2,4,7-trinitrofluoren-9-one Induced Triphenylene And Oligorners Liquid Crystal Research

The discotic liquid crystal molecules display the liquid crystal properties due to the interaction of the flexible side chains and the rigid core of the planar symmetric structure.However,the self-assembling behavior of the liquid crystal molecules is affected by too many or too long flexible side chains.The rigid central core is irregular,and even the molecule is multimer or polymer.Induction of liquid crystal properties of the molecules by mixing other molecules is a common method to improve the self-assembly of molecules.For example,toping electron rich 2,4,7-trinitro 9-fluorenone(TNF)to the discotic liquid crystal materials can form charge transfer complex.The previous study on the interaction mode between HAT and TNF is controversial.Ringsdord et al said there was ABAB...intrcalation,quoting that their phase diagram shows a maximum at 50:50.On the other hand,Picken et al have a model where TNF is not intercalated between HATs but is lying on the side of the columns.But for their model they also assumed a 1:1 complex.This thesis is focused on the investigation of the interaction mode between triphenylene(HAT5)and TNF complex.Furthermore,in order to expand the research areas,two new triphenylene tetramers were designed and synthesized.The important role of TNF to induce their liquid crystal properties was also described.The main contents are as follows:The first part is the investigation of liquid crystal property of HAT5-TNF complex.HAT5 is a typical liquid crystal molecule,which can be self-assembled into hexagonal column phase.By doping the TNF molecule to form the electron donor-acceptor complex,the liquid crystal phase of the mixture compound is expanded from 70-115 ? to 0-250 ?,which greatly improves the stability of the liquid crystal.XRD experiments showed that hexagonal unit cell parameter decreases with increasing TNF concentration and the spacing between disks aking the column remains constant(0.34 nm).So it is not that the disks were tilting but clearly shows that TNF is intercalated.Their interaction mode is ABABAB…type.It is also confirmed by the microscope experiments.Phase diagram was done and found that the maximum is at 40% TNF.The second part is host-guest and liquid crystalline properties of complex between TNF and triphenylene tetramers.We successfully designed and synthesized two novel triphenylene tetramers(4HAT-P[5]A and 4HAT5-TPE).The central linkers of the tetramers are the pillar[5]arene unit for 4HAT-P[5]A and tetraphenyl-ethylene group for 4HAT5-TPE,respectively..NMR and UV-Vis spectroscopy showed that the two triphenylene tetramers both can form electron donor-acceptor complex with TNF.The NMR titration experiments showed that the ratio between guest and host are both 1:2,and the interaction constants are 0.215×104 M-1 for 4HTA-P[5]A·TNF and 8.807×104 M-1 for 4HTA-TPE·TNF,respectively.Futhermore,the liquid crystalline properties of these two triphenylene tetramers and their complexes after doping TNF were studied.The results showed that pure 4HTA-P[5]A or 4HTA-TPE don't form liquid crystalline phase.After doping TNF,4HTA-P5 A still did not show liquid crystalline property,while 4HTA-TPE showed liquid crystalline phase from 0? to 107?.Based on the two phase diagrams of 4HTA-TPE and TNF,the maximum ratio of the 4HTA-TPE and TNF is 1:3 in the solid state,which is in accordance with HAT5 and TNF(the maximum is 2:3).These work expand the research area of the triphenylene oligomers,and it is helpful to deep understand the liquid crystalline behavior of the charge transfer complex.