Simulation of Metal–Ligand Self-Assembly into Spherical Complex M₆L₈

Molecular dynamics simulations were performed to study the self-assembly of a spherical complex through metal–ligand coordination interactions. M₆L₈, a nanosphere with six palladium ions and eight pyridine-capped tridentate ligands, was selected as a target system. We successfully observed the spontaneous formation of spherical shaped M₆L₈ cages over the course of our simulations, starting from random initial placement of the metals and ligands. To simulate spontaneous coordination bond formations and breaks, the cationic dummy atom method was employed to model nonbonded metal–ligand interactions. A coarse-grained solvent model was used to fill the gap between the time scale of the supramolecular self-assembly and that accessible by common molecular dynamics simulation. The simulated formation process occurred in the distinct three-stage (assembly, evolution, fixation) process that is well correlated with the experimental results. We found that the difference of the lifetime (or the ligand exchange rate) between the smaller-sized incomplete clusters and the completed M₆L₈ nanospheres is crucially important in their supramolecular self-assembly

Coordination-Directed Self-Assembly of M₁₂L₂₄ Nanocage: Effects of Kinetic Trapping on the Assembly Process

We demonstrate the spontaneous formation of spherical complex M₁₂L₂₄, which is composed of 12 palladium ions and 24 bidentate ligands, by molecular dynamics simulations. In contrast to our previous study on the smaller M₆L₈ cage, we found that the larger M₁₂L₂₄ self-assembly process involves noticeable kinetic trapping at lower nuclearity complexes, <i>e.g.</i>, M₆L₁₂, M₈L₁₆, and M₉L₁₈. We also found that the kinetic trapping behaviors sensitively depend on the bend angle of ligands and the metal–ligand binding strength. Our results show that these kinetic effects, that have generally been neglected, are important factor in self-assembly structure determination of larger complexes as M₁₂L₂₄ in this study

Origin of the High Carrier Mobilities of Nonperipheral Octahexyl Substituted Phthalocyanine

The carrier transport properties of nonperipheral octahexyl substituted phthalocyanine H₂Pc­(C₆H₁₃)₈^np in its crystal and columnar (Col) liquid crystal (LC) phase were investigated using density functional theory (DFT) calculations in combination with molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. In the crystal phase, we found that the nonperipherally substituted chains of H₂Pc­(C₆H₁₃)₈^np, that interpenetrate adjacent phthalocyanines (Pcs), significantly alter the Pc-core stacking such that higher hole mobilities are observed for this system than for the nonsubstituted H₂Pc. This chain interpenetration was found to be inherited by the column stacking in the Col phase and hindered the Pc-core in-plane rotations between adjacent Pcs. This rotational hindrance further caused a nonuniform distribution of the adjacent dimer Pc-core in-plane orientation configurations. The relatively high carrier mobility in the Col phase in this system can be rationalized by the nonuniform distribution of the dimer configurations that give relatively high electronic coupling between the adjacent dimers. Our results show the remarkable effects of nonperipheral substitutions on the carrier transport properties in both the crystal and Col LC phases

Extended and Modulated Thienothiophenes for Thermally Durable and Solution-Processable Organic Semiconductors

