A ‘donor-free’ chromophore with a silicon-based acceptor group for second order nonlinear optics

• Published in: Inorganica Chimica Acta 2022-04, Vol.533, p.120745, Article 120745
• Main Authors: Orbelli Biroli, A., Tessore, F., Di Carlo, G., Righetto, S., Forni, A., Fantucci, P., Pizzotti, M.
• Format: Article
• Language: English
• Subjects: Chromophores; Nonlinear optics; Nonlinearity; Physical properties; Second-order nonlinear optics; Silanes; Siloxane; Terthiophene; ‘Donor-free’ NLO-phore
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2021.120745

[Display omitted] •Terthiophene with a pull Si-based group shows second-order NLO activity.•Si-based group impacts only on the nonlinear properties of the molecule.•Si-based pull unit ensures nonlinearity/transparency trade-off to terthiophene unit. In this paper we report an investigation on the linear and nonlinear properties of a non-classic push-pull molecule, based on the molecular design concept of a ‘donor-free’ chromophore. Herein a terthiophene unit acts both as a donor and a π-spacer group and a tris(trimethylsiloxy)silane substituent as an acceptor group. This latter can represent a model of a fragment of silica surface and it has been compared with a classic acceptor unit like the nitro group. The ‘donor-free’ chromophores have also been compared to more typical push-pull chromophores by replacing the terthiophene unit with the N,N-dimethylamino donor group. Despite the silane group only slightly impacts on the electronic and linear properties of the terthiophene, our results reveal high μβEFISH values for silane-functionalized derivatives producing a NLO activity stronger than that of the nitro substituted. Finally, the investigated ‘donor-free’ NLO-phore exhibits interesting physical properties relevant in term of nonlinearity/transparency trade-off, a highly desired requirement for second-order NLO materials.