Studies On The Synthesis And Third-Order Optical Nonlinearities Of Novel Organic Chromophore Compounds

In the rapidly growing field of the organic functional materials,organic nonlinear optical (NLO) materials, especially of the third-order, areat the forefront of research activities. Organic third-order nonlinear opticalmaterials have numerous applications, such as optical fiber communication,optical computing, optical data storage, dynamic holography, laser medicaltreatment, laser weapon and so on.Three series of 41 novel organic chromophore compounds such asbisazo-9,10-anthracenedione, azo-1, 3, 4-thiadiazole and symmetricalbenzodifuranone were designed and synthesized in the dissertation. Theoff-resonant third-order optical nonlinearities of these novel compoundswere investigated.The influence of the molecular structures on thethird-order optical nonlinearities was studied.A series of 16 bisazo-9,10-anthracenedione compounds weresynthesized by bisdiazotizing of 2,6-diaminoanthraquinone or 1,5-diaminoanthraquinone with nitrosylsulfuric acid, then coupling withaniline, phenol or substituted phenol. The yields were 14.0～65.2%. 14 ofthem were new compounds.2-Amino-1,3,4-thiadiazole and 2-amino-5-methyl-1,3,4-thiadiazolewere prepared by dehydrating cyclization of formic acid or acetic acid withthiosemicarbazide. The yields were 63.4% and 64.3%, respectively.2-amino-5-(p-chlorophenyl)-1,3,4-thiadiazole were prepared bycondensation of p-chlorobenzaldehyde with thiosemicarbazide, thenoxidative cyclization with ferric chloride. The yield was 47.3%. A series of21 azo-1,3,4-thiadiazole compounds were synthesized by diazotizing of2-amino-5-alkyl-1,3,4-thiadiazole with nitrosylsulfuric acid, then couplingwith phenol, substituted phenol or naphthol. The yields were 19.6～58.8%.16 of them were new compounds.Mandelic acid or substituted mandelic acid were prepared by phasetransfer catalysis of benzaldehyde or substituted benzaldehyde withchloroform and sodium hydroxide. The yields were 86.8～90.1%. A seriesof 4 symmetrical benzodifuranone compounds were synthesized bydehydrating cyclization of mandelic acid or substituted mandelic acidwith hydroquinone, then oxidation with oxygen. The yields were 32.640.0%. 1 of them was the new compound.The structures of 41 desired compounds were confirmed by UV, IR,¹H NMR and elemental analysis. The synthetic methods and mechanisms of reaction were studied. The process parameters were evaluatedexperimentally.By using femtosecond laser, the third-order optical nonlinearities of41 desired compounds were measured with the geometry of DegenerateFour-wave Mixing (DFWM) technique. The third-order nonlinear opticalsusceptibilities x³, the nonlinear refractive indexes n₂, the second-orderhyperpolarizabilities of the moleculesγand the response timesÏ„werecalculated based on the principle of the third-order optical nonlinearity. Asfor bisazo-9,10-anthracenedione compounds, the x³ were 2.623.93×10^-13esu. The n₂ were 4.82～7.24×10^-12esu. Theγwere 2.573.84×10^-31esu. TheÏ„were 86～116 fs. As for azo-1, 3, 4-thiadiazolecompounds, the x³ were 3.31～4.29×10^-13esu. The n₂ were 6.087.89×10^-12esu. Theγwere 3.44～4.29×10^-31esu. TheÏ„were 69～112 fs.As for symmetrical benzodifuranone compounds, the x³ were 2.86～3.21×10^-13esu. The n₂ were 5.26～5.91×10^-12esu. Theγwere 2.923.42×10^-31esu. TheÏ„were 88～98 fs.The influence of the molecular structures on the third-order opticalnonlinearities was studied. The factors such as conjugate framework withsmall conjugation energy, central asymmetry, long conjugate chain,introduction of electron donors-acceptors, strong electron-donating orelectron-withdrawing abilities, long distance between electron donors andelectron acceptors, good coplanarity and so on lead to high third-order optical nonlinearities.