Preparation and solid-state structural, electronic, and magnetic properties of the 5-cyano-1,3-benzene-bridged bis(1,2,3,5-dithiadiazolyl) and bis(1,2,3,5-diselenadiazolyl) [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se)

Haddon, Robert C.; Hicks, Robin G.; Kennepohl, Dietmar; Oakley, Richard T.; Palstra, Thomas; Schneemeyer, Lynn; Scott, Syrona R.; Waszczak, J. V.; Cordes, A. W.

doi:10.1021/cm00030a017

Cited by 29 publications

(22 citation statements)

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“…0.5 × 0.2 × 0.01 mm). The high resistance of 1 is not unexpected for such strongly Peierls-distorted structures and comparable with other pristine DTDA derivatives . On the other hand, this crystal shows clear photoconducting behavior upon light irradiation with an LED lamp.…”

Section: Resultssupporting

confidence: 72%

“…Such multicenter “pancake bonding” interactions between radicals are common in these systems and afford a singlet ground-state configuration . These dimers pack parallel to the crystallographic a -axis, affording a Peierls-distorted structure, similar to other DTDA radicals. , The interdimer S···S distances along the stacking direction are 4.131(2) and 4.230(2) Å. Although the DTDA stacking is significantly distorted the distance between the pyrenyl rings along the stacking direction is much closer to regular with the closest C···C contacts in the range of 3.280(7)–3.397(7) Å. Inter-stack contacts comprise electrostatically favorable S δ+ ···N δ− (3.189(5)–3.374(4) Å) and dispersion-driven S···S contacts (3.259(2)–3.280(2) Å) leading to the formation of a layer-like structure in the bc -plane (Figure b).…”

Section: Resultsmentioning

confidence: 97%

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Multifunctional Dithiadiazolyl Radicals: Fluorescence, Electroluminescence, and Photoconducting Behavior in Pyren-1′-yl-dithiadiazolyl

et al. 2018

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The pyren-1'-yl-functionalized dithiadiazolyl (DTDA) radical, CHCNSSN (1), is monomeric in solution and exhibits fluorescence in the deep-blue region of the visible spectrum (440 nm) upon excitation at 241 nm. The salt [1][GaCl] exhibits similar emission, reflecting the largely spectator nature of the radical in the fluorescence process, although the presence of the radical leads to a modest quenching of emission (Φ = 98% for 1 and 50% for 1) through enhancement of non-radiative decay processes. Time-dependent density functional theory studies on 1 coupled with the similar emission profiles of both 1 and 1 are consistent with the initial excitation being of predominantly pyrene π-π* character. Spectroscopic studies indicate stabilization of the excited state in polar media, with the fluorescence lifetime for 1 (τ = 5 ns) indicative of a short-lived excited state. Comparative studies between the energies of the frontier orbitals of pyren-1'-yl nitronyl nitroxide (2, which is not fluorescent) and 1 reveal that the energy mismatch and poor spatial overlap between the DTDA radical SOMO and the pyrene π manifold in 1 efficiently inhibit the non-radiative electron-electron exchange relaxation pathway previously described for 2. Solid-state films of both 1 and [1][GaCl] exhibit broad emission bands at 509 and 545 nm, respectively. Incorporation of 1 within a host matrix for OLED fabrication revealed electroluminescence, with CIE coordinates of (0.205, 0.280) corresponding to a sky-blue emission. The brightness of the device reached 1934 cd/m at an applied voltage of 16 V. The crystal structure of 1 reveals a distorted π-stacked motif with almost regular distances between the pyrene rings but alternating long-short contacts between DTDA radicals. Solid state measurements on a thin film of 1 reveal emission occurs at shorter wavelengths (375 nm) whereas conductivity measurements on a single crystal of 1 show a photoconducting response at longer wavelength excitation (455 nm).

