Synthesis Of Tribenzylamine/Phosphine Derivatives And Its Applications In Molecular Recognition And Self-Assembly

Urea groups can form a-tape motif aggregates via the NH…O=C hydrogen bonding interactions in apolar solution,wherea the hydrogen bonding can be dissociated in polar solution.Urea groups can also form stable hydrogen bonding with some anions.According to the literature report,tripodal tris-urea ligands not only were reported as dimeric aggregates and supramolecular gels via the urea-urea hydrogen bonding interactions,but also tris(urea)motif has been applied in a number of stable host-guest complex via binding some anions.On the other hand,based on the research of Prof.Leyong Wang’s gyroscope-like molecules when he worked in Gladysz’s group,Dr.Jun Han in our group designed supramolecular gyroscopes which the metal as a rotator with a P-M-P axis and the tris(3-ureidobenzyl)phosphine dimeric aggregates via urea-urea hydrogen bonds as a stator framework in 2008.However,we cannot get the ideal compounds.Hence we had to found other applications about the triureas.We found that our designed triureas can develop new applications among dimeric aggregates,supramolecular gels and anion recognition base on its functions.In addition,based in the research of gyroscope-like molecules in our groups,we are developing another close-ring strategy to synthesize the di/tribenzylphosphine oxide diacetylene macrocycles through Alkyne-Coupling from O=P(CH2-m/p-C6H40CH2C≡CH)3 or O=PPh(CH2-m/p-C6H40CH2C≡CH)2.This dissertation focused on the synthesis and applications of tribenzylamine/phosphine derivatives and carried out four parts of research work:Part 1,We synthesised tris(3-ureidobenzyl)amine derivative 2-N1(a-b),it can form stable dimeric aggregates in apolar solution(special for chloroform)via urea-urea hydrogen bonds.We also designed and synthesised novel tris(3-ureidobenzyl)phosphine oxide 2-PO1 that instead of tris(ureidobenzyl)amine.However,ill-defined aggregates of tris(3-ureidobenzyl)phosphine oxide 2-PO1 are present in chloroform.Compared to the crystal structure of model compound tris(3-ureidophenyl)phosphine oxide 2-P02,we presumed that 2-PO1 may show the structure of macrocyclic hydrogen-bonded dimeric aggregates which may be formed by stabilized double hydrogen bonds between P=O groups and ureas.Finally,we tried to change the P=O groups into P·BH3 and synthesised tripodal tris(3-ureidobenzyl)phosphine borane 2-PB1.We presumed that 2-PB1 may form dimeric aggregates in CDC13 solution via urea-urea hydrogen bonds,and we also use the concentration-dependent 1H NMR,DOSY NMR spectra,the formation of heterodimers and solvent-tuning experiments between hydrogen bonds confirm that urea-urea hydrogen bonded dimeric aggregates can be formed in apolar solution.Part 2,We designed and synthesised tris(3-ureidobenzyl)amine derivatives 3-N1,which can form dimeric aggregates in apolar solution and in the solid state via urea-urea hydrogen bonds.Specifically,tris(urea)3-Nla would transform into supramolecular gels in certain solvents(such as acetonitrile,chloroform/methanol)via sonication.SEM was employed to study the morphologies of xerogel of 3-Nla,which shows the thread-like nature of gel nanofibres.We use concentration-dependent 1H NMR spectroscopy and solvent-tuning experiments etc confirm that intermolecular hydrogen bonding plays an essential role in the formation of supramolecular aggregates.Finally,we presumed possible transform model of tris(urea)3-Nla related to the transformation between dimeric capsules and supramolecular gels by sonication.Part 3,We analyzed the trisbenzylamine scaffolds that it may provide a large cavity to incluse some anions.The interactions of tris(urea)3-Nla with sulfates were examined by 1H NMR titrations conducted in DMSO-d6 and CD3CN solutions.Both of slow exchange processes were observed during the titration of one equiv.of SO42-and finally the stable 1:1 complex can be formed between 3-Nla and SO42-.The 2D NOESY spectra and optimal calculations confirmed that SO42-can be inclused in the cavity of 3-Nla.3-Nla shows good selective binding with SO42-.On the other hand,we also use tris(3-ureidobenzyl)phosphine oxide 2-PO1 apply in recognizing anions with different shapes(Br-,NO3-and H2PO4-)by UV-vis and 1H NMR spectra,and we found that 2-PO1 showed showing more binding sensitivity for H2PO4-than NO3-or Br-.Compared to 2-PO1,we designed tris(3-ureido/thioureidobenzyl)phosphine oxide 4-PO(1-2)which presents stronger binding ability of the NH groups.By means of UV-vis spectra,4-PO(1-2)also were applied in recognizing the same anions,which demonstrated best selective binding with H2PO4-,especially for 4-PO1,whose binding ability to H2PO4-is better than that to F-,Br-,AcO-,HS04-or NO3-in polar solvent.The Job plot and ESI-MS experiments indicated that all three receptors formed 1:1 stoichiometric complex with H2PO4-.According to the experiments and literature report,we presumed the possible binding model for the complex formed between P-bridgehead all three receptor and H2PO4-.Part 4,Based in the research of gyroscope-like molecules in our groups,we were developed another close-ring strategy through Glaser Alkyne-Coupling.We synthesised O=P(CH2-m/p-C6H4OCH2C≡CH)3 5-7(a-b),The structures of the major alkyne coupling products 5-1a and 5-1b1 which were a combination of two intramolecular alkyne coupling and one intermolecular alkyne coupling were determined by NMR and ESI-MS.We also synthesised O=PPh(CH2-m/p-C6H4OCH2C≡CH)2 5-7(c-d),after alkyne coupling 5-7c only product intramolecular alkyne coupling products 5-1c,wherea 5-7d not only product intramolecular alkyne coupling products 5-ldl,but also occur intermolecular molecular alkyne coupling.The crystal of 5-1 c assembled into columnar structures by orient effect of P=O group providing the possibility for 1,4-diacetylene topochemical polymerization by heating or lighting.DSC,solid UV-Vis absorption and Raman spectrum can afford proofs of the solid-state polymerization reaction under the condition of heating,wherea the polymerization only take place in the surface under the condition of lighting.The polymerization process of 5-1c can be observed by confocal Raman microscopic spectra via laser light irradiation.In summary,this dissertation has studied the applications of tribenzylanime/phosphine derivatives in the research of dimeric aggregates,supramolecular gels,anion recognition,and diacetylene macrocycles in depth,and paved a way for succeeding works.