Synthesis and Two‐Photon Absorption Property Characterizations of Small Dendritic Chromophores Containing Functionalized Quinoxaliniod Heterocycles

Abstract

A series of star-shaped multi-polar chromophores (compounds 1-3) containing functionalized quinoxaline and quinoxalinoid (indenoquinoxaline and pyridopyrazine) units has been synthesized and characterized for their two-photon absorption (2PA) properties both in the femtosecond and the nanosecond time domain. Under our experimental conditions, these model fluorophores are found to manifest strong and wide-dispersed two-photon absorption in the near-infrared region. It is demonstrated that molecular structures with multi-branched π frameworks incorporating properly functionalized quinoxalinoid units would possess large molecular nonlinear absorptivities within the studied spectral range. Effective optical-power attenuation and stabilization behaviors in the nanosecond time domain of a selected representative dye molecule (i.e., compound 2) from this model compound set were also investigated and the results indicate that such structural motif could be a useful approach for the molecular design toward strong two-photon-absorbing material systems for quick-responsive and broadband optical-suppressing-related applications, particularly to confront long laser pulses.

High‐Performance Organic Dyes with Electron‐Deficient Quinoxalinoid Heterocycles for Dye‐Sensitized Solar Cells under One Sun and Indoor Light

“…The reaction of diketone 4 with variousq uinoxalinoid ortho-diaminesp roduced the respective products 5, 7,a nd 12. [50] The length of the pbridge can be elongated by insertinga ne xtra thiopheneo r phenylene unit through aS tille coupling reaction to produce the aldehydes 6, 8, 15,a nd 17 in 60-76 %. Finally,all aldehydes were subjected to Knoevenagel condensation reactions to yield the target compounds.M ore details of the synthesis can be found in the Supporting Information.…”

“…In our earlier report, we have shown that by the introductiono fq uinoxaline and quinoxalinoid functionalities, the absorption extinction coefficient may be doubled. [49,50] In this work, we continue this design by incorporating quinoxalinoid groups in six Y-shaped D-A-p-A systems( MM-1 to MM-6 in Figure 1) and apply them in DSSCs. The synthetic procedures are shown in Scheme 1, with all compounds having been confirmed by spectroscopic analyses.…”

Multi-photon properties of branched chromophores derived from indenoquinoxaline and oxadiazole heterocyclic units

“…Once these two diamines are in our hands, the same final coupling protocol can be conducted to prepare the targeted model chromophores 1 and 2 under an acid-catalyzed condition using a previously reported diketone ( i.e. compound 17) as the corresponding reactant 8 All the precursors and final compounds were carefully purified and their structures were confirmed by 1 H NMR, 13 C NMR and high resolution mass spectrometry.…”

“…These compounds were prepared by following the reported procedures. 8,13 The details for the synthesis of other key intermediates ( i.e. compounds 4–9 and 11–16) and targeted model compounds are presented below:…”

“… 7 For the past few years, we have been focused on searching new and useful heterocyclic π-units for the development of efficient 2PA-chromophores and have found that functionalized quinoxalinoids are beneficial moieties for the enhancement of molecular 2PA. 8–12 Among these investigations, some of the quinoxalinoid systems were even found to manifest strong 3PA in both nanosecond and femtosecond time domain 11,12 and such experience has lead us to consider that it may be worthy to explore the potentiality of using quinoxalinoids as the building units for 3PA materials. Following this line of concept, herein we would like to present our combined studies of degenerate 2PA and 3PA, up-converted emission and order of the absorption process (OAP) across a spectral range of 680–1500 nm based on a set of new multi-branched chromophores derived from 2,3,8-trifunctionalized indenoquinoxalines and oxadiazoles in the femtosecond time domain.…”