Synthesis And Optical Properties Of Novel Conjugated Organic Compounds

Organic two-photon absorption materials shows attractive application prospect in two-photon absorption optical limiting materials,three-dimensional optical data storage,two-photon fluorescence microscopy and imaging and dynamic light therapy.Therefore,exploring the new high-performance two-photon absorption materials has became the hotspot in research of photoelectric functional materials.We designed and synthesized seven novel conjugated compounds(T1-T7),and we studied the linear optical properties of four azoles conjugate compounds(T1-T4).Furthermore,we studied the linear and nonlinear optical properties of four conjugate aromatic olefine aldehydes(FQQ?KZQ?JYQ and T6).We used p-dimethoxybenzene as the starting material to realize the synthesis of2,5-dimethoxy-4-[(1E)-2-(4-pyridinyl)ethenyl]benzaldehyde(Z3)by the following three-step reactions:(1)bis-bromethylation reaction;(2)Arbuzov reaction;(3)Knoevenagel reaction;which was then reacted with benzil,1,10-phenanthroline-5,6-dione and 2-methylbenzothiazole by the condensation reaction to form the4-[(1E)-[2-[2,5-dimethoxy-4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl]ethenyl]pyridine(T1),2-[2,5-dimethoxy-4-[(1E)-2-(4-pyridinyl)ethenyl]phenyl]-1H-imidazo[4,5-f]-[1,10]phenanthroline(T2)and 2-[(1E)-2-[2,5-dimethoxy-4-[(1E)-2-(4-pyridinyl)ethenyl]phenyl]ethenyl]benzothiazole(T3),respectively.The 4,4'-[(2,5-dimethoxy-1,4-phenylene)di-(1E)-2,1-ethenediyl]bis(2,5-dimethoxy benzaldehyde)(Z7)was synthetized by the following reactions:(1)Bis-bromethylation reaction;(2)Arbuzov reaction;(3)Aldehyde protection reaction;(4)Horner-information-Emmons reaction,which was then reacted with benzil by the condensation reaction to form the 2,2'-[(2,5-dimethoxy-1,4-phenylene)bis[(1E)-2,1-ethenediyl-(2,5-dimethoxy-4,1-phenylene)]]bis(4,5-diphenyl-1H-imidazole)(T4).The 9-ethenyl-3-[(1E)-2-[2,5-dicyano-[4-(1E)-2-(3,4-dimethoxyphenyl)ethenyl] phenyl]ethenyl]-9H-carbazole(T5)was synthetized by the following reactions:(1)Bromination reaction;(2)Arbuzov reaction;(3)Horner-wadsworth-Emmons reaction.The 4-[(1E)-2-[4-[(1E)-2-(4-chlorophenyl)ethenyl]phenyl]ethenyl]benzaldehyde(T6)was synthetized by the following reactions:(1)Arbuzov reaction;(2)Horner-wadsworth-Emmons reaction;(3)Heck reaction.The 1-ethyl-4-[(1E)-2-[4-[(1E)-2-[4-[(1E)-2-(9-ethyl-9H-carbazol-3-yl)ethenyl]phenyl]ethenyl]phenyl]ethenyl]pyridinium bromide(T7)was synthetized by the following reactions:(1)Vilsmeier reaction;(2)Arbuzov reaction;(3)Horner-Wadsworth-Emmon reaction;(4)Heck reaction and Knoevenagel condensation reaction.The novel conjugated compounds were characterized by ¹H NMR,IR,MS and elemental analysis,etc.The linear optical properties of four conjugated aromatic olefine aldehydes(FQQ?KZQ?JYQ and T6)were studied.The experiment results indicate that the maximum linear absorption wavelength rang from 376 nm to 407 nm;the one photon fluorescence emission wavelength rang from 440 nm to 570 nm;the stokes shift rang from 3823 cm^-1to 7728 cm^-1.The fluorescence quantum yield reaches the maximumn in TOL which are 0.28,0.88,0.97 and 0.68,respectively.Furthermore,four conjugated aromatic olefine aldehydes showed obvious solvatochromic effects in different solvents.The linear optical properties of four azoles conjugated compounds(T1?T2?T3and T4)were studied.The experiment results indicate that the maximum linear absorption wavelength rang from 392 nm to 450 nm;the one photon fluorescence emission wavelength rang from 443 nm to 512 nm;the stokes shift rang from 2543cm^-1to 5226 cm^-1.The fluorescence quantum yield of T1 and T2 in THF are 0.78 and0.73,and the fluorescence quantum yield of T3 and T4 in TOL are 0.84 and 0.75.Furthermore,we studied the relationships between the polarity of solvents and the linear optic properties.Under the excitation of titanium sapphire femtosecond lasers,the two-photon induced fluorescence method was used to study the nonlinear optical properties of four conjugated aromatic olefine aldehydes.The maximum two-photon fluorescence emission wavelength of four conjugated aromatic olefine aldehydes in THF are 830nm,830 nm,790 nm and 790 nm,respectively.And the two-photon absorption cross section are 145 GM(FQQ),707 GM(KZQ),286 GM(JYQ)and 85 GM(T6),respectively.KZQ with large two-photon absorption cross section and obvious solvatochromic effects which provide a promising alternative as a polarity-sensitive two-photon fluorescent probe.Aided with the quantum chemical density functional theory calculations,the relationships between the structures and the properties were studied.We can get the following conclusions:the ways increasing the coplanar of molecular structure,increasing the effective molecular conjugation length and improving the strength of electronic donor/acceptor can obviously improve the intramolecular charge transfer,which significantly improve the two-photon absorption properties of conjugated compounds.