Novel Rich Nitrogen-Embeded Polycyclic Aromatic Hydrocarbons:Molecular Design,Synthesis And Properties

The research work in this dissertation is mainly focused on developing novel nitrogen-embedded organicπ-conjugated systems,systematically investigating their structure properties and electronic behaviors,and demonstrating their promising applications in ionic recognition and sensing.Efficient synthetic strategies were developed to synthesize novel N-substituted organicπ-conjugated materials,and the relationship between structure and properties was deeply studied.This paper mainly includes the two parts:in the first part,synthesized a series of new conjugated molecules based on phthalazine containing triphenylamine,tetraphenylethylene,triphenyl borone.In the second part,we expanded the containing nitrogen system of the conjugated area,developed a simple synthetic route,1,2,7,8-tetraazaperylene and its derivatives were synthesized.The investigations of their photophysical,electrochemical and fluorescence sensing properties.Some novel results have been obtained,as outlined below:1)Two new benzoheteroarene-bridged organic mixed-valence molecules consisting of two triphenylamine chromophores and one phthalazine（PTZ-TPA）or isothianaphthene（ITN-TPA）as bridge have been achieved in good yields.It was found that they exhibit open-shell or close-shell character dependent on the bridge moiety.PTZ-TPA and ITN-TPA were readily oxidized by Cu（II）in CH₃CN to form open shell dication radicals or close shell dications,respectively.On the other hand,PTZ-TPA shows strong coordination to Hg（II）,but not for ITN-TPA.2)Using an efficient synthetic strategy,the syntheses of three benzoheteroarene derivatives that containing phthalazine（PTZ-TPE）,isothianaphthene（ITN-TPE）or isoindolenaphthene（IDN-TPE）subunits as central core and tetraphenylethene as the two lateral units are presented.The physical properties of the as-synthesized benzoheterocycle derivatives can be finely tuned through the structures of the aromatic central core.In the aggregation states,PTZ-TPE shows very weak fluorescence due to intersystem crossing effect.Whereas,ITN-TPE and IDN-TPE exhibited typical AIE phenomenon.Since PTZ-TPE exhibited unique fluorescence properties in the state of aggregation as compared with ITN-TPE and IDN-TPE,which can be released by the synergetic effect of AIE and the protonated on the 1,2-diazine segment,probably applicable for probing the strong acids within a precise pKa range.ITN-TPE exhibits colorimetric and fluorimetric detection for Cu²⁺with high selectivity and sensitivity via the formation of cation radical.3)A novel B-N chelated BODIPY analogue based on phthalazine has been synthesized in good yields,and their photophysical properties were studied.The unique molecular structure renders this N,O-chelated BODIPY analogue with rich photophysical properties in either solution or solid state,including a large stokes shift,AIE phenomenon and reversible piezochromism effect.Furthermore,this N,O-chelated BODIPY analogue polymer exhibits good capabilitiy for imaging living cells.4)Using an efficient synthetic strategy,a new class of 1,2-diazine-embedded perylene,namely 1,2,7,8-tetraaza-perylene derivatives,have been successfully synthesized.These molecules were fully characterized by X-ray diffraction analysis,optical spectroscopy and electrochemistry.The low-lying lowest unoccupied molecular orbital（LUMO）levels of these molecules suggested their potential as good electron acceptors.5)Two B-N chelated BODIPY analogues based on 1,2,7,8-tetraaza-perylene,have been designed and successfully synthesized.These molecules were fully characterized by X-ray diffraction analysis,optical spectroscopy and electrochemistry.This BODIPY analogues exhibit significantly large Stokes shifts.6)Two novel D-A polymers（P1-P2）and D-A-D-A polymer（P3）based on electron-deficient 1,2,7,8-tetraaza-perylene and BDT,DPP were designed and synthesized.Their electrochemical and spectroscopic properties were systematically investigated.In summary,this thesis is focused on developing novel N-embedded organicπ-conjugated systems based on pyridazine,some novel rich nitrogen-embeded polycyclic aromatic hydrocarbons moleculars have been synthesized,providing a new way for the further exploration of the related research.