Premium
Noncentrosymmetric Organic Solids with Very Strong Harmonic Generation Response
Author(s) -
Zhao Hong,
Li YongHua,
Wang XiSen,
Qu ZhiRong,
Wang LiZhong,
Xiong RenGen,
Abrahams Brendan F.,
Xue Ziling
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305425
Subject(s) - chemistry , piperidine , indole test , stereochemistry , asymmetric carbon , pyridine , space group , stereoselectivity , acentric factor , medicinal chemistry , crystallography , organic chemistry , alkyl , x ray crystallography , catalysis , physics , diffraction , optics
The molten reaction of 2‐naphthol, 4‐(aminomethyl)pyridine, and 4‐pyridinecarboxaldehyde at about 180 °C yields trans ‐2,3‐dihydro‐2,3‐di(4′‐pyridyl)benzo[ e ]indole ( 1 ) which possesses two chiral centers, rather than an expected Betti‐type reaction product with only one chiral carbon center. The same reactions, using 3‐pyridinecarboxaldehyde, 4‐cyanobenzaldehyde, or 3‐ cyanobenzaldehyde instead of 4‐pyridinecarboxaldehyde produce the related compounds trans ‐2,3‐dihydro‐2‐(4′‐pyridyl)‐3‐(3′′‐pyridyl)benzo[ e ]indole ( 2 ), trans ‐2,3‐dihydro‐2‐(4′‐pyridyl)‐3‐(4′′‐cyanophenyl)benzo[ e ]indole ( 3 ), and trans ‐2,3‐dihydro‐2‐(4′‐pyridyl)‐3‐(3′′‐cyanophenyl)benzo[ e ]indole ( 4 ), respectively. This reaction proceeds with a high degree of stereoselectivity with a trans / cis ratio of about 98:2 at elevated temperature. Compounds 1 , 2 , and 4 crystallize in a noncentrosymmetric space group ( Pca 2 1 , Pca 2 1 , and Cc ), while compound 3 has a chiral space group ( P 2 1 ). These successfully acentric packing arrangements are probably due to the molecule bearing both two chiral centers and potential hydrogen‐bonding groups. Furthermore, the reaction of racemic 6‐hydroxy‐2′‐methyl‐2‐naphthaleneacetic acid with ethyl‐2‐cyano‐1‐(4′‐pyridyl)acrylic acetate in the presence of piperidine gives 1‐pyridyl‐2‐ethoxycarbonyl‐3‐amino‐1 H ‐naphtho[2,1‐ b ]pyran‐2′‐methylacetic acid ( 5 ), which likewise crystallizes in a chiral space group. All of compounds are second harmonic generation (SHG) active, and have a very strong SHG response approximately about 8.0, 5.0, 12.0, 6.0, and 1.4 (for 1 – 5 compounds) times that of urea. Ferroelectric property measurements indicate that compounds 1 , 2 , 4 , and 5 may display ferroelectric behavior.