Ultraviolet-visible and infrared spectroscopic study of Langmuir-Blogett films of a charge transfer complex based on 2-dodecyl-7,7,8,8-tetracyanoquinodimethane and copper

摘要

Electronic absorption spectra of Langmuir films of 2-dodecyl-7,7,8,8-tetracyano-quinodimethane (C(12)TCNQ) mixed with CuI, prepared on pure water, indicated charge-transfer (CT) reactions in these films. The films could be deposited onto solid substrates as Langmuir-Blogett (LB) films and optically characterized. The CT degree of C(12)TCNQ in these LB films was estimated at -1 from the red shifts of C=C and C=N stretching modes. The polarized infrared spectra and x-ray diffraction patterns suggested a bimolecular-layer structure for the present films, in contrast to the alkyldicyanoquinonediimine-CuI mixed LB films, for which a monomolecular-layer structure was previously proposed. This distinct difference reflects the effect of the number of cyano groups in acceptor molecules on the structure of LB films based on this kind of transition metal-organic acceptor complexes. (C) 2002 American Institute of Physics. [References: 23]