Quantum Chemical Studies on Electron-Accepting Overcrowded Ethylene with a Polarizable Skeleton

Abstract

We report the quantum chemical studies on the neutral and radical anion forms of an electron-accepting overcrowded ethylene (OCE1) featuring a highly polarizable skeleton based on the density functional theory (DFT) approach using the M06-2X hybrid functional. Calculated results indicate that OCE1 (bis{4H,8H-4-(dicyanomethylene)benzo[1,2-c:4,5-c']bis[1,2,5]thiadiazol-8-ylidene}) shows conformational behaviors and energetics similar to those of bianthrone (OCE2), a typical thermochromic overcrowded ethylene. Neutral OCE1 and its radical anion have antifolded (afOCE1) and twisted (tOCE1) isomers on their potential energy surfaces. The calculated isomerization barrier heights of OCE1 and its radical anion are considerably low, indicating that its conformation is susceptible to interactions with surrounding molecules. While two afOCE1 molecules can form a simple π-stacked dimer, tOCE1 tends to be converted to afOCE1 when the two tOCE1 molecules come close together, indicating the instability of tOCE1 in the homogeneous OCE1 solid state. The thermochromic behavior difference between OCE1 and OCE2 in solution is closely associated with the considerably small energy difference between the afOCE1 and the tOCE1 as compared with OCE2. The properties of OCE1 are also compared with other typical electron-accepting overcrowded ethylenes in terms of electronic structure, energetics, and conformational behaviors.

Electric-Field-Controllable Conductance Switching of an Overcrowded Ethylene Self-Assembled Monolayer

“…Furthermore, the conformational behavior of 1 is very susceptible to the redox state as well as external environments . In particular, in the anion radical state of 1 , the twisted form is largely stabilized, creating an energy difference of 0.43 eV from the anion radical of the folded form . With the theoretical results, we consider that when a high negative bias voltage is applied to the flat phase of folded 1 , an anion radical-like electronic structure might be generated at the Au–molecule contact to facilitate the folded-to-twisted conformational change.…”

“…The energy difference between the LUMO and the Fermi level of Au for the twisted conformer ( E – E F = 0.10 eV) is much smaller than that for the folded one ( E – E F = 0.35 eV) (Figure S5), supporting the hypothesis that the former passes a larger tunneling current than the latter. For comparison, the calculated activation energies for the twisted-to-folded and folded-to-twisted conformational isomerizations of 1 in the gas phase were 0.76 and 0.59 eV, respectively . Thus, the activation energies of the conformational isomerization in both directions of 1 adsorbed on Au(111) are estimated to decrease to half of those in the gas phase.…”

“…A recent theoretical study on overcrowded ethylene 1 revealed that the energy difference between its folded and twisted conformers is as low as 0.13 eV in vacuum . Furthermore, the conformational behavior of 1 is very susceptible to the redox state as well as external environments .…”

“…A recent theoretical study on overcrowded ethylene 1 revealed that the energy difference between its folded and twisted conformers is as low as 0.13 eV in vacuum . Furthermore, the conformational behavior of 1 is very susceptible to the redox state as well as external environments . In particular, in the anion radical state of 1 , the twisted form is largely stabilized, creating an energy difference of 0.43 eV from the anion radical of the folded form .…”

Bayesian Estimation of Equivalent Circuit Parameters of Photovoltaic Cell with S‐Shaped Current–Voltage Characteristic

“…For example, the change of R s plays a key role in previous studies. [22] Table 2 summarizes the means and standard deviations obtained by Bayesian estimation for each parameter. The ideality factors of the diodes n 1 and n 2 are estimated within a sufficiently narrow range, that is, we have successfully determined the ideality factor of each diode from the measured data, which was difficult to do with the least-squares method.…”