Dendritic Conjugated Organic Molecules: Synthesis, Structure And Photoelectric Properties

The functionalized dendrimers are extensively applied as organic photoelectric materialsfor its highly ordered structure, therefore more and more researchers pay attention on itrecently. Compared with traditional organic small molecules and polymer optoelectronicmaterials, functionalized dendrimers applied as organic optoelectronic with incomparableadvantages. Therefore, it is the final target to design and synthesize a series of functionalizeddendrimers with excellent photoelectric properties in this paper. For the structure offunctionalized dendrimers can be regulated, especially the dendron can be changed easilyunder control, we obtain different types of dendritic conjugated organic molecules throughreplacing different dendron. On the basis of obtaining the target dendritic conjugated organicmolecules,at the beginning, we compare the relationship between photoelectric properties andstructure of the series of target dendritic conjugated organic molecules. Subsequently, thedendritic conjugated organic molecules with boron are the focus of research in this paper, wefirstly research the solvents effect on this type of dendritic conjugated organic molecules; andsecongdly throuhgh the fluoride titration experiments, we evaluate the value of the dendrimerconjugated organic molecules with boron as the fluoride fluorescent probes. The results ofour study are shown as follows:1. The dendritic conjugated organic molecules of S3, SC3, N2S, N2SC, SC3B3andN2SB are firstly synthesized in this paper. And their molecular structure are shown asfollows. 2. During the experiment, we cultured the single crystal of05and SC3.And we analyzedthe crystal strcture of05and SC3by X-ray diffraction. The crystal data of05indicates thatthe truxene would have perfect rigid planar stucture and some certain degree of π conjugatedeffect. The crystal data of SC3indicates that the bond length between the thiophene ring andthe ethynyl is14.17(9) nm, implying good conjugation. Additionally, the distance betweenneighboring layer in the crystal is44.95(8) nm, this data demonstrates a certain π-π stackinginteraction.3. The spectroscopy data of S3, SC3,N2S and N2SC show that the expansion of πconjugated system and introduction of strong electron dendron, will shorten the gap of energy range in π conjugated system, manifestating of redshift in the spectrum. Additionally, thoughcomparing the spectral data of SC3B3and N2SB with their precursor compounds SC3andN2S, we find that the dimesitylboryl dendron shows multi-dendrons absorption and singledendron fluorescent emission; at the same time, we also find that the synergies of theelectronic push/pull types of dendron exist in these series of dendritic conjugated organicmolecules.4. The spectroscopy data of SC3B3and N2SB in different polar solvents indicate thatsolvents effect of N2SB is more strongly than SC3B3, in the other word, N2SB is moresensitive than SC3B3to response to the polarity of chemical environment. Additionally, theresult of fluoride titration experiments of SC3B3and N2SB shows that in aprotic solvents,SC3B3is "turn-off" type of fluoride fluorescent probe and N2SB is "turn-on" type offluoride fluorescent probe.In summary, the relationship of photoelectrical properties and structure of targetcompounds are systematic compared in this paper. This study will provide a certain value ofreference to the studies on the relationship of structure and properties of these series ofmolecules. In addition, the solvents effect and the value of fluoride fluorescent probes ofSC3B3and N2SB are evaluated in this paper and the results show that N2SB is moresensitive than SC3B3to response to the polarity of chemical environment, while N2SB is anexcellent "turn-on" type of fluoride fluorescent probe.