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The crystal packings of two charge-transfer complexes based on tetrathiafulvalene and substituted fluorenes—2,4,5,7-tetranitro-9-dicyanomethylenefluorene (in complex I) or 2,7-dicyano-4,5-dinitro-9-dicyanomethylenefluorene (in complex II)—are analyzed. Crystals of complex II involve a third component, namely, C[sub 6]H[sub 5]Cl solvate molecules. Crystals of both complexes are characterized by the formation of stacks composed of alternating donor and acceptor molecules and sheets in which the molecules are linked through different-type weak interactions. In structure II, chlorobenzene molecules occupy cavities that are formed in stacks in the vicinity of the tetrathiafulvalene molecules due to the larger difference in size of the donor and acceptor molecules in complex II as compared to that in complex I. The chlorobenzene molecules provide a close packing. These molecules are involved in the system of weak interactions to form the Cl···N and C-H···N secondary bonds with the CN groups of the acceptor molecules in the sheets. [ABSTRACT FROM AUTHOR]

A comprehensive investigation of the complementary H-bonding-mediated self-assembly between dipyrrolo[2,3-b:3',2'-e]pyridine (P2P) electron donors and naphthalenediimide/perylenediimide (NDI/PDI) acceptors is reported. The synthesis of parent P2P and several aryl-substituted derivatives is described, along with their optical, redox, and single-crystal packing characteristics. The dual functionality of heteroatoms in the P2P/NDI(PDI) assembly, which act as proton donors/acceptors and also contribute to π-conjugation, leads to H-bonding-induced perturbation of electronic levels. Concentration-dependent NMR and UV/Vis spectroscopic studies revealed a cooperative effect of H-bonding and π-π stacking interactions. This H-bonding-mediated co-assembly of donor (D) and acceptor (A) components leads to a new charge-transfer (CT) absorption that can be controlled throughout the visible range. The electronic interactions between D and A were further investigated by time-dependent DFT, which provided insights into the nature of the CT transition. Electropolymerization of difuryl-P2P afforded the first conjugated polymer incorporating H-bonding recognition units in its main chain., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the title complex, C(10)F(8) x C(6)H(4)S(4), planar centrosymmetric molecules of tetrathiafulvalene and octafluoronaphthalene, inclined to each other by 9.6 (1) degrees, form a mixed stack which does not exhibit charge transfer. Adjacent stacks pack in a herring-bone motif.

We report the use of the electron-donating 4,5-dipentyl-4'-methyl-TTF (TTF = tetrathiafulvalene) moiety in combination with the electron acceptor 11,11,12,12-tetracyanoanthraquinodimethane (TCNAQ) unit in the novel D-sigma-A diad molecules 11, 17, and 18. These compounds display a weak, broad, low-energy intramolecular charge-transfer (ICT) band in the UV-vis spectra (lambda(max) 430-450 nm). Cyclic voltammetric studies show two reversible one-electron oxidation processes for the R(3)TTF moiety, and a reversible two-electron reduction process for the TCNAQ moiety. The electron affinity of TCNAQ is significantly enhanced by the electron-withdrawing sulfonamide and sulfonic ester groups (compounds 17 and 18, respectively). Simultaneous electrochemistry and EPR (SEEPR) experiments show no significant intramolecular interaction between the R(3)TTF and TCNAQ moieties in compounds 11 and 18. X-ray crystallographic data are presented for 5, 11, and 20. The structure of 5 reveals hydrogen-bonded dimers. In molecule 11 the bond lengths and conformations of both donor and acceptor moieties are typical for neutral species. Compound 20 is an unusual calcium complex of TCNAQ derivative obtained by dicyanomethylation of anthraquinone-2-carboxylic acid.

[structure: see text] The synthesis, solution redox behavior, EPR, and intramolecular charge transfer properties of novel donor-acceptor diads of TTF-sigma-A type (TTF = substituted tetrathiafulvalene, sigma = saturated spacer, A = polynitrofluorene acceptor) are reported. The HOMO-LUMO gap for compound 6 is as small as 0.3 eV, and spectroelectrochemical experiments reveal its electrochromic behavior in the near-IR region.

Flash photolysis of bis[4.5-di(methylsulfanyl) 1,3-dithiol-2-ylidene]-9,10(-dihydroanthracene (1) in chloroform leads to formation of the transient radical cation species 1.+ which has a diagnostic broad absorption band at lambdamax approximately 650 nm. This band decays to half its original intensity over a period of about 80 micros. Species 1.+ has also been characterised by resonance Raman spectroscopy. In degassed solution 1.+ disproportionates to give the dication 1(2+), whereas in aerated solutions the photodegradation product is the 10-[4,5-di(methylsulfanyl) 1,3-dithiol-2-ylidene]anthracene-9(10 H)one (2). The dication 1(2+) has been characterised by a spectroelectrochemical study [lambdamax (CH2Cl2) = 377, 392, 419, 479 nm] and by an X-ray crystal structure of the salt 1(2-) (ClO4)2, which was obtained by electrocrystallisation. The planar anthracene and 1,3-dithiolium rings in the dication form a dihedral angle of 77.2 degrees; this conformation is strikingly different from the saddle-shaped structure of neutral 1 reported previously.