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![(a) Calculated [B3LYP/6-31G(d)] orbital energies of the individual 1, 2, and a (red lines), the H-bonded complex 1a (black lines), and π-stacked clusters (green lines) observed in cocrystals 1a and 2a (full DFT optimization was done for individual molecules and the H-bonded complex, while only the position of the hydrogen atoms was optimized in crystallographic structure of the clusters). (b) Band structure calculations for infinite stacks of complexes: (left) 1a(||) denotes two stacks that are H-bonded to one another; (right) 1a(|) denotes a single π-stack (no Hbonding). (c) PESA measurements for 1, 2, 1a, and 2a.](profile/Nathan-Yee-3/publication/350918988/figure/fig2/AS:1015449617723393@1619113463591/a-Calculated-B3LYP-6-31Gd-orbital-energies-of-the-individual-1-2-and-a-red.png)
(a) Calculated [B3LYP/6-31G(d)] orbital energies of the individual 1, 2, and a (red lines), the H-bonded complex 1a (black lines), and π-stacked clusters (green lines) observed in cocrystals 1a and 2a (full DFT optimization was done for individual molecules and the H-bonded complex, while only the position of the hydrogen atoms was optimized in crystallographic structure of the clusters). (b) Band structure calculations for infinite stacks of complexes: (left) 1a(||) denotes two stacks that are H-bonded to one another; (right) 1a(|) denotes a single π-stack (no Hbonding). (c) PESA measurements for 1, 2, 1a, and 2a.
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![Figure 2. (a) Calculated [B3LYP/6-31G(d)] orbital energies of the...](profile/Nathan-Yee-3/publication/350918988/figure/fig2/AS:1015449617723393@1619113463591/a-Calculated-B3LYP-6-31Gd-orbital-energies-of-the-individual-1-2-and-a-red_Q320.jpg)
We report a comparative study of two structurally similar donor-acceptor complexes with (1a) and without (2a) H-bonding using X-ray crystallography, spectroscopic analysis, and density functional theory calculations. H-Bonding enhances the donor-acceptor interactions, as manifested in a narrower band gap and shorter π-stacking distance in 1a versus...
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... for 2a, predictably D/A interactions are far weaker for a (--) complex (S HL = 0.022) compared to a (=) complex (S HL = 0.175). Figure 2a shows the perturbation of the orbital energies due to H-bonding and π-stacking for 1a. The calculated ΔE offset between the individual 1 and a is 0.65 eV, but the HOMO− LUMO gap (HLG) of the complex (1a) in the gas phase is only 0.52 eV. ...
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... it was not possible to directly measure the orbital perturbation by H-bonding in solution by CV measurements 26,33 due to the extremely low solubility of 1a in noncompeting solvents. The photoelectron yield spectroscopy in air (PESA) of cocrystals showed that the ionization potentials (IP) of 1a and 2a are slightly (∼0.1 eV) higher compared to those of pure 1 and 2 (Figure 2c). ...
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... also calculated the one-dimensional (1D) band structure (Figure 2b) on infinite π-stacks of H-bonded pairs of 1a (1a(||)) and compared it to a single stack of 1a (1a(|)), which exhibits the same π-interactions but no H-bonding. The Hbonded stack 1a(||) exhibited a smaller band gap (1.46 eV) and higher band dispersion energies along the direction of π-stacking than 1a(|) (band gap 1.80 eV), suggesting that Hbonding strengthens the electronic interaction in the crystals. ...
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... the full charge transfer (ρ = 1) should result in an 80 cm −1 red shift of the ν(CO), and we estimated ρ = 0.5 for 1a and ρ = 0.2 in 2a ( Figure S5). While such donor−acceptor complexes with strong chargetransfer interactions often display a pronounced electron paramagnetic resonance (EPR) signal, 26 which was indeed originally observed for 1a and 2a, after a careful purification of the D/A components the freshly prepared complexes were found to be EPR silent ( Figure S2). This should not be surprising considering the band gap in these CT complexes is much larger than kT (0.026 eV). ...
