Linear and Third‐Order Nonlinear Optical Properties of Chalcogenopyrylium‐Terminated Heptamethine Dyes with Rigid, Bulky Substituents

Abstract

The aggregation of chalcogenopyrylium-terminated heptamethine dyes in high-chromophore density films can be substantially suppressed by attachment of rigid, bulky substituents that project out of the plane of the conjugated π-system of the dye, allowing the retention in the solid state of favorable linear and nonlinear optical properties relevant to all-optical signal processing (AOSP). Dye structures are systematically engineered with a range of out-of-plane substituents to investigate the impacts on the optical properties at 1550 nm in the solid state. Large magnitudes of the third-order susceptibility are obtained for solid films. Very high values of the two-photon figure-of-merit (2PA-FOM), an important parameter for AOSP, are observed in dilute solutions of seleno-and telluropyrylium dyes (in several cases >30). In the case of the telluropyrylium dye, the 2PA-FOM is not measureable for 50 wt% blends with polymers. Blends of the selenopyrylium examples exhibit 2PA-FOM values that, although decreased substantially relative to the solution values, in some cases meet the requirements for AOSP.

Zero-, one-, two- and three-dimensional supramolecular architectures sustained by Se…O chalcogen bonding: A crystallographic survey

“…The chemical diagrams of the mono-nuclear selenium(II) molecules, i.e. 107 – 123 [152] , [163] , [164] , [165] , [166] , [167] , [168] , [169] , [170] , [171] , [172] , [173] , [174] , [175] , [176] , [177] and 124 – 126 [159] , [178] , [179] , forming, respectively, helical and twisted supramolecular chains in their crystals based on Se … O chalcogen bonding contacts are shown in Fig. 10 .…”

“…The remaining helical structures feature cyclised selenium atoms. The five-membered rings in 113 [169] , 114 [170] and 115 [171] also feature C 2 donor sets as does the selenium atom in 116 [172] , Fig. 11 c, which is now incorporated within a six-membered ring.…”

The Appeal of Small Molecules for Practical Nonlinear Optics

“…Newly synthesized molecules, when studied in the solid‐state, have often been diluted into a polymer matrix, as a blended, or guest‐host system [2–5] . This is a relatively simple way to create a solid state material, but such a solution to the problem of going from molecule to materials intrinsically implies that any advantage that may come from a larger molecular nonlinearity would be frustrated by a low molecular number density.…”

Redox-switching of ternary Ni(ii) and Cu(ii) complexes: synthesis, experimental and theoretical studies along with second-order nonlinear optical properties

“…On the other hand , the first monomeric pyranyl-radicals have recently been isolated in the solid state, being prepared from redoxswitchable carbene/pyrylium hybrids featuring three stable rredox-states. 25 Pyrylium moieties act as chromophores and as such their non linear properties have been the subject of many studies, that are , for instance, relevant to all-optical signal processing, 26 or assessement of their potential as optical limiters 27 Interestingly, exchanging the labile pyridine ligand by its pyridylmethylenepyran…”