Herein, we report the rational design of practical small-molecule organic semiconductors based on a π-electron skeleton of benzothieno­[3,2-<i>b</i>]­naphtho­[2,3-<i>b</i>]­thiophene (BTNT) whose layered herringbone (LHB) packing is intentionally modulated by the designated asymmetric substitutions with the phenyl group and normal alkyl chains. The thermal stability of the hybrid BTNT core is high enough, as it lies between those of dinaphtho­[2,3-<i>b</i>:2′,3′-<i>f</i>]­thieno­[3,2-<i>b</i>]­thiophene (DNTT) and benzothieno­[3,2-<i>b</i>]­benzothiophene (BTBT), although the solvent solubility for the substituted BTNT at ordinary 2,8-substituting positions by the alkyl chain and phenyl group remains extremely low. We show in the BTBT and BTNT derivatives that the tuning of the substituting position works to slightly bend the rodlike organic semiconductor molecules and thus to decrease the cohesive energy of the crystals with retention of the bilayer-type herringbone (<i>b</i>-LHB) packing for the asymmetric rodlike molecules. This modification eventually leads to an increase in solvent solubility, a decrease in phase transition temperature, and the suppression of liquid-crystalline phases at high temperatures. By using the substituting effect, we successfully achieve the organic semiconductors with modulated alkylated Ph-BTNT that exhibits both a sufficiently high solvent solubility and a sufficiently high thermal stability. The variation in the crystal packing also enhances the intermolecular transfer integrals along the T-shaped contacts within the intralayer herringbone packing. Spin coating of the material under ambient conditions affords high-performance bottom-gate, bottom-contact organic thin-film transistors, exhibiting high thermal durability in the device characteristics below 150 °C. The obtained devices also exhibit a higher mobility, a lower threshold voltage, and a smaller subthreshold swing, by initial thermal treatment at 140 °C, composed to those of the as-prepared films, because the thermal treatment stabilizes the <i>b</i>-LHB packing and thus suppresses the residual minority holes and shallow traps. These findings should be crucial in the design and development of organic semiconductor materials for practical printed electronics applications

Extended and Modulated Thienothiophenes for Thermally Durable and Solution-Processable Organic Semiconductors

Herein, we report the rational design of practical small-molecule organic semiconductors based on a π-electron skeleton of benzothieno­[3,2-<i>b</i>]­naphtho­[2,3-<i>b</i>]­thiophene (BTNT) whose layered herringbone (LHB) packing is intentionally modulated by the designated asymmetric substitutions with the phenyl group and normal alkyl chains. The thermal stability of the hybrid BTNT core is high enough, as it lies between those of dinaphtho­[2,3-<i>b</i>:2′,3′-<i>f</i>]­thieno­[3,2-<i>b</i>]­thiophene (DNTT) and benzothieno­[3,2-<i>b</i>]­benzothiophene (BTBT), although the solvent solubility for the substituted BTNT at ordinary 2,8-substituting positions by the alkyl chain and phenyl group remains extremely low. We show in the BTBT and BTNT derivatives that the tuning of the substituting position works to slightly bend the rodlike organic semiconductor molecules and thus to decrease the cohesive energy of the crystals with retention of the bilayer-type herringbone (<i>b</i>-LHB) packing for the asymmetric rodlike molecules. This modification eventually leads to an increase in solvent solubility, a decrease in phase transition temperature, and the suppression of liquid-crystalline phases at high temperatures. By using the substituting effect, we successfully achieve the organic semiconductors with modulated alkylated Ph-BTNT that exhibits both a sufficiently high solvent solubility and a sufficiently high thermal stability. The variation in the crystal packing also enhances the intermolecular transfer integrals along the T-shaped contacts within the intralayer herringbone packing. Spin coating of the material under ambient conditions affords high-performance bottom-gate, bottom-contact organic thin-film transistors, exhibiting high thermal durability in the device characteristics below 150 °C. The obtained devices also exhibit a higher mobility, a lower threshold voltage, and a smaller subthreshold swing, by initial thermal treatment at 140 °C, composed to those of the as-prepared films, because the thermal treatment stabilizes the <i>b</i>-LHB packing and thus suppresses the residual minority holes and shallow traps. These findings should be crucial in the design and development of organic semiconductor materials for practical printed electronics applications

Extended and Modulated Thienothiophenes for Thermally Durable and Solution-Processable Organic Semiconductors

