Nonplanar Donor–Acceptor Chiral Molecules with Large Second-Order Optical Nonlinearities: 1,1,4,4-Tetracyanobuta-1,3-diene Derivatives

Abstract

We have investigated the chiroptical, linear, and second-order nonlinear optical (NLO) properties of five 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) derivatives and elucidated structure-property relationships from the micromechanism. The experimental UV-vis absorption and circular dichroism (CD) spectra were well reproduced by our calculations at TDB3LYP/6-31+G* level of theory. The electron transition property and chiroptical origin have been assigned and analyzed. The results show that the studied compounds possess large molecular first hyperpolarizabilities, especially for compound 5 which has a value of 35 × 10(-30) esu, which is comparable with the measured value for highly π-delocalized phenyliminomethyl ferrocene complex and about 200 times larger than the average first hyperpolarizability of the organic urea molecule. Despite the nonplanarity of these compounds, efficient intramolecular charge transfer (CT) from electron donor to electron acceptor moieties was observed, which plays the key role in determining the NLO response. The intramolecular charge transfer cooperativity was also probed. In view of the first hyperpolarizability values, intrinsic noncentrosymmetric electronic structure, and high stability, the studied compounds have the possibility to be excellent second-order NLO materials.

The [2+2] Cycloaddition‐Retroelectrocyclization (CA‐RE) Click Reaction: Facile Access to Molecular and Polymeric Push‐Pull Chromophores

“…Thee lectronic circular dichromism (ECD) spectra for the pure enantiomers were calculated from the experimental spectra (Figure 6). [78] Another approach was the use of sterically congested p-systems.C 60 -TCBD conjugate 94 was prepared in 80 %yield by aCA-RE reaction between TCNE and the corresponding C 60 derivative at 20 8 8C. [76] However,i nt his case,t he CA reaction with TCNQ was not accelerated because of negligible ring strain.…”

“…[73a, 77c,d] TheE CD spectra showed Cotton effects associated with the ICT absorptions,t hereby indicating chiral induction from the optically active elements into the TCBD moieties.Atheoretical calculation suggested the potential use of the chiral TCBD derivatives in secondorder nonlinear optics. [78] Another approach was the use of sterically congested p-systems.C 60 -TCBD conjugate 94 was prepared in 80 %yield by aCA-RE reaction between TCNE and the corresponding C 60 derivative at 20 8 8C. [79] TheN MR spectra suggested hindered rotation around the central buta-1,3-diene CÀCsingle bond, thus rendering them axially chiral.…”

“…The ECD spectra showed Cotton effects associated with the ICT absorptions, thereby indicating chiral induction from the optically active elements into the TCBD moieties. A theoretical calculation suggested the potential use of the chiral TCBD derivatives in second‐order nonlinear optics . Another approach was the use of sterically congested π‐systems.…”

Die [2+2]‐Cycloadditions‐Retroelektrocyclisierungs(CA‐RE)‐Klick‐Reaktion: ein einfacher Zugang zu molekularen und polymeren Push‐pull‐Chromophoren

“…Die ECD‐Spektren zeigten Cotton‐Effekte, die mit den ICT‐Absorptionen assoziiert sind, was die chirale Induktion von den optisch aktiven Elementen in die TCBD‐Einheiten belegt. Theoretische Studien legten eine Verwendung chiraler TCBD‐Derivate in der nichtlinearen Optik zweiter Ordnung nahe . Ein anderer Ansatz war die Verwendung sterisch überladener π‐Systeme.…”

Tetrathiafulvalene derivatives as cation sensor: density functional theory investigation of the hyper-Rayleigh scattering first hyperpolarizability

“…And thus the oxidation leads to a signicant enhancement of the second-order NLO response. [18][19][20][21][22][23][24][25] Recently, an extended (ex) TTF derivative, containing a furanoquinonoid spacer and pyridine functional groups, has been prepared by Sallé group 26 (see Chart 2). Because of the presence of pyridine with chelating functional groups, such exTTF derivatives can coordinate with various metal ions.…”