On the Convergence of the Physicochemical Properties of [n]Helicenes

Abstract

The results of a series of DFT and DFT−D calculations are reported with the aim to predict the physicochemical properties (equilibrium structures, stabilization energies, redox potentials, excitation and CD spectra, electronic conductivity, and elasticity) of elongating helical structures (i.e., [n]helicenes, n = 1−14). It was shown that many of them are converged at [14]helicene with an interpitch distance of R pitch = 3.75 Å, an incremental stabilization energy of ΔG n = 11 kJ mol-1 (thus suggesting the inherent destabilization of the growing helical structures), an S0−S1 energy difference to the estimated band gap of 2.60 eV, and redox potentials, corresponding to the reduction of [n]helicenes, of E 0 = −2.2 V. The elasticity was shown to decrease as a linear function of m (i.e., k ≈ m) with k = 0.01056 a.u. for [14]helicene. Moreover, the conductivity properties were discussed in terms of hole and excess electron densities. Possible implications of the calculated data in nanoscience are discussed.

Quantum‐chemistry based calibration of the alkali metal cation series (Li+Cs+) for large‐scale polarizable molecular mechanics/dynamics simulations

“…[60] Based on the present QC and SIBFA results, it is of particular interest to assess the affinities and discriminative powers of the ligands studied toward the group IA mono-cations.…”

Theoretical and Experimental Studies on Circular Dichroism of Carbo[n]helicenes

“…For the geometrical optimization of helicenes, we selected dispersion-corrected density functional theory (the second generation, DFT-D2) with B97-D functional and Ahlrichs' TZVP basis-set. 24 As demonstrated previously, 49,50 the structures of helicenes are best reproduced by the DFT-D method, in particular for higher homologues with overlapped benzene rings. The differences of the experimental versus DFT-D2 calculated C−C bonds and nonbonded distances are well less than 1% for most of the helicenes (excepting the error of ca.…”

“…The incremental stabilization energy (and the accompanying structural changes), as well as the other physicochemical properties, are known to converge at around [14]helicene. 49 To better describe the convergent behavior, we now introduce a new parameter "effective carbon volume (V c )," which is obtained by dividing the van der Waals molecular volume (V) by the number of total carbon atoms: V c = V/(4n + 2). We may further define a related parameter "effective volume increment (4V c )" upon each addition of a fused benzene ring.…”

Anodic Deposition of Enantiopure Hexahelicene Layers

“…It is obvious that there will be an extensive utilization of helicenes in various areas of materials science, especially in optoelectronics. However, to the best of our knowledge no studies have been performed investigating the basic electrochemical behavior of carbohelicenes, only theoretical papers have been published . The purpose of this work is to provide an electrochemical study of [ n ]helicenes.…”