Projects per year
Abstract
We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracyanoquinodimethane (TCNQ) grown by physical vapor transport (PVT) in argon atmosphere. One of the polymorphs, named β, has stoichiometry 1:1 and adds to the three known structures with stoichiometry 1:1 (α), 2:1, and 3:1. Interestingly, below (280 ± 10) K the β structure undergoes a phase transition to what we refer to as the γ polymorph, with halving of the unit cell and reduction of symmetry from monoclinic to triclinic. Both new crystal structures present two alternating stacks with different intermolecular and intramolecular geometries. In stack S-I the perylene molecules show substantial deviations from planarity, with the angle between the naphthalene intramolecular moieties of 6.69°, and with the perylene and TCNQ molecular centroids shifted by 1.95 Å. In the second stack, S-II, the perylene is planar, and the centroids almost coincident. Structural investigations on bond length complemented by vibrational IR spectroscopy indicate that in the new polymorphs the degree of charge transfer, ρ, can be 0 or 0.12. The higher value of ionicity to be due to donor-acceptor pairs in the S-II, while molecules in S-I are closer to neutrality. Thus, the ionicity of the donor-acceptor pair depends on the stack and is comparable to that of the α polymorph which we redetermined as ρ = 0.15 ± 0.05.
Original language | English |
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Pages (from-to) | 2003-2009 |
Number of pages | 7 |
Journal | Crystal Growth and Design |
Volume | 18 |
Issue number | 4 |
DOIs | |
Publication status | Published - 4 Apr 2018 |
ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
Fingerprint
Dive into the research topics of 'New Polymorphs of Perylene-Tetracyanoquinodimethane Charge Transfer Cocrystals'. Together they form a unique fingerprint.Projects
- 2 Finished
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RCaH Impact Acceleration Fellowships and Workshops
Engineering and Physical Sciences Research Council
9/10/14 → 8/10/16
Project: Research council
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Applying Long-Lived Metastable States in Switchable Functionality via Kinetic Control of Molecular Assembly
Raithby, P., Burrows, A., Lewis, D., Marken, F., Parker, S., Walsh, A. & Wilson, C.
Engineering and Physical Sciences Research Council
1/11/12 → 30/04/18
Project: Research council
Equipment
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Dual source (Cu and Mo) Single Crystal Diffractometer (SuperNova)
Material and Chemical Characterisation (MC2)Facility/equipment: Equipment
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MC2- X-ray diffraction (XRD)
Material and Chemical Characterisation (MC2)Facility/equipment: Technology type