Syntheses,Structures And Nonlinear Optic Properties Of C₃ And S₄ Symmetric Cyclized Indole Compounds

Cyclized polyindoles mainly refer to the triindoles and tetraindoles and three types of structure are involved in this paper, which are shown in Figure 1.In this thesis, a series of cyclized polyindoles were synthesized taking indolone compounds as precursors, many crystal structures were also attained and nonlinear properties were studied. The main results are as follows:1. SynthesisFour tetraindole compounds were synthesized (TTr, TTr-Me4, TTr-Me3, TTr-Me1), three of which (TTr-Me4, TTr-Me3, TTr-Me1) firstly were synthesized. A new asymmetry cyclized triindole (isoTr-Ph) was also prepared. Sixteen triindoles have been synthesized, and 14 of which are new compounds. The structures of several typical compounds are as follows:2. Crystal structuresNineteen new crystal structures have been determined, and 5 of which are structures of the indolin-2-one derivatives,11 of which are structures of symmetric triindole compounds,1 of which is structure of asymmetric cyclized triindole (isoTr-Ph3),2 of which are structures of symmetric cyclized tetraindoles (TTr and TTr-Me4).In the series of 5-X-N-phenyl-indolone crystals, the dipole moments gradually decrease from 2.834 D of 1-1 (the center of symmetry),1.951 D of 1-2 (the center of symmetry) to 1.930 D of 1-3 (non-centrosymmetric). The data of crystal structure and the dipole moments indicate’that relatively smaller dipole moment and larger non-electrostatic intermolecular interaction are the main reasons for the noncentrosymmetric structure of 1-3.The structural data of TTr and TTr-Me4 show that dihedral angle between two indole-planes is an important factor to form a non-centrosymmetric space group. The optimized structures and crystal structures furtherly illustrate if the hydrogen atoms were attached to the nitrogen atoms, the tetramers are easier to form a large dihedral angle. That provides a guideline for the synthesis of tetrameric compounds with non-centrosymmetric structures.The crystal structure data show that:triindole-core has a good planery and N-phenyltriindoles usually have two molecular configurations (u,u,u and u,u,d). The differences in C-C bonds connected the inner and out benzene rings or the C-N indicate the three isomeric triindole compounds taking different charge transfer modes.3. Linear and nonlinear optical propertiesAbsorption and fluorescent spectra showed tetramers have good transmission of light relative to the trimers and the asymmetric trimer (isoTr-Ph3) displays stronger fluorescence. These also show that the order of charge transfer ability in position isomeric triindoles is as following:2,7,12--substituted compounds> 3,8,13-substituted compounds> 5,10,15-substituted compounds.Tr-Ph3 and TTr display remarkable second order NLO properties, whose SHG intensity respectively is 5 and 11 times that of KDP.Although the molecular NLO coefficient of TTr is smaller than that of Tr-Ph3, it showed a stronger macroscopic second NLO effect, which stems from its saddle S4 symmetry and 14 space group symmetry. The NLO property of TTr gives us an inspiration:it could be a potential central core for the construction of macroscopic nonlinear optic material.The study of the two-photo properties shows that the 2,7,12-substitued triindole owns larger TPA cross section relative to its 3,8,13-substituted isomer.4. Main innovation pointsa. We firstly study the NLO properties of tetraindole compounds and report the structure of TTr. The saddle-like TTr is the first well-characterized pure octupolar organic compound which holds strict S4-symmetry (at both molecular and crystalline levels) and exhibits remarkable macroscopic second-NLO effect. The results provided new thoughts for designing macroscopic second order NLO materials.b. A pair of triindole isomers were synthesized and their optical properties were studied. The difference of the properties was ascribed to their different symmetry.c. Three large-scale symmetric triindole compounds with molecular weight of 1618.6 (each isomers) have been synthesized, whose two-photon properties also been studies. The results display that the two photon properties of 2,7,12-substituted compound are superior to its 3,8,13-substituted isomer. We also expanded the synthesis of 5,10,15-substituted isomer and its properties were also studied.