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Citations
... Organic cocrystals are constructed from two or more different species through noncovalent intermolecular interactions, such as π-π interactions, halogen and hydrogen bonds, and charge transfer (CT) interactions [14], of which the CT interactions are the most prominent. CT interactions occur through charge transfer between the highest occupied molecular orbital (HOMO) of the electron-rich donor and the lowest unoccupied molecular orbital (LUMO) of the electron-deficient acceptor [15][16][17][18]. These interactions are facilitated when strong charge acceptors, such as fullerenes, are paired with suitable charge donors, such as porphyrins and ferrocene (Fc). ...
Organic cocrystals, which are assembled by noncovalent intermolecular interactions, have garnered intense interest due to their remarkable chemicophysical properties and practical applications. One notable feature, namely, the charge transfer (CT) interactions within the cocrystals, not only facilitates the formation of an ordered supramolecular network but also endows them with desirable semiconductor characteristics. Here, we present the intriguing ambipolar CT properties exhibited by nanosheets composed of single cocrystals of C70/ferrocene (C70/Fc). When heated to 150 °C, the initially ambipolar monoclinic C70/Fc nanosheet-based field-effect transistors (FETs) were transformed into n-type face-centered cubic (fcc) C70 nanosheet-based FETs owing to the elimination of Fc. This thermally induced alteration in the crystal structure was accompanied by an irreversible switching of the semiconducting behavior of the device; thus, the device transitions from ambipolar to unipolar. Importantly, the C70/Fc nanosheet-based FETs were also found to be much more thermally stable than the previously reported C60/Fc nanosheet-based FETs. Furthermore, we conducted visible/near-infrared diffuse reflectance and photoemission yield spectroscopies to investigate the crucial role played by Fc in modulating the CT characteristics. This study provides valuable insights into the overall functionality of these nanosheet structures.
... For instance, an unusual mixed stacked packing arrangement was documented for the system dithieno[3,2a :2 ,3 -c ]phenazine (DTPhz)-TCNQ (2:1 D:A ratio) accompanied by stronger electronic interactions orthogonal to stacks and originated from edge-to-edge d -D and A-A contacts [15] . When developing CT organic materials, crystal engineering is useful to explore the relation between crystal packing and charge carrier polarity and to analyze the supramolecular networks and intermolecular interactions as the channels for electron and hole transport [16][17][18][19][20][21] . ...
... A halogen bond is a noncovalent interaction [1,2] similar to the typical hydrogen bond [3][4][5][6]. In the case of a halogen bond, a halogen atom is shared both by a donor D and an acceptor A [7]. ...
Halogen bonds play an important role in many fields, such as biological systems, drug design and crystal engineering. In this work, the structural characteristics of the halogen bond between heteronuclear halogen XD (ClF, BrCl, IBr, ICl, BrF and IF) and benzene were studied using density functional theory. The structures of the complexes between heteronuclear halogen and benzene have Cs symmetry. The interaction energies of the complexes between heteronuclear halogen XD (ClF, BrCl, IBr, ICl, BrF and IF) and benzene range from −27.80 to −37.18 kJ/mol, increasing with the increases in the polarity between the atoms of X and D, and are proportional to the angles of a between the Z axis and the covalent bond of heteronuclear halogen. The electron density (ρ) and corresponding Laplacian (∇²ρ) values indicate that the interaction of the heteronuclear halogen and benzene is a typical long-range weak interaction similar to a hydrogen bond. Independent gradient model analysis suggests that the van der Waals is the main interaction between the complexes of heteronuclear halogen and benzene. Symmetry-adapted perturbation theory analysis suggests that the electrostatic interaction is the dominant part in the complexes of C6H6⋯ClF, C6H6⋯ICl, C6H6⋯BrF and C6H6⋯IF, and the dispersion interaction is the main part in the complexes of C6H6⋯BrCl, C6H6⋯IBr.