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 97%

Multifunctional Dithiadiazolyl Radicals: Fluorescence, Electroluminescence, and Photoconducting Behavior in Pyren-1′-yl-dithiadiazolyl

et al. 2018

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“…[20] The polyradical character in the dimer aggregate 9 2 is illustrated in Figure14b and it arises from the partial occupancy of all [63a] (b) Dimero fatridentate triradical. [89] (c) Chaino fabidentated iradical [88] (d) Alternatingc hain of atridentate triradical. [90] Carbon atomsa re grey,nitrogens are purple, sulfurs are yellow,a nd hydrogensare blue.…”

Section: Double and Multiple Pancake Bondingmentioning

confidence: 99%

“…(b) Dimer of a tridentate triradical . (c) Chain of a bidentate diradical (d) Alternating chain of a tridentate triradical . Carbon atoms are grey, nitrogens are purple, sulfurs are yellow, and hydrogens are blue.…”

Section: Multiradicals Forming Two and Three Pancake Bondsmentioning

confidence: 99%

Pancake Bonding: An Unusual Pi‐Stacking Interaction

Kertész

2018

Chemistry A European J

213

227

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A category of parallel π-stacking interaction, termed pancake bonding, is surveyed. The main characteristics are: the interaction occurs among radicals with highly delocalized π-electrons in their singly occupied molecular orbitals (SOMOs), the contact distances in the π-stacking direction are shorter than the typical van der Waals distances, and the stabilization obtained by the bonding combination of the SOMO orbitals leads to direct atom-to-atom overlap with strong orientational preferences. These atypical intermolecular interactions contain a component of electron sharing between the radicals that can be viewed as covalent-like. Pancake bonded dimers characteristically have low-lying singlet and triplet states and show characteristic interlayer vibrational modes. Pancake bonded aggregates serve as molecular components in many conducting and other functional organic materials. The role of van der Waals (vdW) interactions in pancake bonded dimers, chains, and other aggregates is different from closed shell vdW aggregates: here the Pauli repulsions reduce the attractive dispersion interaction significantly. Fluxionality between π- and σ-bonded aggregates often occur in the context of pancake bonding. Both experimental and computational aspects are reviewed.

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“…Experimental estimates for the band gaps of 0.55 and 0.77 eV have been derived for the a -and P-phases, respectively. The unusual zigzag stacking found in the a-phase of the 1,3-derivatives prompted us to pursue molecular variants, including the furan-bridged and 5-cyanobenzene-bridged compounds 30 (46) and 31 (52). The former elected to crystallize in a totally different motif, one more reminiscent of the 1,4-derivatives 28, and while the latter adopts a zigzag stacking arrangement, the lateral intercolumnar contacts are f a r less effective than those observed in the parent 1,3-derivatives, and the observed conductivities are correspondingly lower.…”

mentioning

confidence: 99%

1993 ALCAN Award Lecture Chemical binding within and between inorganic rings; the design and synthesis of molecular conductors

Oakley¹

1993

Can. J. Chem.

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For a given number of skeletal atoms, the π-electron count of an unsaturated heterocycle can be modified by the incorporation of heteroatoms from different periodic groups. Sulfur and nitrogen are particularly effective in this regard, as their high electronegativity can stabilize electron-rich π-systems. A variety of aromatic, anti-aromatic, and radical systems can be prepared from admixtures of these elements. While the properties of these ring systems are interesting in their own right, the compounds are not without relevance in the design of new materials. The strong interannular interactions that are developed between these rings in the solid state makes them ideal candidates for the fabrication of molecular conductors. The origins and development of this area of research are the subjects of this presentation.

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Preparation and solid-state structural, electronic, and magnetic properties of the 5-cyano-1,3-benzene-bridged bis(1,2,3,5-dithiadiazolyl) and bis(1,2,3,5-diselenadiazolyl) [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se)

Cited by 29 publications

References 0 publications

Multifunctional Dithiadiazolyl Radicals: Fluorescence, Electroluminescence, and Photoconducting Behavior in Pyren-1′-yl-dithiadiazolyl

Multifunctional Dithiadiazolyl Radicals: Fluorescence, Electroluminescence, and Photoconducting Behavior in Pyren-1′-yl-dithiadiazolyl

Pancake Bonding: An Unusual Pi‐Stacking Interaction

1993 ALCAN Award Lecture Chemical binding within and between inorganic rings; the design and synthesis of molecular conductors

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