Accessing New Charge-Transfer Complexes by Mechanochemistry: A Tetrathiafulvalene Chloranilic Acid Polymorph Containing Segregated Tetrathiafulvalene Stacks

Published

September 4, 2019

Author(s)

Jeffrey Jones, Vinh Ta Phuoc, Leire del Campo, Nestor E. Massa, Craig Brown, Silvina Pagola

Abstract

Two polymorphs of tetrathiafulvalene chloranilic acid (ITF-CAH₂) have been synthesized by mechanochemistry. The previously known "ionic" polymorph (form I), was prepared by liquid assisted grinding (LAG) using various highly polar solvents; as well as protic, but moderately polar solvents, such as alcohols of one to four carbon atoms. A new TTF-CAH₂ polymorph (from II), was obtained by LAG and slurry mechanochemistry using aprotic, low-polarity solvents, as well as nonpolar solvents and neat grinding. The crystal structure of the new TTF-CAH₂ polymorph was determined from the combined analysis of synchrotron X-ray powder diffraction and neutron powder diffraction data at room temperature. The material displays segregated stacks of TTF and CAH₂ molecules. FT-IR spectroscopy as a function of the temperature (10 K - 300 K) indicates TTF-CAH₂ form II is an electrical semiconductor with a small band gap of approximately equal} 0.146 eV for the "ionic" form I), and there is no indication of phase transitions in that temperature interval. The examination of the frequency regions wherein the absorption bands of TTF and TTF species occur, suggests TTF-CAH₂ form II is most likely a neural phase/

Citation

Crystal Growth & Design

Volume

19

Issue

9

Pub Type

Journals

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Keywords

tetrathiafulvalene, charge transfer salts, mechanochemistry, liquid assisted grinding, polymorphism, powder diffraction

Citation

Jones, J. , Phuoc, V. , del Campo, L. , Massa, N. , Brown, C. and Pagola, S. (2019), Accessing New Charge-Transfer Complexes by Mechanochemistry: A Tetrathiafulvalene Chloranilic Acid Polymorph Containing Segregated Tetrathiafulvalene Stacks, Crystal Growth & Design, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=927484 (Accessed November 1, 2025)