Synthesis And Characterization Of Ladder-type Conjugated Polymers Containing Carbazole Via Heteroatom Bridges

In the past few decades,due to its good optical properties and electronic properties,trapezoidal conjugated polymers have been widely used in fields such as organic effect transistors and organic light-emitting diodes.With the continuous development of synthetic methods of conjugated polymers,people are encouraged to prepare more organic conjugated molecules with special structural units.These unique structures make the conjugated molecules have good physical,chemical and optical properties.The introduction of different heteroatoms into the molecular chain can effectively fine-tune the valence electron structure to adjust the structure with required physical and chemical properties,thereby providing conjugated organic materials with required properties.Therefore,it is of great significance to develop new trapezoidal conjugated polymers containing heteroatom bridges.In this paper,a carbazole-based ladder-shaped conjugated polymer containing heteroatom bridges is designed and synthesized.The main contents of the thesis are as follows:1.Designed and synthesized a small molecule compound with a B-O bridge with a ladder-shaped conjugated structure and its corresponding polymer.The synthesis of small molecule compounds is mainly to provide a suitable route for polymers.A series of precursor compounds containing methoxy and hydroxyl groups were synthesized.Under the catalysis of palladium complexes,aryl borate and chlorinated aromatic hydrocarbons are cross-coupled,and a regular ladder-type conjugated polymer containing B-O bridges is obtained through triphenylboron complexation.The yields of Suzuki reaction and complexation reaction are higher.The characterization of the synthesized compound by hydrogen NMR,carbon,mass spectrometry and infrared spectroscopy shows that we have successfully prepared ladder-type conjugated polymers containing B-O bridges,and the final product is soluble in dichloromethane and tetrahydrofuran,etc.Common organic solvents.The maximum ultraviolet absorption wavelengths of polymers P1 and P3 are 408 nm and 498 nm,respectively,and the fluorescence emission peaks of P1 and P3 are 502 nm and 668 nm,respectively.Studies have shown that the synthesized polymer has good optical activity.The thermal decomposition temperatures of polymers P1 and P3 with a weight loss rate of 5%are273 ^oC and 284 ^oC,respectively.It shows that the synthesized polymer has good thermal stability.2.A new method for synthesizing regular ladder-type oligo-p-aniline and ladder-type poly-p-aniline through intermolecular ring-closure reaction(SNAr)is proposed.Precursor compounds containing F and N-H groups are mainly synthesized.Under the catalysis of transition metals,aromatic F atoms are easily replaced by nucleophiles,and intermolecular ring-closure reactions(SNAr)occur to form C-N bonds.At the same time,the smaller steric hindrance also allows the Suzuki reaction to proceed smoothly.The yields of intermolecular ring-closure reaction(SNAr)and Suzuki polymerization reaction are higher.Characterization of the synthesized compounds by ¹H NMR,¹³C-NMR,mass spectrometry and infrared spectroscopy can show that we have successfully prepared ladder-type oligo-p-aniline and poly-p-aniline.The characterization of the synthesized compound by ultraviolet spectroscopy and fluorescence spectroscopy can show that the ladder-type poly-p-aniline has good optical activity.When the thermal weight loss of C2 and C4 is 5%,the temperature of C2 and C4 are almost the same,and both start to lose weight at 405?,while the temperature of C6 and M2is lower,and they start to lose weight at 315?.When the temperature rises to 800?,the weight loss of C2 and C4 is close to 70%,the weight loss of C6 and M2 is almost the same,and the weight loss is close to 50%.This may be because the larger conjugated structure leads to more residues of C6 and M2.More,the planar conjugated structure is enhanced,and the rigidity of the molecular chain is enhanced,so that C6 and M2 have better thermal stability.