Synthesis And Properties Of A Series Of Dinaphthosilole Derivatives

Siloles are?*-?*conjugated molecules.The interaction between the?*orbital of the silicon-carbon bond and the?*orbital of the butadiene segment leads to a low-lying lowest unoccupied molecular orbital?LUMO?energy level,and siloles are favorable for the electron injection and transport.Good electronic and optical properties make it more and more widely used in luminescent materials.The?*-?*conjugation effect of polybenzothiramine is stronger because of its rigid co-planar special structure of the molecular skeleton,together with its lower LUMO level,polybenzothiramine is expected to have better electronic performance.At present,most of the researches are concentrating on changing the substituents on the thiadiazoleringtoenhancethephotoelectricproperties.Reportson polybenzothiadiazole compounds are very few.As the polybenzothiene compounds have excellent photoelectric properties,this paperdesignedfourdinaphthylpyrrolemolecules.Theyare6,6-dimethyl-1,2,3,4,8,9,10,11-octapropyl-6H-dinaphtho[2,3-b:2?,3?-d]silole?4a?,1,2,3,4,8,9,10,11-octabutyl-6,6-dimethyl-6H-dinaphtho[2,3-b:2?,3?-d]silole?4b?,6,6-diphenyl-1,2,3,4,8,9,10,11-octapropyl-6H-dinaphtho[2,3-b:2?,3?-d]silole?4c?,and1,2,3,4,8,9,10,11-octabutyl-6,6-diphenyl-6H-dinaphtho[2,3-b:2?,3?-d]silole?4d?.The molecular properties of 4a-4d were proformed by B3LYP/6-31G?d?with Gaussian 03software,including geometrical structure of ground state,frontier molecular orbit,energy gap,ionization potential,electron affinity,reorganization energy.Their degree of electrons separation is relatively high,witch facilitate the injection of electrons and holes and transmission.Then on the basis of this,we synthesized 4a-4d.We proposed a new synthesis process,the first step was using alkyne as raw materials,reacting with Negishi reagent to obtain zirconium cyclopentadiene,and then coupled with halogenated benzene to obtain diiodonaphthalenes 2a and 2b,the yield was 65%and 58%;the second step was dropping n-butyllithium to diiodonaphthalenes slowly to form binaphthalene 3a and 3b,the yield was 75%and 74%;the third step was dropping t-butyllithium to binaphthalene,then adding Ph₂SiCl₂ or Me₂SiCl₂,direct substitution of two chloride ions from Ph₂SiCl₂ or Me₂SiCl₂ with 3,3?-dilithio-2,2?-binaphthalene yielded the multi-substituted silole 4a-4d,Their yields were 60%,58%,50%and 49%,respectively.In this paper,the optical properties of 4a-4d were measured by UV-Vis spectroscopy,and the optical properties were studied by cyclic voltammetry.The thermal stability was studied by differential scanning calorimetry?DSC?and thermogravimetric analysis.The results show that they have similar light absorption bands?300 nm?and very low HOMO values?-5.50 eV?.Their thermal decomposition temperatures are around 300°C,indicating that they have good thermal stability.Finally,A multilayer electroluminescent device was fabricated using 4b as a light-emitting layer.The resulting device produced bright blue emission,indicating that these siloles may be suitable materials in organic light-emitting devices.