Charge transfer tuning by chemical substitution and uniaxial pressure in the organic complex tetramethoxypyrene–tetracyanoquinodimethane

  • In the search for novel organic charge transfer salts with variable degrees of charge transfer we have studied the effects of two modifications of the recently synthesized donor–acceptor system [tetramethoxypyrene (TMP)]–[tetracyanoquinodimethane (TCNQ)]. One is of chemical nature by substituting the acceptor TCNQ molecules by F4TCNQ molecules. The second consists in simulating the application of uniaxial pressure along the stacking axis of the system. In order to test the chemical substitution, we have grown single crystals of the TMP–F4TCNQ complex and analyzed its electronic structure via electronic transport measurements, ab initio density functional theory (DFT) calculations and UV/VIS/IR absorption spectroscopy. This system shows an almost ideal geometrical overlap of nearly planar molecules stacked alternately (mixed stack) and this arrangement is echoed by a semiconductor-like transport behavior with an increased conductivity along the stacking direction. This is in contrast to TMP–TCNQ which shows a less pronounced anisotropy and a smaller conductivity response. Our band structure calculations confirm the one-dimensional behavior of TMP–F4TCNQ with pronounced dispersion only along the stacking axis. Infrared measurements illustrating the C[triple bond, length as m-dash]N vibration frequency shift in F4TCNQ suggest however no improvement in the degree of charge transfer in TMP–F4TCNQ with respect to TMP–TCNQ. In both complexes about 0.1e is transferred from TMP to the acceptor. Concerning the pressure effect, our DFT calculations on the designed TMP–TCNQ and TMP–F4TCNQ structures under different pressure conditions show that application of uniaxial pressure along the stacking axis of TMP–TCNQ may be the route to follow in order to obtain a much more pronounced charge transfer.

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Author:Milan RudloffGND, Kai Ackermann, Michael HuthORCiDGND, Harald O. JeschkeORCiD, Milan TomićORCiDGND, Roser ValentíORCiDGND, Benedikt Wolfram, Martin BröringORCiDGND, Michael BolteORCiD, Dennis CherckaGND, Martin BaumgartenORCiDGND, Klaus MüllenORCiDGND
URN:urn:nbn:de:hebis:30:3-824143
DOI:https://doi.org/10.1039/C4CP04461D
ISSN:1463-9084
ISSN:1463-9076
ArXiv Id:http://arxiv.org/abs/1410.5552
Parent Title (English):Physical chemistry, chemical physics
Publisher:Royal Society of Chemistry
Place of publication:Cambridge
Document Type:Article
Language:English
Date of Publication (online):2014/12/22
Date of first Publication:2014/12/22
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2024/02/20
Volume:17.2015
Page Number:9
First Page:4118
Last Page:4126
HeBIS-PPN:520346823
Institutes:Physik / Physik
Biochemie, Chemie und Pharmazie / Biochemie und Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0