2,4-bis[4-(N,N-dibutylamino)phenyl]squaraine: X-ray crystal structure of a centrosymmetric dye and the second-order non-linear optical properties of its non-centrosymmetric Langmuir-Blodgett films

被引:49
作者
Ashwell, GJ
Bahra, GS
Brown, CR
Hamilton, DG
Kennard, CHL
Lynch, DE
机构
[1] DEF RES AGCY,SEVENOAKS TN14 7BP,KENT,ENGLAND
[2] UNIV QUEENSLAND,DEPT CHEM,BRISBANE,QLD 4072,AUSTRALIA
关键词
D O I
10.1039/jm9960600023
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Crystals of the title compound exist as a green monoclinic phase [space group P2(1)/c with a = 9.046(1), b - 19.615(2), c =9.055(1) Angstrom, beta=116.107(5)degrees, Z=2] and a purple triclinic phase. The chromophore is both planar and centrosymmetric and its dimensions indicate a tendency towards a quinoidal structure with extensive delocalisation. The Langmuir-Blodgett (LB) films show two types of aggregation with absorption maxima at 655 nm and 540 nm. These monolayers also exhibit strong second harmonic generation (SHG) comparable to the intensity from films of hemicyanine dyes. The anomalous non-linear optical properties are attributed to a serendipitous non-centrosymmetric packing arrangement within the films and to an intermolecular charge transfer contribution to the bulk second-order susceptibility.
引用
收藏
页码:23 / 26
页数:4
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