Design,Synthesizes And Properties Of Pyrene-Based Aggregation-Induced Emission Luminogens

How to design aggregation-induced emission luminogens（AIEgens）that satisfied the specific requirements for OLEDs,biomedicine and luminescent sensors,has become the main focuses in the field of organic luminous materials since the revolution concept of aggregation-induced emission（AIE）was established in 2001.Herein,we designed and synthesized three types of pyrene-based AIEgens by utilizing the basic mechanism of AIE to modify the blue emitting luminogens named pyrene,whose practical applications were limited by their aggregation-induced quenching（ACQ）effect.Based on it,we mitigated ACQ effect of the molecule in aggregation state and endowed the pyrene-based AIEgens various of properties,such as aggregation-induced emission enhancement（AEE）,mechanofluorochromism（MFC）and crystal-induced emission enhancement（CIEE）.This work has positive significance for enriching AIEgens’system and realizing the specific application of pyrene functional materials in the field of organic luminous materials.This paper mainly carried out the following three parts of work:1.A series of new HAB derivatives 3a-f,in which a pyrene unit and a para-substituted phenyl group were employed in a HAB scaffold,were synthesized in reasonable yield by employing Sonogashira coupling and Diels-Alder reactions,and characterized its’structure subsequently.The derivatives exhibited AEE properties in the aggregated state by means of THF/H₂O mixtures.Techniques such as theoretical calculations,single crystal X-ray diffraction,and photophysical measurements in solution and in the solid state were employed to illustrate the tunable,variable,and sensitive AEE features in this system.Therein,an obvious dual emissive behavior was observed from 3f,which is expected to be used to synthesize single molecule luminescent materials with white emission.Combined with the above experimental results,the structure-property relationships of the pyrene-based HAB derivatives were investigated and interpreted,which indicated the potential to achieve multiple emission emitters.2.In this paper,two cyanoethylene-functionalized pyrene-based MFC luminogens were synthesized and characterized.Because of differ only in the para substituent on the terminal phenyl group,their optical properties in both solution and in the solid state are distinct.Compound 3a displayed a blue-shift（～10 nm）with enhanced emission upon mechanical stimulation.In contrast,compound 3b exhibited a significant red-shift（～50 nm）with attenuated luminescence using a grinding procedure.So the intriguing emission behaviour was further explored by in-depth theoretical simulations combined with molecular packing morphology based on X-ray crystallography.These results indicate that the significant inter-layer slippage upon grinding in 3a contributes to the blue-shift and enhanced emission by weakening theπ-πinteractions,while the collapsed intermolecular interactions in 3b through mechanical stimulation give rise to the red-shifted and attenuated luminescence by strengthening the molecular motion freedom and planar configuration.The present work provides a valuable strategy to construct pyrene-based MCL materials based on the substituent effect,has great potential in the field of sensors meanwhile.3.In the present work,three alkyl chain-dependent blue emitting pyrene-based luminogens were synthesized by Suzuki-Miyaura coupling reaction and characterized precisely.The experimental results show that these luminogens exhibited high photoluminescence efficiency both in solution（>86%）and in the solid state（>35%）.1,3,6,8-tetrakis（pentylphenyl）pyrene（TPPy）,as a photoelectric functional material,was endowed with higher quantum yield（72%）and competitiveness due to a remarkable crystallization-induced emission enhancement（CIEE）property.More importantly,TPPy exhibits high sensitivity and selectivity for ortho-nitroaniline（o-NA）with low limit of detection(9.99×10^-8 M),which is mainly due to the distinctive odd-even effects of the terminal alkyl chain.The results demonstrate that this type of luminogen can potentially be utilized for practical applications in the field of contaminant or explosive detection as a sensitive and portable fluorimeter.