Synthesis And Characterization Of High Soluble Aza-heterocyclic Compounds

Aza-fused compounds are one of the important members of organic semiconductor materials,which can be used as active layers of organic field-effect transistors.It has been in wide use in organic solar cells,sensors,organic memory,radio frenquency identification tags etc.Organic semiconductors used as active materials in organic field-effect transistors are required to have good carrier mobility,which can be achieved by increasing the conjugate degree of the molecular structure.One of the typical materials is pentacene,but as the number of benzene rings increases,the molecules become less stable and they are essily degraded by oxidation or self-polymerization.The introduction of N atoms into the skeleton of benzene ring to replace methine is a good solution,which not only maintains the planarity of the molecular structure but also greatly improves the stability of the compound.Inaddition,nitrogen also changes the electronic energy level of the compound to some extent,which can be helpful to improve the carrier mobility of the field effect material.By mainting the planarity of the whole molecule,highly conjugated small field-effect molecules with high conjugate may be constructed via carbon-carbon coupling reactions to increase the number of rings.Such coupling reaction conditions require the construction of numerous ‘C-C’ bonds and this process is not easy.As to aza-fused ring compounds,the synthesis is relatively simple.Azaacenes can be prepared by condensing amino groups with hydroxyl groups,halogens,carbonyl groups,cyano groups,etc.In this study,we used triisopropylsilyl(TIPS)ethynyl substituted aromatic diamino compounds and 3,5-ditert-butyl-1,2-benzoquinone for condensation reaction to prepare a variety of diazacenes with solubilizing side-chain groups.We isolated a kind of imidazole ring fused seven-membered ring compounds,which have not yet been reported in the literature.However,in the reported papers,the products of the condensation reaction between o-diamine and o-dione(or other ortho-dihalogens,etc.)are mostly six-membered pyrazine rings,and dihydropyrazine ring compounds are a minority.The reaction mechanism for this unexpectedly discovered product was studied,and a possible pathway for the formation of this kind of imidazole seven-membered ring product and reasonable explanations were proposed.Given the specificity of this type of product,we used a controlled variable approach in experiments.By replacing different reaction substrates,we tried to find a universal response pattern.After many attempts,we found that the product of the imidazole fused seven-membered ring will be only obtained under the limited substrate in our experiments.In the series of aza-heterocylic compounds synthesized in this paper,the introduction of TIPS ethynyl group as a solubilizing group not only improves the solubility of the compound,but also increases their stability.Molecular crystallinity is improved for the introduction of the side chain also,which has important reference significance for the preparation of active materials and devices in organic field effect transistors.