... Hybrid assemblies have become important in the field of selfassembly 17,18 . Binary or ternary hybrid assemblies have been prepared through molecular doping between organic semiconducting components 19 , involving noncovalent intermolecular interactions, such as van der Waals force, π-π stacking, and hydrogen bonding [20][21][22] . The forms of hybrid assemblies can be classified into hetero structures 23,24 and uniform- 25,26 or gradient-doped 27 structures. ...
We reveal the fundamental understanding of molecular doping of DNAs into organic semiconducting tris (8-hydroxyquinoline) aluminum (Alq3) crystals by varying types and numbers of purines and pyrimidines constituting DNA. Electrostatic, hydrogen bonding, and π-π stacking interactions between Alq3 and DNAs are the major factors affecting the molecular doping. Longer DNAs induce a higher degree of doping due to electrostatic interactions between phosphate backbone and Alq3. Among four bases, single thymine bases induce the multisite interactions of π-π stacking and hydrogen bonding with single Alq3, occurring within a probability of 4.37%. In contrast, single adenine bases form multisite interactions, within lower probability (1.93%), with two-neighboring Alq3. These multisite interactions facilitate the molecular doping into Alq3 particles compared to cytosines or guanines only forming π-π stacking. Thus, photoluminescence and optical waveguide phenomena of crystals were successfully tailored. This discovery should deepen our fundamental understanding of incorporating DNAs into organic semiconducting crystals.
In this study, a computational design of a new type of donor‐acceptor mixed stacking cocrystals is introduced. Our approach involves functionalizing trisilasumanene frameworks with electron‐donating groups (−CH3, −OH, −NH2) and electron‐withdrawing groups (−F, −CN), and then stacking donors and acceptors alternatively while connecting them either by sp³‐ and sp‐carbon chains. Using the B3LYP‐D3/6‐31+G(d) level of theory, we demonstrate that these covalently bonded cocrystals can overcome the issue of thermal and mechanical instabilities observed in the non‐covalently mixed stacking. Furthermore, modifying donor and acceptor groups can vary the bandgaps, approximated by the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gaps, from 1.50 to 3.50 eV. The results also predict the covalently bonded mixed stacking cocrystals having much larger conductance via Yoshizawa model. In addition, variations in bridge lengths were found to have a small effect on the HOMO‐LUMO gaps but allow for a new control parameter regarding the porosity of the materials. These results encourage experimental explorations.
Donor–acceptor (D-A) complexes, formed between two or more molecules held together by intermolecular forces, show interesting tunable properties and found applications in diverse fields, including semiconductors, catalysis, and sensors. In this study, we investigated the D-A complexes formed between perylene and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and their chalcogen (S, Se) and fluorine derivatives. It was observed that interaction energies due to complex formation increase while the HOMO–LUMO gaps decrease with chalcogen substitutions. A redshift in the electronic absorption spectra of the complexes was observed with chalcogen substitutions. The substitution of fluorine further enhanced these changes without altering the trend. These changes were found to be more for substitution with selenium compared to that of sulfur.
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Within the framework of the density functional theory approximation, quantum-chemical calculations were performed and data on the structure and properties of charge-transfer complexes of 9,10-phenanthrenquinone nitro derivatives with 9-methyl-9 H -carbazole were obtained. The formation energies of complexes, the average distances between the donor and acceptor planes, and the values of charge transfer from the donor to the acceptor have been calculated. The crystal and molecular structure of the complex of 2,4,7-trinitro-9,10-phenanthrenquinone with 9-methyl-9 H -carbazole (C14H5N3O8·C13H11N) was determined by X-ray diffraction analysis. In the crystal of the complex, the donor and acceptor molecules form parallel stacks of the {-D-A-D-A-}∞ mixed type with average interplanar distances of 3.29 and 3.35 Å. Each acceptor molecule forms intermolecular hydrogen bonds C-H···O 2.42-2.69 Å.
