled intermolecular interactions in mixed solvent systems, but more importantly provides new opportunities for the design and preparation of high-performance sensing devices.Through the electronic absorption and fluorescence spectroscopy of 2PDIF-TAZ in different solvent, we can find that 2PDIF-TAZ is non-assembly in dichloromethane(DCM) solvent and is H-type congeries assembly in methanol solution. In methanol solution, the temperature has little impact on its spectrum. It indicated that the aggregations of 2PDIF-TAZ were not affected by temperature and stable at 70℃. Comparing the spectra of 2PDIF-TAZ in solid and in solution, 2PDIF-TAZ changed from H-type congeries to J-type congeries. Adding different organic small molecular reagents ino the methanol could enhance fluorescence of 2PDIF-TAZ. The carbon tetrachloride solution increase largest, fluorescence intensity increased three times. 2PDIF-TAZ in methanol solution has promising application potentials organic small molecule fluorescence recognition.