Design,Synthesis,Structure-function Relationship And Properties Of Polysubstituted Single-benzene Derivative Luminescent Crystal Materials

Organic luminescent crystal materials have attracted extensive attention in the fields of optic functional devices,sensors and bio-imaging caused by their clear crystal structures,uniform physicochemical properties and good biocompatibilities.Among them,polysubstituted single-benzene derivatives have the advantages of small molecular weights,simple structures and easy modification.However,this type of crystal materials faces challenges in the realization of efficient aggregated state fluorescence emission,long-wavelength emission and multi-stimulus responsive properties.In this paper,a series of organic crystal materials of single-benzene derivatives with different optical and mechanical properties were prepared through chemical synthesis and crystal engineering manipulation.Furthermore,the following studies were carried out around the role of polymorphic manipulation of fluorescence materials,the construction of novel efficient aggregation-induced emission fluorophores and the realization of multi-stimulus responsive properties.1)2,5-Bis（5-methyl-2-thienyl）terephthalaldehyde（BMeTPAL）was synthesized by the introduction of methylthiophene and three polymorphs of it were prepared.A combined method of crystal structure analysis and photoelectron spectroscopy was proposed to investigate the relationship between the molecular structures,stacking modes and function from the perspective of the difference of electron conjugation degree in different polymorphs.And the single-crystal-to-single-crystal transformation of crystalline products under thermal stimulation was clarified.2)Based on the additives assisted solution crystallization method,the preparation of metastable crystal form II of BMeTPAL was realized.The conformation of BMeTPAL in solution was determined by molecular simulation.Through the analysis of the interactions of different components in the solution and NMR titration experiments,it was found that the strong halogen bond andπ-πinteractions between additives and solutes inhibited the acquisition of crystal form I.3)Dimethyl 2,5-bis（（3-chloropropyl）amino）terephthalate（BCPAL）with long-wavelength emission was designed and synthesized.Two red emission polymorphs were obtained by different crystallization methods.It was found that BCPAL can recognize Cu²⁺in solution and aggregated state.In acetonitrile water mixed solvent,it has good selectivity and the detection limit can reach 0.303μM.4)A novel flexible single-benzene fluorophore dimethyl 1,2,3,4,6,7,8,9-octahydropyrido[2,3-g]quinoline-5,10-dicarboxylate（DHQB）was prepared by tandem reaction and sublimation crystallization.And it also showed aggregation-induced emission enhancement（AIEE）,optical waveguide,acid-base detection and ion selective detection properties.The results of crystal structure analysis,nano indentation and molecular interaction energy calculation showed thatπ-πand various hydrogen bond interactions in the crystal environment play a key role in the flexibility of DHQB.5)Dimethyl 1,6-dimethyl-1,2,3,4,6,7,8,9-octahydropyrido[2,3-g]quinoline-5,10-dicarboxylate（Me DHQB）was obtained by methylation of DHQB.Two efficient aggregation-induced emission（AIE）polymorphs were prepared.The single crystal structure analysis and simulation calculation showed that the enhancement of molecular vibration caused by the introduction of methyl can be effectively suppressed in the aggregated states,resulting in AIE phenomenon.Meanwhile,it was found that MeDHQBmanifested optical waveguide properties,acid-base stimulus-responsive properties and crystal phase transformation abilities.