Crystal growth and characterization of solvated organic charge-transfer complexes built on TTF and 9-dicyanomethylenefluorene derivatives

Abstract

A series of 1:1 organic complexes has been synthesized by reaction between TTF (tetrathiafulvalene) and three 9dicyanomethylenefluorene derivatives: 9-dicyanomethylene-2,7-dinitrofluorene (DDF), 9-dicyanomethylene-2,4,7trinitrofluorene (DTF) and 9-dicyanomethylene-4,5,7-10 trinitrofluorene-2-carboxylic acid (DC2TF). The following formulas were determined by X-ray diffraction and elemental analysis for these complexes: (TTF-DDF).CH 3 CN (1), (TTF-DDF).0.5PhCl( 2), (TTF-DTF).CH 3 CN (3), (TTF-DTF).0.5Me 2 CO (4) and (TTF-DC2TF).H 2 O (5). A sixth15 solvated compound was also obtained, with a different stoichiometry, (TTF) 3 (DC2TF) 2 .2CH 3 CN (6). The degree of charge transfer in 1-5 was estimated by IR and Raman spectroscopy. Lattice solvent, acetonitrile, chlorobenzene, or acetone, is slowly released from crystals of complexes 1-4, 20 inducing a significant decrease of the charge transfer over time. These crystals converge over months towards materials close to the neutral state. Hydrate 5 is air-stable, and displays a degree of charge transfer, = . ૡ ‫܍‬ ି , close to the range of semi-conducting or metallic organic complexes. Finally, 25 compound 6 is an ionic crystal, and is thus expected to be an insulating material. 65 ߜ = 2ሺΔߥ ߥ ⁄ ሻ 1 − ሺߥ ଵ ߥ ⁄ ሻ ଶ where ߥ and ߥ ଵ are the vibrational frequencies for neutral (ߜ = 85 0) and ionized (ߜ = 1) component, respectively, and ∆ߥ =A series of solvated donor-acceptor organic complexes was shown to slowly release lattice solvent, while the degree of charge transfer decreases steadily. This behavior is not observed in the case of a hydrate.

Tuning the Organogelating and Spectroscopic Properties of a C3‐Symmetric Pyrene‐Based Gelator through Charge Transfer

“…0.31 e − per molecule), [77–79] and for (DCTNF) 3 /( C 3 Pyr ) 1 (2227 cm −1 , Table 2, Figures S8 and S9c) with a lower DCT (ca. 0.07 e − /molecule) [80] respectively to (TCNQ) 3 /( C 3 Pyr ) 1 , which is in line with the π‐accepting character of each acceptor unit (vide supra).…”

Charge transfer in mixed and segregated stacks of tetrathiafulvalene, tetrathianaphthalene and naphthalene diimide: a structural, spectroscopic and computational study

“…Solid state Raman spectroscopy is a powerful technique for probing the redox states of electroactive species and has been widely employed in the characterisation of r in CT complexes. [55][56][57][58][59] For example, work by Matsuzaki and colleagues reported on the Raman frequencies of TTF in its neutral and radical cation states, as well as in CT complexes such as TTF-TCNQ and the TTFhalide series of materials where TTF is partially charged. 55 A clear dependence of the Raman frequencies of TTF as a function of its charge was elucidated.…”

The Role of Secondary Interactions in Centrosymmetry of Charge Transfer Complexes with Nitrated Acceptors

“…Literature examples of mixed-stack cocrystal systems formed by DDF derivatives, including 2-(2,4,7-trinitro-9 H -fluoren-9-ylidene)­malononitrile (CSD code: ICINEN) and 2-(2,4,5,7-tetranitro-9 H -fluoren-9-ylidene)­malononitrile (CSD code: GONBAM), show close interchain interactions contributed by NO 2 groups forming parallel sheets between the DA stacks. − Due to the conformational flexibility of nitro groups, most nitroaromatic acceptors create molecular chains guided by C–H···O interactions. − However, DDF:DHDMP I does not display any NO 2 close contacts from DDF; instead, the closest interactions are the parallel-displaced π–π interactions between DDF and DHDMP (Figure a). Additionally, DDF:DHDMP I shows that these close interactions are not consistent throughout the stacking arrangement.…”