Cyclooctatetrathiophene-Nitrogenous Heterocycle Derivatives:Synthesis,AIE Property And Coordination Self-assembly

Cycloctatetrathiophene?COTh?is a typical cyclic-shaped oligothiophene,which has a"saddle-shaped"three-dimensional structure,with four active?-sites and easy to be functionalized.COTh is a novel aggregation induced emission?AIE?compound based on the mechanism of intramolecular vibrational resistance?RIV?.In this thesis,we have designed and synthesized cyclooctatetrathiophene-nitrogenous heterocycle derivatives based on COTh as building blocks.Besides the synthetic work,the aggregation induced emission and coordination assembly properties of the cyclooctatetrathiophene-nitrogenous heterocycle derivatives are also explored.The main work of the thesis can be divided into two parts as follows:1.Synthesis,AIEPropertyandCoordinationAssemblyPropertyof cyclooctatetrathiophene-nitrogenous heterocycle derivatives with two COTh units and one nitrogenous heterocycle unitWith 13 as the starting material,compound 14 is obtained by selective TMS deprotection of 13,and then deprotonation with n-BuLi and borylation with isopropoxyboronic acid pinacol ester.Compounds 1-5 were synthesized via Suzuki reactions between 15 and2,6-dibromopyridine,4,6-dibromopyrimidine,6,6'-dibromo-2,2'-bipyridine,2,9-dibromo-1,10-phenanthroline and 2,4-dichloro-1,3,5-triazine respectively.The five target compounds were characterized by ¹H NMR,¹³C NMR spectrum and high resolution mass spectrometry.In addition,the single crystal structure of the compound 1 and 4 was obtained.Molecule 1 shows a racemate,in which the thiophene unit and Triazine unit adopt a preferred syn-locked conformation ascribed to the intramolecular N···S interaction.Molecule 2 shows a mesomer,in which the thiophene unit and pyrimidine unit adopt a preferred syn-locked conformation ascribed to the intramolecular N···S interaction.UV-vis spectroscopy indicated that 1-5 all contain the four obvious absorption bands.The absorption band-??peaked at 230 nm?and band-??peaked at 290 nm?are from the skeleton absorption of COTh,and the two absorption peaks in long wavelength region band-??330-350 nm?and band-??390-410 nm?are from the conjugation effect and intramolecular charge transfer?CT?absorption,respectively.The experimental results confirmed that 1-5 all showed obvious AIE phenomenon.Compound 3 showed the weakest fluorescence quantum yield of 1.87%due to the reasonable rotation from the single bond of bipyridines.The fluorescence intensity of 5 gave a strongest fluorescence quantum yield of 9.69%due to the strong intramolecular charge transfer?ICT?and good co-planar conformation between the thiophene unit and triazine unit.The coordination self-assembly properties for 1-4 showed that the four compounds have good coordination abilities with Ag?I?or Cu?I?.¹H NMR titration and the Job's plot curve showed the 1 and 4 with Ag?I?at a ratio of 2:1 and 1:1,respectively.The ¹H NMR spectra of complexes1-Ag and 4-Ag showed a set of intense,well-resolved signals.¹H NMR titration showed the 2 and3 and Cu?I?at a ratio of 2:1,and the ¹H NMR spectra shows that multiple sets of signals.2.Synthesis,AIEPropertiesandCoordinationAssemblyPropertiesof cyclooctatetrathiophene-nitrogenous heterocycle derivatives with mutiple COTh and pyridine unitsCompounds 7 and 8 were designed and synthesized by using mutiple COTh units as the building blocks and pyridyl groups as the linking groups.All intermediates and targets were characterized by ¹H NMR,¹³C NMR spectroscopy and high resolution mass spectrometry.Compounds 6,7 and 8 showed similar UV-vis behaviors to that of 1-5,and their absorption intensity increased depends on the number of COTh and pyridine units in the molecules.In the THF-H₂O binary solvent system,Compounds 6,7and 8 showed AIE properties when the volume fraction of water reached up to 80%,70%and 70%,respectively.When the volume of water reached up to 90%,6-8 showed the strongest fluorescence intensity,and their fluorescence quantum yields reach to 0.22%,0.63%,0.71%with the fluorescence emission peaks at 560 nm,556 nm and 555 nm,respectively.Their fluorescence quantum yield enhanced with the increase of the number of COTh and pyridine units in the molecule,which is related to the intramolecular local conjugation effect.The coordination assembly properties of 7and 8are studied.The ¹H NMR titration experiment and the Job's plot curve indicate that 7 and 8coordinated to Ag?I?with ratios of 2:3and 1:2,respectively.As the increasing number of COTh and pyridine units,the solubility of the ligand and the complex deteriorates,resulting in the disappearance of the nuclear magnetic signal peak of the Ag?I?complex of 8.