Herein, we report the rational design of practical small-molecule organic semiconductors based on a π-electron skeleton of benzothieno­[3,2-<i>b</i>]­naphtho­[2,3-<i>b</i>]­thiophene (BTNT) whose layered herringbone (LHB) packing is intentionally modulated by the designated asymmetric substitutions with the phenyl group and normal alkyl chains. The thermal stability of the hybrid BTNT core is high enough, as it lies between those of dinaphtho­[2,3-<i>b</i>:2′,3′-<i>f</i>]­thieno­[3,2-<i>b</i>]­thiophene (DNTT) and benzothieno­[3,2-<i>b</i>]­benzothiophene (BTBT), although the solvent solubility for the substituted BTNT at ordinary 2,8-substituting positions by the alkyl chain and phenyl group remains extremely low. We show in the BTBT and BTNT derivatives that the tuning of the substituting position works to slightly bend the rodlike organic semiconductor molecules and thus to decrease the cohesive energy of the crystals with retention of the bilayer-type herringbone (<i>b</i>-LHB) packing for the asymmetric rodlike molecules. This modification eventually leads to an increase in solvent solubility, a decrease in phase transition temperature, and the suppression of liquid-crystalline phases at high temperatures. By using the substituting effect, we successfully achieve the organic semiconductors with modulated alkylated Ph-BTNT that exhibits both a sufficiently high solvent solubility and a sufficiently high thermal stability. The variation in the crystal packing also enhances the intermolecular transfer integrals along the T-shaped contacts within the intralayer herringbone packing. Spin coating of the material under ambient conditions affords high-performance bottom-gate, bottom-contact organic thin-film transistors, exhibiting high thermal durability in the device characteristics below 150 °C. The obtained devices also exhibit a higher mobility, a lower threshold voltage, and a smaller subthreshold swing, by initial thermal treatment at 140 °C, composed to those of the as-prepared films, because the thermal treatment stabilizes the <i>b</i>-LHB packing and thus suppresses the residual minority holes and shallow traps. These findings should be crucial in the design and development of organic semiconductor materials for practical printed electronics applications

Extended and Modulated Thienothiophenes for Thermally Durable and Solution-Processable Organic Semiconductors

Herein, we report the rational design of practical small-molecule organic semiconductors based on a π-electron skeleton of benzothieno­[3,2-<i>b</i>]­naphtho­[2,3-<i>b</i>]­thiophene (BTNT) whose layered herringbone (LHB) packing is intentionally modulated by the designated asymmetric substitutions with the phenyl group and normal alkyl chains. The thermal stability of the hybrid BTNT core is high enough, as it lies between those of dinaphtho­[2,3-<i>b</i>:2′,3′-<i>f</i>]­thieno­[3,2-<i>b</i>]­thiophene (DNTT) and benzothieno­[3,2-<i>b</i>]­benzothiophene (BTBT), although the solvent solubility for the substituted BTNT at ordinary 2,8-substituting positions by the alkyl chain and phenyl group remains extremely low. We show in the BTBT and BTNT derivatives that the tuning of the substituting position works to slightly bend the rodlike organic semiconductor molecules and thus to decrease the cohesive energy of the crystals with retention of the bilayer-type herringbone (<i>b</i>-LHB) packing for the asymmetric rodlike molecules. This modification eventually leads to an increase in solvent solubility, a decrease in phase transition temperature, and the suppression of liquid-crystalline phases at high temperatures. By using the substituting effect, we successfully achieve the organic semiconductors with modulated alkylated Ph-BTNT that exhibits both a sufficiently high solvent solubility and a sufficiently high thermal stability. The variation in the crystal packing also enhances the intermolecular transfer integrals along the T-shaped contacts within the intralayer herringbone packing. Spin coating of the material under ambient conditions affords high-performance bottom-gate, bottom-contact organic thin-film transistors, exhibiting high thermal durability in the device characteristics below 150 °C. The obtained devices also exhibit a higher mobility, a lower threshold voltage, and a smaller subthreshold swing, by initial thermal treatment at 140 °C, composed to those of the as-prepared films, because the thermal treatment stabilizes the <i>b</i>-LHB packing and thus suppresses the residual minority holes and shallow traps. These findings should be crucial in the design and development of organic semiconductor materials for practical printed electronics applications

Effects of Substituted Alkyl Chain Length on Solution-Processable Layered Organic Semiconductor Crystals

Effects of Substituted Alkyl Chain Length on Solution-Processable Layered Organic Semiconductor Crystal

Effects of Substituted Alkyl Chain Length on Solution-Processable Layered Organic Semiconductor Crystals

Effects of Substituted Alkyl Chain Length on Solution-Processable Layered Organic Semiconductor Crystal