Tetrathiafulvalene Derivatives as NLO-phores:  Synthesis, Electrochemistry, Raman Spectroscopy, Theoretical Calculations, and NLO Properties of Novel TTF-Derived Donor-π-Acceptor Dyads

Abstract

Novel pi-conjugated donor-acceptor chromophores, based on the strong electron-donating tetrathiafulvalene moiety and different electron-withdrawing acceptors, exhibit large second-order optical nonlinearities. The effect of increasing the length of the polyenic spacer and the influence of the nature of the acceptor moiety on the NLO properties have been studied by using the electric field-induced second-harmonic generation (EFISH) technique as well as by semiempirical and ab initio theoretical calculations. A charge-transfer band has been observed in the absorption spectra of these D-pi-A compounds that undergoes an hypsochromic shift when increasing the number of vinylenic spacer units connecting both donor and acceptor moieties. The degree of the intramolecular charge transfer from the donor to the acceptor has also been analyzed by means of Raman spectroscopy.

Tetrathiafulvalene–Polychlorotriphenylmethyl Dyads: Influence of Bridge and Open‐Shell Characteristics on Linear and Nonlinear Optical Properties

“…As expected, the reduction process in 1a-c originates in the PTM unit and gives rise to a negatively charged closed-shell species. It is important to note that the β hyperpolarizabilities calculated for our radical D-π-A dyads surpass those reported for similar closed-shell TTF-A dyads, which are in the order of 200-500 × 10 -30 esu, [11,17,18] and for the unsubstituted PTM radical (362 × 10 -30 esu). [26] …”

“…[36,37] The improved synthesis of 3b was reported by González et al [11] and involves the reaction of the monolithio-TTF with N,N-dimethylacrolein to yield the transvinylogue amide according to the coupling constants in the 1 H-NMR spectra. Finally, the larger formyl-TTF vinylogue 3c was obtained by a Wittig reaction of 3b with the phosphorane 4 in a 40 % yield.…”

Quadratic nonlinear optical properties of novel pyridinium salts

“…[47][48][49][50][51] As far as we are aware, the only previously reported donor-acceptor polyenes in which the ICT bands blue-shift with chain extension are compounds containing tetrathiafulvalenyl (TTF) donor groups and various strong electron acceptors including 2,2-dicyanovinyl and 4-methylidene-1,3-diethyl-2-thiobarbituric acid. 52 The cyclic voltammetric data in Table 4 show that the Ru III/II E 1/2 values decrease by ca 50 mV on moving from n = 0 to 1, indicating that the Ru centres become more electron rich due to the mildly electron donating influence of the 4-vinyl groups. However, further extension of the conjugated bridge leads to only very small changes in the Ru III/II potentials.…”

Push–pull chromophores comprising benzothiazolium acceptor and thiophene auxiliary donor moieties: Synthesis, structure, linear and quadratic non-linear optical properties

“…On the other hand, E s -DE DA has been shown to display different behaviors as a function of n. In some instances, monotonous hypsochromic shift was observed [37][38][39][40]. As a border case between monotonous hypso-and bathochromic shifts, E s -DE DA can be nearly independent of the p-system length [22].…”