The Functionalization of Thermally Stable Third-Order NLO Chromophores

There is a need to functionalize NLO chromophore systems to incorporate them into polymeric matricies by covalent attachment. The functionalization of a series of NLO chromophores based on the N,N-diphenyl-N-[7-(2-benzothiazolyl)-9,9-diethyl-2- fluorenyl ]amine structure has been investigated. All the chromophores were synthesized from the intermediate chromophore N-phenyl-N-[4-(4-bromophenyl)phenyl ]-N-[7-(2- benzothiazolyl)-9,9-diethyl-2-fluorenyl ]amine which was prepared by a six-step process. Bromination of fluorene yielded 2,7-dibromo-fluorene which could be converted to 2,7- dibromo-9,9-diethylfluorene by alkylation with ethyl iodide in DMSO.Reaction of 2,7- dibromo-9,9-diethylfluorene with one equivalent of butyl lithium followed by reaction with DMF provides 2-bromo-7-formyl-9,9-diethylfluorene.Condensation of 2-bromo-7- formyl-9,9-diethylfluorene and 2-aminobenzenethiol in DMSO results in the formation of 7-(2-benzothiazolyl)-2-bromo-9,9-diethylfluorene. The palladium catalyzed reaction of 7- (2-benzothiazolyl)-2-bromo-9,9-diethylfluorene with aniline afforded N-phenyl-N-[7-(2- benzothiazolyl)-9,9-diethyl-2-fluorenyl ]amine which was subjected to a second palladium catalyzed reaction with 4,4 ’-dibromobiphenyl to yield N-phenyl-N-[4-(4- bromophenyl)phenyl ]-N-[7-(2-benzothiazolyl)-9,9-diethyl-2-fluorenyl ]amine. Further reactions have yielded a series of thermally stable NLO chromophores in which the functional group is located in the para position to the amine nitrogen